Co-reporter:Lijun Gao;Ying Wang;Haobo Li;Qihao Li;Na Ta;Qiang Fu;Xinhe Bao
Chemical Science (2010-Present) 2017 vol. 8(Issue 8) pp:5728-5734
Publication Date(Web):2017/07/24
DOI:10.1039/C7SC01615H
The development of low-cost and high-performance electrocatalysts remains a challenge for the hydrogen oxidation reaction (HOR) in alkaline membrane fuel cells. Here, we have reported novel Ni@h-BN core–shell nanocatalysts consisting of nickel nanoparticles encapsulated in few-layer h-BN shells. The Ni@h-BN catalysts exhibit an improved HOR performance compared with the bare Ni nanoparticles. In situ characterization experiments and density functional theory calculations indicate that the interactions of the O, H, and OH species with the Ni surface under the h-BN shell are weakened, which helps to maintain the active metallic Ni phase both in air and in the electrolyte and strengthen the HOR processes occurring at the h-BN/Ni interfaces. These results suggest a new route for designing high-performance non-noble metal electrocatalysts with encapsulating two-dimensional material overlayers for HOR reactions.
Co-reporter:Huan Ren, Ying Wang, Xun Tang, Juntao Lu, ... Lin Zhuang
Journal of Energy Chemistry 2017 Volume 26, Issue 4(Volume 26, Issue 4) pp:
Publication Date(Web):1 July 2017
DOI:10.1016/j.jechem.2017.05.001
An environmentally friendly precursor, adenosine, has been used as a dual source of C and N to synthesize nitrogen-doped carbon catalyst with/without Fe. A hydrothermal carbonization method has been used and water is the carbonization media. The morphology of samples with/without Fe component has been compared by HRTEM, and the result shows that Fe can promote the graphitization of carbon. Further electro-chemical test shows that the oxygen reduction reaction (ORR) catalytic activity of Fe-containing sample (CFeN) is much higher than that of the Fe-free sample (CN). Additionally, the intermediates of CFeN formed during each synthetic procedure have been thoroughly characterized by multiple methods, and the function of each procedure has been discussed. The CFeN sample exhibits high electro-catalytic stability and superior electro-catalytic activity toward ORR in alkaline media, with its half-wave potential 20 mV lower than that of commercial Pt/C (40 wt%). It is further incorporated into alkaline polymer electrolyte fuel cell (APEFC) as the cathode material and led to a power density of 100 mW/cm2.Adenosine has been used to synthesize highly active Fe/N/C catalyst. The ORR catalytic activity of the catalyst is superior not only on RDE test but also on alkaline polymer electrolyte membrane fuel cell application.Download high-res image (127KB)Download full-size image
Co-reporter:Ping Song, Heather M. Barkholtz, Ying Wang, Weilin Xu, ... Lin Zhuang
Science Bulletin 2017 Volume 62, Issue 23(Volume 62, Issue 23) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.scib.2017.10.020
We demonstrate a new and simple method for pre-treating the carbon material and iron precursor to prepare oxygen reduction reaction (ORR) catalysts, which can produce super-high performance and stability in alkaline solution, with high performance in acid solution. This strategy using cheap materials is simply controllable. Moreover, it has achieved smaller uniform nanoparticles to exhibit high stability, and the synergetic effect of Fe and N offered much higher performance in ORR than commercial Pt/C, with high maximum power density in alkaline and acid fuel cell test. So it can make this kind of catalysts be the most promising alternatives of Pt-based catalysts with best performance/price.A new type of low-cost FeNx/C catalyst for oxygen reduction reaction (ORR) is prepared based on pretreatment of carbon and iron with a simple acid refluxing step. The catalyst shows high ORR performance in both alkaline and acid media, making it one of the most promising alternatives to Pt-based ones for ORR in fuel cells.Download high-res image (56KB)Download full-size image
Co-reporter:Zilong Liu, Zhenglei Yin, Zhaomin Wan, Li Xiao, Hualong Ma, Juntao Lu, Lin Zhuang
Electrochemistry Communications 2016 Volume 67() pp:69-72
Publication Date(Web):June 2016
DOI:10.1016/j.elecom.2016.04.002
•An 8% efficient photoanode is here implemented based on chlorine evolution reaction in saturated NaCl solution.•Photocurrent rises at 0.6 V (vs. RHE), and the RuO2/TiO2/Si photoanode produces Cl2 exclusively without detectable O2.•Photoelectrochemical tests are combined with on-line mass spectroscopy for product detection.The photoelectrochemical water splitting is an artificial photosynthetic approach that could provide a sustainable supply of clean energy, however, the sluggish kinetics of the oxygen evolution reaction (OER) has been a bottleneck to the solar-to-chemical conversion. Here we report an implementation of 8% efficient photoanode based on the photoelectrolysis of saturated NaCl solution. Replacing the OER with the chlorine evolution reaction (CER) has transformed both the thermodynamic basis and the kinetic process of the photoelectrolysis, more chemical energy can be produced with much less driving force. The RuO2/TiO2/n-Si photoanode exhibits a high rate of photoelectrochemical conversion (35 mA/cm2 at equilibrium potential), which steadily and exclusively produces Cl2 without detectable O2.
Co-reporter:Gongwei Wang, Jianxin Guan, Li Xiao, Bing Huang, Nian Wu, Juntao Lu, Lin Zhuang
Nano Energy 2016 Volume 29() pp:268-274
Publication Date(Web):November 2016
DOI:10.1016/j.nanoen.2016.04.005
•A Pd skin with 2–3 atomic layers on AuCu intermetallic nanoparticles (PdSAuCu iNPs) is controllably fabricated.•The PdSAuCu iNPs exhibit excellent electrocatalytic activity towards the oxygen reduction reaction (ORR) in alkaline media, far better and more stable than the commercial Pt/C catalyst.•The AuCu intermetallic substrate causes a shrink strain in Pd lattice of the skin, which reduces the oxygen affinity of Pd and thus enhances the catalytic activity.Core–shell structured catalysts have been widely investigated for fuel cell applications in the recent decade. The skin-substrate interaction has provided a well tunable basis for the design of better catalysts. Herein, we report an implementation of fabricating a Pd skin onto the AuCu intermetallic nanoparticles (denoted as PdSAuCu iNPs), and its exceptionally high activity towards the oxygen reduction reaction (ORR) in alkaline media. The structure of PdSAuCu iNPs was well characterized through combining a variety of techniques, including high-angle annular dark field scanning transmission electron microscopy (HAADF-STEM) and energy dispersive X-ray (EDX) line scanning analysis, synchrotron X-ray diffraction patterns (SXRD), X-ray photoelectron spectra (XPS), X-ray fluorescence analysis (XRF), and electrochemical measurements. The AuCu intermetallic core was identified to be fully wrapped by a Pd skin with 2–3 atomic layers. The catalytic activity of PdSAuCu iNPs towards the ORR in alkaline is more than 8-times higher in surface-specific activity (SA), and 20-times higher in mass-specific activity (MA), than that of the commercial Pt/C catalyst, and remains reasonably stable in thousands cycles of potential sweep. Such an outstanding performance is attributed to the reduction in the oxygen affinity of the Pd skin caused by a proper and stable shrink in Pd lattice induced by the AuCu intermetallic substrate.
