Metal-Organic-Framework-Based Photocatalysts Optimized by Spatially Separated Cocatalysts for Overall Water Splitting

Efficient charge separation and utilization are critical factors in photocatalysis. Herein, it is demonstrated that the complete spatial separation of oxidation and reduction cocatalysts enhances the efficacy of charge separation and surface reaction. Specifically, a Pt@NH₂ -UiO-66@MnO_x (PUM) heterostructured photocatalyst with Pt and MnO_x as cocatalysts is designed for the optimization of the NH₂ -UiO-66 photocatalyst. Compared with the pristine NH₂ -UiO-66, Pt@NH₂ -UiO-66 (PU), and NH₂ -UiO-66@MnO_x (UM) samples, the PUM sample exhibits the highest hydrogen production activity. As cocatalysts, Pt favors trapping of electrons, while MnO_x tends to collect holes. Upon generation from NH₂ -UiO-66, electrons and holes flow inward and outward of the metal-organic framework photocatalyst, accumulating on the corresponding cocatalysts, and then take part in the redox reactions. The PUM photocatalyst greatly prolongs the lifetime of the photogenerated electrons and holes, which favors the electron-hole separation. Furthermore, the PUM sample facilitates overall water splitting in the absence of sacrificial agents, thereby demonstrating its potential as a modification method of MOF-type semiconductors for the overall water-splitting reaction.