In-situ synthesis of Pd nanocrystals with exposed surface-active facets on g-C3N4 for photocatalytic hydrogen generation

Engineering surface-active facets of metal cocatalysts is one of the most widely explored strategies to develop advanced photocatalysts and promote photocatalytic solar energy conversion. Here, the surface-active facets of Pd nanocrystals in Pd/g-C3N4 photocatalyst was related to the injection flow rate of PdCl2. When PdCl2 was injected at a low flow rate of 7.5 mL/h (7.5-Pd/g-C3N4), the Pd nanocrystals were uniformly dispersed onto the g-C3N4 with exposed low-index {100} and {111} surface-active facets. However, increasing the injection flow rate to 150 mL/h (150-Pd/g-C3N4) formed Pd nanocrystals where only the {100} surface-active facet was exposed. Under visible light irradiation, the 7.5-Pd/g-C3N4 nanocomposite exhibited excellent water splitting activity for hydrogen production (7.61 mmol g-1 h-1), which was significantly better than with the 150-Pd/g-C3N4 nanocomposite (3.3 mmol g-1 h-1). Theoretical calculations and experimental results confirmthe importance of the {111} surface-active facets in the 7.5-Pd/g-C3N4 nanocomposite for promoting photocatalytic activity. (c) 2022 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.