Co-reporter:Mingbo Ruan, Ping Song, Jing Liu, Erling Li, and Weilin Xu
The Journal of Physical Chemistry C November 22, 2017 Volume 121(Issue 46) pp:25882-25882
Publication Date(Web):November 9, 2017
DOI:10.1021/acs.jpcc.7b08787
In the present work, we proposed an effective method to regenerate sintered gold catalyst by improving the dispersion of gold nanoparticles. With the liquid oxychlorination reaction, a sintered carbon-supported gold (Au/C) nanocatalyst was effectively regenerated by improving the redispersion of Au nanoparticles with additional carbon support. The Au-catalyzed model reaction between 4-nitrophenol and sodium borohydride (NaBH4) indicates that the apparent activity of the optimal Au/C regenerated (Au 0.45 wt %) exceeds that of the initial fresh Au/C (Au 1 wt %), making Au utilization tripled and potentially sustainable for their extensive application in industry.
Co-reporter:Mingbo Ruan;Menggai Jiao;Zhijian Wu;Ping Song;Zhemin Wu;Ying Wang;Yong Wang
The Journal of Physical Chemistry C February 23, 2017 Volume 121(Issue 7) pp:3911-3919
Publication Date(Web):February 3, 2017
DOI:10.1021/acs.jpcc.6b11935
The sintering-induced irreversible deactivation of precious metal nanocatalysts is one of the main obstacles for their sustainable application. Here, by adding fluorine (F)-doped carbon support to improve the redispersion and tune the morphology of platinum (Pt) nanoparticles, a sintered Pt/C electrocatalyst for methanol electro-oxidation was completely regenerated in activity and doubled in amount of catalyst and tripled in metal utilization. The morphology-tuning-induced highly efficient regeneration based on F-doped carbon was further confirmed from the regeneration of a spent Pt/C for fuel cells. The quantum chemical calculation shows that the improved redispersion and the morphology transformation of Pt nanocatalyst could be mainly attributed to the strong interaction between d states of Pt and p states of F doped on carbon. The work presented here indicates that the morphology tuning of metal nanocatalysts is another way for highly efficient regeneration of precious metal nanocatalysts. It also opens a new pathway for people to get new functional materials with tunable morphology sustainably.
Co-reporter:Tao Chen, Sheng Chen, Ping Song, Yuwei Zhang, Hongyang Su, Weilin Xu, and Jie Zeng
ACS Catalysis April 7, 2017 Volume 7(Issue 4) pp:2967-2967
Publication Date(Web):March 17, 2017
DOI:10.1021/acscatal.7b00087
By studying the nanocatalysis of individual Pd nanoparticles (Pd NPs) in two shapes (cube with (100) facet and octahedron with (111) facet) with single-turnover resolution, the facet-dependent activities and dynamics were apparently observed. The results indicate that Pd octahedrons possess higher intrinsic catalytic activity per site than Pd nanocubes. Within a competitive Langmuir–Hinshelwood mechanism, the facet-dependent activities are derived at single-particle level, and the facet-dependent adsorption behaviors of substrate molecules on Pd(111) and Pd(100) are revealed and clarified by theoretical calculation. Furthermore, the facet-dependent restructuring behaviors of the particle surfaces were also observed. This study gives deeper insight into Pd-based nanocatalysts.Keywords: fluorescence microscopy; nanocatalysis; Pd nanoparticles; shape effect; single molecule;
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:Xin Guo;Xiaopeng Jia;Ping Song;Jing Liu;Erling Li;Mingbo Ruan
Journal of Materials Chemistry A 2017 vol. 5(Issue 33) pp:17470-17475
Publication Date(Web):2017/08/22
DOI:10.1039/C7TA05334G
Ultrahigh pressure (UHP) was employed for the first time as a green method for the synthesis of highly efficient Fe, N co-doped carbon-based (FeNx/C) electrocatalysts for the oxygen reduction reaction (ORR). Compared with traditional pyrolysis under atmospheric conditions, the synthesis of FeNx/C catalysts under UHP could be done efficiently with much less consumption of time, energy and chemicals. The observed highly efficient synthesis and high ORR activity of such catalysts could be due to the fast heating system (12 °C per second) under UHP, which leads to highly efficient doping of heteroatoms on carbon with much less consumption of chemicals and energy; the UHP-induced high graphitization degree of the carbon support and the selective formation of highly active sites of pyridinic N and Fe–Nx for the ORR also contribute in part to the high ORR catalytic activity of the catalyst. The work presented here paves a new way for the green, environmentally friendly synthesis of heteroatom-doped highly efficient catalysts for energy or chemical processes.
