WO3/FeOOH heterojunction for improved charge carrier separation and efficient photoelectrochemical water splitting

Photoanodes with sufficient visible light absorption, efficient photogenerated carrier separation and fast transport are still the main challenges for realizing high-efficiency photoelectrochemical (PEC) water splitting. Herein, we prepared the WO3/FeOOH heterojunction in situ grown on the FTO glass substrates by a facile seed-mediated two-step hydrothermal method. Under simulated sunlight irradiation, the prepared WO3/FeOOH heterojunction exhibits the enhanced photocurrent density of 2.63 mA cm−2 at 1.23 V vs. RHE, which is much higher than that of the bare WO3 film (1.62 mA cm−2 at 1.23 V vs. RHE). The excellent PEC performance of the sample can be attributed to the improved oxygen evolution kinetics and the extended visible light absorption range due to FeOOH, and the facilitation of carrier separation together with the suppressed recombination of photogenerated electron-hole pairs due to the formation of type-II WO3/FeOOH heterojunction. This work provides a promising approach for developing a highly efficient and cost-effective photoanode for application in solar-driven PEC water splitting.