Efficient hydrogen evolution from water over thin film photocathode composed of solid solutions between ZnSe and Cu(In, Ga)Se2 with composition gradient

2021 ◽  
Vol 119 (12) ◽  
pp. 123905
Author(s):  
Tsutomu Minegishi ◽  
Shingi Yamaguchi ◽  
Masakazu Sugiyama
Keyword(s):  
Thin Film ◽  
Hydrogen Evolution ◽  
Solid Solutions ◽  
Composition Gradient

scholarly journals Electrodeposition of Iridium-Nickel Thin Films on Copper Foam: Effects of Loading and Solution Temperature on HER Performance of Electrocatalyst in Alkaline Water

2020 ◽  
Author(s):  
Jianwen Liu ◽  
Wangping Wu ◽  
Xiang Wang
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
Hydrogen Evolution ◽  
Electrocatalytic Activity ◽  
Electrochemical Impedance ◽  
Low Cost ◽  
Solution Temperature ◽  
High Deposition Rate ◽  
Hydrogen Energy ◽  
Copper Foam

Developing novel hydrogen evolution reaction (HER) catalysts with high activity, high stability and low cost is of great importance for the applications of hydrogen energy. In this work, iridium-nickel (Ir-Ni) thin films were electrodeposited on a copper foam as electrocatalyst for HER, and electrodeposition mechanism of Ir-Ni film was studied. The morphology and chemical composition of thin films were determined by scanning electron microscopy and energy-dispersive spectroscopy, respectively. The electrocatalytic performances of the films were estimated by linear sweep voltammograms, electrochemical impedance spectroscopy and cyclic voltammetry. The results show that Ir-Ni thin films were attached to the substrate of porous structure and hollow topography. The deposition of Ni was preferable in the electrolyte without the addition of additives, and Ir-Ni thin film was alloyed, resulting in high deposition rate for Ir42Ni58 thin film, and subsequently an increase of Ir content in the thin films of Ir80Ni20 and Ir88Ni12. Ir-Ni thin films with Tafel slopes of 40-49 mV·dec-1 exhibited highly efficient electrocatalytic activity for HER. The electrocatalytic activity of Ir-Ni thin films showed a loading dependence. As the solution temperature raised from 20 oC to 60 oC, the hydrogen evolution performance of Ir-Ni thin films improved. The apparent activation energy value of Ir88Ni12 film was 7.1 kJ·mol-1. Long-term hydrogen evolution tests exhibited excellent electrocatalystic stability in alkaline solution.

scholarly journals Thin-film chemical expansion of ceria based solid solutions: laser vibrometry study

2021 ◽  
Vol 0 (0) ◽  
Author(s):  
Hendrik Wulfmeier ◽  
Dhyan Kohlmann ◽  
Thomas Defferriere ◽  
Carsten Steiner ◽  
Ralf Moos ◽  
...  
Keyword(s):  
Thin Film ◽  
Thin Films ◽  
High Temperature ◽  
Film Thickness ◽  
Solid Solutions ◽  
Low Voltage ◽  
Excitation Frequency ◽  
Dimensional Change ◽  
Potential Core ◽  
Chemical Expansion

Abstract The chemical expansion of Pr0.1Ce0.9O2–δ (PCO) and CeO2–δ thin films is investigated in the temperature range between 600 °C and 800 °C by laser Doppler vibrometry (LDV). It enables non-contact determination of nanometer scale changes in film thickness at high temperatures. The present study is the first systematic and detailed investigation of chemical expansion of doped and undoped ceria thin films at temperatures above 650 °C. The thin films were deposited on yttria stabilized zirconia substrates (YSZ), operated as an electrochemical oxygen pump, to periodically adjust the oxygen activity in the films, leading to reversible expansion and contraction of the film. This further leads to stresses in the underlying YSZ substrates, accompanied by bending of the overall devices. Film thickness changes and sample bending are found to reach up to 10 and several hundred nanometers, respectively, at excitation frequencies from 0.1 to 10 Hz and applied voltages from 0–0.75 V for PCO and 0–1 V for ceria. At low frequencies, equilibrium conditions are approached. As a consequence maximum thin-film expansion of PCO is expected due to full reduction of the Pr ions. The lower detection limit for displacements is found to be in the subnanometer range. At 800 °C and an excitation frequency of 1 Hz, the LDV shows a remarkable resolution of 0.3 nm which allows, for example, the characterization of materials with small levels of expansion, such as undoped ceria at high oxygen partial pressure. As the correlation between film expansion and sample bending is obtained through this study, a dimensional change of a free body consisting of the same material can be calculated using the high resolution characteristics of this system. A minimum detectable dimensional change of 5 pm is estimated even under challenging high-temperature conditions at 800 °C opening up opportunities to investigate electro-chemo-mechanical phenomena heretofore impossible to investigate. The expansion data are correlated with previous results on the oxygen nonstoichiometry of PCO thin films, and a defect model for bulk ceria solid solutions is adopted to calculate the cation and anion radii changes in the constrained films during chemical expansion. The constrained films exhibit anisotropic volume expansion with displacements perpendicular to the substrate plane nearly double that of bulk samples. The PCO films used here generate high total displacements of several 100 nm’s with high reproducibility. Consequently, PCO films are identified to be a potential core component of high-temperature actuators. They benefit not only from high displacements at temperatures where most piezoelectric materials no longer operate while exhibiting, low voltage operation and low energy consumption.

Aged Co-Mo alloy thin film catalyst for hydrogen evolution reaction in acidic solution

2021 ◽  
pp. 2151018
Author(s):  
Cihan Kuru
Keyword(s):  
Thin Film ◽  
Hydrogen Evolution ◽  
Hydrogen Evolution Reaction ◽  
Current Density ◽  
Acidic Solution ◽  
Alloy Film ◽  
Surface Oxide Layer ◽  
Alloy Thin Film ◽  
Acidic Solutions ◽  
Thin Film Catalyst

In this study, aged Co–Mo (3:10) alloy film has been demonstrated as an efficient and durable catalyst for hydrogen evolution reaction (HER) in acidic solution. The Co–Mo alloy films with varying Co/Mo atomic ratios have been deposited by magnetron sputtering. The catalytic activity of Mo film is outperformed by the Co–Mo alloys, among which the Co–Mo (3:10) alloy exhibits the highest HER activity with an overpotential of 310 mV at 10 mA cm[Formula: see text] current density, exchange current density of 1.74 × 10[Formula: see text] A cm[Formula: see text] and a Tafel slope of 61 mV dec[Formula: see text]. Combined with the good stability provided by the surface oxide layer, the aged Co–Mo (3:10) alloy is a promising catalyst for HER in acidic solutions.

scholarly journals Direct In Situ Growth of Centimeter‐Scale Multi‐Heterojunction MoS 2 /WS 2 /WSe 2 Thin‐Film Catalyst for Photo‐Electrochemical Hydrogen Evolution

2019 ◽  
Vol 6 (13) ◽  
pp. 1900301 ◽  
Author(s):  
Sehun Seo ◽  
Seungkyu Kim ◽  
Hojoong Choi ◽  
Jongmin Lee ◽  
Hongji Yoon ◽  
...  
Keyword(s):  
Thin Film ◽  
Hydrogen Evolution ◽  
In Situ Growth ◽  
Thin Film Catalyst
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