Rational design of Ruddlesden–Popper perovskite electrocatalyst for oxygen reduction to hydrogen peroxide

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+delta) 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+delta, and the molybdenum substitution improves the H2O2 selectivity during the ORR process, in 0.1 M KOH, from 60% of Pr2NiO4+delta to 79% of Pr2Ni0.8Mo0.2O4+delta at 0.55 V versus RHE. A limiting H2O2 concentration of 0.24 mM for Pr2NiO4+delta and 0.42 mM for Pr2Ni0.8Mo0.2O4+delta was obtained at a constant current of 10 mA/cm(2) using a flow-cell reactor using a gas-diffusion electrode.