Co-reporter:Bing Huang;Li Xiao;Juntao Lu
Angewandte Chemie International Edition 2016 Volume 55( Issue 21) pp:6239-6243
Publication Date(Web):
DOI:10.1002/anie.201601824
Abstract
A new property is reported that accurately quantifies and spatially describes the chemical reactivity of solid surfaces. The core idea is to create a reactivity weight function peaking at the Fermi level, thereby determining a weighted summation of the density of states of a solid surface. When such a weight function is defined as the derivative of the Fermi–Dirac distribution function at a certain non-zero temperature, the resulting property is the finite-temperature chemical softness, termed Fermi softness (SF), which turns out to be an accurate descriptor of the surface reactivity. The spatial image of SF maps the reactive domain of a heterogeneous surface and even portrays morphological details of the reactive sites. SF analyses reveal that the reactive zones on a Pt3Y(111) surface are the platinum sites rather than the seemingly active yttrium sites, and the reactivity of the S-dimer edge of MoS2 is spatially anisotropic. Our finding is of fundamental and technological significance to heterogeneous catalysis and industrial processes demanding rational design of solid catalysts.
Co-reporter:Bing Huang;Li Xiao;Juntao Lu
Angewandte Chemie 2016 Volume 128( Issue 21) pp:6347-6351
Publication Date(Web):
DOI:10.1002/ange.201601824
Abstract
A new property is reported that accurately quantifies and spatially describes the chemical reactivity of solid surfaces. The core idea is to create a reactivity weight function peaking at the Fermi level, thereby determining a weighted summation of the density of states of a solid surface. When such a weight function is defined as the derivative of the Fermi–Dirac distribution function at a certain non-zero temperature, the resulting property is the finite-temperature chemical softness, termed Fermi softness (SF), which turns out to be an accurate descriptor of the surface reactivity. The spatial image of SF maps the reactive domain of a heterogeneous surface and even portrays morphological details of the reactive sites. SF analyses reveal that the reactive zones on a Pt3Y(111) surface are the platinum sites rather than the seemingly active yttrium sites, and the reactivity of the S-dimer edge of MoS2 is spatially anisotropic. Our finding is of fundamental and technological significance to heterogeneous catalysis and industrial processes demanding rational design of solid catalysts.
Co-reporter:Ying Wang, Gongwei Wang, Guangwei Li, Bing Huang, Jing Pan, Qiong Liu, Juanjuan Han, Li Xiao, Juntao Lu and Lin Zhuang
Energy & Environmental Science 2015 vol. 8(Issue 1) pp:177-181
Publication Date(Web):02 Oct 2014
DOI:10.1039/C4EE02564D
A current challenge to alkaline polymer electrolyte fuel cells (APEFCs) is the unexpectedly sluggish kinetics of the hydrogen oxidation reaction (HOR). A recently proposed resolution is to enhance the oxophilicity of the catalyst, so as to remove the Had intermediate through the reaction with OHad, but this approach is questioned by other researchers. Here we report a clear and convincing test on this problem. By using PtRu/C as the HOR catalyst for the APEFC, the peak power density is boosted to 1.0 W cm−2, in comparison to 0.6 W cm−2 when using Pt/C as the anode catalyst. Such a remarkable improvement, however, can hardly be explained as an oxophilic effect, because, as monitored by CO stripping, reactive hydroxyl species can generate on certain sites of the Pt surface at more negative potentials than on the PtRu surface in KOH solution. Rather, the incorporation of Ru has posed an electronic effect on weakening the Pt–Had interaction, as revealed by the voltammetric behavior and from density-functional calculations, which thus benefits the oxidative desorption of Had, the rate determining step of HOR in alkaline media. These findings further our fundamental understanding of the HOR catalysis, and cast new light on the exploration of better catalysts for APEFCs.
Co-reporter:Juanjuan Han, Qiong Liu, Xueqi Li, Jing Pan, Ling Wei, Ying Wu, Hanqing Peng, Ying Wang, Guangwei Li, Chen Chen, Li Xiao, Juntao Lu, and Lin Zhuang
ACS Applied Materials & Interfaces 2015 Volume 7(Issue 4) pp:2809
Publication Date(Web):January 16, 2015
DOI:10.1021/am508009z
Aromatic ether-based alkaline polymer electrolytes (APEs) are one of the most popular types of APEs being used in fuel cells. However, recent studies have demonstrated that upon being grafted by proximal cations some polar groups in the backbone of such APEs can be attacked by OH–, leading to backbone degradation in an alkaline environment. To resolve this issue, we performed a systematic study on six APEs. We first replaced the polysulfone (PS) backbone with polyphenylsulfone (PPSU) and polyphenylether (PPO), whose molecular structures contain fewer polar groups. Although improved stability was seen after this change, cation-induced degradation was still obvious. Thus, our second move was to replace the ordinary quaternary ammonia (QA) cation, which had been closely attached to the polymer backbone, with a pendant-type QA (pQA), which was linked to the backbone through a long side chain. After a stability test in a 1 mol/L KOH solution at 80 °C for 30 days, all pQA-type APEs (pQAPS, pQAPPSU, and pQAPPO) exhibited as low as 8 wt % weight loss, which is close to the level of the bare backbone (5 wt %) and remarkably lower than those of the QA-type APEs (QAPS, QAPPSU, and QAPPO), whose weight losses under the same conditions were >30%. The pQA-type APEs also possessed clear microphase segregation morphology, which led to ionic conductivities that were higher, and water uptakes and degrees of membrane swelling that were lower, than those of the QA-type APEs. These observations unambiguously indicate that designing pendant-type cations is an effective approach to increasing the chemical stability of aromatic ether-based APEs.Keywords: alkaline polymer electrolyte; backbone degradation; chemical stability; fuel cell application; pendant-type quaternary ammonia cation; phase separation
Co-reporter:Chi Chen, Xiao-Dong Yang, Zhi-You Zhou, Yu-Jiao Lai, Muhammad Rauf, Ying Wang, Jing Pan, Lin Zhuang, Qiang Wang, Yu-Cheng Wang, Na Tian, Xin-Sheng Zhang and Shi-Gang Sun
Chemical Communications 2015 vol. 51(Issue 96) pp:17092-17095
Publication Date(Web):29 Sep 2015
DOI:10.1039/C5CC06562C
N,S,Fe-doped graphene nanosheets were directly synthesized from aminothiazole, a precursor molecule that contains N and S atoms, through Fe catalysis under heat treatment. The graphene nanosheets exhibited high electrocatalytic activity toward oxygen reduction reaction in both acidic and alkaline media during rotating disk electrode half-cell and fuel cell tests.
Co-reporter:Jing Pan, Chen Chen, Yao Li, Lei Wang, Lisheng Tan, Guangwei Li, Xun Tang, Li Xiao, Juntao Lu and Lin Zhuang
Energy & Environmental Science 2014 vol. 7(Issue 1) pp:354-360
Publication Date(Web):17 Oct 2013
DOI:10.1039/C3EE43275K
Alkaline polymer electrolytes (APEs) are an emerging material that enables the use of nonprecious-metal catalysts in electrochemical energy technology, such as fuel cell and water electrolysis. Yet the OH− conduction in APE has been of much lower efficiency than the H+ conduction in its acidic counterpart (typically Nafion), leading to a large dissipative loss in energy conversion applications. Here we report that, by properly constructing ion-aggregating structures in APE, a OH− conducting highway can be built, such that the OH− conduction in APE becomes as efficient as the H+ conduction in Nafion (greater than 0.1 S cm−1 at 80 °C under moderate ion-exchange capacity 1.0 mmol g−1). The optimal approach to constructing such an ionic highway is first screened computationally using coarse-grained molecular dynamics (CGMD) simulations, and then implemented experimentally based on a quaternary ammonia polysulfone (QAPS) model system. The resulting ordered structure of ion assembly has been unambiguously revealed by both the theoretically calculated structure factor and experimental results of TEM and SAXS. These findings have not only furthered our understanding about the ionic channels in APE, but also provided a general strategy for the rational design of polymer electrolytes.
