Double-Site Substitution of Ce into (Ba, Sr)MnO₃ Perovskites for Solar Thermochemical Hydrogen Production

Solar thermochemical hydrogen production (STCH) is a renewable alternative to hydrogen production using fossil fuels. While serial bulk experimental methods can accurately measure STCH performance, screening chemically complex materials systems for new promising candidates is more challenging. Here we identify double-site Ce-substituted (Ba,Sr)MnO3 oxide perovskites as promising STCH candidates using a combination of bulk synthesis and high-throughput thin-film experiments. The Ce substitution on the B-site in 10H-BaMnO3 and on the A-site in -SrMnO3 leads to 2–3 times higher hydrogen production compared to CeO2, but these bulk single-site substituted perovskites suffer from incomplete reoxidation. Double-site Ce substitution on both A- and B-sites in (Ba,Sr)MnO3 thin films increases Ce solubility and extends the stability of 10H and 3C structures, which is promising for their thermochemical reversibility. This study demonstrates a high-throughput experimental method for screening complex oxide materials for STCH applications.