Long-Lived, Visible-Light-Excited Charge Carriers of TiO2/BiVO4Nanocomposites and their Unexpected Photoactivity for Water Splitting

2013 ◽  
Vol 4 (5) ◽  
pp. 1300995 ◽  
Author(s):  
Mingzheng Xie ◽  
Xuedong Fu ◽  
Liqiang Jing ◽  
Peng Luan ◽  
Yujie Feng ◽  
...  
2018 ◽  
Vol MA2018-01 (31) ◽  
pp. 1910-1910
Author(s):  
Il Yong Choi ◽  
Donghun Kim ◽  
Tae Hwa Jeon ◽  
Byeong-Gyu Chae ◽  
Kug-Seung Lee ◽  
...  

Solar-powered photoelectrochemical (PEC) water splitting has been a promising candidate for producing hydrogen in a clean and renewable way. Photoelectrodes are key components in PEC cells for efficient and stable hydrogen generation because they play crucial roles in absorption of photons, the separation and transportation of photo-generated charge carriers, as well as the chemical reactions with water. A variety of metal oxides for efficient photoelectrode have been intensively explored, but it is still challenging to find desirable materials to satisfy lots of requirements for PEC water splitting. Iron oxide (hematite, Fe2O3) has recently attracted much attention due to its earth abundance, low cost as well as desirable material properties for PEC water oxidation including narrow band gap energy of 2.0~2.2eV for visible light absorption and proper energy band alignment, etc. However, Fe2O3 has very short hole diffusion length and low carrier mobility, which causes considerable recombination of photo-generated electrons and holes. A lot of approaches such as nanostructures, heterojunction with other materials, surface modification, etc. have been reported to prevent the recombination of charge carriers and improve electrical properties of Fe2O3; however, these require complex manufacturing processes. In the present work, we found a much simpler way to improve the electrical properties of Fe2O3 film, namely defect-pairs due to co-doping. Titanium (Ti) and carbon (C) co-doped thin Fe2O3 film (i.e. (Ti,C)-Fe2O3) has been realized via a combination of simple solution-based spin-coating and tube furnace annealing process. This film turns out to lead significantly enhanced PEC performance when used as a photoanode: an impressively high photocurrent density of more than 4.5mAcm-2 was achieved at 1.23VRHE under AM1.5G solar spectrum and 1 sun illumination. This is compared to the value of Ti-doped Fe2O3 film, which is only about 2.6mAcm-2 photocurrent density at 1.23VRHE even though the optical properties of each film are similar. The origin for such substantial enhancement was revealed using a series of experimental and computational spectroscopies. X-ray absorption spectroscopy, electrochemical impedance measurements and density-functional-theory calculations both indicate that C atoms can be more deeply and heavily doped under the existence of Ti dopants in Fe2O3 film and then the defect-pairs of Ti and C increase not only charge carrier density but also electron’s mobility. An emphasis should be placed on the fact that this achievement was not assisted by co-catalysts and complex nanostructuring methods; hence even higher performance is expected when the film is further treated with extra-cares.


2021 ◽  
Vol 12 (1) ◽  
Author(s):  
Vikas Nandal ◽  
Ryota Shoji ◽  
Hiroyuki Matsuzaki ◽  
Akihiro Furube ◽  
Lihua Lin ◽  
...  

AbstractOxysulfide semiconductor, Y2Ti2O5S2, has recently discovered its exciting potential for visible-light-induced overall water splitting, and therefore, imperatively requires the probing of unknown fundamental charge loss pathways to engineer the photoactivity enhancement. Herein, transient diffuse reflectance spectroscopy measurements are coupled with theoretical calculations to unveil the nanosecond to microsecond time range dynamics of the photogenerated charge carriers. In early nanosecond range, the pump-fluence-dependent decay dynamics of the absorption signal is originated from the bimolecular recombination of mobile charge carriers, in contrast, the power-law decay kinetics in late microsecond range is dominated by hole detrapping from exponential tail trap states of valence band. A well-calibrated theoretical model estimates various efficiency limiting material parameters like recombination rate constant, n-type doping density and tail-states parameters. Compared to metal oxides, longer effective carrier lifetime ~6 ns is demonstrated. Different design routes are proposed to realize efficiency beyond 10% for commercial solar-to-hydrogen production from oxysulfide photocatalysts.


