High-Entropy Metal Oxychloride Photocatalyst for Visible-Light-Driven H2O2 Synthesis up to 600 nm

The development of inorganic photocatalysts with broad visible-light response is crucial for achieving efficient solar-driven H 2 O 2 production. In this work, based on a high-entropy mixing strategy, a high-entropy metal oxychloride (Bi 2 R mix O 4 Cl, R mix = La, Nd, Sm, Gd, and Y) was designed and synthesized. This material exhibits a significantly red-shifted absorption edge extending to about 600 nm in the visible region, corresponding to a narrowed bandgap of 2.27 eV. By loading spatially separated 1 wt % Pd and 0.5 wt % CoO x dual cocatalysts via photodeposition, the optimized catalyst achieves efficient photocatalytic H 2 O 2 synthesis from O 2 and H 2 O in phosphate buffer solution (pH = 6). Under broad-spectrum visible light, including monochromatic irradiation near 600 nm, the catalyst shows excellent H 2 O 2 production activity (∼90 μM/h) and maintains good stability in cycling tests. In situ ATR-FTIR and open-circuit voltage decay (OCVD) analyses further reveal its effective charge carrier separation and O 2 activation pathway. This study offers a design strategy for developing inorganic photocatalysts with broad visible-light response and high stability.