G-C3N4 Hydrogen-Bonding Viologen for Significantly Enhanced Visible-Light Photocatalytic H2 Evolution

Abstract

Graphitic carbon nitride (g-C3N4) has recently emerged as a promising metal-free photocatalytic material for the conversion of solar energy into chemical energy under visible-light irradiation. Unfortunately, the photocatalytic activity of g-C3N4 is still unsatisfactory due to the serious recombination of photogenerated electron–hole pairs. Here, we develop a strategy to construct a type of g-C3N4-based composite photocatalyst (C3N4/CBV2+), a g-C3N4 surface coupled with a viologen redox mediator (1,1′-bis(4-carboxylatobenzyl)-4,4′-bipyridinium dichloride, denoted as CBV2+) through hydrogen bonds, for enhanced H2 production from water under visible-light irradiation. The CBV2+ molecules not only provide sites for metal particle formation but also act as an efficient electron transfer mediator to transfer the photoinduced electrons from g-C3N4 to platinum nanoparticles (Pt NPs). The vectorial charge transfer results in an efficient spatial separation of electrons and holes in the C3N4/CBV2+ composite photoc...