Experimental Study and Optimization Analysis of Operating Conditions on Photo-Thermochemical Cycle of Water Splitting for Hydrogen Production Based on CeO2 Catalyst

The photo-thermochemical cycle (PTC) for water splitting offers a sustainable method for hydrogen production by efficiently utilizing solar energy. This study explored the use of CeO2 as a catalyst in the PTC system to enhance hydrogen yield. A nanostructured CeO2 catalyst was synthesized via the sol-gel method, achieving an H2 yield of 8.35 μmol g−1 h−1. Stability tests over five cycles showed consistent yields between 7.22 and 8.35 μmol g−1 h−1. Analysis revealed that oxygen vacancies (VOs) increased after the photoreaction and depleted during the thermal reaction, which aligns with the expected PTC mechanism for hydrogen production. Single-factor experiments highlighted that photoreaction duration mainly influenced VOs generation, while thermal duration and temperature impacted VOs consumption and intermediate reaction rates. A response surface methodology (RSM) model predicted optimal conditions for maximum H2 yield (8.85 μmol g−1 h−1) with a photoreaction duration of 46.6 min, thermal duration of 45.4 min, and thermal temperature of 547.2 °C.