Water Splitting on Composite Plasmonic-Metal/Semiconductor Photoelectrodes: Evidence for Selective Plasmon-Induced Formation of Charge Carriers near the Semiconductor Surface

2011 ◽  
Vol 133 (14) ◽  
pp. 5202-5205 ◽  
Author(s):  
David B. Ingram ◽  
Suljo Linic
Keyword(s):  
Water Splitting ◽  
Charge Carriers ◽  
Semiconductor Surface

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 ◽  
...  
Keyword(s):  
Visible Light ◽  
Water Splitting ◽  
Charge Carriers

scholarly journals Stability and Degradation Mechanismof Si-based Photocathodes for Water Splitting with Ultrathin TiO2 Protection Layer

2019 ◽  
Vol 0 (0) ◽  
Author(s):  
Emanuel Ronge ◽  
Thorsten Cottre ◽  
Katharina Welter ◽  
Vladimir Smirnov ◽  
Natalie Jacqueline Ottinger ◽  
...  
Keyword(s):  
Water Splitting ◽  
Atomic Layer ◽  
Degradation Process ◽  
Alkaline Media ◽  
Semiconductor Surface ◽  
Nucleation Sites ◽  
Enhanced Solubility ◽  
High Structural Perfection ◽  
Protection Layer ◽  
The Stability

Abstract Using transmission and scanning electron microscopy, we study mechanisms which determine the stability of Silicon photocathodes for solar driven water splitting. Such tandem or triple devices can show a promising stability as photocathodes if the semiconductor surface is protected by an ultrathin TiO2 protection layer. Using atomic layer deposition (ALD) with Cl-precursors, 4–7 nm thick TiO2 layers can be grown with high structural perfection. The layer can be electrochemically covered by Pt nanoparticels serving as electro-catalysts. However, Cl-remnants which are typically present in such layers due to incomplete oxidation, are the origin of an electrochemical degradation process. After 1 h AM1.5G illumination in alkaline media, circular shaped corrosion craters appear in the topmost Si layer, although the TiO2 layer is intact in most parts of the crater. The crater development is stopped at local inhomogenities with a higher Pt coverage. The observations suggests that reduced Titanium species due to Cl−/O2− substitution are nucleation sites of the initial corrosion steps due to enhanced solubility of reduced Ti in the electrolyte. This process is followed by electrochemical dissolution of Si, after direct contact between the electrolyte and the top Si layer surface. To increase the stability of TiO2 protected photocathodes, formation of reduced Ti species must be avoided.

scholarly journals TiO2 Nanosheet Arrays with Layered SnS2 and CoOx Nanoparticles for Efficient Photoelectrochemical Water Splitting

2019 ◽  
Vol 14 (1) ◽  
Author(s):  
Zhou Cao ◽  
Yanling Yin ◽  
Peng Fu ◽  
Dong Li ◽  
Yulan Zhou ◽  
...  
Keyword(s):  
Water Splitting ◽  
Water Oxidation ◽  
Environmental Issues ◽  
Charge Carriers ◽  
Oxidation Catalyst ◽  
Hydrogen Fuel ◽  
Nanosheet Array ◽  
Nanosheet Arrays ◽  
Global Energy Supply ◽  
Pec Water Splitting

Abstract Converting solar energy into sustainable hydrogen fuel by photoelectrochemical (PEC) water splitting is a promising technology to solve increasingly serious global energy supply and environmental issues. However, the PEC performance based on TiO2 nanomaterials is hindered by the limited sunlight-harvesting ability and its high recombination rate of photogenerated charge carriers. In this work, layered SnS2 absorbers and CoOx nanoparticles decorated two-dimensional (2D) TiO2 nanosheet array photoelectrode have been rationally designed and successfully synthesized, which remarkably enhanced the PEC performance for water splitting. As the result, photoconversion efficiency of TiO2/SnS2/CoOx and TiO2/SnS2 hybrid photoanodes increases by 3.6 and 2.0 times under simulated sunlight illumination, compared with the bare TiO2 nanosheet arrays photoanode. Furthermore, the TiO2/SnS2/CoOx photoanode also presented higher PEC stability owing to CoOx catalyst served as efficient water oxidation catalyst as well as an effective protectant for preventing absorber photocorrosion.

scholarly journals Photocatalytic water splitting by N-TiO2 on MgO (111) with exceptional quantum efficiencies at elevated temperatures

2019 ◽  
Vol 10 (1) ◽  
Author(s):  
Yiyang Li ◽  
Yung-Kang Peng ◽  
Liangsheng Hu ◽  
Jianwei Zheng ◽  
Dharmalingam Prabhakaran ◽  
...  
Keyword(s):  
Water Splitting ◽  
Elevated Temperatures ◽  
Practical Method ◽  
Charge Carriers ◽  
Molar Ratio ◽  
Electron Hole ◽  
Photocatalytic Water Splitting ◽  
The Past ◽  
Electron Hole Pair ◽  
Electric Field Polarization