Co-reporter:Gongwei Wang ; Bing Huang ; Li Xiao ; Zhandong Ren ; Hao Chen ; Deli Wang ; Héctor D. Abruña ; Juntao Lu
Journal of the American Chemical Society 2014 Volume 136(Issue 27) pp:9643-9649
Publication Date(Web):June 17, 2014
DOI:10.1021/ja503315s
The dependence on Pt catalysts has been a major issue of proton-exchange membrane (PEM) fuel cells. Strategies to maximize the Pt utilization in catalysts include two main approaches: to put Pt atoms only at the catalyst surface and to further enhance the surface-specific catalytic activity (SA) of Pt. Thus far there has been no practical design that combines these two features into one single catalyst. Here we report a combined computational and experimental study on the design and implementation of Pt-skin catalysts with significantly improved SA toward the oxygen reduction reaction (ORR). Through screening, using density functional theory (DFT) calculations, a Pt-skin structure on AuCu(111) substrate, consisting of 1.5 monolayers of Pt, is found to have an appropriately weakened oxygen affinity, in comparison to that on Pt(111), which would be ideal for ORR catalysis. Such a structure is then realized by substituting the Cu atoms in three surface layers of AuCu intermetallic nanoparticles (AuCu iNPs) with Pt. The resulting Pt-skinned catalyst (denoted as PtSAuCu iNPs) has been characterized in depth using synchrotron XRD, XPS, HRTEM, and HAADF-STEM/EDX, such that the Pt-skin structure is unambiguously identified. The thickness of the Pt skin was determined to be less than two atomic layers. Finally the catalytic activity of PtSAuCu iNPs toward the ORR was measured via rotating disk electrode (RDE) voltammetry through which it was established that the SA was more than 2 times that of a commercial Pt/C catalyst. Taking into account the ultralow Pt loading in PtSAuCu iNPs, the mass-specific catalytic activity (MA) was determined to be 0.56 A/mgPt@0.9 V, a value that is well beyond the DOE 2017 target for ORR catalysts (0.44 A/mgPt@0.9 V). These findings provide a strategic design and a realizable approach to high-performance and Pt-efficient catalysts for fuel cells.
Co-reporter:Zilong Liu, Kexin Wang, Li Xiao, Xuejiao Chen, Xiaodi Ren, Juntao Lu and Lin Zhuang
RSC Advances 2014 vol. 4(Issue 71) pp:37701-37704
Publication Date(Web):05 Aug 2014
DOI:10.1039/C4RA05733C
Hematite has been a popular photoanode for photoelectrochemical water splitting; however, its performance varies widely in the literature. In-depth understanding of the structure–performance relationship of hematite photoanode is still lacking. Here, we report a finding that without the use of co-catalysts or any alteration in crystal structure, the performance of hematite photoanode can be markedly improved by properly enlarging the space among α-Fe2O3 nanocrystalline, i.e., by increasing the pore size in the electrode. Such a finding indicates that in addition to the known catalytic and crystal effects, the internal structure of the hematite electrode is also a very sensitive factor to PEC efficiency.
Co-reporter:Chen Chen, Kangjie Lu, Xuefeng Li, Jinfeng Dong, Juntao Lu and Lin Zhuang
RSC Advances 2014 vol. 4(Issue 13) pp:6545-6555
Publication Date(Web):03 Jan 2014
DOI:10.1039/C3RA47275B
The fluid–fluid spontaneous capillary displacement is a model related to many important natural processes and industrial applications, such as groundwater remediation and oil recovery. To study the displacement process in microscale where experimental observations are hard to perform, computational simulations are an adequate approach. In the present work, we report a many-body dissipative particle dynamics (MDPD) simulation study on the fluid–fluid spontaneous capillary displacement. System parameters such as the wetting property of both fluids, the miscibility between them, and the capillary radius, can be adjusted independently and separately in the simulation, thus their influences on the spontaneous capillary displacement process can be observed individually. Based on our previous study of MDPD simulations on fluid imbibition, we are able to monitor the motion of the fluid–fluid interface in this spontaneous capillary displacement simulation accurately. Combined with the new method for three-phase contact angle calculation proposed in the present study, the displacement curve obtained is in good accordance with the theoretical description even in the very beginning of the spontaneous capillary displacement motion. Our findings provide microscopic information about the fluid–fluid spontaneous displacement process, and lay a basis for further studies on more complex systems.
Co-reporter:Xuejiao Chen ; Huan Ren ; Wei Peng ; Huiming Zhang ; Juntao Lu
The Journal of Physical Chemistry C 2014 Volume 118(Issue 36) pp:20791-20798
Publication Date(Web):August 18, 2014
DOI:10.1021/jp5061792
Among the challenges in molecular electrocatalysis is how to increase the catalyst loading on electrode surface so as to enhance the catalytic efficiency. We found that, through electrochemical polymerization of the 1,10-phenanthroline ligand (phen), the [Co(tpy)(phen)Cl]Cl catalyst (mCo) can be fabricated on the electrode surface with a very high loading. Differential electrochemical mass spectroscopy (DEMS) measurements showed that, on such a poly[Co(tpy)(phen)Cl]Cl electrode (pCo), the onset potential of the hydrogen evolution reaction (HER) is only 370 mV in a buffer solution of pH = 3, with the TOF being 10 s–1 and a TON of ca. 2.2 × 106 at overpotential less than 0.5 V, which is among the best molecular catalysts thus found for HER. Characterized by X-ray photoelectron spectroscopy (XPS), the active site in pCo was found to be in molecular state, rather than in metallic state. By polymerizing mCo onto a Cu2O photocathode, a molecular catalyst/p-type semiconductor photocathode was realized for the HER, which can work stably at 0 V (vs RHE) under illumination, with the HER photocurrent increased by 40%, in comparison to that on bare Cu2O photocathode.
Co-reporter:Jing Pan, Yao Li, Juanjuan Han, Guangwei Li, Lisheng Tan, Chen Chen, Juntao Lu and Lin Zhuang
Energy & Environmental Science 2013 vol. 6(Issue 10) pp:2912-2915
Publication Date(Web):23 Jul 2013
DOI:10.1039/C3EE41968A
Alkaline polymer electrolytes (APEs) are a new class of polyelectrolytes enabling the use of nonprecious metal catalysts in electrochemical devices, such as fuel cells and water electrolyzers. However, the current development of APEs is facing a severe difficulty, the conductivity–stability dilemma. Specifically, to acquire high ionic conductivity, the polymer backbone has to be grafted with enough cationic functional groups, typically quaternary ammonium (–NR3+), but such a modification in structure has damaged the chemical inertness of the polymer backbone and induced degradation in an alkaline environment. Here we demonstrate a strategy for disentangling such a dilemma. To alleviate the damage to the polymer backbone, we reduce the grafting degree (GD) of functional groups, but design two cations on each grafted functional group so as to retain sufficient ion concentration. Such a seemingly simple change in structure has brought a notable effect in performance: not only can both high ionic conductivity and much improved chemical stability be achieved, but also the intermolecular interaction between polymer chains has thus been enhanced, rendering the resulting APE membrane much stronger in mechanical strength and highly anti-swelling in water even at 80 °C.
Co-reporter:Bing Huang, Lin Zhuang, Li Xiao and Juntao Lu
Chemical Science 2013 vol. 4(Issue 2) pp:606-611
Publication Date(Web):25 Oct 2012
DOI:10.1039/C2SC21232C
The chemical bond is a still mysterious force that glues atoms together to form molecules and materials. Unlike conventional electromagnetic interactions, the chemical bond cannot be quantified in strength by any known property of the participating species. Here we report an extraordinary principle that the bond energy (EAB), a quantitative measure of the bond strength, can be decoupled into two contributions of the participating reactants, with each described by a characteristic complex quantity (): . Such a principle has been verified by more than 300 typical bonds, including covalent bonds in molecules and adsorption bonds on metal surfaces; and it can be applied in a wide range of chemical research. Particularly, the characteristic complex quantity, termed chemical amplitude in the present work, can serve as an accurate and unified descriptor for the chemical reactivity of both molecules and metal surfaces, which greatly benefits the study of heterogeneous catalysis. Our finding has not only enabled a direct and practical evaluation of the bond energy, but also revealed a new aspect of the chemical interaction.
