Oxygen Atoms in Pd Single‐Atom Loaded Cs 2 SnCl 6 Perovskite as Electron–Hole Separated Channel for Efficient Photo‐Assisted Electrocatalytic Oxygen Evolution Reaction

ABSTRACT Studies on halide perovskites for electrocatalysis remain in their infancy, largely limited to preliminary attempts at inducing oxygen atoms and improving stability. A key challenge lies in the lack of effective strategies for controlled oxygen atom introduction. Herein, we design a facile method to generate oxygen atoms in Pd single‐atom‐loaded Cs 2 SnCl 6 (O‐Cs 2 SnCl 6 @Pd) by using hydrogen peroxide. Under Xe light irradiation, it exhibits a low overpotential (135 mV at 10 mA cm −2 ) during the oxygen evolution reaction (OER) with long stability for 100 h. DFT calculations illustrate that the incorporation of oxygen atoms in O‐Cs 2 SnCl 6 @Pd modulates the electronic structure, as evidenced by a lowered overpotential for key intermediate species. This modulation further increases electron density, promoting the adsorption and activation of OER intermediates, as well as enabling the population of a new excited state. Femtosecond transient absorption spectroscopy further evidences that O atoms reduce the recombination of electron–hole, thereby significantly facilitating charge‐transfer to active sites that promote electrocatalytic reactions. This study introduces a novel strategy for the rational design and synthesis of high‐performance photo‐assisted electrocatalytic materials, offering a pathway to enhanced catalytic efficiency and functionality.