Efficient promotion of charge separation with reduced graphene oxide (rGO) in BiVO4/rGO photoanode for greatly enhanced photoelectrochemical water splitting
Efficient promotion of charge separation with reduced graphene oxide (rGO) in BiVO4/rGO photoanode for greatly enhanced photoelectrochemical water splitting
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DOI：
10.1016/j.solmat.2018.05.050
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发表时间：
2018-10-01
影响因子：
6.9
通讯作者：
Lee, Byeong-Kyu
中科院分区：
文献类型：
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作者：
Soltani, Teyyebah;Tayyebi, Ahmad;Lee, Byeong-Kyu
尽管 BiVO4 (BVO) 作为一种理想的反应半导体继续受到广泛关注，但其光电化学 (PEC) 水分解性能仍然较低，因为大多数电荷载流子在到达氟掺杂二氧化锡 (FTO) 之前很容易在本体或光阳极表面上重新组合。本研究提出了一种简便、可见光辅助的光催化还原氧化石墨烯 (GO) 方法，使用 BVO 制备具有两种不同 rGO 重量比（5% 和 10%）的高度稳定的 BVO/还原 GO (rGO) 纳米复合材料。然后将这些制备好的 BVO/rGO 纳米复合材料滴铸在 FTO 基底上，以证明 rGO 在极大改善 BVO/rGO 薄膜中的电子传输方面发挥的关键作用。在PEC水分解实验中，与BVO (111.7 mu A cm(-2))和BVO/rGO-5% (377.9 mu A cm(-2))相比，BVO/rGO-10%光电极表现出最高的光电流密度(554.4 mu A cm(-2) at 1.2 V vs. Ag/AgCl)。与 BVO 相比，稳定的 BVO/rGO 还表现出最高的载流子密度，具有更长的使用寿命和更高的导电性。这些结果有助于 BVO/rGO 光电阳极优异的 PEC 性能。在模拟太阳光照射下，由于薄膜中电子空穴分离的增强，BVO/rGO 薄膜的开路电位（OCP）向更负的值移动。 BVO 和 BVO/rGO 电极的光电流产量取决于溶液 pH 值。 NaOH 电解质（1 M，pH = 13.5）中的光电流密度在整个测量电势范围（0 至 + 1.2 V vs. Ag/AgCl）上均高于 Na2SO4 电解质（0.1 M，pH = 6.5）中的光电流密度。这项工作证明了 rGO 覆盖在 BVO/rGO 薄膜中通过 rGO 的电子传输的极大增强中的重要作用。
Although BiVO4 (BVO) continues to attract strong attention as an ideal reactive semiconductor, its photoelectrochemical (PEC) water splitting performance remains low because most of the charge carriers are easily recombined in the bulk or on the surface of the photoanode before reaching the fluorine-doped tin dioxide (FTO). This study presents a facile and simple, visible-light-assisted, photocatalytic reduction of graphene oxide (GO) by using BVO for the preparation of highly stable BVO/reduced GO (rGO) nanocomposites with two different rGO weight ratios (5% and 10%). These as-prepared BVO/rGO nanocomposites were then drop-cast on an FTO substrate to demonstrate the key role played by the rGO in greatly improving the electron transport in the BVO/rGO films. In PEC water splitting experiments, the BVO/rGO-10% photoelectrode showed the highest photo current density (554.4 mu A cm(-2) at 1.2 V vs. Ag/AgC1), compared to BVO (111.7 mu A cm(-2)) and BVO/rGO-5% (377.9 mu A cm(-2)). The stable BVO/rGO also showed the highest charge carrier density, with an extended lifetime and improved the electrical conductivity, as compared to BVO. These results contributed to the excellent PEC performance of the BVO/rGO photoanode. Under simulated solar light illumination, the open-circuit potential (OCP) of the BVO/rGO films was shifted to a more negative value due to the enhanced electron-hole separation in the films. The photocurrent yields of the BVO and BVO/rGO electrodes were dependent on the solution pH. The photocurrent densities were higher over the full range of measured potential (0 to + 1.2 V vs. Ag/AgCl) in the NaOH electrolyte (1 M, pH = 13.5) than in the Na2SO4 electrolyte (0.1 M, pH = 6.5). This work demonstrates the essential role of the rGO coverage in the great enhancement of electron transport through the rGO in the BVO/rGO film.