Co-reporter:Cuixia Yang, Bing Huang, Li Xiao, Zhandong Ren, Zilong Liu, Juntao Lu and Lin Zhuang
Chemical Communications 2013 vol. 49(Issue 94) pp:11023-11025
Publication Date(Web):11 Sep 2013
DOI:10.1039/C3CC46522E
Combined computational and experimental studies reveal a noble, non-d-band effect on Ag activation and electrocatalysis: upon coating Ag onto the even more inert Au surface, the catalytic activity toward the oxygen reduction reaction in alkaline media can be improved by about half an order of magnitude in comparison to the usual Ag surface.
Co-reporter:Xuejiao Chen, Xiaodi Ren, Zilong Liu, Lin Zhuang, Juntao Lu
Electrochemistry Communications 2013 Volume 27() pp:148-151
Publication Date(Web):February 2013
DOI:10.1016/j.elecom.2012.11.026
Most implementations of the photoanode for water splitting are based on semiconductors and inorganic catalysts, wherein the surface defect and the grain boundary of inorganic materials have been a major barrier hindering the charge transfer between the light absorber and the catalyst. Here we report a new type of photoanode for water splitting, featuring the combination of α-Fe2O3 and molecular Ru catalysts. Fabricated by self-assembly, the semiconductor/molecule interface is not only efficient for the light-induced charge separation but also highly catalytic toward the water oxidation reaction. This work opens a new avenue for improving the efficiency of the solar-to-fuel conversion.Graphical abstractHighlights► A new type of photoanode combining hematite and Ru molecular catalysts ► The semiconductor/molecule heterojunction facilitates the light-induced charge separation. ► The catalytic activity of the molecular catalyst toward the water oxidation reaction is tunable.
Co-reporter:Yubao Sun, Juntao Lu, Lin Zhuang
Journal of Electroanalytical Chemistry 2013 Volume 688() pp:189-195
Publication Date(Web):1 January 2013
DOI:10.1016/j.jelechem.2012.08.007
Titanium supported Pt catalyst (Pt/Ti) is successfully prepared by a simultaneous etching-displacement method, in which the surface oxides on Ti particles is pre-etched by a home-made etching solution followed by a Pt deposition process via a displacement reaction of Pt precursor with newly exposed surface titanium atoms in the presence of etching reagents. In comparison with two carbon supported Pt (Pt/C) samples with different Pt particle sizes, the cyclic voltammetry of Pt/Ti shows a positive shift in the peak potential for surface oxide reduction, indicating a weakened oxygen adsorption. In accordance, the catalytic activity of Pt/Ti toward the oxygen reduction reaction (ORR) is remarkably improved in terms of both the surface activity and the mass activity. Pt/Ti also shows an improved catalytic activity toward the oxidative removal of adsorbed CO as revealed by an about 0.1 V negative shift in oxidation peak potential and a 0.3 V negative shift in the oxidation onset potential.Highlights► Titanium supported Pt catalyst (Pt/Ti) prepared by an etching-displacement method. ► Weaker oxygen adsorption on Pt/Ti compared to Pt. ► The catalytic activity of Pt/Ti toward the ORR is remarkably high.
Co-reporter:Chen Chen, Kangjie Lu, Lin Zhuang, Xuefeng Li, Jinfeng Dong, and Juntao Lu
Langmuir 2013 Volume 29(Issue 10) pp:3269-3273
Publication Date(Web):February 17, 2013
DOI:10.1021/la304598h
Traditionally, the meniscus bottom is taken as the fluid front when tracking the fluid motion in capillary, but in simulation studies, the thus-calculated motion curve deviates notably from the modified Lucas–Washburn equation. Here, we report that, by considering a volume equivalent of the meniscus part, the motion of the equivalent front agrees very well with the theoretical prediction; furthermore, such an effective fluid front can be directly represented by a specific position of the meniscus, which is independent of the capillary radius. These findings provide an accurate and practical method for describing the motion of the fluid front in capillary.
Co-reporter:Li Xiao, Shuai Zhang, Jing Pan, Cuixia Yang, Minglong He, Lin Zhuang and Juntao Lu
Energy & Environmental Science 2012 vol. 5(Issue 7) pp:7869-7871
Publication Date(Web):11 May 2012
DOI:10.1039/C2EE22146B
A new type of water electrolysis is implemented using an alkaline polymer electrolyte (APE) and non-precious metal catalysts, and working only with pure water. The membrane–electrode assembly (MEA) is fabricated by sandwiching a self-crosslinking quaternary ammonia polysulfone (xQAPS) membrane between a Ni–Fe anode and a Ni–Mo cathode, both impregnated with xQAPS ionomer. Such an initial prototype of APE water electrolysis has exhibited decent performance comparable to that of the well-developed alkaline water electrolyzer.
Co-reporter:Jing Pan, Chen Chen, Lin Zhuang, and Juntao Lu
Accounts of Chemical Research 2012 Volume 45(Issue 3) pp:473
Publication Date(Web):November 10, 2011
DOI:10.1021/ar200201x
Although the polymer electrolyte fuel cell (PEFC) is a superior power source for electric vehicles, the high cost of this technology has served as the primary barrier to the large-scale commercialization. Over the last decade, researchers have pursued lower-cost next-generation materials for fuel cells, and alkaline polymer electrolytes (APEs) have emerged as an enabling material for platinum-free fuel cells.To fulfill the requirements of fuel cell applications, the APE must be as conductive and stable as its acidic counterpart, such as Nafion. This benchmark has proved challenging for APEs because the conductivity of OH– is intrinsically lower than that of H+, and the stability of the cationic functional group in APEs, typically quaternary ammonia (−NR3+), is usually lower than that of the sulfonic functional group (−SO3–) in acidic polymer electrolytes.To improve the ionic conductivity, APEs are often designed to be of high ion-exchange capacity (IEC). This modification has caused unfavorable changes in the materials: these high IEC APEs absorb excessive amounts of water, leading to significant swelling and a decline in mechanical strength of the membrane. Cross-linking the polymer chains does not completely solve the problem because stable ionomer solutions would not be available for PEFC assembly.In this Account, we report our recent progress in the development of advanced APEs, which are highly resistant to swelling and show conductivities comparable with Nafion at typical temperatures for fuel-cell operation. We have proposed two strategies for improving the performance of APEs: self-cross-linking and self-aggregating designs. The self-cross-linking design builds on conventional cross-linking methods and works for APEs with high IEC. The self-aggregating design improves the effective mobility of OH– and boosts the ionic conductivity of APEs with low IEC.For APEs with high IEC, cross-linking is necessary to restrict the swelling of the membrane. In our self-cross-linking design, a short-range cross-linker, tertiary amino groups, is grafted onto the quaternary ammonia polysulfone (QAPS) so that the cross-linking process can only occur during membrane casting. Thus, we obtain both the stable ionomer solution and the cross-linked membrane. The self-cross-linked QAPS (xQAPS) possesses a tight-binding structure and is highly resistant to swelling: even at 80 °C, the membrane swells by less than 3%.For APEs with low IEC, the key is to design efficient OH– conducting channels. In our self-aggregating design, long alkyl side-chains are attached to the QAPS. Based on both the transmission electron microscopy (TEM) observations and the molecular dynamics (MD) simulations, these added hydrophobic groups effectively drive the microscopic phase separation of the hydrophilic and hydrophobic domains and produce enlarged and aggregated ionic channels. The ionic conductivity of the self-aggregated QAPS (aQAPS) is three-fold higher than that of the conventional QAPS and is comparable to that of Nafion at elevated temperatures (e.g., greater than 0.1 S/cm at 80 °C).