Co-reporter:Ping Song;Mi Luo;Xiaozhi Liu;Wei Xing;Zheng Jiang;Lin Gu
Advanced Functional Materials 2017 Volume 27(Issue 28) pp:
Publication Date(Web):2017/07/01
DOI:10.1002/adfm.201700802
The authors report first a new type of nitrogen-triggered Zn single atom catalyst, demonstrating high catalytic activity and remarkable durability for the oxygen reduction reaction process. Both X-ray absorption fine structure spectra and theoretical calculations suggest that the atomically dispersed Zn-N4 site is the main, as well as the most active, component with O adsorption as the rate-limiting step at a low overpotential of 1.70 V. This work opens a new field for the exploration of high-performance Pt-free electrochemical oxygen reduction catalysts for fuel cells.
Co-reporter:Tao Chen, Yuwei Zhang, and Weilin Xu
Journal of the American Chemical Society 2016 Volume 138(Issue 38) pp:12414-12421
Publication Date(Web):August 31, 2016
DOI:10.1021/jacs.6b05600
By monitoring the temperature-dependent catalytic activity of single Au nanocatalysts for a fluorogenic reaction, we derive the activation energies via multiple methods for two sequential catalytic steps (product formation and dissociation) on single nanocatalysts. The wide distributions of activation energies across multiple individual nanocatalysts indicate a huge static heterogeneity among the individual nanocatalysts. The compensation effect and isokinetic relationship of catalytic reactions are observed at the single particle level. This study exemplifies another function of single-molecule nanocatalysis and improves our understanding of heterogeneous catalysis.
Co-reporter:Tao Chen, Yuwei Zhang and Weilin Xu
Physical Chemistry Chemical Physics 2016 vol. 18(Issue 32) pp:22494-22502
Publication Date(Web):18 Jul 2016
DOI:10.1039/C6CP02719A
Due to the well-known significant effect of the size on the catalytic activity of nanocatalysts, here we use single-molecule fluorescence microscopy to study the size-dependent catalytic kinetics and dynamics of individual Pd nanocubes. A series of size-dependent catalytic properties were revealed in both product formation and product desorption processes. It was found that, due to the different adsorption mechanisms of substrate molecules on Pd nanocubes, H2 adsorption is independent of the size of Pd nanocubes, while the large flat resazurin molecules show stronger adsorption on larger sized Pd nanocubes. Apparently, the Pd nanocubes can be divided into three types: when the size of the Pd nanocube is small, substrate binding can prohibit product desorption and product desorption prefers the direct pathway; when the size is in an appropriate range, the product desorption process could be independent of substrate binding and shows no selectivity between two parallel desorption pathways; if the size is large enough, substrate binding can promote product desorption and product desorption prefers the indirect pathway. We also observed the surface-restructuring-induced dynamic heterogeneity of individual Pd nanocubes in both product formation and desorption processes with timescales of about tens to one hundred seconds. The activity fluctuation of individual Pd nanocubes was found to be mainly due to the spontaneous surface-restructuring rather than the catalysis. Furthermore, we estimated the size-dependent activation energies and time scales of spontaneous dynamic surface restructuring, which are fundamental to heterogeneous catalysis. The work presented here reveals new insight into nanocatalysis and exemplifies the advantages of the single-molecule approach in probing the catalytic properties of nanocatalysts.
