Abstract Although the oxygen reduction process to hydrogen peroxide (H2O2) is a green option for H2O2 generation, the low activity and selectivity hindered the industry's process. In recent years, the electrochemical synthesis of H2O2 through a 2e– transfer method of oxygen reduction reaction (ORR) has piqued the interest of both academics and industry. Metal oxide catalysts have emerged as a novel family of electrochemical catalysts due to their unusual physical, chemical, and electrical characteristics. In this work, we first developed a Ruddlesden–Popper perovskite oxide (Pr2NiO4+δ) as a highly selective and active catalyst for 2e– ORR to produce H2O2. Molybdenum was introduced here to adjust the oxidation states of these transition metals with successful substitution into Ni‐site to prepare Pr2Ni1‐xMoxO4+δ, and the molybdenum substitution improves the H2O2 selectivity during the ORR process, in 0.1 M KOH, from 60% of Pr2NiO4+δ to 79% of Pr2Ni0.8Mo0.2O4+δ at 0.55 V versus RHE. A limiting H2O2 concentration of 0.24 mM for Pr2NiO4+δ and 0.42 mM for Pr2Ni0.8Mo0.2O4+δ was obtained at a constant current of 10 mA/cm2 using a flow‐cell reactor using a gas‐diffusion electrode.
