Co-reporter:Jianyou Chen, Jinkui Song, Feihong Huang, Hao Li, Shuangshuang Liu, Mingkui Wang, and Yan Shen
The Journal of Physical Chemistry C August 17, 2017 Volume 121(Issue 32) pp:17053-17053
Publication Date(Web):July 12, 2017
DOI:10.1021/acs.jpcc.7b03279
Antisolvent method has been widely applied to fabricate hybrid halide perovskite solar cells. However, the quality of perovskite film is unable to effectively control for the excessively fast crystallization. In this work, we investigated the effect of precursor concentration and spinning speed as well as additive CH3NH3Cl on quality perovskite film and thus the performance solar cells. The growth of crystal toward the orientation parallel to the direction of facet (002)/(004) slows down as the concentration and spinning speed increases. The lattice constants points out the expansion of crystal size in the direction along the c-axis of around 0.04 Å due to the size difference between I and Cl ions. A vertical growth mechanism was proposed to elaborate the crystallite growth of CH3NH3PbI3(Cl) perovskite film. Consequently, the perovskite solar cell efficiency impressively increases from ∼12% to ∼16% along enlarging the crystal size. Various advanced characterization techniques including ultrafast spectroscopy and electronic impedance spectroscopy elucidated that an optimal film with large grain size and less defect states could result in the enhancement of charge transport and collection efficiency.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Yanping Luo, Xiaowei Lv, Yan Shen
Applied Surface Science 2017 Volume 391(Part B) pp:288-294
Publication Date(Web):1 January 2017
DOI:10.1016/j.apsusc.2016.07.035
Highlights
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Surface modification of TiO2 improve its photoelectrochemical (PEC) activity.
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The phosphate modified N/Si co-doped TiO2 nanorods film Exhibits 1.44 mA cm−2 photocurrent.
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The improvement can be attributed to charge transfer associated with phosphate modification.
Co-reporter:Weina Shi, Hao Li, Jianyou Chen, Xiaowei Lv, Yan Shen
Electrochimica Acta 2017 Volume 225(Volume 225) pp:
Publication Date(Web):20 January 2017
DOI:10.1016/j.electacta.2016.12.166
In the present work, we report on a facile and effective approach to significantly enhance the photoelectrochemical activity of WO3. WO3 nanoflakes with hierarchical architecture prepared with a two-step hydrothermal method exhibits a significant enhancement of photocurrent density by a factor of 1.3 as compared with the pristine counterpart. The improved photoelectrochemical activity could be attributed to the enhanced light-harvesting capability induced by multiple light scattering and better interfacial charge transfer properties by facilitating the exposure of active sites benefited from the hierarchical architecture. An integration of the hierarchical WO3 electrode with a single-junction perovskite solar cell gives a solar energy conversion efficiency of 1.30% without external bias.
Co-reporter:Yahui He;Xin Xiao;Lin Gao;Shaohui Li; Yan Shen
ChemElectroChem 2017 Volume 4(Issue 3) pp:607-612
Publication Date(Web):2017/03/01
DOI:10.1002/celc.201600843
AbstractThe bouquet-like NiCo2O4@CoNi2S4 ternary heterostructure on nickel foam is successfully synthesized through a hydrothermal method and electrodeposition. CoNi2S4 nanosheets uniformly cover the surface of nanoneedle-like NiCo2O4 arrays. The as-prepared NiCo2O4@CoNi2S4 material was characterized by using scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). Their electrochemical performance was tested by using cyclic voltammetry (CV) and galvanostatic charge-discharge (GCD) methods. The bouquet-like NiCo2O4@CoNi2S4 material with a ternary heterostructure shows the advantages of fast electron and ion transport, a large electroactive surface, and a remarkable areal capacitance (6.25 F cm−2 at current density of 2 mA ⋅ cm−2), which suggests NiCo2O4@CoNi2S4 is a promising material in practical application for pseudocapacitors.
Co-reporter:Minglei Cao, Lin Gao, Xiaowei Lv, Yan Shen
Journal of Power Sources 2017 Volume 350(Volume 350) pp:
Publication Date(Web):15 May 2017
DOI:10.1016/j.jpowsour.2017.03.070
•TiO2-B@VS2 heterogeneous nanowire arrays (TVNAs) are prepared.•Layered VS2 nanoparticles are deposited on TiO2-B nanowire arrays surface.•The TVNAs electrode exhibits enhanced capacity and rate capability.•VS2 improves the electrical conductivity and contributes to extra capacity.Heterogeneous nanostructured materials are currently studied as promising electrode materials for lithium-ion batteries (LIBs) due to effective synergy. Herein, we report on TiO2-B@VS2 heterogeneous nanowire arrays (TVNAs) as additives-free anodes for LIBs. The VS2 is a two-dimensional (2D) material with intrinsically metallic nature. Importantly, this layered 2D material offers a large interlayer spacing for facile intercalation of lithium-ions and possesses a high theoretical capacity. The TVNAs electrode shows a reversible capacity of 365.4 mA h g−1 after 500 cycles at a current density of 1 C (335 mA g−1), being significantly superior than the pure TiO2-B nanowire arrays (TNAs) electrode (192.7 mA h g−1). Impressively, the TVNAs electrode delivers a high rate capacity of 171.2 mA h g−1 at 10 C rate. The merits of the TVNAs electrode could be ascribed to the outstanding structural stability of the TNAs and the high capacity and conductivity of VS2.
Co-reporter:Dekang Huang, Shu Li, Xin Xiao, Minglei Cao, Lin Gao, Yong-Gang Xiang, Hao Chen, Yan Shen
Journal of Power Sources 2017 Volume 371(Volume 371) pp:
Publication Date(Web):15 December 2017
DOI:10.1016/j.jpowsour.2017.10.043
•An ultrafast method was applied to prepare tellurium nanorods on nickel foam.•This Te@Ni materials can be used as cathode without any binders and carbon additives.•Carbon cloth used as interlayer can further improve the battery performance.Recently, tellurium has been regarded as a promising cathode material for rechargeable lithium-ion batteries due to its high theoretical volumetric capacity. However, a plethora of research are focusing on impregnating the tellurium into porous carbon materials by the thermal-diffusion method, which would consume large amounts of energy and take prolonged time. Herein, a carbon and binder-free cathode with 100% Te is fabricated by a facile galvanic replacement method on a nickle foam. Driven by the large electrochemical potential difference between Ni and Te, desirable amounts of Te can be obtained in just 10 min with no need of energy input. Li-Te batteries constructed by the as-obtained cathode show relatively good performance in DMSO solvent. To further elevate the performance of this battery especially at low current density, commercial carbon cloth is added between the separator and Te electrode as an interlayer. The cell with interlayer delivers a gravimetric capacity of 116.2 mAh g−1 after 70 cycles at the current density of 100 mA g−1, which is 2.8 times as high as that of a cell without interlayer (40.4 mAh g−1).