Abstract Photocatalytic water splitting is attracting enormous interest for the storage of solar energy but no practical method has yet been identified. In the past decades, various systems have been developed but most of them suffer from low activities, a narrow range of absorption and poor quantum efficiencies (Q.E.) due to fast recombination of charge carriers. Here we report a dramatic suppression of electron-hole pair recombination on the surface of N-doped TiO2 based nanocatalysts under enhanced concentrations of H+ and OH−, and local electric field polarization of a MgO (111) support during photolysis of water at elevated temperatures. Thus, a broad optical absorption is seen, producing O2 and H2 in a 1:2 molar ratio with a H2 evolution rate of over 11,000 μmol g−1 h−1 without any sacrificial reagents at 270 °C. An exceptional range of Q.E. from 81.8% at 437 nm to 3.2% at 1000 nm is also reported.

scholarly journals First Principle Calculation of Electronic, Optical Properties and Photocatalytic Potential of CuO Surfaces

2016 ◽  
Vol 1 ◽  
Author(s):  
Faozan Ahmad
Keyword(s):  
Optical Properties ◽  
Electronic Structure ◽  
Band Gap ◽  
Water Splitting ◽  
Co2 Reduction ◽  
Band Edge ◽  
Semiconductor Surface ◽  
First Principle Calculation ◽  
Stable Surface ◽  
Input Parameters

<p class="TTPKeywords">We have performed DFT calculations of electronic structure, optical properties and photocatalytic potential of the low-index surfaces of CuO. Photocatalytic reaction on the surface of semiconductor requires the appropriate band edge of the semiconductor surface to drive redox reactions. The calculation begins with the electronic structure of bulk system; it aims to determine realistic input parameters and band gap prediction. CuO is an antiferromagnetic material with strong electronic correlations, so that we have applied DFT + U calculation with spin polarized approach, beside it, we also have used GW approximation to get band gap correction. Based on the input parameters obtained, then we calculate surface energy, work function and band edge of the surfaces based on a framework developed by Bendavid et al (J. Phys. Chem. B, 117, 15750-15760) and then they are aligned with redox potential needed for water splitting and CO<sub>2</sub> reduction. Based on the calculations result can be concluded that not all of low-index CuO have appropriate band edge to push reaction of water splitting and CO2 reduction, only the surface CuO(111) and CuO(011) which meets the required band edge. Fortunately, based on the formation energy, CuO(111) and CuO(011) is the most stable surface. The last we calculate electronic structure and optical properties (dielectric function) of low-index surface of CuO, in order to determine the surface state of the most stable surface of CuO.</p>

scholarly journals Hierarchical Ternary Sulfides as Effective Photocatalyst for Hydrogen Generation Through Water Splitting: A Review on the Performance of ZnIn2S4

Catalysts ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 277
Author(s):  
Ravichandran Janani ◽  
Raja Preethi V ◽  
Shubra Singh ◽  
Aishwarya Rani ◽  
Chang-Tang Chang
Keyword(s):  
Water Splitting ◽  
Light Absorption ◽  
Hydrogen Generation ◽  
Low Cost ◽  
Charge Carriers ◽  
Special Focus ◽  
Material Efficiency ◽  
Photocatalytic Hydrogen Generation ◽  
Ternary Sulfide ◽  
Cost Efficient

One of the major aspects and advantages of solar energy conversion is the photocatalytic hydrogen generation using semiconductor materials for an eco-friendly technology. Designing a low-cost efficient material to overcome limited light absorption as well as rapid recombination of photogenerated charge carriers is essential to achieve considerable hydrogen generation. In recent years, sulfide based semiconductors have attracted scientific research interest due to their excellent solar response and narrow band gap. The present review focuses on the recent approaches in the development of hierarchical ternary sulfide based photocatalysts with a special focus on ZnIn2S4. We also observe how the electronic structure of ZnIn2S4 is beneficial for water splitting and the various strategies involved for improving the material efficiency for photocatalytic hydrogen generation. The review places emphasis on the latest advancement/new insights on ZnIn2S4 being used as an efficient material for hydrogen generation through photocatalytic water splitting. Recent progress on essential aspects which govern light absorption, charge separation and transport are also discussed in detail.

Defect-Pairs of Titanium and Carbon in Iron Oxide Film for Efficient Visible Light Driven Water Splitting

2018 ◽  
Vol MA2018-01 (31) ◽  
pp. 1910-1910
Author(s):  
Il Yong Choi ◽  
Donghun Kim ◽  
Tae Hwa Jeon ◽  
Byeong-Gyu Chae ◽  
Kug-Seung Lee ◽  
...  
Keyword(s):  
Iron Oxide ◽  
Electrical Properties ◽  
Visible Light ◽  
Water Splitting ◽  
Density Functional ◽  
Photocurrent Density ◽  
Band Alignment ◽  
Charge Carriers ◽  
Charge Carrier Density ◽  
Pec Water Splitting

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.

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