Photocathode Characteristics of a Spray-Deposited Cu2ZnGeS4 Thin Film for CO2 Reduction in a CO2-Saturated Aqueous Solution
Photocathode Characteristics of a Spray-Deposited Cu2ZnGeS4 Thin Film for CO2 Reduction in a CO2-Saturated Aqueous Solution
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DOI：
10.1021/acsaem.9b01418
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发表时间：
2019-09-01
影响因子：
6.4
通讯作者：
Kudo, Akihiko
中科院分区：
文献类型：
--
作者：
Ikeda, Shigeru;Fujikawa, Shotaro;Kudo, Akihiko
通过喷雾沉积含有组成元素的水溶液，然后在硫气氛中热处理，在Mo涂覆的玻璃基底上制备了锌黄锡石Cu 2 ZnGeS 4（CZGS）薄膜。通过光电子能谱（PES）分析CZGS薄膜的电离势和基于CZGS薄膜的太阳能电池器件的外量子效率（EQE）谱的结果表明，该化合物具有较好的电致发光性能。0.7电子伏特的负导带底（CBM）比已研究的锌黄锡矿Cu 2 ZnSnS 4（CZTS），但几乎相同的价带顶（VBM）的CZTS的能级。由于相对浅的CBM，CZGS膜作为光电化学（PEC）CO2还原在中性水溶液（0.1 M KHCO 3）中饱和的CO2通过施加一个偏压低于用于诱导反应在黑暗条件下，而CZTS膜不能在相同的条件下工作的光电阴极。本文还根据CZGS-ZnS界面的电子结构讨论了在CZGS-ZnS薄膜表面覆盖ZnS层对PEC CO2还原活性的增强作用。
A kesterite Cu2ZnGeS4 (CZGS) thin film was prepared on an Mo-coated glass substrate by spray deposition of an aqueous solution containing constituent elements followed by heat treatment in a sulfur atmosphere. The results of analysis of the ionization potential of the CZGS thin film by photoelectron spectroscopy (PES) and the external quantum efficiency (EQE) spectrum of a solar cell device based on the CZGS thin film showed that this compound had ca. 0.7 eV more negative conduction band minimum (CBM) than that of the well-studied kesterite Cu2ZnSnS4 (CZTS) but had almost the same energy level of the valence band maximum (VBM) as that of CZTS. Owing to the relatively shallow CBM, the CZGS film worked as a photocathode for photoelectrochemical (PEC) CO2 reduction in a neutral aqueous solution (0.1 M KHCO3) saturated with CO2 by applying a bias potential lower than that for inducing the reaction under a dark condition, whereas the CZTS film could not work under the same condition. Enhancement of PEC CO2 reduction activity by surface coverage of the CZGS thin film with a ZnS layer is also discussed on the basis of the electronic structure of the thus-formed CZGS-ZnS interface.