Co-reporter:Hong Yin;Ming-Lei Cao;Xiang-Xiang Yu;Chong Li;Ming-Qiang Zhu
RSC Advances (2011-Present) 2017 vol. 7(Issue 22) pp:13250-13256
Publication Date(Web):2017/02/24
DOI:10.1039/C6RA27216A
In the present report, hierarchical CuBi2O4 microspheres are prepared through a hydrothermal route, and applied as anode materials for LIBs. The hierarchical CuBi2O4 microspheres of diameter 2.0–4.0 μm are assembled by crystalline tetragonal nanoparticles with a size of 50–60 nm. The electrochemical performance of the hierarchical CuBi2O4 microspheres shows strong temperature-dependence whereby higher temperatures evidently enhance the electrochemical performance. At an elevated temperature of 70 °C, a reversible capacity of 525.1 mA h g−1 has been achieved after 500 cycles at a current density of 100 mA g−1. Even after being cycled at a high current density of 6.4 A g−1, the hierarchical CuBi2O4 microspheres are still able to deliver a capacity of 585 mA h g−1 when the current density is set back to 100 mA g−1. The superior high-temperature electrochemical performance of the hierarchical CuBi2O4 microspheres is ascribed to their hierarchical structure and outstanding thermostability.
Co-reporter:Bingyan Zhang, Xiaofan Zhang, Xin Xiao, and Yan Shen
ACS Applied Materials & Interfaces 2016 Volume 8(Issue 3) pp:1606
Publication Date(Web):December 31, 2015
DOI:10.1021/acsami.5b07180
Fast charge transfer kinetics at the photoelectrode/electrolyte interface is critical for efficient photoelectrochemical (PEC) water splitting system. Thus, far, a measurement of kinetics constants for such processes is limited. In this study, scanning electrochemical microscopy (SECM) is employed to investigate the charge transfer kinetics at the photoelectrode/electrolyte interface in the feedback mode in order to simulate the oxygen evolution process in PEC system. The popular photocatalysts BiVO4 and Mo doped BiVO4 (labeled as Mo:BiVO4) are selected as photoanodes and the common redox couple [Fe(CN)6]3–/[Fe(CN)6]4– as molecular probe. SECM characterization can directly reveal the surface catalytic reaction kinetics constant of 9.30 × 107 mol–1 cm3 s–1 for the BiVO4. Furthermore, we find that after excitation, the ratio of rate constant for photogenerated hole to electron via Mo:BiVO4 reacting with mediator at the electrode/electrolyte interface is about 30 times larger than that of BiVO4. This suggests that introduction of Mo6+ ion into BiVO4 can possibly facilitate solar to oxygen evolution (hole involved process) and suppress the interfacial back reaction (electron involved process) at photoanode/electrolyte interface. Therefore, the SECM measurement allows us to make a comprehensive analysis of interfacial charge transfer kinetics in PEC system.Keywords: feedback mode; interfacial charge transfer; kinetics; photoelectrochemical water splitting; scanning electrochemical microscopy
Co-reporter:Weina Shi, Xiaofan Zhang, Jérémie Brillet, Dekang Huang, Man Li, Mingkui Wang, Yan Shen
Carbon 2016 Volume 105() pp:387-393
Publication Date(Web):August 2016
DOI:10.1016/j.carbon.2016.04.051
This work reports on single-crystal WO3 nanoflakes decorated with carbon quantum dots (CQDs) for efficient photoelectrochemical energy conversion system. The promising photoanodes can be fabricated via seed-mediated solvothermal method in combination with subsequent impregnation-assembling. A photocurrent density of 1.46 mA cm−2 at 1.0 V vs. Ag/AgCl can be achieved for the CQDs/WO3 electrode when performing linear sweep voltammetry measurements in 1 M H2SO4 solution under AM 1.5G illumination, which is about two times higher than that of the bare WO3 electrode. The enhancement of photoelectrochemical performance is ascribed to the enhanced light harvesting ability of CQDs and its accelerating charge transfer across the interface between CQDs/WO3 electrode and electrolyte. The improved activity indicates the potential of CQDs/WO3 as an efficient electrode for photoelectrochemical solar energy conversion.
Co-reporter:Yanping Luo, Dekang Huang, Man Li, Xin Xiao, Weina Shi, Mingkui Wang, Jun Su, Yan Shen
Electrochimica Acta 2016 Volume 219() pp:187-193
Publication Date(Web):20 November 2016
DOI:10.1016/j.electacta.2016.09.151
Robust and stable electrocatalyst with high activity is highly desirable for hydrogen evolution reaction (HER). In this work, we report on MoS2 nanosheets prepared by hydrothermal method followed by deposition of trace loads of Pt nanoparticles as electrocatalyst for HER, exhibiting excellent electrochemical activity with an onset potential of 0 mV, a Tafel slope of 49 mV dec−1, an exchange current density of 0.75 mA cm−2, and a good durability. The composite can be efficiently synthesized by deposition of trace loads of Pt on MoS2 nanosheets using a facile electrochemical method, during which carbon cloth (CC) was used as a conductive substrate. Compared to the commercial Pt/C catalysts (20 wt% Pt on Vulcan carbon black), the prepared Pt/MoS2/CC catalyst with very low Pt loading (1.26 wt%) exhibits a comparable HER activity.
Co-reporter:Dan Li, Jin Cui, Hao Li, Dekang Huang, Mingkui Wang, Yan Shen
Solar Energy 2016 Volume 131() pp:176-182
Publication Date(Web):June 2016
DOI:10.1016/j.solener.2016.02.049
•The GO/PEDOT:PSS hybrid bilayer as hole extracting layer is proposed.•The hybrid bilayer suppresses leakage current and reduces recombination at the interfaces.•30% improvement in power conversion efficiency had been achieved.This work reports on graphene oxide (GO) and poly(3,4-ethylenedioxy thiophene)–poly(styrenesulfonate) (PEDOT:PSS) hybrid bilayer as hole extracting layer for CH3NH3PbI3-based inverted planar heterojunction perovskite solar cells. Remarkably, the incorporation of GO could suppress leakage current and reduce recombination via efficient hole transporting and electron blocking, resulting in 30% improvement of power conversion efficiency.
