Construction of g-C3N4/Ti3CN MXene Schottky heterojunctions for boosting photocatalytic hydrogen production

Abstract

Converting solar energy into clean hydrogen (H2) fuel via photocatalytic hydrogen production technology is a promising strategy for sustainable social development. Graphitic carbon nitride (g-C3N4) has attracted much attention due to its unique visible light activity and excellent tunable atomic structure. However, bulk g-C3N4 suffers from challenges such as sluggish charge carrier dynamics and limited active catalytic sites, resulting in lower solar-to-hydrogen conversion efficiency. Herein, we prepare defective ultrathin g-C3N4 nanosheets and subsequently construct 2D g-C3N4/2D Ti3CN MXene heterojunction via electrostatic-driven assembly. The optimized composite CM-2 exhibits the highest hydrogen evolution rate of 7630.5 μmol g−1 h−1. The increase in the hydrogen production rate is attributed to the effective coupling of two materials to form Schottky heterojunctions, which may inhibit the recombination of electron-hole pairs. Additionally, this work explores the pathway of electron transfer in Schottky photocatalyst, and further unveils the synergy of defects and built-in electric field in accelerating photo-induced charge transport as well as enhancing the hydrogen-evolving activity, thereby providing valuable insights for the rational design of highly efficient photocatalytic materials.