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Unraveling Charge Transfer in CoFe Prussian Blue Modified BiVO4 Photoanodes
ACS Energy Letters ( IF 19.3 ) Pub Date : 2018-12-26 00:00:00 , DOI: 10.1021/acsenergylett.8b02225
Benjamin Moss 1 , Franziska Simone Hegner 2 , Sacha Corby 1 , Shababa Selim 1 , Laia Francàs 1 , Núria López 2 , Sixto Giménez 3 , José-Ramón Galán-Mascarós 2, 4 , James Robert Durrant 1
Affiliation  

Catalyst modification of metal oxide photoanodes can result in markedly improved water oxidation efficiency. However, the reasons for improvement are often subtle and controversial. Upon depositing a CoFe Prussian blue (CoFe-PB) water oxidation catalyst on BiVO4, a large photocurrent increase and onset potential shift (up to 0.8 V) are observed, resulting in a substantially more efficient system with high stability. To elucidate the origin of this enhancement, we used time-resolved spectroscopies to compare the dynamics of photogenerated holes in modified and unmodified BiVO4 films. Even in the absence of strong positive bias, a fast (pre-ms), largely irreversible hole transfer from BiVO4 to CoFe-PB is observed. This process retards recombination, enabling holes to accumulate in the catalyst. Holes in CoFe-PB remain reactive, oxidizing water at a similar rate to holes in pristine BiVO4. CoFe-PB therefore enhances performance by presenting a favorable interface for efficient hole transfer, combined with the catalytic function necessary to drive water oxidation.

中文翻译:

在CoFe普鲁士蓝修饰的BiVO 4光电阳极中展开电荷转移

金属氧化物光阳极的催化剂改性可以显着提高水的氧化效率。但是,改进的原因通常是微妙的和有争议的。在BiVO 4上沉积CoFe普鲁士蓝(CoFe-PB)水氧化催化剂时,观察到较大的光电流增加和起始电势偏移(最高0.8 V),从而产生了效率更高,稳定性更高的系统。为了阐明这种增强作用的起因,我们使用了时间分辨光谱技术来比较改性和未改性BiVO 4膜中光生空穴的动力学。即使没有强烈的正偏压,BiVO 4的快速(毫秒前),很大程度上不可逆的空穴转移观察到对CoFe-PB的污染。该过程阻碍了重组,使空穴在催化剂中积累。CoFe-PB中的孔保持反应性,以与原始BiVO 4中的孔相似的速率氧化水。因此,CoFe-PB通过提供有利于有效空穴传输的良好界面以及驱动水氧化所必需的催化功能,从而提高了性能。
更新日期:2018-12-26
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