Enhancing O2 adsorption and activation over porous S-doped g-C3N4 rod toward efficient photocatalytic rhodamine-B degradation

Abstract

Photocatalytic oxygen molecular (O2) activation to generate reactive oxygen species (ROS) is a promising strategy for the oxidative degradation of organic pollutants. Herein, a porous S-doped g-C3N4 rod (S-g-CN-rod) was synthesized and applied to photocatalytic superoxide radicals (.O2- ) evolution and rhodamine-B (RhB) degradation. The morphological, structural, and optical properties of all samples were investigated. DFT calculation demonstrated that the carbon site adjacent to S was energetically favorable for O2 adsorption, which was conducive to .O2- evolution. The porous S-g-CN-rod exhibited an excellent photocatalytic .O2- evolution rate of 268.2 mu mol L-1 h-1, which was the main active species to degrade RhB. Conceivably, the porous S-g-CN-rod demonstrated exceptionally high efficiency of photocatalytic RhB degradation and achieved almost complete disposal of RhB (99.7 %) in only 30 min, which was higher than most reported photocatalysts. The experimental results and theoretical calculations demonstrated that the preeminent photocatalytic activities were ascribed to enhanced light-harvesting, improved migration and separation of photo-induced electrons, and the superior O2 adsorption and activation induced by S doping.