Coupling photocatalytic fuel cell based on S-scheme g-C3N4/TNAs photoanode with H2O2 activation for p-chloronitrobenzene degradation and simultaneous electricity generation under visible light

Abstract

Environmental pollution and energy scarcity have become two major challenges with the vigorous development of industry, especially wastewater containing refractory organic pollutants with sufficient chemical energy. Photocatalytic fuel cells (PFCs) have been considered as effective techniques for refractory organic pollutants degradation and simultaneous chemical energy recovery. The poor visible light utilization of photoanode and limited mass transfer efficiency are unfavorable to organic pollution degradation and electricity generation of PFC system. In view of this, the hydrogen peroxide assisted photocatalytic fuel cell (H2O2-PFC) system with S-scheme g-C3N4/TNAs photoanode was constructed for refractory p-Chloronitrobenzene (p-CNB) degradation and electricity generation under visible light. The formed internal electric field between g-C3N4 and TiO2 enhanced visible-light absorption ability and photoelectrochemical properties through the inhibition of photogenerated carrier recombination. The activation of H2O2 in H2O2-PFC system promoted electron transfer and active radical production, which caused more superior p-CNB degradation and electricity generation performances of H2O2-PFC system than those of PFC system. The H2O2-PFC system possessed good stability for p-CNB degradation and electricity generation. The •OH was predominant active radical for p-CNB degradation, and photogenerated holes, •O2– and 1O2 were also involved in p-CNB degradation in H2O2-PFC system. The p-CNB degradation pathways were proposed through density functional theory calculation and gas chromatography mass spectrometry. The toxicity prediction demonstrated that the comprehensive toxicity of p-CNB was alleviated after degradation in H2O2-PFC system.