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 degrees 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 degrees 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.