Hydrogen production by visible light photocatalysis with Chl@g-C3N4/Ti3C2Tx S-scheme heterojunction

Abstract

Sustainable conversion of solar energy to hydrogen energy by photocatalytic splitting of water through the use of semiconductor photocatalytic materials is considered to be a promising and sustainable alternative proposal to replace conventional fossil fuels. However, efficient solar-driven photocatalytic hydrogen production has remained a great challenge due to the prevailing problems of existing semiconductor photocatalytic materials. It is shown that constructing heterostructures is a very powerful way to improve the photocatalytic hydrogen production capacity of composites under visible light. Therefore, in this work, an organic heterojunction structure based on chlorophyll (Chl) molecules and graphitic carbon nitride (g-C3N4) is reported and exploited for efficient solar energy-driven photocatalytic hydrogen evolution reaction (HER). Meanwhile, noble metal-free photocatalysts were successfully constructed with Ti3C2Tx MXene nanosheets through a simple stepwise complexation process of Chl, g-C3N4, and Ti3C2Tx for the achievement of HER for the photocatalytic decomposition of water. The results show that the optimal Chl@g-C3N4/Ti3C2Tx organic heterojunction composite has a remarkably advanced HER performance of 131 μmol/h/gcat, as compared with the traditional Chl@Ti3C2Tx and g-C3N4/Ti3C2Tx composites. The results provide new ideas for exploring MXene based catalysts for highly efficient conversion of solar energy.