Co-reporter:Qiang Fu;Guangjun Ran
Nano Research 2016 Volume 9( Issue 11) pp:3247-3256
Publication Date(Web):2016 November
DOI:10.1007/s12274-016-1203-x
Densely packed and ordered “suprastructures” are new types of nanomaterials exhibiting broad applications. The direct self-assembly of cetyltrimethylammonium bromide (CTAB)-capped gold nanotriangles to form “suprastructures” was systematically investigated by varying the temperature and tilt angle of the silicon wafer used in the assembly process. Under optimal conditions, nanotriangles form into regular patterns, maintain their integrity, and form edge-to-edge, point-to-point, and face-to-face connections to form ordered “suprastructures” within an area of hundreds of square microns, achieving a high level of regularity. The formation of the “suprastructures” under optimal conditions could be mainly attributed to the complex balance between multiple temperature-dependent factors, including the atom diffusion rate, solvent evaporation rate, self-assembly rate, and the time for which the nanoparticle stays in the wet medium.
Co-reporter:Tao Chen, Yuwei Zhang, and Weilin Xu
ACS Nano 2016 Volume 10(Issue 9) pp:8434
Publication Date(Web):August 23, 2016
DOI:10.1021/acsnano.6b03327
Electro-redox-induced heterogeneous fluorescence of an individual single-layer graphene sheet was observed in real time by a total internal reflection fluorescence microscope. It was found that the fluorescence intensity of an individual sheet can be tuned reversibly by applying periodic voltages to control the redox degree of graphene sheets. Accordingly, the oxidation and reduction kinetics of an individual single-layer graphene sheet was studied at different voltages. The electro-redox-induced reversible variation of fluorescence intensity of individual sheets indicates a reversible band gap tuning strategy. Furthermore, correlation analysis of redox rate constants on individual graphene sheets revealed a redox-induced spatiotemporal heterogeneity or dynamics of graphene sheets. The observed controllable redox kinetics can rationally guide the precise band gap tuning of individual graphene sheets and then help their extensive applications in optoelectronics and devices for renewable energy.Keywords: electro-redox; fluorescence; fluorescence microscopy; graphene oxide
Co-reporter:Tao Chen;Sheng Chen;Yuwei Zhang;Yifeng Qi;Yuzhou Zhao;Dr. Weilin Xu;Dr. Jie Zeng
Angewandte Chemie International Edition 2016 Volume 55( Issue 5) pp:1839-1843
Publication Date(Web):
DOI:10.1002/anie.201509165
Abstract
To understand the catalytic properties or roles of different types of surface atoms on metal nanocatalysts, the catalytic kinetics and dynamics of the different types of surface atoms (plane and edge) were revealed for the first time by a statistical quantitative deconvolution of observables obtained from traditional single-molecule nanocatalysis of Pd nanocrystals.It was found that the edge and plane of Pd nanocubes show similar size-dependent product formation processes, but inverse product dissociation processes. This work helps push the traditional single-molecule nanocatalysis method towards the sub-particle level.
Co-reporter:Dr. Yuwei Zhang;Tao Chen;Dr. Shaun Alia; Bryan S. Pivovar;Dr. Weilin Xu
Angewandte Chemie International Edition 2016 Volume 55( Issue 9) pp:3086-3090
Publication Date(Web):
DOI:10.1002/anie.201511071
Abstract
By coupling a Pt-catalyzed fluorogenic reaction with the Pt-electrocatalyzed hydrogen-oxidation reaction (HOR), we combine single-molecule fluorescence microscopy with traditional electrochemical methods to study the real-time deactivation kinetics of a Pt/C electrocatalyst at single-particle level during electrocatalytic hydrogen-oxidation reaction. The decay of the catalytic performance of Pt/C could be mainly attributed to the electrocatalysis-induced etching or dissolution of Pt nanoparticles. Spontaneous regeneration of activity and incubation period of the Pt electrocatalyst were also observed at single-particle level. All these new insights are practically useful for the understanding and rational design of highly efficient electrocatalysts for application in fuel cells.