Co-reporter:Bin-Bin Ma, Hua Zhang, Yu Wang, Yu-Xin Peng, Wei Huang, Ming-Kui Wang and Yan Shen
Journal of Materials Chemistry A 2015 vol. 3(Issue 29) pp:7748-7755
Publication Date(Web):22 Jun 2015
DOI:10.1039/C5TC00909J
Two small molecular chromogenic sensors (azine MS-1 and azomethine MS-2) were synthesized for acid–base discoloration and optoelectronic investigations. It was found that the color of both sensors in solution and in the solid state changed obviously from yellow to purple and blue after treatment with acid, which could be easily detected by the naked eye. Furthermore, single-crystal conductance of MS-1 and MS-2 could be significantly enhanced after treatment with HCl gas flow. On the other hand, MS-2 showed relatively good film-forming ability and could be used as a hole transport material (HTM) in perovskite solar cells, exhibiting a power conversion efficiency (PCE) of 6.68%. To the best of our knowledge, this is the first demonstration of perovskite solar cells including a HTM based on a low-cost Schiff-base.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Kun Cao, Jérémie Brillet, Jianyou Chen, Mingkui Wang and Yan Shen
Journal of Materials Chemistry A 2015 vol. 3(Issue 43) pp:21630-21636
Publication Date(Web):02 Sep 2015
DOI:10.1039/C5TA05838D
Converting solar energy into hydrogen via photoelectrochemical water splitting has attracted significant attention during the past decades. Herein, we design a novel core/shell TiO2@BiVO4 photoanode in combination with a CH3NH3PbI3-based perovskite solar cell for unassisted solar water splitting. Compared to pristine TiO2 NRs, the resulting TiO2@BiVO4 film exhibits a 3.25-fold enhanced photocurrent density (∼1.3 mA cm−2) under irradiation (xenon lamp coupled with an AM 1.5 G filter, 100 mW cm−2). This significant enhancement is attributed to the excellent light absorption properties of BiVO4 and a fast electron transfer process in the single crystalline TiO2 NRs. Especially, the type-II band alignment between the BiVO4 and rutile TiO2 NRs provides a large driving force for electron injection from the BiVO4 to the TiO2. The perovskite solar cell-TiO2@BiVO4 photoelectrochemical tandem device exhibits an overall solar-to-hydrogen efficiency of 1.24%, comparable to other TiO2-based PV/PEC systems.
Co-reporter:Lin Gao, Shaohui Li, Dekang Huang, Yan Shen and Mingkui Wang
Journal of Materials Chemistry A 2015 vol. 3(Issue 18) pp:10107-10113
Publication Date(Web):23 Mar 2015
DOI:10.1039/C5TA01054C
This work reports on porous Li4Ti5O12 (LTO)–TiO2 nanosheet arrays prepared via a versatile hydrothermal method for lithium ion batteries, exhibiting a high initial discharge capacity of 184.6 mA h g−1 at 200 mA g−1 and possessing excellent electrochemical stability with only 8.3% loss of specific capacity at 1 A g−1 in a prolonged charge–discharge process (1000 cycles). The excellent electrochemical performance can be attributed to the interconnected mesoporous/macroporous structures and the abundant grain boundaries generated by the existing multiphase materials, as well as the direct connection between the nanoarrays and conductive Ti substrates which facilitates the lithium ion and electron transportation. A flexible lithium ion battery has been further designed by using the nanosheet LTO–TiO2 arrays as the anode and LiCoO2 as the cathode, enabling it to reliably power an LED light under severe mechanical bending. This is very promising for future potential application in high performance flexible energy storage devices.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Zhixiang Zuo, Mingkui Wang and Yan Shen
Journal of Materials Chemistry A 2015 vol. 3(Issue 18) pp:10020-10025
Publication Date(Web):27 Mar 2015
DOI:10.1039/C5TA00613A
Chemical modification of the aligned single crystalline TiO2 nanorods provides possibilities to improve their photoelectrochemical (PEC) activity under visible light. This work reports on the N/Si co-doped single crystal rutile TiO2 nanorods fabricated by a flexible one-step hydrothermal procedure for PEC water splitting, exhibiting a photocurrent of 1.77 mA cm−2 at 1.23 V vs. RHE and a noticeable visible-light response under standard testing conditions (xenon lamp with an AM 1.5 G filter, 100 mW cm−2). The excellent PEC activity can be attributed to the synergetic effect of N and Si co-dopants, which enhances the incident photon to current conversion efficiency both in ultraviolet and visible regions, and improves the charge transfer at the photoanode/electrolyte interface. A solar-powered water splitting device has been designed by combining an efficient perovskite solar cell with the N/Si co-doped TiO2 NRs-based PEC system, achieving an overall solar-to-hydrogen efficiency of 1.1%. This has been the highest value reported for TiO2-based PEC systems so far.
Co-reporter:Weina Shi, Xiaofan Zhang, Shaohui Li, Bingyan Zhang, Mingkui Wang, Yan Shen
Applied Surface Science 2015 Volume 358(Part A) pp:404-411
Publication Date(Web):15 December 2015
DOI:10.1016/j.apsusc.2015.08.223
Highlights
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Cu2O nanowire covered with amorphous carbon thin layer was fabrication.
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A photocurrent density of up to 2.7 mA cm−2 at 0 V (vs. RHE) was achieved.
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Carbon covered Cu2O electrode shows improved stability.
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Carbon layer can increase the charge separation and collection efficiency.
Co-reporter:Bingyan Zhang, Jianhai Zhou, Shaohui Li, Xiaofan Zhang, Dekang Huang, Yahui He, Mingkui Wang, Guang Yang, Yan Shen
Talanta 2015 Volume 131() pp:243-248
Publication Date(Web):January 2015
DOI:10.1016/j.talanta.2014.07.027
•Bacterial cellulose (BC) is used to functionalize MWCNTs to get a flexible film matrix.•MP-11 adsorbed on the MWCNTs-BC flexible electrode achieved the direct electron transfer.•The resulting flexible electrode displayed excellent electrochemical catalytic activities toward of H2O2.In the present work, we report on an experimental study of flexible nanocomposite film for electrochemical detection of hydrogen peroxide (H2O2) based on bacterial cellulose (BC) and multi-walled carbon nanotubes (MWCNTs) in combination with microperoxidase-11 (MP-11). MWCNTs are used to functionalize BC and provide a flexible conductive film. On the other hand, BC can improve MWCNTs׳ biocompatibility. The investigation shows that MP-11 immobilized on the flexible film of MWCNTs–BC can easily present a pair of well-defined and quasi-reversible redox peaks, revealing a direct electrochemistry of MP-11 on the nanocomposite film. The apparent heterogeneous electron-transfer rate constant ks is estimated to be 11.5 s−1. The resulting flexible electrode presents appreciated catalytic properties for electrochemical detection of H2O2, comparing to traditional electrodes (such as gold, glassy carbon electrode) modified with MP-11. The proposed biosensor exhibits a low detection limit of 0.1 µM (at a signal-to-noise ratio of 3) with a linear range of 0.1–257.6 µM, and acquires a satisfactory stability.
