High-throughput measurement of the influence of pH on hydrogen production from BaTiO3/TiO2 core/shell photocatalysts

The rates of hydrogen production from four different BaTiO3/TiO2 core/shell photocatalysts and their components were measured as a function of pH using a parallelized and automated photochemical reactor (PAPCR) to determine the optimized structure and pH condition for photochemical hydrogen production. The amount of hydrogen produced by each reactor in a 96-reactor array was quantified by the color change of a hydrogen-sensitive material. For the core/shell photocatalysts annealed at 600 °C, the increase in hydrogen production rate with pH at pH 3–9 is ascribed to the adsorption of more negatively charged species that bend the bands upward, promoting hole transport to the surface and the oxidation half reaction. At intermediate pH, the core/shell catalyst annealed at 600 °C had the highest reactivity, indicating that the generation and transport of charge carriers were improved by the BaTiO3/TiO2 core/shell structure. The results demonstrate that PAPCR is an effective way to compare the performance of hydrogen-producing catalysts with different structures and in different operating conditions.