Oxygen­Vacancy­Introduced BaSnO3？δ Photoanodes with Tunable Band Structures for Efficient Solar­Driven Water Splitting

Abstract

To achieve excellent photoelectrochemical water&#8208

splitting activity, photoanode materials with high light absorption and good charge&#8208

separation efficiency are essential. One effective strategy for the production of materials satisfying these requirements is to adjust their band structure and corresponding bandgap energy by introducing oxygen vacancies. A simple chemical reduction method that can systematically generate oxygen vacancies in barium stannate (BaSnO3 (BSO)) crystal is introduced, which thus allows for precise control of the bandgap energy. A BSO photoanode with optimum oxygen&#8208

vacancy concentration (8.7%) exhibits high light&#8208

absorption and good charge&#8208

separation capabilities. After deposition of FeOOH/NiOOH oxygen evolution cocatalysts on its surface, this photoanode shows a remarkable photocurrent density of 7.32 mA cm&#8722

2 at a potential of 1.23 V versus a reversible hydrogen electrode under AM1.5G simulated sunlight. Moreover, a tandem device constructed with a perovskite solar cell exhibits an operating photocurrent density of 6.84 mA cm&#8722

2 and stable gas production with an average solar&#8208

to&#8208

hydrogen conversion efficiency of 7.92% for 100 h, thus functioning as an outstanding unbiased water&#8208

splitting system.