Ternary Oxide CuWO4/BiVO4/FeCoOx Films for Photoelectrochemical Water Oxidation: Insights into the Electronic Structure and Interfacial Band Alignment

Author(s)

Rosa, Washington S. ; Rabelo, Lucas G. ; Tiveron Zampaulo, Luis Gustavo ; Goncalves, Renato, V

• Document type: Journal article
• Source: ACS APPLIED MATERIALS & INTERFACES; v. 14, n. 20, p. 12-pg., 2022-01-12.

Abstract

Photoelectrochemical (PEC) water oxidation using ternary oxide systems has been considered a promising approach for investigating the effective utilization of sunlight and the production of green fuel. Herein, we report a ternary-oxide-based CuWO4/BiVO4/FeCoOx film deposited entirely by RF-magnetron sputtering using homemade ceramic targets. Our CuWO4/BiVO4 photoanode exhibits a significant photocurrent density of 0.82 mA cm(-2) at 1.23 V vs RHE under AM 1.5G illumination, which is a record 382% increase compared to that of the bare CuWO4 film. To further boost the PEC performance, we deposited an ultrathin layer of amorphous FeCoOx cocatalyst, resulting in a triple CuWO4/BiVO4/FeCoOx heterojunction with a significant reduction in onset potential and a 500% increase in the photocurrent density of bare CuWO4. Experimental and theoretical approaches were used to provide insights into the interfacial band alignment and photoinduced charge carrier pathway across heterojunctions. Our results reveal noticeable interface potential barriers for charge carriers at the CuWO4/BiVO4 heterojunction, potentially limiting its application in tandem systems. Conversely, the deposition of the FeCoOx ultrathin layer over the CuWO4/BiVO4 heterojunction induces a p-n junction on the BiVO4/FeCoOx interface, which, when combined with the abundant FeCoOx oxygen vacancies, results in improved charge separation and transport as well as enhanced photoelectrochemical stability. Our study provides a feasible strategy for producing photocatalytic heterojunction systems and introduces simple tools for investigating interface effects on photoinduced charge carrier pathways for PEC water splitting. (AU)

• FAPESP's process: 19/18724-1 - Development of CuWO4 film and study of electronic properties for application in artificial photosynthesis
• Grantee: Lucas Gabriel Rabelo
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• FAPESP's process: 19/15434-2 - Integration of the synthesis strategies to improve the charge carriers transport and efficiency of BiVO4 applied in artificial photosynthesis under sunlight
• Grantee: Renato Vitalino Gonçalves
• Support Opportunities: Regular Research Grants
• FAPESP's process: 17/18716-3 - Artificial photosynthesis: development of Tandem systems for hydrogen production from water and sunlight
• Grantee: Renato Vitalino Gonçalves
• Support Opportunities: Research Grants - Young Investigators Grants