High-Performance Visible-Light Photocatalysts for H2 Production: Rod-Shaped Co3O4/CoO/Co2P Heterojunction Derived from Co-MOF-74

Photocatalyst systems generally consist of catalysts and cocatalysts to realize light capture, charge carrier migration, and surface redox reactions. Developing a single photocatalyst that performs all functions while minimizing efficiency loss is extremely challenging. Herein, rod-shaped photocatalysts Co3O4/CoO/Co2P are designed and prepared using Co-MOF-74 as a template, which displays an outstanding H2 generation rate of 6.00 mmol·g-1·h-1 when exposed to visible light irradiation. It is 12.8 times higher than pure Co3O4. Under light excitation, the photoinduced electrons migrate from the catalysts of Co3O4 and CoO to the cocatalyst Co2P. The trapped electrons can subsequently undergo a reduction reaction to produce H2 on the surface. Density functional theory calculations and spectroscopic measurements reveal that enhanced performance results from the extended lifetime of photogenerated carriers and higher charge transfer efficiency. The ingenious structure and interface design presented in this study may guide the general synthesis of metal oxide/metal phosphide homometallic composites for photocatalysis.