Co-reporter:Bingyan Zhang, Xiaofan Zhang, Dekang Huang, Shaohui Li, Huailiang Yuan, Mingkui Wang, Yan Shen
Talanta 2015 Volume 141() pp:73-79
Publication Date(Web):15 August 2015
DOI:10.1016/j.talanta.2015.03.048
•Co9S8 Is firstly used for the non-enzymatic detection of Hydrogen peroxide.•The limit of detection for H2O2 based on Co9S8/GC electrode is 0.02 μM.•The Co9S8 sensor also exhibits good response toward glucose.This work reports on an experimental investigation of Co9S8 hollow spheres with excellent interfacial charge transfer ability for the electrochemical detection of hydrogen peroxide and glucose in alkaline environment. The result reveals that the Co9S8 hollow spheres exhibit excellent electrocatalytic activity for the reduction of hydrogen peroxide. An electrochemical sensor based on Co9S8 can be further realized, exhibiting a linear response range from 0.0001 to 11.11 mM for hydrogen peroxide with a low detection limit of 0.02 μM, and a high sensitivity of 267.2 mA mol−1 cm−2, which is one of the highest values among the non-enzymatic sensors based on inorganic oxides. The Co9S8 sensor also exhibits good response toward glucose at different concentrations. These results demonstrate that the as-prepared Co9S8 hollow spheres have a potential application in the development of sensors for enzyme-free detection of H2O2 and glucose.
Co-reporter:Shaohui Li;Dekang Huang;Bingyan Zhang;Xiaobao Xu;Mingkui Wang;Guang Yang
Advanced Energy Materials 2014 Volume 4( Issue 10) pp:
Publication Date(Web):
DOI:10.1002/aenm.201301655
Supercapacitors based on freestanding and flexible electrodes that can be fabricated with bacterial cellulose (BC), multiwalled carbon nanotubes (MWCNTs), and polyaniline (PANI) are reported. Due to the porous structure and electrolyte absorption properties of the BC paper, the flexible BC-MWCNTs-PANI hybrid electrode exhibits appreciable specific capacitance (656 F g−1 at a discharge current density of 1 A g−1) and remarkable cycling stability with capacitance degradation less than 0.5% after 1000 charge–discharge cycles at a current density of 10 A g−1. The facile and low-cost of this binder-free paper electrode may have great potential in development of flexible energy-storage devices.
Co-reporter:Bingyan Zhang, Huailiang Yuan, Xiaofan Zhang, Dekang Huang, Shaohui Li, Mingkui Wang, and Yan Shen
ACS Applied Materials & Interfaces 2014 Volume 6(Issue 23) pp:20913
Publication Date(Web):November 14, 2014
DOI:10.1021/am505569w
A fast quantum dots (QDs) regeneration process is necessary for highly efficient QDs-sensitized solar cells. Herein, CdSe and CdS QDs regeneration rates (kQD′) in three redox electrolytes, which are triiodide and iodide ions (I3–/I–), Co(bpy)3(PF6)2 and Co(bpy)3(PF6)3 (Co3+/Co2+), and 1-methy-1-H-tetrazole-5-thiolate and its dimer (T2/T–), have been first investigated with scanning electrochemical microscopy (SECM). The results reveal that the kinetics of QDs regeneration depends on the nature of the QDs and the redox shuttles presented in QDSSCs. For QDs of CdSe and CdS, the regeneration rate (kQD′) in the case of a T2/T–-based electrolyte is about two times larger than that of Co3+/Co2+ and I3–/I–. Additionally, the kQD′ for CdSe is about two times larger than that of CdS in the same redox shuttle electrolyte, which could be due to a large driving force for the reaction between the exited state quantum dots (QD+) and redox electrolytes.Keywords: interfacial charge transfer; quantum dots; regeneration kinetics; scanning electrochemical microscopy; solar cell
Co-reporter:Jianfeng Lu, Bingyan Zhang, Shuangshuang Liu, Hao Li, Huailiang Yuan, Yan Shen, Jie Xu, Yibing Cheng and Mingkui Wang
Physical Chemistry Chemical Physics 2014 vol. 16(Issue 45) pp:24755-24762
Publication Date(Web):06 Oct 2014
DOI:10.1039/C4CP03425B
This work introduces cyclopenta[1,2-b:5,4-b′]dithiophene (CPDT) as a spacer between the porphyrin chromophore and cyanoacetic acid to obtain a porphyrin dye (coded as LW9). The resultant novel porphyrin dye exhibits extended absorption spectra and a split B band at 520 nm. Therefore, a full spectrum light harvesting characterization of sensitized TiO2 mesoporous film can be achieved. To conduct a thorough investigation of the influence of the spacer unit, new sensitizers conjugated with biphenyl (LW7) and bithiophene (LW8) have been synthesized. As the electron-donating ability of the spacer varies from biphenyl to bithiophene and cyclopenta[1,2-b:5,4-b′]dithiophene, stepwise red-shifted electronic absorption spectra and the consistently decreasing energy gap of the dye are presented. These novel porphyrins have been evaluated in dye-sensitized solar cells, achieving a power efficiency of 6.5% employing a [Co(bpy)3]2+/3+ redox couple for the LW9 device under reporting conditions. Detailed investigation, including time-resolved photoluminescence, transient photovoltage decay, and scanning electrochemical spectroscopy measurements, provides important information on the factors affecting the principal photovoltaic parameters. The present report highlights the potential of D–π–D–A porphyrin for the development of efficient sensitizers with broad light absorption properties.
Co-reporter:Getachew Alemu, Jin Cui, Kun Cao, Junpeng Li, Yan Shen and Mingkui Wang
RSC Advances 2014 vol. 4(Issue 93) pp:51374-51380
Publication Date(Web):03 Oct 2014
DOI:10.1039/C4RA07908F
This work reports on a study of regeneration kinetics of organic dyes with pyridine ring group sensitized NiO electrodes in combination with iodide-based and organic thiolate-based electrolytes by scanning electrochemical microscopy (SCEM) with a feedback model. These dyes have showed promising performance in p-type dye-sensitized solar cells. The investigation reveals that the anchoring group affects the effective rate constant, showing an efficient dye-regeneration process for the dye with carboxylic acid anchoring groups. Meanwhile, it is worth noting that the regeneration process between the reduced dye and the oxidized state of the thiolate-based electrolyte is much faster than that of the iodide-based electrolyte.