Co-reporter:Gongwei Wang, Li Xiao, Bing Huang, Zhandong Ren, Xun Tang, Lin Zhuang and Juntao Lu
Journal of Materials Chemistry A 2012 vol. 22(Issue 31) pp:15769-15774
Publication Date(Web):11 Jun 2012
DOI:10.1039/C2JM32264A
In the present work, a one-pot method is employed to synthesize AuCu intermetallic nanoparticles (AuCu iNPs) supported on high-surface-area carbon. To avoid blocking the active sites of the AuCu iNPs for the subsequent study of electrocatalysis, no surfactant has been applied in the entire synthetic process. After refluxing in glycerol at 300 °C, the ordered structure is formed in the carbon-supported AuCu iNPs, whose superlattice is evidently demonstrated by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Such intermetallic nanoparticles show very interesting electrochemical behaviors which have hitherto not been reported in the literature. In addition to the peculiar cyclic voltammetry (CV), the AuCu iNPs exhibit a superior catalytic activity, in comparison to that of ordinary Au nanoparticles, toward the oxygen reduction reaction (ORR) in alkaline media. The alteration in the surface electronic properties of Au, caused by the incorporation of Cu, has also been studied by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.
Co-reporter:Dr. Qiang Wang; Chuan-Sin Cha; Juntao Lu; Lin Zhuang
ChemPhysChem 2012 Volume 13( Issue 2) pp:514-519
Publication Date(Web):
DOI:10.1002/cphc.201100784
Abstract
It is commonly recognized that the ionic conductivity of pure water is very poor because of very low ionic concentrations. However, this work indicates that pure water in charged porous matrixes can be moderately conductive because of the ions in the electric double layer established at the solid/water interfaces. The ionic conductivity of pure water in a charged matrix changes with the electrode potential of the matrix and is influenced by the structural parameters. Both experimental measurements and theoretical calculations reveal that ionic conductivity may reach the order of 10−3 S cm−1 in commonly accessible potential region in a porous matrix made of gold nanoparticles. These results would help to understand and optimize the electrode processes in electrochemical devices without deliberately added electrolytes, such as polymer electrolyte membrane fuel cells.
Co-reporter:Chen Chen, Lin Zhuang, Xuefeng Li, Jinfeng Dong, and Juntao Lu
Langmuir 2012 Volume 28(Issue 2) pp:1330-1336
Publication Date(Web):December 1, 2011
DOI:10.1021/la204207s
The forced water–oil displacement in capillary is a model that has important applications such as the groundwater remediation and the oil recovery. Whereas it is difficult for experimental studies to observe the displacement process in a capillary at nanoscale, the computational simulation is a unique approach in this regard. In the present work, the many-body dissipative particle dynamics (MDPD) method is employed to simulate the process of water–oil displacement in capillary with external force applied by a piston. As the property of all interfaces involved in this system can be manipulated independently, the dynamic displacement process is studied systematically under various conditions of distinct wettability of water in capillary and miscibility between water and oil as well as of different external forces. By analyzing the dependence of the starting force on the properties of water/capillary and water/oil interfaces, we find that there exist two different modes of the water–oil displacement. In the case of stronger water–oil interaction, the water particles cannot displace those oil particles sticking to the capillary wall, leaving a low oil recovery efficiency. To minimize the residual oil content in capillary, enhancing the wettability of water and reducing the external force will be beneficial. This simulation study provides microscopic insights into the water–oil displacement process in capillary and guiding information for relevant applications.
Co-reporter:Li Xiao, Bing Huang, Lin Zhuang and Juntao Lu
RSC Advances 2011 vol. 1(Issue 7) pp:1358-1363
Publication Date(Web):13 Oct 2011
DOI:10.1039/C1RA00378J
Understanding the structure–activity relationship (SAR) is essential for catalyst innovation. Here we report a methodology to unravel the elusive SAR of fuel-cell catalysts by individually studying the electronic structure–surface reactivity (ES–SR) relationship and the surface reactivity–catalytic activity (SR–CA) relationship. In the light of this methodology, we demonstrate a strategy for optimizing fuel-cell alloy catalysts, featuring the rational manipulation of the surface reactivity through electronic effects. For Pt-alloy cathode catalysts with Pt-rich surface, such as Pt-segregated Pt-Ni alloy, the key is to weaken the surface reactivity through the strain effect; optimum catalytic activity toward the oxygen reduction reaction (ORR) is predicted to be achieved on a contraction in Pt lattice by 1.9%. For Pd-based anode catalysts, on the other hand, the ligand effect will play an important role, and enhancing the surface reactivity by alloying with Cu can boost the catalytic activity toward the formic-acid oxidation reaction (FAOR) by orders in magnitude.
Co-reporter:Wei Peng ; Li Xiao ; Bing Huang ; Lin Zhuang ;Juntao Lu
The Journal of Physical Chemistry C 2011 Volume 115(Issue 46) pp:23050-23056
Publication Date(Web):October 18, 2011
DOI:10.1021/jp2081148
The ammonia oxidation reaction (AOR) cannot proceed on Pt surface at potentials corresponding to the formation of surface oxygenated species (Oads and OHads), it is thus suspicious that, in addition to the Nads, the surface oxygenated species may also play an inhibitive role. Yet this is difficult to be proven in aqueous media where the AOR is always accompanied with the water oxidation reaction. In the present work, we carry out differential electrochemical mass spectroscopy (DEMS) studies of the AOR in nonaqueous media where no surface oxygenated species is involved, and the results turn out be remarkably different from those obtained in KOH solution. It is evident that, without the blocking of oxygenated species, the Pt surface can remain continuously active for AOR, and N2 is the dominant product. More strikingly, Pd becomes highly active for the AOR in nonaqueous media, a result enormously different from that in KOH solution where Pd exhibits a very low catalytic activity because of severer surface passivation by oxygenated species. This work provides compelling evidence for the inhibition effect of surface oxygenated species on the AOR, and illuminates our understanding of relevant reaction mechanisms.
Co-reporter:Jing Pan;Shanfu Lu;Yan Li;Aibin Huang;Juntao Lu
Advanced Functional Materials 2010 Volume 20( Issue 2) pp:312-319
Publication Date(Web):
DOI:10.1002/adfm.200901314
Abstract
Although the proton exchange membrane fuel cell (PEMFC) has made great progress in recent decades, its commercialization has been hindered by a number of factors, among which is the total dependence on Pt-based catalysts. Alkaline polymer electrolyte fuel cells (APEFCs) have been increasingly recognized as a solution to overcome the dependence on noble metal catalysts. In principle, APEFCs combine the advantages of and alkaline fuel cell (AFC) and a PEMFC: there is no need for noble metal catalysts and they are free of carbonate precipitates that would break the waterproofing in the AFC cathode. However, the performance of most alkaline polyelectrolytes can still not fulfill the requirement of fuel cell operations. In the present work, detailed information about the synthesis and physicochemical properties of the quaternary ammonia polysulfone (QAPS), a high-performance alkaline polymer electrolyte that has been successfully applied in the authors' previous work to demonstrate an APEFC completely free from noble metal catalysts (S. Lu, J. Pan, A. Huang, L. Zhuang, J. Lu, Proc. Natl. Acad. Sci. USA2008, 105, 20611), is reported. Monitored by NMR analysis, the synthetic process of QAPS is seen to be simple and efficient. The chemical and thermal stability, as well as the mechanical strength of the synthetic QAPS membrane, are outstanding in comparison to commercial anion-exchange membranes. The ionic conductivity of QAPS at room temperature is measured to be on the order of 10−2 S cm−1. Such good mechanical and conducting performances can be attributed to the superior microstructure of the polyelectrolyte, which features interconnected ionic channels in tens of nanometers diameter, as revealed by HRTEM observations. The electrochemical behavior at the Pt/QAPS interface reveals the strong alkaline nature of this polyelectrolyte, and the preliminary fuel cell test verifies the feasibility of QAPS for fuel cell applications.
