Functional Groups Induced Microenvironment Regulation of Pt Catalytic Sites in MOF/COF Heterojunction for Enhanced Photocatalytic Hydrogen Evolution

Microenvironmental regulation plays a crucial role in enhancing photocatalytic active sites. Herein, considering the diversity of ligands in metal‐organic frameworks (MOFs), different microenvironmental platforms were provided for Pt nanoparticles (NPs) by modulating the functional groups (─CF 3 , ─F, ─CH 3 , and ─NH 2 ) in the ligands of UIO‐66. Subsequently, through the construction of Pt‐MOF with TpPa‐1 heterogeneity, the electron transfer was facilitated. The experimental results showed that the activity of Pt@UIO‐x‐TpPa (PUT‐x) was gradually enhanced as the electron‐withdrawing property of the microenvironment around Pt NPs increased, with the order being PUT‐NH 2 <PUT‐CH 3 <PUT‐F<PUT‐CF 3 . The optimized sample, PUT‐CF 3 , achieved an H 2 production rate of 4161 mmol g Pt −1 h −1 under visible light, which benefited from the strong electron‐withdrawing microenvironment provided by the CF 3 groups. PUT‐CF 3 represented a 2.07‐fold enhancement over PUT‐NH 2 and a 34.08‐fold improvement compared to pristine TpPa. This result emphasized the regulatory role of the microenvironment in the active sites. Theoretical calculations concluded that the modulation of the functional groups to the catalytic ability was achieved by tuning the electron density and d‐band center of Pt active sites, which was also verified by X‐ray photoelectron spectroscopy (XPS) and CO adsorption diffuse reflectance infrared Fourier transform spectroscopy (CO‐DRIFTs) tests.