Interfacial engineering of CuWO4/WO3 thin films precisely fabricated by ultrasonic spray pyrolysis for improved solar water splitting

Herein, we proposed the interfacial engineering of CuWO4/WO3 thin film to improve the photoelectrochemical (PEC) performance for solar water splitting. Our theoretical calculation reveals the significantly accelerated charge separation in CuWO4/WO3 heterojunction due to an in situ formed built-in electric field. Accordingly, an efficient ultrasonic spray pyrolysis technique was developed to readily fabricate the heterostructural CuWO4/WO3 thin films on FTO glass substrates with accurately tunable thickness and composition. The resultant CuWO4/WO3 photoanode with an optimized CuWO4/WO3 composition (1 : 1) and thickness (& SIM;4.0 & mu;m) shows a high and stable photocurrent density of 0.66 mA cm(-2) (1.23 V vs. RHE) under AM 1.5 G illumination, which is & SIM;15 times higher than that of the CuWO4 thin films (0.042 mA cm(-2)). The significantly enhanced light absorption and accelerated photoexcited charge separation and transfer enabled by the CuWO4/WO3 heterojunction are deemed to largely account for the highly improved PEC performance of the CuWO4/WO3 film for solar water splitting.

Automated summary

In this study, interfacial engineering of CuWO4/WO3 thin film was proposed to enhance the photoelectrochemical (PEC) performance for solar water splitting. The theoretical calculation revealed significantly accelerated charge separation in the CuWO4/WO3 heterojunction due to an in situ formed built-in electric field. An efficient ultrasonic spray pyrolysis technique was developed for the fabrication of heterostructural CuWO4/WO3 thin films on FTO glass substrates with tunable thickness and composition. The optimized CuWO4/WO3 film showed a high and stable photocurrent density of 0.66 mA cm(-2) (1.23 V vs. RHE) under AM 1.5 G illumination, which is approximately 15 times higher than that of pure CuWO4 thin films (0.042 mA cm(-2)). The enhanced light absorption and improved charge separation and transfer in the CuWO4/WO3 heterojunction contributed to the improved PEC performance of the CuWO4/WO3 film for solar water splitting.