Co-reporter:Jin Cui ; Jianfeng Lu ; Xiaobao Xu ; Kun Cao ; Zhong Wang ; Getachew Alemu ; Huailiang Yuang ; Yan Shen ; Jie Xu ; Yibing Cheng ;Mingkui Wang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 30) pp:16433-16440
Publication Date(Web):January 2, 2014
DOI:10.1021/jp410829c
Recently, p-type dye-sensitized solar cells (p-DSSCs) have attracted increasing attention. The widely used carboxylic acid groups for TiO2 based sensitizers may not be the optimal choice for p-DSSCs. Herein new donor-π-acceptor organic sensitizers with pyridine ring as anchoring group are designed and synthesized for p-DSSCs. The detailed investigation demonstrates that carboxylic acid groups may have an effect on the negative shift of the valence band edge of NiO induced by surface protonation, which lowers the hole-injection process and the device photovoltage, while the pyridine ring works effectively without this problem. The p-DSSC based on the new sensitizer shows an overall conversion efficiency of ∼0.16% under full sunlight (AM 1.5G, 100 mW cm–2) irradiation.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Dekang Huang, Huailiang Yuan, Mingkui Wang, Yan Shen
Carbon 2014 80() pp: 591-598
Publication Date(Web):
DOI:10.1016/j.carbon.2014.09.002
Co-reporter:Jianfeng Lu ; Bingyan Zhang ; Huailiang Yuan ; Xiaobao Xu ; Kun Cao ; Jin Cui ; Shuangshuang Liu ; Yan Shen ; Yibing Cheng ; Jie Xu ;Mingkui Wang
The Journal of Physical Chemistry C 2014 Volume 118(Issue 27) pp:14739-14748
Publication Date(Web):June 17, 2014
DOI:10.1021/jp5014829
Two new D−π–A porphyrin sensitizers (coded as LW5 and LW6) with extended conjugation units at π moiety are designed and synthesized for mesoscopic solar cells. While keeping the same donor moiety to the well-investigated porphyrin LD14, introduction of various linker units in the two new sensitizers with electron rich property can red-shift the absorption spectra to 710 nm, such as thiophene for the LW5 dye between porphyrin macrocycle and 4-ethynylbenzoic acid (i.e., the acceptor). The excited singlet state lifetime and charge regeneration rate constants have been examined to be ∼140 ps and 1 × 10–3 cm s–1 with time-resolved photoluminescence and scanning electrochemical microscopy measurements, respectively, indicating fast electron injection from the excited dyes to the TiO2 conduction band followed by quick charge regeneration of dye cations by electrolytes containing a [Co(bpy)3]2+/3+ redox couple. LW5 and LW6 dyes have been evaluated in dye-sensitized solar cells, showing efficiencies of 7.8% and 6.1% with [Co(bpy)3]2+/3+ based electrolytes (measured under standard test conditions), respectively. A detailed investigation with transient photovoltage decay measurement provides important information on factors affecting the principal photovoltaic parameters.
Co-reporter:Bingyan Zhang;Xiaobao Xu;Xiaofan Zhang;Dekang Huang;Shaohui Li;Yibo Zhang;Fang Zhan;Mingzhang Deng;Yahui He; Wei Chen; Yan Shen; Mingkui Wang
ChemPhysChem 2014 Volume 15( Issue 6) pp:1182-1189
Publication Date(Web):
DOI:10.1002/cphc.201301076
Abstract
Sensitizers are responsible for the light harvesting and the charge injection in dye-sensitized solar cells (DSSCs). A fast dye-regeneration process is necessary to obtain highly efficient DSSC devices. Herein, dye-regeneration rates of two DSSC device types, that is, the reduction of immediately formed photo-oxidized sensitizers (ruthenium complex C106TBA and porphyrin LD14, kox′) by iodide ions (I−) and [Co(bpy)3]2+, and the oxidation of formed photo-reduced sensitizers (organic dye P1, kre′) by triiodide ions (I3−) and the disulfide dimer (T2) are investigated by scanning electrochemical microscopy (SECM). We provide a thorough experimental verification of the feedback mode to compare the kinetics for dye-regeneration by using the above mentioned mediators. The charge recombination at the dye/semiconductor/electrolyte interface is further investigated by SECM. A theoretical model is applied to interpret the current response at the tip under short-circuit conditions, providing important information on factors that govern the dynamics of dye-regeneration onto the dye-sensitized heterojunction.
Co-reporter:Shaohui Li, Dekang Huang, Junchuan Yang, Bingyan Zhang, Xiaofan Zhang, Guang Yang, Mingkui Wang, Yan Shen
Nano Energy 2014 Volume 9() pp:309-317
Publication Date(Web):October 2014
DOI:10.1016/j.nanoen.2014.08.004
Advanced binder-free electrode materials with high mass-loading (~10 mg cm−2) have proved to be extremely important in determining the performance of pseudo-capacitors. In this work, freestanding and highly conductive paper electrodes with high mass loading in the range of 7–12 mg cm−2 are prepared using bacterial cellulose–polypyrrole nanofibres in combination with multi-walled carbon nanotubes via a simple vacuum-filtering method to realize highly stable and efficient pseudo-capacitors. A high capacitance of 2.43 F cm−2 at a mass of 11.23 mg cm−2 is achieved under standard reporting condition with these hybrid electrodes. By direct coupling of two membrane electrodes, symmetric supercapacitors can be easily fabricated without using any binders, conductive additives, and additional current collectors. The devices are able to offer large capacitance (590 mF cm−2) and excellent cycling stability (94.5% retention after 5000 cycles). Particularly, the electrode materials can be prepared in a large yield, which may open up new opportunities for development of low-cost and environmentally friendly paper-based energy-storage devices.Supercapacitors based on freestanding paper electrodes using bacterial cellulose–polypyrrole nanofibers in combination with multi-walled carbon nanotubes via a simple vacuum-filtering method show high performance 2.43 F cm−2 at the mass of 11.23 mg cm−2.
Co-reporter:Dekang Huang;Yanping Luo;Shaohui Li;Bingyan Zhang
Nano Research 2014 Volume 7( Issue 7) pp:1054-1064
Publication Date(Web):2014 July
DOI:10.1007/s12274-014-0468-1
Over the past few years, electrocatalysis for the oxygen reduction reaction in alkaline solutions has undergone tremendous advances, and non-precious metal catalysts are of prime interest. In this study, we present a highly promising CoO@Co/N-C (where N-C represents a N-doped carbon material) catalyst, achieving an onset potential of 0.99 V (versus the reversible hydrogen electrode (RHE)) and a limiting current density of 7.07 mA·cm−2 (at 0.3 V versus RHE) at a rotation rate of 2,500 rpm in an O2-saturated 0.1 M KOH solution, comparable to a commercial Pt/C catalyst. The H2-O2 alkaline fuel cell test of CoO@Co/N-C as the cathode reveals a maximum power density of 237 mW·cm−2. Detailed investigation clarifies that a synergistic effect, induced by C-N, Co-N-C, and CoO/Co moieties, is responsible for the bulk of the gain in catalytic activity.
Co-reporter:Dekang Huang, Jianfeng Lu, Shaohui Li, Yanping Luo, Chen Zhao, Bin Hu, Mingkui Wang, and Yan Shen
Langmuir 2014 Volume 30(Issue 23) pp:6990-6998
Publication Date(Web):2017-2-22
DOI:10.1021/la501052m
Here we report on an experimental study of an electrocatalyst for the hydrogen evolution reaction (HER) based on cobalt porphyrin and electrochemically reduced graphene oxide (ERGO) functional multilayer films, which are prepared by the alternating layer-by-layer (LBL) assembly of negatively charged graphene oxide (GO) and positively charged [tetrakis (N-methylpyridyl) porphyrinato] cobalt (CoTMPyP) in combination with an electrochemical reduction procedure. The resulting [ERGO@CoTMPyP]n multilayer films display relatively high electrocatalytic activity and superior stability toward HER in alkaline media. Electrochemical studies indicate that CoTMPyP in the multilayer films is the active catalyst for the reduction of protons to dihydrogen.
