Integrating Covalent Organic Framework with Transition Metal Phosphide for Noble-Metal-Free Visible-Light-Driven Photocatalytic H2 Evolution.

Abstract

2D covalent organic frameworks (COFs) are considered as one kind of the most promising crystalline porous materials for solar-driven hydrogen production. However, adding noble metal co-catalysts into the COFs-based photocatalytic system is always indispensable. Herein, through a simple solvothermal synthesis method, TpPa-1-COF, a typical 2D COF, which displays a wide light absorption region, is rationally combined with transition metal phosphides (TMPs) to fabricate three TMPs/TpPa-1-COF hybrid materials, named Ni12 P5 (Ni2 P or CoP)/TpPa-1-COF. The incorporated TMPs can be served as electron collectors for accelerating the transfer of charges on TpPa-1-COF, thus the composites are demonstrated to be efficient photocatalysts for promoting water splitting. Benefitting from the richer surface reactive sites and lower H* formation energy barrier, the Ni12 P5 can most effectively improve the photocatalytic performance of the TpPa-1-COF, and the H2 evolution rate can reach up to 31.6 µmol h-1 , approximately 19 times greater than pristine TpPa-1-COF (1.65 µmol h-1 ), and is comparable to the Pt/TpPa-1-COF (38.8 µmol h-1 ). This work is the first example of combining COFs with TMPs to construct efficient photocatalysts, which may offer new insight for constructing noble-metal-free COF-based photocatalysts.