Turning the unwanted surface bismuth enrichment to favourable BiVO4/BiOCl heterojunction for enhanced photoelectrochemical performance

• Published in: Applied catalysis. B, Environmental Vol. 241; pp. 506 - 513
• Main Authors: Liu, Cong, Zhou, Jinglan, Su, Jinzhan, Guo, Liejin
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.02.2019
• Subjects: Bismuth enrichment; BiVO4/BiOCl heterojunction; Water oxidation; Bismuth enrichment; BiVO4/BiOCl heterojunction; Water oxidation
• ISSN: 0926-3373; 1873-3883
• DOI: 10.1016/j.apcatb.2018.09.060

Unwanted bismuth enrichment at the surface part of BiVO4 photoanode was turned to favourable BiVO4/BiOCl heterojunction for enhanced photoelectrochemical water oxidation. [Display omitted] •BiVO4/BiOCl heterojunction was first prepared on BiVO4 photoanode by turning the unwanted Bi enrichment layer to BiOCl layer.•An excellent PEC performance was obtained over BiVO4/BiOCl heterojunction compared to pristine BiVO4 photoanode.•The enhanced charge separation leads to the improvement of PEC performance. Bismuth enrichment as a common issue at the surface of bismuth vanadate (BiVO4) has been frequently reported as a severe limitation to its water oxidation kinetics. To address this problem, this study reports a novel approach to eliminate the surface bismuth enrichment by forming BiVO4/BiOCl heterojunction via surface hydrochloric acid treatment. Benefiting from type II band alignment of the BiVO4/BiOCl heterojunction, the treated photoanode delivers excellent PEC performance with a photocurrent density of 1.83 mA/cm2 at 1.23 V (vs. Ag/AgCl), compared to 1.27 mA/cm2 of untreated BiVO4 photoanode. This improvement could be attributed to the effective charge separation in heterojunction interface as the charge separation efficiency of BiVO4 increased from 28% to 41% at 1.23 V (vs. Ag/AgCl) after formation of BiVO4/BiOCl heterojunction.