Co-reporter:Tao Chen;Sheng Chen;Yuwei Zhang;Yifeng Qi;Yuzhou Zhao;Dr. Weilin Xu;Dr. Jie Zeng
Angewandte Chemie 2016 Volume 128( Issue 5) pp:1871-1875
Publication Date(Web):
DOI:10.1002/ange.201509165
Abstract
To understand the catalytic properties or roles of different types of surface atoms on metal nanocatalysts, the catalytic kinetics and dynamics of the different types of surface atoms (plane and edge) were revealed for the first time by a statistical quantitative deconvolution of observables obtained from traditional single-molecule nanocatalysis of Pd nanocrystals.It was found that the edge and plane of Pd nanocubes show similar size-dependent product formation processes, but inverse product dissociation processes. This work helps push the traditional single-molecule nanocatalysis method towards the sub-particle level.
Co-reporter:Dr. Yuwei Zhang;Tao Chen;Dr. Shaun Alia; Bryan S. Pivovar;Dr. Weilin Xu
Angewandte Chemie 2016 Volume 128( Issue 9) pp:3138-3142
Publication Date(Web):
DOI:10.1002/ange.201511071
Abstract
By coupling a Pt-catalyzed fluorogenic reaction with the Pt-electrocatalyzed hydrogen-oxidation reaction (HOR), we combine single-molecule fluorescence microscopy with traditional electrochemical methods to study the real-time deactivation kinetics of a Pt/C electrocatalyst at single-particle level during electrocatalytic hydrogen-oxidation reaction. The decay of the catalytic performance of Pt/C could be mainly attributed to the electrocatalysis-induced etching or dissolution of Pt nanoparticles. Spontaneous regeneration of activity and incubation period of the Pt electrocatalyst were also observed at single-particle level. All these new insights are practically useful for the understanding and rational design of highly efficient electrocatalysts for application in fuel cells.
Co-reporter:Mingbo Ruan, Xiujuan Sun, Yuwei Zhang, and Weilin Xu
ACS Catalysis 2015 Volume 5(Issue 1) pp:233
Publication Date(Web):November 26, 2014
DOI:10.1021/cs5013427
By adding pure carbon support to improve the redispersion of platinum (Pt), a sintered Pt/C electrocatalyst for methanol electrooxidation was effectively regenerated in activity and doubled in amount on the basis of a one-step liquid oxychlorination. The apparent activity (mA mgcata.–1) of the optimal Pt/C regenerated (Pt 3.3 wt %) is close to the initial fresh Pt/C (Pt 10 wt %) and about two times that of fresh Pt/C (Pt 3.3 wt %), making Pt utilization doubled and then the resource-limited Pt potentially sustainable. The new nucleation of metal atoms on added pure support surface was found to be the key for both the improved redispersion of metal nanoparticles and the effective regeneration of catalytic activity in situ.Keywords: electrocatalyst; precious metal; Pt; regeneration; support
Co-reporter:Ping Song, Yuwei Zhang, Jing Pan, Lin Zhuang and Weilin Xu
Chemical Communications 2015 vol. 51(Issue 10) pp:1972-1975
Publication Date(Web):15 Dec 2014
DOI:10.1039/C4CC07677J
A family of cheap carbon black based Fe–Nx/C electrocatalysts with superhigh-performance for oxygen reduction reaction (ORR) were synthesized. The one with Fe 10 wt% and N 1.57 wt% shows the best performance. The activity order of different active sites for ORR was revealed firstly: Fe–N4/2–C > Fe4–N–C > N–C ≫ Fe4–C ≈ C.
Co-reporter:Qiang Fu, Guangjun Ran and Weilin Xu
RSC Advances 2015 vol. 5(Issue 47) pp:37512-37516
Publication Date(Web):09 Apr 2015
DOI:10.1039/C5RA02461G
A continuous, microfluidic-based, seed-mediated synthesis of high-purity gold nanoplates with different thicknesses was developed. The thickness of the nanoplates can be fairly tuned from less than 1 nm to a few nm by varying the flow rate. Depending on the thickness, the obtained nanoplates could be rigid and flat-surfaced with thicknesses larger than 2 nm or flexible with crumpled or rolled shapes when the thickness is around 1 nm. These nanoplates are poly-crystalline with different crystal faces and show high electrochemical activity towards glucose oxidation.