Co-reporter:Jianfeng Lu, Xiaobao Xu, Kun Cao, Jin Cui, Yibo Zhang, Yan Shen, Xiaobo Shi, Liangsheng Liao, Yibing Cheng and Mingkui Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 34) pp:10008-10015
Publication Date(Web):20 Jun 2013
DOI:10.1039/C3TA11870C
In this study, new push–pull alkoxy-wrapped zinc porphyrin dyes with intramolecular donor–π–acceptor structures have been designed and synthesized for dye-sensitized solar cells (DSCs). The linkers based on thiophene or 2,3-dihydrothieno[3,4-b][1,4] dioxine with cyanoacetic acid can broaden the spectral response of porphyrins into the near-IR region (∼850 nm), which is mainly attributed to the cyanoacetic acid group. However, porphyrins with cyanoacrylic acid as an anchoring group lead to a faster charge recombination rate at the dye-sensitized heterojunction interface, which lowers the device photovoltaic performance. By using porphyrins with a rigid π-linker feature structure that is 5-ethynylthiophene-2-carboxylic acid, highly efficient DSC devices with a power conversion efficiency of 9.5% can be obtained. Spectral, electrochemical, photovoltage transient decay and impedance measurements are performed to reveal the influence of π-conjugated linkers and anchoring groups upon the optoelectronic features of porphyrin dyes in DSCs.
Co-reporter:Xiaobao Xu, Bingyan Zhang, Jin Cui, Dehua Xiong, Yan Shen, Wei Chen, Licheng Sun, Yibing Cheng and Mingkui Wang
Nanoscale 2013 vol. 5(Issue 17) pp:7963-7969
Publication Date(Web):04 Jun 2013
DOI:10.1039/C3NR02169F
Herein, an organic redox couple 1-methy-1H-tetrazole-5-thiolate (T−) and its disulfide dimer (T2) redox shuttle, as an electrolyte, is introduced in a p-type dye-sensitized solar cell (DSC) on the basis of an organic dye (P1) sensitizer and nanocrystal CuCrO2 electrode. Using this iodide-free transparent redox electrolyte in conjunction with the sensitized heterojunction, we achieve a high open-circuit voltage of over 300 mV. An optimal efficiency of 0.23% is obtained using a CoS counter electrode and an optimized electrolyte composition under AM 1.5 G 100 mW cm−2 light illumination which, to the best of our knowledge, represents the highest efficiency that has so far been reported for p-type DSCs using organic redox couples.
Co-reporter:Dekang Huang, Bingyan Zhang, Yibo Zhang, Fang Zhan, Xiaobao Xu, Yan Shen and Mingkui Wang
Journal of Materials Chemistry A 2013 vol. 1(Issue 4) pp:1415-1420
Publication Date(Web):05 Nov 2012
DOI:10.1039/C2TA00552B
In this work we report on functional multilayer films containing electrochemically reduced graphene oxide (ERGO) by the alternating layer-by-layer (LBL) assembly of negatively charged graphene oxide (GO) and positively charged poly (diallyldimethylammonium chloride) (PDDA) in combination with an electrochemical reduction procedure. As a metal-free catalyst, the resulting [PDDA@ERGO] multilayer film possesses a remarkable electro-catalytic activity toward the oxygen reduction reaction (ORR) with superior methanol tolerance in alkaline media. Further research indicates that the unusual catalytic activity of the prepared hybrid films arises from synergetic chemical coupling effects between PDDA and ERGO. Importantly, the [PDDA@ERGO] multilayer film as a metal free oxygen reduction catalyst reported here is easy to build up with the advantages of fine control of the film thickness, being energy effective, fast and green without using dangerous and corrosive substances.
Co-reporter:Bingyan Zhang, Dekang Huang, Xiaobao Xu, Getachew Alemu, Yibo Zhang, Fang Zhan, Yan Shen, Mingkui Wang
Electrochimica Acta 2013 Volume 91() pp:261-266
Publication Date(Web):28 February 2013
DOI:10.1016/j.electacta.2012.12.026
In this study we develop a sensor based on helical carbon nanotubes (HCNTs) for the simultaneous electrochemical determination of ascorbic acid (AA), dopamine (DA), and uric acid (UA). A water soluble cationic polymer, poly(diallyl dimethylammonium chloride) (PDDA), is used to functionalize the nanotubes’ surface, aiming to improve the HCNTs dispersibility and adhesion to substrates. After electrochemical pre-treatment, the PDDA@HCNTs coated glassy carbon electrodes can separate the anodic oxidation potential of AA, DA and UA with well-defined peak separation in the presence of each other. The calibration curves were obtained in the range of 25–1045 μM L−1 for AA, 2.5–10 μM L−1 for DA, and 5.0–175 μM L−1 for UA. Detection limits of 0.12 μM L−1, 0.08 μM L−1, and 0.22 μM L−1 were obtained for AA, DA, and UA at pH 7.4, respectively. The analytical performance of this sensor has been evaluated for simultaneous detection of AA, DA, and UA in the fetal bovine serum samples.Highlights► Water soluble cationic polymer is used to functionalize HCNTs’ surface to improve their dispersibility and adhesion to substrates. ► The PDDA@HCNTs displays excellent electrocatalytic activity toward the electrochemical oxidation of AA, DA and UA ► The PDDA@HCNTs could simultaneously detect the AA, DA and UA in the fetal bovine serum samples.
Co-reporter:Yan Shen, Fang Zhan, Jianfeng Lu, Bingyan Zhang, Dekang Huang, Xiaobao Xu, Yibo Zhang, Mingkui Wang
Thin Solid Films 2013 Volume 545() pp:327-331
Publication Date(Web):31 October 2013
DOI:10.1016/j.tsf.2013.08.002
•Hybrid films were fabricated with layer-by-layer self-assembly method.•The catalytic activity of hybrid films to oxygen reduction reaction was studied.•The aggregation of composites could be contributed to the decreased activity.We report on the fabrication of hybrid films of gold nanoparticles (AuNPs) and [tetrakis (N-methylpyridyl)porphyrinato] cobalt (CoTMPyP) based on electrostatic layer-by-layer (LBL) self-assembly technique. A three-dimensional nanostructured film composed of positively charged CoTMPyP and negatively charged poly(acrylic acid)-stabilized AuNPs can be formed onto various substrates, including 4-aminobenzoic acid modified glassy carbon electrode, 11-mercaptotroponic acid modified gold film, and quartz plate with negatively charged surface. The regular growth of hybrid films is investigated by UV–vis spectroscopy, surface plasma resonance, and impedance spectroscopy. The prepared multilayer films possess flexible electro-catalytic activity toward O2 reduction reaction. It is noted that the electro-catalytic capability of the prepared multilayer film decreases as bilayer number increases. The unexpected observation of catalytic activity with bilayer number is investigated in detail.
