Oxygen Vacancy-Modified WO3 for Advanced Photoelectrochemical H2S Sensing via Synergistic Interfacial and Surface Optimization.

Hydrogen sulfide (H2S), a corrosive and extremely poisonous gas, poses serious threats to environmental security and human health, necessitating the development of highly sensitive and stable room-temperature sensing technologies. Conventional gas sensors are often limited by high operating temperatures and rapid deactivation. Herein, a solar-driven photoelectrochemical (PEC) sensor for room-temperature gas sensing is developed by precisely controlling the oxygen vacancies (VOs) concentration in WO3, which optimizes interfacial transport and surface reaction kinetics. The results of integrated differential phase contrast imaging, in situ PEC characterization, and computational simulations collectively reveal that VOs improve the spatial separation of photoexcited carriers, optimize interfacial contact and charge transfer kinetics, and lower the adsorption energy of O2 and H2S, which accelerates surface reactions. The optimized sensor delivers a 67-fold enhancement in the room-temperature H2S response compared with pristine WO3, along with excellent stability, high selectivity, and a part per billion-level detection limit. This work provides a rational strategy for designing high-performance, room temperature-operable, light-excited, thick-film electrode sensors via interface-surface synergistic enhancement.