Ca2+ and Ga3+ doped LaMnO3 perovskite as a highly efficient and stable catalyst for two-step thermochemical water splitting

Abstract

High performance and stable catalysts for two-step thermochemical water splitting are key to synthesising direct fuels in the form of H₂ or liquid hydrocarbon fuels by the Fischer–Tropsch process. Herein, we designed and synthesised LaMnO₃ perovskite structured oxides doped on both the A and B sites for two-step thermochemical water splitting. First, Ca²⁺, Sr²⁺ and Ba²⁺ divalent cations were successfully doped on the A site of LaMnO₃ and the thermochemical water splitting performances were analysed. After that, Al³⁺ and Ga³⁺ ions were doped on the B site of the perovskites produced in the first step. Through this strategy, a novel perovskite composition (La_0.6Ca_0.4Mn_0.8Ga_0.2O₃) was found with remarkable water splitting performance, producing 401 μmol g⁻¹ of H₂ at low thermochemical cycle temperatures between 1300 and 900 °C. The as-prepared perovskite exhibits twelve times higher H₂ production than the benchmark CeO₂ catalyst under the same experimental conditions. This novel perovskite is also capable of maintaining steady-state redox activity during the water splitting cycles.