Co-reporter:Jianfeng Lu;Xiaobao Xu;Zhihong Li;Kun Cao;Jin Cui;Yibo Zhang; Yan Shen;Yi Li; Jun Zhu; Songyuan Dai; Wei Chen; Yibing Cheng; Mingkui Wang
Chemistry – An Asian Journal 2013 Volume 8( Issue 5) pp:956-962
Publication Date(Web):
DOI:10.1002/asia.201201136
Abstract
Anchoring groups are extremely important in controlling the performance of dye-sensitized solar cells (DSCs). The design and characterization of sensitizers with new anchoring groups, in particular non-carboxylic acid groups, has become a recent focus of DSC research. Herein, new donorπacceptor zincporphyrin dyes with a pyridine ring as an anchoring group have been designed and synthesized for applications in DSCs. Photophysical and electrochemical investigations demonstrated that the pyridine ring worked effectively as an anchoring group for the porphyrin sensitizers. DSCs that were based on these new porphyrins showed an overall power-conversion efficiency of about 4.0 % under full sunlight (AM 1.5G, 100 mW cm−2).
Co-reporter:Jie Bai;Xiaobao Xu;Dr. Ling Xu;Jin Cui;Dekang Huang; Wei Chen; Yibing Cheng; Yan Shen; Mingkui Wang
ChemSusChem 2013 Volume 6( Issue 4) pp:622-629
Publication Date(Web):
DOI:10.1002/cssc.201200935
Abstract
ZnO nanoparticles are doped with K and applied in p-type dye-sensitized solar cells (DSCs). The microstructure and dynamics of hole transportation and recombination are investigated. The morphology of the K-doped ZnO nanoparticles shows a homogeneous distribution with sizes in the range 30–40 nm. When applied in p-type DSCs in combination with C343 as sensitizer, the K-doped ZnO nanoparticles achieve a photovoltaic power conversion efficiency of 0.012 % at full-intensity sunlight. A further study on the device by transient photovoltage/photocurrent decay measurements shows that the K-doped ZnO nanoparticles have an appreciable hole diffusion coefficient (ca. 10−6 cm2 s−1). Compared to the widely used p-type NiO nanoparticles, this advantage is crucial for further improving the efficiency of p-type DSCs.
Co-reporter:Xiaobao Xu, Kun Cao, Dekang Huang, Yan Shen, and Mingkui Wang
The Journal of Physical Chemistry C 2012 Volume 116(Issue 48) pp:25233-25241
Publication Date(Web):November 7, 2012
DOI:10.1021/jp308109t
Redox electrolyte has been proven to be extremely important in determining the optoelectronic properties in dye-sensitized solar cells (DSCs). Herein, we report on the application of various disulfide/thiolate redox shuttles within organic or aqueous electrolyte in conjunction with a dye-sensitized heterojunction. Electrochemical impedance spectroscopy is used to explore the difference in DSCs’ performance using disulfide/thiolate-based redox shuttles system in term of solvent effect and cations effect. A long interfacial charge recombination lifetime is found in disulfide/thiolate-based cells compared with that in iodide/triiodide cells, which can be attributed to different recombination states in these devices.
Co-reporter:Xiaowei Lv, Minglei Cao, Weina Shi, Mingkui Wang, Yan Shen
Carbon (June 2017) Volume 117() pp:
Publication Date(Web):June 2017
DOI:10.1016/j.carbon.2017.02.096
In the present work, we report on a two-step vapor deposition (TVD) process of depositing graphitic carbon nitride (g-CN) films for photoelectrochemical (PEC) application. The method is versatile for various monomers including cyanamide, dicyanamide and melamine as well as different substrates. The role of deposition temperature and amount of monomers has been investigated in detail. Structural and surface morphological studies suggest uniform and pinhole-free g-CN films could be achieved with this feasible method. Photon-induced oxygen evolution upon anodic polarization in aqueous electrolytes brings up a photocurrent density of 63 μA cm−2 for the g-CN films prepared with dicyanamide. This is the highest value to date for a pristine g-CN photoanode at the bias of 1.23 V (versus reversible hydrogen electrode) without sacrificial reagents. The good performance could be attributed to an enhanced light harvesting and decreased charge transport resistance at the film/electrolyte interface with an increase of amount of monomers. Accordingly, the strategy of TVD brings g-CN another step to applying as photoactive material in various photoelectronic fields. Furthermore, this method can also be easily extended to synthesis of heterojunction in the second-step of TVD process by choosing proper substrates to further enhance the PEC properties.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Zhixiang Zuo, Mingkui Wang and Yan Shen
Journal of Materials Chemistry A 2015 - vol. 3(Issue 18) pp:NaN10025-10025
Publication Date(Web):2015/03/27
DOI:10.1039/C5TA00613A
Chemical modification of the aligned single crystalline TiO2 nanorods provides possibilities to improve their photoelectrochemical (PEC) activity under visible light. This work reports on the N/Si co-doped single crystal rutile TiO2 nanorods fabricated by a flexible one-step hydrothermal procedure for PEC water splitting, exhibiting a photocurrent of 1.77 mA cm−2 at 1.23 V vs. RHE and a noticeable visible-light response under standard testing conditions (xenon lamp with an AM 1.5 G filter, 100 mW cm−2). The excellent PEC activity can be attributed to the synergetic effect of N and Si co-dopants, which enhances the incident photon to current conversion efficiency both in ultraviolet and visible regions, and improves the charge transfer at the photoanode/electrolyte interface. A solar-powered water splitting device has been designed by combining an efficient perovskite solar cell with the N/Si co-doped TiO2 NRs-based PEC system, achieving an overall solar-to-hydrogen efficiency of 1.1%. This has been the highest value reported for TiO2-based PEC systems so far.
Co-reporter:Xiaofan Zhang, Bingyan Zhang, Kun Cao, Jérémie Brillet, Jianyou Chen, Mingkui Wang and Yan Shen
Journal of Materials Chemistry A 2015 - vol. 3(Issue 43) pp:NaN21636-21636
Publication Date(Web):2015/09/02
DOI:10.1039/C5TA05838D
Converting solar energy into hydrogen via photoelectrochemical water splitting has attracted significant attention during the past decades. Herein, we design a novel core/shell TiO2@BiVO4 photoanode in combination with a CH3NH3PbI3-based perovskite solar cell for unassisted solar water splitting. Compared to pristine TiO2 NRs, the resulting TiO2@BiVO4 film exhibits a 3.25-fold enhanced photocurrent density (∼1.3 mA cm−2) under irradiation (xenon lamp coupled with an AM 1.5 G filter, 100 mW cm−2). This significant enhancement is attributed to the excellent light absorption properties of BiVO4 and a fast electron transfer process in the single crystalline TiO2 NRs. Especially, the type-II band alignment between the BiVO4 and rutile TiO2 NRs provides a large driving force for electron injection from the BiVO4 to the TiO2. The perovskite solar cell-TiO2@BiVO4 photoelectrochemical tandem device exhibits an overall solar-to-hydrogen efficiency of 1.24%, comparable to other TiO2-based PV/PEC systems.