Co-reporter:Jing Pan, Yan Li, Lin Zhuang and Juntao Lu
Chemical Communications 2010 vol. 46(Issue 45) pp:8597-8599
Publication Date(Web):18 Oct 2010
DOI:10.1039/C0CC03618H
We report a specially designed alkaline polymer electrolyte (APE) with extraordinary stability in both physical and chemical properties, which enables applications of fuel cells and electrolysis at elevated temperatures.
Co-reporter:Yubao Sun, Juntao Lu, Lin Zhuang
Electrochimica Acta 2010 Volume 55(Issue 3) pp:844-850
Publication Date(Web):1 January 2010
DOI:10.1016/j.electacta.2009.09.047
The rotating disk electrode (RDE) is a useful technique for precise determination of exchange current density (j0) in electrochemistry. For the study of powder catalysts, a common practice is to apply the powder onto an inert disk substrate (such as glassy carbon). However, this approach in its usual version will lead to wrong results for the exchange current density of hydrogen electrode reactions at carbon-supported Pt nanoparticles (Pt/C) because of the poor utilization of the loaded Pt nanoparticles. Our new approach is to dilute the Pt/C powder with a large amount of pristine carbon support to make the catalyst layer. In this way, all the catalyst particles in the catalyst layer have nearly the same and much enhanced mass transport so that rational exchange current density can be obtained. Using the new approach, the current density for hydrogen electrode reactions at Pt/C in 0.1 M perchloric acid at 25 °C is found to be 27.2 ± 3.5 mA/cm2 with an apparent activation energy 43 kJ/mol. These results are in agreement with the j0 estimation based on real fuel cell experiments.
Co-reporter:Daoping Tang, Juntao Lu, Lin Zhuang, Peifang Liu
Journal of Electroanalytical Chemistry 2010 Volume 644(Issue 2) pp:144-149
Publication Date(Web):1 June 2010
DOI:10.1016/j.jelechem.2009.11.031
After reviewing relevant equations for the calculation of exchange current density, a new equation is derived for hydrogen electrode reactions to correct for the influences of the hydrogen concentration change in the vicinity to the electrode surface. This equation is able to describe the polarization curve shape in the small polarization region as well as to calculate the exchange current (density). The abilities of this equation are demonstrated by the data obtained with a Pt rotating disk electrode in 0.1 mol l−1 KOH solution. The exchange current density at 298 K under 1 atmosphere hydrogen pressure is found to be 0.103 mA cm−2 with an apparent activation energy of 33.5 kJ mol−1. At a constant temperature, the exchange current is found to be proportional to the square root of the hydrogen partial pressure in the solution.
Co-reporter:Chen Chen, Chunning Gao, Lin Zhuang, Xuefeng Li, Pingcang Wu, Jinfeng Dong and Juntao Lu
Langmuir 2010 Volume 26(Issue 12) pp:9533-9538
Publication Date(Web):March 12, 2010
DOI:10.1021/la100105f
The spontaneous capillary imbibition and drainage processes are studied using many-body dissipative particle dynamics (MDPD) simulations. By adjusting the solid−liquid interaction parameter, different wetting behavior between the fluid and the capillary wall, corresponding to the static contact angle ranging from 0° to 180°, can be controllably simulated. For wetting fluids, the spontaneous capillary imbibition (SCI) is evident in MDPD simulations. It is found that, whereas the corrected Lucas−Washburn equation (taking into account the dynamic contact angle and the fluid inertia) can well describe the SCI simulation result for the completely wetting fluid, it deviates, to a notable degree, from the results of partly wetting fluids. In particular, this corrected equation cannot be used to describe the spontaneous capillary drainage (SCD) processes. To solve this problem, we derive an improved form of the Lucas−Washburn equation, in which the slip effects of fluid particles at the capillary wall are treated. Such an improved equation turns out to be capable of describing all the simulation results of both the SCI and the SCD. These findings provide new insights into the SCI and SCD processes and improve the mathematical base.
Co-reporter:DaoPing Tang;Jing Pan;ShanFu Lu;JunTao Lu
Science China Chemistry 2010 Volume 53( Issue 2) pp:357-364
Publication Date(Web):2010 February
DOI:10.1007/s11426-010-0080-5
Polymer electrolyte membrane fuel cells (PEMFC) have been recognized as a significant power source in future energy systems based on hydrogen. The current PEMFC technology features the employment of acidic polymer electrolytes which, albeit superior to electrolyte solutions, have intrinsically limited the catalysts to noble metals, fundamentally preventing PEMFC from widespread deployment. An effective solution to this problem is to develop fuel cells based on alkaline polymer electrolytes (APEFC), which not only enable the use of non-precious metal catalysts but also avoid the carbonate-precipitate issue which has been troubling the conventional alkaline fuel cells (AFC). This feature article introduces the principle of APEFC, the challenges, and our research progress, and focuses on strategies for developing key materials, including high-performance alkaline polyelectrolytes and stable non-precious metal catalysts. For alkaline polymer electrolytes, high ionic conductivity and satisfactory mechanical property are difficult to be balanced, therefore polymer cross-linking is an ultimate strategy. For non-precious metal catalysts, it is urgent to improve the catalytic activity and stability. New materials, such as transition-metal complexes, nitrogen-doped carbon nanotubes, and metal carbides, would become applicable in APEFC.
Co-reporter:Qiang Wang, Chuan-Sin Cha, Juntao Lu and Lin Zhuang
Physical Chemistry Chemical Physics 2009 vol. 11(Issue 4) pp:679-687
Publication Date(Web):25 Nov 2008
DOI:10.1039/B810429H
The nature and properties of Pt surfaces in contact with pure water in PEM-H2O reactors were mimetically studied by employing CV measurements with microelectrode techniques. These “Pt/water” interfaces were found to be electrochemically polarizable, and the local interfacial potential relative to reversible hydrogen electrode (RHE) potential in pure water is numerically the same as the potential value measured against a RHE in contact with PEM as the reference electrode. However, the structural parameters of the electric double layer at the “Pt/water” interfaces can be quite different from those at the “Pt/PEM” interfaces, and the kinetics of electrode processes could be seriously affected by the structure of electric double layer in pure water media. Besides, there is active diffusional flow of intermediates of electrode reactions between the “Pt/water” and the “Pt/PEM” interfaces, thus facilitating the active involvement of the “Pt/water” interfaces in the current-generation mechanism of PEM fuel cells and other types of PEM-H2O reactors.
Co-reporter:Li Xiao, Lin Zhuang, Yi Liu, Juntao Lu and Héctor D. Abruña
Journal of the American Chemical Society 2008 Volume 131(Issue 2) pp:602-608
Publication Date(Web):December 24, 2008
DOI:10.1021/ja8063765
Pd has been the focus of recent research for Pt-alternative catalysts for the oxygen reduction reaction (ORR). It has been found that upon appropriate modification of its electronic structure, the catalytic activity of Pd can become comparable to that of Pt. However, the structure−activity relationships of Pd catalysts have hitherto not been well studied or understood. In the present work, we report a new finding that there is a strong dependence of the activity of Pd toward the ORR on its morphology. By simply adjusting the precursor concentration in the electrochemical deposition of Pd, we are able to tailor the morphology of the deposited Pd from nanoparticles to nanorods. Surprisingly, the surface-specific activity of Pd nanorods (Pd-NRs) toward the ORR was found to be not only 10-fold higher than that of Pd nanoparticles (Pd-NPs), the conventional shape of electrocatalysts, but also comparable to that of Pt at operating potentials of fuel cell cathodes. The morphology−activity relationships of Pd-NRs were further studied through a combination of electrochemical experiments and density functional theory (DFT) calculations. As revealed by its characteristic profile for CO stripping, the morphology of Pd-NRs features the exposure of Pd(110) facets, which exhibit superior ORR activity. The underlying mechanism, indicated by DFT calculations, could be ascribed to the exceptionally weak interaction between an O adatom and a Pd(110) facet. This finding furthers our understanding of Pd catalysis and casts a new light on the relevant catalyst design criteria.