Co-reporter:Guangjun Ran, Qiang Fu and Weilin Xu
RSC Advances 2015 vol. 5(Issue 19) pp:14740-14746
Publication Date(Web):26 Jan 2015
DOI:10.1039/C4RA12145G
A simple custom-made microfluidic reactor is used to synthesize Pt nanoparticles supported on carbon (Pt/C) as electrocatalysts for fuel cells. By varying the flow rate of reactant in the microfluidic reactor, Pt/C catalyst obtained with a flow rate of 90 μL min−1 of substrate was found to be optimal for both anode and cathode electro-catalytic reactions (oxygen reduction reaction (ORR), methanol and formic acid electro-oxidation). An optimal size of Pt nanoparticles was found to be about 2.8 nm. This microfluidic reactor provides a versatile and portable approach to the large-scale synthesis of uniformly-dispersed carbon supported precious metal catalysts with high performance for fuel cells. The preparation is portable, versatile, fast and energy efficient, and can be a general method for the preparation of other supported metal and alloy systems.
Co-reporter:Qiang Fu, Yuping Sheng, Hongjie Tang, Zhening Zhu, Mingbo Ruan, Weilin Xu, Yutian Zhu, and Zhiyong Tang
ACS Nano 2015 Volume 9(Issue 1) pp:172
Publication Date(Web):December 17, 2014
DOI:10.1021/nn5027998
The synthesis of colloidal supraparticles (SPs) based on self-assembly of nanoscopic objects has attracted much attention in recent years. Here, we demonstrate the formation of self-limiting monodisperse gold SPs with core–shell morphology based on the building blocks of flexible nanoarms in one step. A flow-based microfluidic chip is utilized to slow down the assembly process of the intermediates, which surprisingly allows for observation of ultrathin gold nanoplates as first intermediates. Notably, these intermediate cannot be observed in traditional synthesis due to their rapid rolling-up to form the second-order nanostructure of flexible hollow nanoarms. The growth mechanism of SPs can then be deconvoluted into two seed-mediated steps. Monte Carlo simulations confirm that the self-limiting growth of binary SPs is governed by a balance between electrostatic repulsion and van der Waals attraction.Keywords: Au; growth mechanism; microfluidics; Monte Carlo simulation; supraparticle;
Co-reporter:Yuwei Zhang;J. Matthew Lucas;Brandon Beberwyck;Qiang Fu;Ping Song;A. Paul Alivisatos
PNAS 2015 Volume 112 (Issue 29 ) pp:8959-8964
Publication Date(Web):2015-07-21
DOI:10.1073/pnas.1502005112
For the practical application of nanocatalysts, it is desirable to understand the spatiotemporal fluctuations of nanocatalytic
activity at the single-nanoparticle level. Here we use time-lapsed superresolution mapping of single-molecule catalysis events
on individual nanoparticles to observe time-varying changes in the spatial distribution of catalysis events on Sb-doped TiO2 nanorods and Au triangle nanoplates. Compared with the active sites on well-defined surface facets, the defects of the nanoparticle
catalysts possess higher intrinsic reactivity but lower stability. Corners and ends are more reactive but also less stable
than flat surfaces. Averaged over time, the most stable sites dominate the total apparent activity of single nanocatalysts.
However, the active sites with higher intrinsic activity but lower stability show activity at earlier time points before deactivating.
Unexpectedly, some active sites are found to recover their activity (“self-healing”) after deactivation, which is probably
due to desorption of the adsorbate. Our superresolution measurement of different types of active catalytic sites, over both
space and time, leads to a more comprehensive understanding of reactivity patterns and may enable the design of new and more
productive heterogeneous catalysts.