Processes ◽  
2021 ◽  
Vol 9 (6) ◽  
pp. 1055
Author(s):  
Yihang Chen ◽  
Yanfei Liu ◽  
Zhen Ma

Protonated g-C3N4 (pCN) formed by treating bulk g-C3N4 with an aqueous HCl solution was modified with D149 dye, i.e., 5-[[4[4-(2,2-diphenylethenyl) phenyl]-1,2,3,3a,4,8b-hexahydrocyclopent[b]indol-7-yl] methylene]-2-(3-ethyl-4-oxo-2-thioxo-5-thiazolidinylidene)-4-oxo-thiazolidin-2-ylidenerhodanine, for photocatalytic water splitting (using Pt as a co-catalyst). The D149/pCN-Pt composite showed a much higher rate (2138.2 µmol·h−1·g−1) of H2 production than pCN-Pt (657.0 µmol·h−1·g−1). Through relevant characterization, the significantly high activity of D149/pCN-Pt was linked to improved absorption of visible light, accelerated electron transfer, and more efficient separation of charge carriers. The presence of both D149 and Pt was found to be important for these factors. A mechanism was proposed.


2020 ◽  
Vol 16 ◽  
Author(s):  
Yuxue Wei ◽  
Honglin Qin ◽  
Jinxin Deng ◽  
Xiaomeng Cheng ◽  
Mengdie Cai ◽  
...  

Introduction: Solar-driven photocatalytic hydrogen production from water splitting is one of the most promising solutions to satisfy the increasing demands of a rapidly developing society. CdS has emerged as a representative semiconductor photocatalyst due to its suitable band gap and band position. However, the poor stability and rapid charge recombination of CdS restrict its application for hydrogen production. The strategy of using a cocatalyst is typically recognized as an effective approach for improving the activity, stability, and selectivity of photocatalysts. In this review, recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation are summarized. In particular, the factors affecting the photocatalytic performance and new cocatalyst design, as well as the general classification of cocatalysts, are discussed, which includes a single cocatalyst containing noble-metal cocatalysts, non-noble metals, metal-complex cocatalysts, metal-free cocatalysts, and multi-cocatalysts. Finally, future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are described. Background: Photocatalytic hydrogen evolution from water splitting using photocatalyst semiconductors is one of the most promising solutions to satisfy the increasing demands of a rapidly developing society. CdS has emerged as a representative semiconductor photocatalyst due to its suitable band gap and band position. However, the poor stability and rapid charge recombination of CdS restrict its application for hydrogen production. The strategy of using a cocatalyst is typically recognized as an effective approach for improving the activity, stability, and selectivity of photocatalysts. Methods: This review summarizes the recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation. Results: Recent developments in CdS cocatalysts for hydrogen production from water splitting under visible-light irradiation are summarized. The factors affecting the photocatalytic performance and new cocatalyst design, as well as the general classification of cocatalysts, are discussed, which includes a single cocatalyst containing noble-metal cocatalysts, non-noble metals, metal-complex cocatalysts, metal-free cocatalysts, and multi-cocatalysts. Finally, future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are described. Conclusion: The state-of-the-art CdS for producing hydrogen from photocatalytic water splitting under visible light is discussed. The future opportunities and challenges with respect to the optimization and theoretical design of cocatalysts toward the CdS photocatalytic hydrogen evolution are also described.


Author(s):  
Xin Zou ◽  
Xueyang Han ◽  
Chengxiong Wang ◽  
Yunkun Zhao ◽  
Chun Du ◽  
...  

Ta3N5 is regarded as a promising candidate material with adequate visible light absorption and band structure for photoelectrochemical water splitting. However, the performance of Ta3N5 is severely limited by the...


Author(s):  
Jacob Schneidewind ◽  
Miguel A. Argüello Cordero ◽  
Henrik Junge ◽  
Stefan Lochbrunner ◽  
Matthias Beller

A new mechanism for light-driven water splitting is described, which decreases the reaction's complexity and offers a new way to extend the range of usable wavelengths far into the visible region.


Author(s):  
Chao Zhang ◽  
Baoquan Liu ◽  
Weiping Li ◽  
Xiangxue Liu ◽  
Ke Wang ◽  
...  

Well-designed honeycomb Co3O4@CdS (H-Co3O4@CdS) was fabricated via a one-step strategy for efficient water splitting. During the decoration of CdS, honeycomb Co3O4 (H-Co3O4) with macropore was formed simultaneously. H-Co3O4 could enhance...


2021 ◽  
Vol 9 (14) ◽  
pp. 4971-4977
Author(s):  
Mehmet Emin Kilic ◽  
Kwang-Ryeol Lee

Tetrahexagonal AlN: a novel two-dimensional family for photocatalytic water splitting with exceptional mechanical, electronic, and optical properties.


Sign in / Sign up

Export Citation Format

Share Document