Co-reporter:Kangli Wang, Kai Jiang, Juntao Lu, Lin Zhuang, Chuansin Cha, Xiaohong Hu, George Z. Chen
Journal of Power Sources 2008 Volume 185(Issue 2) pp:892-894
Publication Date(Web):1 December 2008
DOI:10.1016/j.jpowsour.2008.08.069
This is the first report of a novel anode catalyst, Pt/Ti2O, and its use for the complete 8-electron oxidation of borohydride without hydrogen evolution in a potential region negative to reversible hydrogen electrode (RHE). A major obstacle to the development of direct borohydride fuel cells (DBFC) has been the hydrogen evolution at the negative electrode, which causes low coulombic efficiency and safety problems. Attempts to prevent hydrogen evolution during the oxidation of borohydride on a fuel cell anode have always resulted in a shift of the anode potential to values more positive than the RHE potential, thus losing the advantages of DBFC in comparison to conventional hydrogen fuel cells. Pt supported on conductive titanium oxides (Ti2O) has been found to catalyze the 8-electron oxidation of borohydride without hydrogen evolution in a potential range more negative than RHE, which is desired in order to have a DBFC that is practically applicable. Mechanism of the direct 8-electron oxidation process is discussed on the basis of a synergistic effect at the surface of Pt/Ti2O catalyst.
Co-reporter:Shanfu Lu;Jing Pan;Aibin Huang;Juntao Lu
PNAS 2008 Volume 105 (Issue 52 ) pp:20611-20614
Publication Date(Web):2008-12-30
DOI:10.1073/pnas.0810041106
In recent decades, fuel cell technology has been undergoing revolutionary developments, with fundamental progress being the
replacement of electrolyte solutions with polymer electrolytes, making the device more compact in size and higher in power
density. Nowadays, acidic polymer electrolytes, typically Nafion, are widely used. Despite great success, fuel cells based
on acidic polyelectrolyte still depend heavily on noble metal catalysts, predominantly platinum (Pt), thus increasing the
cost and hampering the widespread application of fuel cells. Here, we report a type of polymer electrolyte fuel cells (PEFC)
employing a hydroxide ion-conductive polymer, quaternary ammonium polysulphone, as alkaline electrolyte and nonprecious metals,
chromium-decorated nickel and silver, as the catalyst for the negative and positive electrodes, respectively. In addition
to the development of a high-performance alkaline polymer electrolyte particularly suitable for fuel cells, key progress has
been achieved in catalyst tailoring: The surface electronic structure of nickel has been tuned to suppress selectively the
surface oxidative passivation with retained activity toward hydrogen oxidation. This report of a H2–O2 PEFC completely free from noble metal catalysts in both the positive and negative electrodes represents an important advancement
in the research and development of fuel cells.
Co-reporter:Caifang Yao, Hanxi Yang, Lin Zhuang, Xinping Ai, Yuliang Cao, Juntao Lu
Journal of Power Sources 2007 Volume 165(Issue 1) pp:125-127
Publication Date(Web):25 February 2007
DOI:10.1016/j.jpowsour.2006.11.050
Borazane (BH3NH3) is a stable and low-toxic crystalline solid with possibly the highest hydrogen content (19.5 wt.%) in chemical compounds. In this communication, we report for the first time the electrooxidation of borazane and a novel direct fuel cell using alkaline borazane solution as alternative fuel. Of particular importance in this work is that non-platinum catalysts were applied for both the anode and the cathode. After a screening of a number of candidates (including Pt, Au, Ni, Cu, etc.), Ag was found to be a highly efficient catalyst for anodic oxidation of borazane, and MnO2 turned out to be a good cathode catalyst showing borazane-tolerance. The energy density of the fuel released by such a preliminary direct fuel cell was ca. 2000 mAh g−1 at 1 mA cm−2 and 0.9 V at room temperature.
Co-reporter:Yange Suo Dr.;Juntao Lu
Angewandte Chemie International Edition 2007 Volume 46(Issue 16) pp:
Publication Date(Web):9 MAR 2007
DOI:10.1002/anie.200604332
The enhanced catalytic activity of Pd-alloy catalysts in oxygen reduction and the “volcano” relationship between activity and degree of alloying were studied by experiment and DFT calculations. Catalytic activity correlates with adsorption energy (AE) of Oads, which in turn depends on lattice strain (a/a0) due to alloying. A guideline for the rational design of such catalysts (see picture) predicts that a Pd11Fe alloy will have similar activity to Pt.
Co-reporter:Yange Suo Dr.;Juntao Lu
Angewandte Chemie 2007 Volume 119(Issue 16) pp:
Publication Date(Web):9 MAR 2007
DOI:10.1002/ange.200604332
Die katalytische Aktivität von Pd-Legierungen in der Sauerstoffreduktion sowie die „Vulkan“-Beziehung zwischen der Aktivität und dem Legierungsgrad wurden experimentell und rechnerisch untersucht. Die katalytische Aktivität korreliert mit der Adsorptionsenergie (AE) von Oads, die wiederum von der Gitterspannung (a/a0) der Legierung abhängt (siehe Diagramm). Die Beziehung sagt voraus, dass Pd11Fe eine ähnliche Aktivität wie Pt aufweist.
Co-reporter:Yang Wang, Li Li, Ling Hu, Lin Zhuang, Juntao Lu, Boqing Xu
Electrochemistry Communications 2003 Volume 5(Issue 8) pp:662-666
Publication Date(Web):August 2003
DOI:10.1016/S1388-2481(03)00148-6
As the proton exchange membrane direct methanol fuel cell (PEMDMFC) faces sustaining obstacles, alkaline membrane direct methanol fuel cell (AMDMFC) is attracting increasing attention. Although some advantages may be expected, the feasibility of AMDMFC does not seem well verified. In this paper, thermodynamic disadvantages and kinetic advantages of AMDMFC are elucidated. In thermodynamic aspect, a large voltage loss due to the pH difference across the membrane is predicted by theoretical calculation; in kinetic aspect, besides the well-known superiority of alkaline media for oxygen reduction, experimental data show much higher anodic performance in carbonate/bicarbonate than in acid. In-situ FTIR measurements indicate that methanol can be fully oxidized to carbon dioxide in carbonate/bicarbonate as in sulfuric acid. Taking into account all the foreseeable advantageous and disadvantageous factors, AMDMFC is worth study, and an alkaline membrane stable at elevated temperatures is the prerequisite for a successful AMDMFC.