Co-reporter:Jing Liu;Ping Song;Zhigang Ning
Electrocatalysis 2015 Volume 6( Issue 2) pp:132-147
Publication Date(Web):2015 March
DOI:10.1007/s12678-014-0243-9
Heteroatom-doped metal-free electrocatalysts for oxygen reduction reaction (ORR) represent one of the most prominent families of electrocatalysts for fuel cells. While nitrogen (N)-doped carbon electrocatalysts toward ORR have experienced great progress throughout the past decades and yielded promising material concepts, also other heteroatom-doped catalysts have gained the researchers’ tremendous interest recently. Boron (B)-doping on carbon has been extensively studied, and due to the contrary electronic properties between N and B, a synergetic effect between the codoped N and B on carbon has been found for ORR. The carbons doped with sulfur (S), phosphorus (P), silicon (Si), and halogen (fluorine (F), chlorine (Cl), bromine (Br), iodine (I)) have also been studied as metal-free electrocatalysts for ORR in both experimental and theoretical ways. It has been known that the difference in electronegativity and size between the heteroatoms (N, B, S, P, Si, Cl, Br, I) and carbon can polarize adjacent carbon atoms to facilitate the oxygen reduction process. Especially, our research group reported the first F-doped or N,F-codoped carbon black as highly efficient ORR electrocatalysts which possess one of the best price/performance ratio ever. In this feature article, we review the recent research progress in the development of heteroatom-doped carbon-based metal-free electrocatalysts for ORR.
Co-reporter:Ping Song, Mingbo Ruan, Xiujuan Sun, Yuwei Zhang, and Weilin Xu
The Journal of Physical Chemistry B 2014 Volume 118(Issue 34) pp:10224-10231
Publication Date(Web):August 5, 2014
DOI:10.1021/jp505739p
In the current work, the whole reduction mechanism of resorufin by sodium borohydride (NaBH4) has been investigated completely using quantum chemical theory for the first time. The possible pathways for each step were considered as much as possible. The calculated results reveal that the reduction mechanism for resorufin undergoes a nucleophilic addition with BH4–, a synchronous proton abstraction from a carbon (C) atom, a protonation in a nitrogen (N) atom, and then a final hydrolysis process to obtain final reduced product dihydroresorufin. Interestingly, it was found that the protonation of N atom could induce a reduced product molecule with a Λ-type structure rather than a planar one, and the large alteration in geometry will induce different optical properties, such as fluorescent or nonfluorescent. More importantly, countercation Na+ and solvation effect of H2O play important roles in reducing the activation energy in elementary steps, and their stabilization effect has been confirmed by NBO analysis. The detailed theoretical investigation for the reduction reaction of resorufin by NaBH4 will support some guidance for the similar reduction reaction for organic compounds like aldehydes and ketones.
Co-reporter:Xiujuan Sun, Ping Song, Tao Chen, Jing Liu and Weilin Xu
Chemical Communications 2013 vol. 49(Issue 87) pp:10296-10298
Publication Date(Web):11 Sep 2013
DOI:10.1039/C3CC45480K
Fluorine-doped carbon blacks as inexpensive, high performance electrocatalysts for acidic oxygen reduction reaction were synthesized. The performance of the optimal catalyst (BP-18F) is close to the level of other reported best non-Pt electrocatalysts in acid, but with superlow H2O2 yield (<0.1%) ever. Their high performance is confirmed by quantum calculations.
Co-reporter:Jing Liu, Ping Song, Weilin Xu
Carbon (May 2017) Volume 115() pp:
Publication Date(Web):May 2017
DOI:10.1016/j.carbon.2017.01.080
Resolving the structure-activity relationship of doped-nitrogen (N)-based active sites on carbon and their variation mechanism during oxygen reduction reaction (ORR) process have been very desirable for the deep understanding of doped-N-based carbon materials. Here, by correlating the ORR catalytic performance with chemical compositions of N-doped carbon samples and performing systematic quantum chemical calculations, we partially resolved the structure-activity relationship of different N-containing active sites on N-doped carbon, including the ORR-induced transformation of both pyridinic and graphitic N to pyrrolic N, the revealing of the catalytic activity order of different N-containing sites for ORR from both experimental and theoretical points of view systematically: pyridinic N > pyrrolic N > graphitic N > oxidized N > C (carbon). The tiny structure difference-induced huge ORR activity difference of N-containing sites was also revealed. All these new understandings to the doped-N-based ORR carbon catalysts can guide the rational design of N-doped metal-free catalysts.
