Efficient Solar Energy Harvesting and Storage through a Robust Photocatalyst Driving Reversible Redox Reactions

Simultaneous solar energy conversion and storage is receiving increasing interest for better utilization of the abundant yet intermittently available sunlight. Photoelectrodes driving nonspontaneous reversible redox reactions in solar‐powered redox cells (SPRCs), which can deliver energy via the corresponding reverse reactions, present a cost‐effective and promising approach for direct solar energy harvesting and storage. However, the lack of photoelectrodes having both high conversion efficiency and high durability becomes a bottleneck that hampers practical applications of SPRCs. Here, it is shown that a WO₃‐decorated BiVO₄ photoanode, without the need of extra electrocatalysts, can enable a single‐photocatalyst‐driven SPRC with a solar‐to‐output energy conversion efficiency as high as 1.25%. This SPRC presents stable performance over 20 solar energy storage/delivery cycles. The high efficiency and stability are attributed to the rapid redox reactions, the well‐matched energy level, and the efficient light harvesting and charge separation of the prepared BiVO₄. This demonstrated device system represents a potential alternative toward the development of low‐cost, durable, and easy‐to‐implement solar energy technologies.