Unraveling the Synergy Mechanism between Photocatalysis and Peroxymonosulfate Activation on a Co/Fe Bimetal-Doped Carbon Nitride

Fenton-like catalysis based on peroxymonosulfate (PMS)activationhas shown great potential in the treatment of organic wastewater.Heterogeneous Fenton-like catalysts containing transition metal activesites are highly efficient for PMS activation. However, the reductionof oxidized metal active sites was usually not prompt due to the sluggishreaction kinetics, which caused the insufficient redox cycle of themetal active sites and further hampered the catalysis efficiency.Recent studies have shown that the synergy effect between photocatalysisand PMS activation may address the above obstacle and boost overallefficiency. However, a deeper understanding of this synergy effectis still missing, making it difficult to be rationally controlled;thus, a poor synergy effect is frequently reported. Herein, a Co/Febimetal-doped graphitic carbon nitride (g-C3N4) was designed representatively through systematical characterizationand theoretical calculation, the synergy effect was revealed to beprofoundly determined by the competitive role of a hole in the systemand the adsorbed metastable PMS* on the catalyst surface, and furthermore,the synergy effect can be rationally manipulated; when the Co/Fe dopingratio is 2.5:2.5, the as-prepared g-C3N4 witha moderate valence band position can endow the catalyst with an optimizedphoto-Fenton-like synergistic effect and the highest catalytic degradationperformance. This work sheds light on the rational design of highlyefficient photo-Fenton-like catalysts.