Photocatalytic Overall Water Splitting with a Solar‐to‐Hydrogen Conversion Efficiency Exceeding 2 % through Halide Perovskite

Photocatalytic water splitting using semiconductors is a promising approach for converting solar energy to clean energy. However, challenges such as sluggish water oxidation kinetics and limited light absorption of photocatalyst cause low solar-to-hydrogen conversion efficiency (STH). Herein, we develop a photocatalytic overall water splitting system using I₃ ^-/I^- as the shuttle redox couple to bridge the H₂-producing half-reaction with the O₂-producing half-reaction. The system uses the halide perovskite of benzylammonium lead iodide (PMA₂PbI₄, PMA=C₆H₅CH₂NH₂) loaded with MoS₂ (PMA₂PbI₄/MoS₂) as the H₂ evolution photocatalyst, and the RuO_x-loaded WO₃ (WO₃/RuO_x) as the O₂ evolution photocatalyst, achieving a H₂/O₂ production in stoichiometric ratio with an excellent STH of 2.07 %. This work provides a detour route for photocatalytic water splitting with the help of I₃ ^-/I^- shuttle redox couple in the halide perovskite HI splitting system and enlightens one to integrate and utilize multi catalytic strategies for solar-driven water splitting.