C₃N₄/Se-CNTs as Advanced Metal-Free Catalysts for the Photoassisted Electrocatalytic Oxygen Evolution Reaction

Photoassisted electrocatalysis is a frontier direction of electrocatalysis for promoting energy conversion. In this work, a metal-free C₃N₄/Se-CNTs is reported as a novel catalyst for photoassisted electrocatalytic oxygen evolution reaction (OER). C₃N₄ has an appropriate bandgap, high specific surface area, and long-term stability. CNTs can modulate the electronic environment of C₃N₄ by strong π-π interaction and greatly enhance the separation efficiency of photogenerated carriers. The distributed Se nanoparticles in CNTs can further increase the charge transfer ability. As a metal-free catalyst, the C₃N₄/Se-CNTs exhibits an overpotential of 231 mV at a current density of 10 mA cm^-2 and a small Tafel slope of 52 mV dec^-1 under illumination, which ranks among the best catalysts for photoassisted OER performance, surpassing most noble and transition metal-based catalysts. The result demonstrates the great potential of C₃N₄-based catalysts in the photoassisted OER process and provides a new perspective to explore the excellent metal-free OER catalysts.