B-Site Engineering in Ruddlesden–Popper Perovskites (A 2 BO 4 ) for H 2 O 2 Production with 4.85% of Solar-to-Chemical Efficiency

The electrochemical synthesis of hydrogen peroxide (H 2 O 2 ) via the oxygen reduction reaction (ORR) offers a promising alternative to the anthraquinone process, addressing environmental concerns without requiring expensive hydrogen. However, developing catalysts that selectively promote the two-electron ORR pathway while maintaining stability remains challenging. Here, we report Ruddlesden–Popper (RP) perovskite oxides as efficient catalysts for selective H 2 O 2 production. Among the tested LaSrBO 4 compositions (B = Ni, Co, Fe, Mn), LaSrNiO 4 (LSN) showed the best two-electron ORR selectivity (∼87%) and activity. Integrated into a photovoltaic–electrochemical system, LSN achieved a solar-to-chemical conversion efficiency of 4.85%, producing a H 2 O 2 production rate of 149.2 μmol cm –2 h –1 with good stability over 50 h. Density functional theory calculations attributed this performance to favorable H 2 O 2 formation and desorption kinetics at the Ni B-site. Overall, RP perovskites offer earth-abundant, efficient, and sustainable catalysts for electrochemical H 2 O 2 generation, providing an alternative to carbon- or noble-metal-based systems.