Insight into Charge Separation in WO3/BiVO4 Heterojunction for Solar Water Splitting

Title
Insight into Charge Separation in WO3/BiVO4 Heterojunction for Solar Water Splitting
Authors
주오심민병권황윤정채상윤정혜진이창수김종학
Keywords
solar water splitting; polymer-assisted synthesis; mesoporous WO3; WO3/BiVO4 heterojunction; charge separation
Issue Date
2017-06
Publisher
ACS Applied Materials & Interfaces
Citation
VOL 9, NO 23-19790
Abstract
Recently, the WO3/BiVO4 heterojunction has shown promising photoelectrochemical (PEC) water splitting activity based on its charge transfer and light absorption capability, and notable enhancement of the photocurrent has been achieved via morphological modification of WO3. We developed a graft copolymer-assisted protocol for the synthesis of WO3 mesoporous thin films on a transparent conducting electrode, wherein the particle size, particle shape, and thickness of the WO3 layer were controlled by tuning the interactions in the polymer/sol– gel hybrid. The PEC performance of the WO3 mesoporous photoanodes with various morphologies and the individual heterojunctions with BiVO4 (WO3/BiVO4) were characterized by measuring the photocurrents in the absence/presence of hole scavengers using light absorption spectroscopy and intensity-modulated photocurrent spectroscopy. The morphology of the WO3 photoanode directly influenced the charge separation efficiency within the WO3 layer and concomitant charge collection efficiency in the WO3/BiVO4 heterojunction, showing the smaller sized nanosphere WO3 layer showed higher values than did the plate-like or rod-like one. Notably, we observed that photocurrent density of WO3/BiVO4 was not dependent on the thickness of WO3 film or its charge collection time, implying slow charge flow from BiVO4 to WO3 can be a crucial issue in determining the photocurrent, rather than the charge separation within the nanosphere WO3 layer.
URI
http://pubs.kist.re.kr/handle/201004/65887
ISSN
1944-8244
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KIST Publication > Article
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