Co-reporter:Dekang Huang, Bingyan Zhang, Yibo Zhang, Fang Zhan, Xiaobao Xu, Yan Shen and Mingkui Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 4) pp:NaN1420-1420
Publication Date(Web):2012/11/05
DOI:10.1039/C2TA00552B
In this work we report on functional multilayer films containing electrochemically reduced graphene oxide (ERGO) by the alternating layer-by-layer (LBL) assembly of negatively charged graphene oxide (GO) and positively charged poly (diallyldimethylammonium chloride) (PDDA) in combination with an electrochemical reduction procedure. As a metal-free catalyst, the resulting [PDDA@ERGO] multilayer film possesses a remarkable electro-catalytic activity toward the oxygen reduction reaction (ORR) with superior methanol tolerance in alkaline media. Further research indicates that the unusual catalytic activity of the prepared hybrid films arises from synergetic chemical coupling effects between PDDA and ERGO. Importantly, the [PDDA@ERGO] multilayer film as a metal free oxygen reduction catalyst reported here is easy to build up with the advantages of fine control of the film thickness, being energy effective, fast and green without using dangerous and corrosive substances.
Co-reporter:Jianfeng Lu, Xiaobao Xu, Kun Cao, Jin Cui, Yibo Zhang, Yan Shen, Xiaobo Shi, Liangsheng Liao, Yibing Cheng and Mingkui Wang
Journal of Materials Chemistry A 2013 - vol. 1(Issue 34) pp:NaN10015-10015
Publication Date(Web):2013/06/20
DOI:10.1039/C3TA11870C
In this study, new push–pull alkoxy-wrapped zinc porphyrin dyes with intramolecular donor–π–acceptor structures have been designed and synthesized for dye-sensitized solar cells (DSCs). The linkers based on thiophene or 2,3-dihydrothieno[3,4-b][1,4] dioxine with cyanoacetic acid can broaden the spectral response of porphyrins into the near-IR region (∼850 nm), which is mainly attributed to the cyanoacetic acid group. However, porphyrins with cyanoacrylic acid as an anchoring group lead to a faster charge recombination rate at the dye-sensitized heterojunction interface, which lowers the device photovoltaic performance. By using porphyrins with a rigid π-linker feature structure that is 5-ethynylthiophene-2-carboxylic acid, highly efficient DSC devices with a power conversion efficiency of 9.5% can be obtained. Spectral, electrochemical, photovoltage transient decay and impedance measurements are performed to reveal the influence of π-conjugated linkers and anchoring groups upon the optoelectronic features of porphyrin dyes in DSCs.
Co-reporter:Jianfeng Lu;Bingyan Zhang;Shuangshuang Liu;Hao Li;Huailiang Yuan;Jie Xu;Yibing Cheng;Mingkui Wang
Physical Chemistry Chemical Physics 2014 - vol. 16(Issue 45) pp:
Publication Date(Web):2014/10/30
DOI:10.1039/C4CP03425B
This work introduces cyclopenta[1,2-b:5,4-b′]dithiophene (CPDT) as a spacer between the porphyrin chromophore and cyanoacetic acid to obtain a porphyrin dye (coded as LW9). The resultant novel porphyrin dye exhibits extended absorption spectra and a split B band at 520 nm. Therefore, a full spectrum light harvesting characterization of sensitized TiO2 mesoporous film can be achieved. To conduct a thorough investigation of the influence of the spacer unit, new sensitizers conjugated with biphenyl (LW7) and bithiophene (LW8) have been synthesized. As the electron-donating ability of the spacer varies from biphenyl to bithiophene and cyclopenta[1,2-b:5,4-b′]dithiophene, stepwise red-shifted electronic absorption spectra and the consistently decreasing energy gap of the dye are presented. These novel porphyrins have been evaluated in dye-sensitized solar cells, achieving a power efficiency of 6.5% employing a [Co(bpy)3]2+/3+ redox couple for the LW9 device under reporting conditions. Detailed investigation, including time-resolved photoluminescence, transient photovoltage decay, and scanning electrochemical spectroscopy measurements, provides important information on the factors affecting the principal photovoltaic parameters. The present report highlights the potential of D–π–D–A porphyrin for the development of efficient sensitizers with broad light absorption properties.
Co-reporter:Bin-Bin Ma, Hua Zhang, Yu Wang, Yu-Xin Peng, Wei Huang, Ming-Kui Wang and Yan Shen
Journal of Materials Chemistry A 2015 - vol. 3(Issue 29) pp:NaN7755-7755
Publication Date(Web):2015/06/22
DOI:10.1039/C5TC00909J
Two small molecular chromogenic sensors (azine MS-1 and azomethine MS-2) were synthesized for acid–base discoloration and optoelectronic investigations. It was found that the color of both sensors in solution and in the solid state changed obviously from yellow to purple and blue after treatment with acid, which could be easily detected by the naked eye. Furthermore, single-crystal conductance of MS-1 and MS-2 could be significantly enhanced after treatment with HCl gas flow. On the other hand, MS-2 showed relatively good film-forming ability and could be used as a hole transport material (HTM) in perovskite solar cells, exhibiting a power conversion efficiency (PCE) of 6.68%. To the best of our knowledge, this is the first demonstration of perovskite solar cells including a HTM based on a low-cost Schiff-base.
Co-reporter:Lin Gao, Shaohui Li, Dekang Huang, Yan Shen and Mingkui Wang
Journal of Materials Chemistry A 2015 - vol. 3(Issue 18) pp:NaN10113-10113
Publication Date(Web):2015/03/23
DOI:10.1039/C5TA01054C
This work reports on porous Li4Ti5O12 (LTO)–TiO2 nanosheet arrays prepared via a versatile hydrothermal method for lithium ion batteries, exhibiting a high initial discharge capacity of 184.6 mA h g−1 at 200 mA g−1 and possessing excellent electrochemical stability with only 8.3% loss of specific capacity at 1 A g−1 in a prolonged charge–discharge process (1000 cycles). The excellent electrochemical performance can be attributed to the interconnected mesoporous/macroporous structures and the abundant grain boundaries generated by the existing multiphase materials, as well as the direct connection between the nanoarrays and conductive Ti substrates which facilitates the lithium ion and electron transportation. A flexible lithium ion battery has been further designed by using the nanosheet LTO–TiO2 arrays as the anode and LiCoO2 as the cathode, enabling it to reliably power an LED light under severe mechanical bending. This is very promising for future potential application in high performance flexible energy storage devices.
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