Co-reporter:Zhandong Ren, Li Xiao, Gongwei Wang, Juntao Lu, Lin Zhuang
Journal of Energy Chemistry (May 2014) Volume 23(Issue 3) pp:265-268
Publication Date(Web):1 May 2014
DOI:10.1016/S2095-4956(14)60145-5
Although most transition metals have been tested as the promoter to Pt for electrocatalysis toward fuel cell reactions, semi-conductor elements, such as Si, have hitherto not been examined. Here we report a simple synthesis of intermetallic Pt2Si electrode using magnetron sputtering and the electrocatalysis toward ethanol oxidation reaction (EOR). In comparison to Pt, the intermetallic Pt2Si surface turns out to be much more active in catalyzing the EOR: the onset potential shifts negatively by 150 mV, and the current density at 0.6 V increases by a magnitude of one order. Such an enormous enhancement in EOR catalysis is ascribed to the promotion effects of Si, which can not only provide active surface oxygenated species to accelerate the removal of COads, but also strongly alter the electronic property of Pt, as clearly indicated by the core-level shift in XPS spectrum.Intermetallic Pt2Si electrode is produced by magnetron sputtering, which exhibits a profound enhancement in the catalytic activity toward the ethanol oxidation reaction in comparison to Pt.Download full-size image
Co-reporter:Kangli Wang, Juntao Lu, Lin Zhuang
Catalysis Today (19 July 2011) Volume 170(Issue 1) pp:99-109
Publication Date(Web):19 July 2011
DOI:10.1016/j.cattod.2010.12.023
In direct borohydride fuel cells, the anodic oxidation of borohydride is often accompanied by hydrogen evolution which decreases the number of electrons released to the external circuit from each borohydride ion and thus lowers the Faradaic efficiency and causes safety problems. Based on the simultaneous measurements of polarization curve and hydrogen evolution for the borohydride oxidation on a number of different catalysts, a two-stage model is proposed for the anodic oxidation of borohydride, featuring a 4-electron oxidation of borohydride to form adsorbed hydrogen atoms Hads* which may then either be oxidized to water or form hydrogen molecules through water reduction, depending on the nature of catalysts and the electrode potentials. In the view of the high reducing ability of borohydride, the intermediate Hads* may have a higher energy state and therefore, it could be oxidized at potentials negative to reversible hydrogen potential (RHE). A possible approach to reach the goal of “8-electron borohydride oxidation at potentials negative to RHE” is also suggested and realized with a titanium-oxide supported Pt catalyst.
Co-reporter:Qiang Wang, Chuan-Sin Cha, Juntao Lu and Lin Zhuang
Physical Chemistry Chemical Physics 2009 - vol. 11(Issue 4) pp:NaN687-687
Publication Date(Web):2008/11/25
DOI:10.1039/B810429H
The nature and properties of Pt surfaces in contact with pure water in PEM-H2O reactors were mimetically studied by employing CV measurements with microelectrode techniques. These “Pt/water” interfaces were found to be electrochemically polarizable, and the local interfacial potential relative to reversible hydrogen electrode (RHE) potential in pure water is numerically the same as the potential value measured against a RHE in contact with PEM as the reference electrode. However, the structural parameters of the electric double layer at the “Pt/water” interfaces can be quite different from those at the “Pt/PEM” interfaces, and the kinetics of electrode processes could be seriously affected by the structure of electric double layer in pure water media. Besides, there is active diffusional flow of intermediates of electrode reactions between the “Pt/water” and the “Pt/PEM” interfaces, thus facilitating the active involvement of the “Pt/water” interfaces in the current-generation mechanism of PEM fuel cells and other types of PEM-H2O reactors.
Co-reporter:Gongwei Wang, Li Xiao, Bing Huang, Zhandong Ren, Xun Tang, Lin Zhuang and Juntao Lu
Journal of Materials Chemistry A 2012 - vol. 22(Issue 31) pp:NaN15774-15774
Publication Date(Web):2012/06/11
DOI:10.1039/C2JM32264A
In the present work, a one-pot method is employed to synthesize AuCu intermetallic nanoparticles (AuCu iNPs) supported on high-surface-area carbon. To avoid blocking the active sites of the AuCu iNPs for the subsequent study of electrocatalysis, no surfactant has been applied in the entire synthetic process. After refluxing in glycerol at 300 °C, the ordered structure is formed in the carbon-supported AuCu iNPs, whose superlattice is evidently demonstrated by the X-ray diffraction (XRD) and transmission electron microscopy (TEM) characterizations. Such intermetallic nanoparticles show very interesting electrochemical behaviors which have hitherto not been reported in the literature. In addition to the peculiar cyclic voltammetry (CV), the AuCu iNPs exhibit a superior catalytic activity, in comparison to that of ordinary Au nanoparticles, toward the oxygen reduction reaction (ORR) in alkaline media. The alteration in the surface electronic properties of Au, caused by the incorporation of Cu, has also been studied by X-ray photoelectron spectroscopy (XPS) and density functional theory (DFT) calculations.
Co-reporter:Lijun Gao, Ying Wang, Haobo Li, Qihao Li, Na Ta, Lin Zhuang, Qiang Fu and Xinhe Bao
Chemical Science (2010-Present) 2017 - vol. 8(Issue 8) pp:
Publication Date(Web):
DOI:10.1039/C7SC01615H
Co-reporter:Chi Chen, Xiao-Dong Yang, Zhi-You Zhou, Yu-Jiao Lai, Muhammad Rauf, Ying Wang, Jing Pan, Lin Zhuang, Qiang Wang, Yu-Cheng Wang, Na Tian, Xin-Sheng Zhang and Shi-Gang Sun
Chemical Communications 2015 - vol. 51(Issue 96) pp:NaN17095-17095
Publication Date(Web):2015/09/29
DOI:10.1039/C5CC06562C
N,S,Fe-doped graphene nanosheets were directly synthesized from aminothiazole, a precursor molecule that contains N and S atoms, through Fe catalysis under heat treatment. The graphene nanosheets exhibited high electrocatalytic activity toward oxygen reduction reaction in both acidic and alkaline media during rotating disk electrode half-cell and fuel cell tests.
Co-reporter:Cuixia Yang, Bing Huang, Li Xiao, Zhandong Ren, Zilong Liu, Juntao Lu and Lin Zhuang
Chemical Communications 2013 - vol. 49(Issue 94) pp:NaN11025-11025
Publication Date(Web):2013/09/11
DOI:10.1039/C3CC46522E
Combined computational and experimental studies reveal a noble, non-d-band effect on Ag activation and electrocatalysis: upon coating Ag onto the even more inert Au surface, the catalytic activity toward the oxygen reduction reaction in alkaline media can be improved by about half an order of magnitude in comparison to the usual Ag surface.
Co-reporter:Jing Pan, Yan Li, Lin Zhuang and Juntao Lu
Chemical Communications 2010 - vol. 46(Issue 45) pp:NaN8599-8599
Publication Date(Web):2010/10/18
DOI:10.1039/C0CC03618H
We report a specially designed alkaline polymer electrolyte (APE) with extraordinary stability in both physical and chemical properties, which enables applications of fuel cells and electrolysis at elevated temperatures.
Co-reporter:Bing Huang, Lin Zhuang, Li Xiao and Juntao Lu
Chemical Science (2010-Present) 2013 - vol. 4(Issue 2) pp:NaN611-611
Publication Date(Web):2012/10/25
DOI:10.1039/C2SC21232C
The chemical bond is a still mysterious force that glues atoms together to form molecules and materials. Unlike conventional electromagnetic interactions, the chemical bond cannot be quantified in strength by any known property of the participating species. Here we report an extraordinary principle that the bond energy (EAB), a quantitative measure of the bond strength, can be decoupled into two contributions of the participating reactants, with each described by a characteristic complex quantity (): . Such a principle has been verified by more than 300 typical bonds, including covalent bonds in molecules and adsorption bonds on metal surfaces; and it can be applied in a wide range of chemical research. Particularly, the characteristic complex quantity, termed chemical amplitude in the present work, can serve as an accurate and unified descriptor for the chemical reactivity of both molecules and metal surfaces, which greatly benefits the study of heterogeneous catalysis. Our finding has not only enabled a direct and practical evaluation of the bond energy, but also revealed a new aspect of the chemical interaction.
![Poly(oxy[1,1'-biphenyl]-4,4'-diyloxy-1,4-phenylenesulfonyl-1,4-phenylene)](/data/chemimg/1105800/25839-81-0.png)
![Poly(oxy[1,1'-biphenyl]-4,4'-diyloxy-1,4-phenylenesulfonyl-1,4-phenylene)](/data/chemimg/1105800/25839-81-0_b.png)
