Linker Engineering of Sandwich-Structured Metal-Organic Framework Composites for Optimized Photocatalytic H2 Production.

Abstract

While the microenvironment around catalytic sites is recognized to be crucial in thermocatalysis, its roles in photocatalysis remain subtle. Herein, a series of sandwich-structured metal-organic framework (MOF) composites, UiO-66-NH2 @Pt@UiO-66-X (X means functional groups), have been rationally constructed for visible-light photocatalytic H2 production. By varying -X groups of UiO-66-X shell, the microenvironment of Pt sites and photosensitive UiO-66-NH2 core can be simultaneously modulated. Significantly, the MOF composites with identical light absorption and Pt loading present distinctly different photocatalytic H2 production rates, following -X group sequence of -H > -Br > -NA (naphthalene) > -OCH3 > -Cl > -NO2 . UiO-66-NH2 @Pt@UiO-66-H demonstrates H2 production rate up to 2708.2μmol g-1 h-1 , ∼222 times that of UiO-66-NH2 @Pt@UiO-66-NO2 . Mechanism investigations suggest that the variation of -X group can balance the charge separation of UiO-66-NH2 core and proton reduction ability of Pt, leading to the optimal activity of UiO-66-NH2 @Pt@UiO-66-H at the equilibrium point. This article is protected by copyright. All rights reserved.