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Surface Modification of Hematite Photoanodes with CeOx Cocatalyst for Improved Photoelectrochemical Water Oxidation Kinetics.
ChemSusChem ( IF 7.5 ) Pub Date : 2020-08-09 , DOI: 10.1002/cssc.202001135
Mahmoud G Ahmed 1, 2 , Mengyuan Zhang 1 , Ying Fan Tay 1 , Sing Yang Chiam 2 , Lydia H Wong 1, 3
Affiliation  

Hematite is a promising photoanode for solar water splitting by photoelectrochemical (PEC) cells, but its performance is limited by the slow kinetics of water oxidation reaction or oxygen evolution reaction (OER). Surface modification of hematite photoanodes with a suitable water oxidation cocatalyst is a key strategy for improving the kinetics of water oxidation. In this study, a CeOx overlayer is deposited on the surface of the hematite photoanode by a water‐based solution method with ceric ammonium nitrate (CAN) followed by heat treatment. The photocurrent of CeOx‐modified hematite is 3 times higher than that of pristine hematite (at 1.23 V vs. RHE) under AM 1.5G, 1 sun conditions. Through hole‐scavenger measurements, Tafel plot analysis, and electrochemical impedance spectroscopy, it is concluded that CeOx overlayer increases the hole injection efficiency, improves the surface catalytic activity, and enhances charge transfer across the photoanode/electrolyte interface. These observations are attributed to the synergistic effects of Ce3+/Ce4+ redox species in CeOx and the oxygen vacancies. This work elucidates the role of CeOx as an efficient cocatalyst overlayer to improve the OER kinetics of photoanodes.

中文翻译:

CeOx助催化剂对赤铁矿光阳极的表面改性,以改善光电化学水氧化动力学。

赤铁矿是一种有前途的光阳极,可用于通过光电化学(PEC)电池分解太阳能水,但其性能受到水氧化反应或放氧反应(OER)缓慢动力学的限制。用合适的水氧化助催化剂对赤铁矿光阳极进行表面改性是改善水氧化动力学的关键策略。在这项研究中,通过水合硝酸铈铵(CAN)的水溶法,然后进行热处理,将CeO x覆盖层沉积在赤铁矿光阳极表面。CeO x的光电流在AM 1.5G,1个阳光条件下,改性的赤铁矿的质量比原始赤铁矿的高3倍(在1.23 V vs. RHE下)。通过空穴清除剂测量,Tafel图分析和电化学阻抗谱,可以得出结论,CeO x覆盖层可提高空穴注入效率,改善表面催化活性,并增强跨光阳极/电解质界面的电荷转移。这些观察结果归因于CeO x中的Ce 3+ / Ce 4+氧化还原物质和氧空位的协同效应。这项工作阐明了CeO x作为提高光阳极OER动力学的有效助催化剂覆盖层的作用。
更新日期:2020-08-09
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