Efficient Schottky Junction Construction in Metal-Organic Frameworks for Boosting H₂ Production Activity

Manipulation of the co-catalyst plays a vital role in charge separation and reactant activation to enhance the activity of metal-organic framework-based photocatalysts. However, clarifying and controlling co-catalyst related charge transfer process and parameters are still challenging. Herein, three parameters are proposed, V _transfer (the electron transfer rate from MOF to co-catalyst), D _transfer (the electron transfer distance from MOF to co-catalyst), and V _consume (the electron consume rate from co-catalyst to the reactant), related to Pt on UiO-66-NH₂ in a photocatalytic process. These parameters can be controlled by rational manipulation of the co-catalyst via three steps: i) Compositional design by partial substitution of Pt with Pd to form PtPd alloy, ii) location control by encapsulating the PtPd alloy into UiO-66-NH₂ crystals, and iii) facet selection by exposing the encapsulated PtPd alloy (100) facets. As revealed by ultrafast transient absorption spectroscopy and first-principles simulations, the new Schottky junction (PtPd (100)@UiO-66-NH₂) with higher V _transfer and V _consume exhibits enhanced electron-hole separation and H₂O activation than the traditional Pt/UiO-66-NH₂ junction, thereby leading to a significant enhancement in the photoactivity.