Co-reporter:Yuwei Zhang, Tao Chen, Ping Song, Weilin Xu
Science Bulletin (28 February 2017) Volume 62(Issue 4) pp:290-301
Publication Date(Web):28 February 2017
DOI:10.1016/j.scib.2017.01.010
Understanding the heterogeneous catalytic properties of nanoparticles is of great significance for the development of high efficient nanocatalysts, but the intrinsic heterogeneities of nanocatalysts were always covered in traditional ensemble studies. This issue can be overcome if one can follow the catalysis of individual nanoparticles in real time. This paper mainly summarizes recent developments in single-molecule nanocatalysis at single particle level in Changchun Institute of Applied Chemistry, Chinese Academy of Sciences. These developments include the revealing of catalytic kinetics of different types (plane & edge) of surface atoms on individual Pd nanocubes, the observing of in situ deactivation of individual carbon-supported Pt nanoparticles during the electrocatalytic hydrogen-oxidation reaction, and the measurement of catalytic activation energies on single nanocatalysts for both product formation process and dissociation process, etc. These studies further indicate the advantages or unique abilities of single-molecule methods in the studies of nanocatalysis or even chemical reactions.Download high-res image (125KB)Download full-size image
Co-reporter:Ping Song, Yuwei Zhang, Jing Pan, Lin Zhuang and Weilin Xu
Chemical Communications 2015 - vol. 51(Issue 10) pp:NaN1975-1975
Publication Date(Web):2014/12/15
DOI:10.1039/C4CC07677J
A family of cheap carbon black based Fe–Nx/C electrocatalysts with superhigh-performance for oxygen reduction reaction (ORR) were synthesized. The one with Fe 10 wt% and N 1.57 wt% shows the best performance. The activity order of different active sites for ORR was revealed firstly: Fe–N4/2–C > Fe4–N–C > N–C ≫ Fe4–C ≈ C.
Co-reporter:Tao Chen, Yuwei Zhang and Weilin Xu
Physical Chemistry Chemical Physics 2016 - vol. 18(Issue 32) pp:NaN22502-22502
Publication Date(Web):2016/07/18
DOI:10.1039/C6CP02719A
Due to the well-known significant effect of the size on the catalytic activity of nanocatalysts, here we use single-molecule fluorescence microscopy to study the size-dependent catalytic kinetics and dynamics of individual Pd nanocubes. A series of size-dependent catalytic properties were revealed in both product formation and product desorption processes. It was found that, due to the different adsorption mechanisms of substrate molecules on Pd nanocubes, H2 adsorption is independent of the size of Pd nanocubes, while the large flat resazurin molecules show stronger adsorption on larger sized Pd nanocubes. Apparently, the Pd nanocubes can be divided into three types: when the size of the Pd nanocube is small, substrate binding can prohibit product desorption and product desorption prefers the direct pathway; when the size is in an appropriate range, the product desorption process could be independent of substrate binding and shows no selectivity between two parallel desorption pathways; if the size is large enough, substrate binding can promote product desorption and product desorption prefers the indirect pathway. We also observed the surface-restructuring-induced dynamic heterogeneity of individual Pd nanocubes in both product formation and desorption processes with timescales of about tens to one hundred seconds. The activity fluctuation of individual Pd nanocubes was found to be mainly due to the spontaneous surface-restructuring rather than the catalysis. Furthermore, we estimated the size-dependent activation energies and time scales of spontaneous dynamic surface restructuring, which are fundamental to heterogeneous catalysis. The work presented here reveals new insight into nanocatalysis and exemplifies the advantages of the single-molecule approach in probing the catalytic properties of nanocatalysts.
Co-reporter:Xiujuan Sun, Ping Song, Tao Chen, Jing Liu and Weilin Xu
Chemical Communications 2013 - vol. 49(Issue 87) pp:NaN10298-10298
Publication Date(Web):2013/09/11
DOI:10.1039/C3CC45480K
Fluorine-doped carbon blacks as inexpensive, high performance electrocatalysts for acidic oxygen reduction reaction were synthesized. The performance of the optimal catalyst (BP-18F) is close to the level of other reported best non-Pt electrocatalysts in acid, but with superlow H2O2 yield (<0.1%) ever. Their high performance is confirmed by quantum calculations.
