Modulating metal activation energy via cerium-mediated heterointerface defect evolution for photovoltaic-driven efficient water electrolysis

Exploring electrocatalysts with high-valence metal sites is crucial to accelerate oxygen evolution reaction (OER), yet it encounters challenges arising from thermodynamic formation barriers. We have in-situ constructed a multi-defective Ce³ ⁺-O_v-M active interface through a dynamic interface defect integration strategy, regulating the ionic conductivity and the formation barrier of high-valence Ni and achieving an ultralow overpotential of 155 mV at 10 mA cm⁻² current density for OER. The recordings from in-situ Raman and UV-Vis spectroscopy illustrate that the modulated catalyst facilitates a cathodic shift in the transition potential for forming γ-NiOOH. Theoretical calculations have confirmed the mechanism, indicating that defect-engineering at the heterointerface leads to electron localization, lower d-band centers enhance the electron distribution at metal active centers, and activate lattice oxygen for efficient water oxidation. This property extended to hydrogen evolution catalysts also exhibits high versatility. Perovskite/crystalline silicon tandem solar cells are used to drive the electrolytic assembly system to achieve 21.01 % solar hydrogen conversion efficiency.