High-valent cobalt-oxo species triggers singlet oxygen for rapid contaminants degradation along with mild peroxymonosulfate decomposition in single Co atom-doped g-C3N4

Abstract

Tailoring the interfacial reaction pathway and low consumption strategy for the high efficiency Fenton-like processes is environmentally desirable but still challenging. Herein, single Co atom-doped g-C3N4 was prepared for peroxymonosulfate (PMS) activation to reveal the interfacial reaction of high-valent cobalt-oxo species [Co(IV) = O] to singlet oxygen (1O2) and construct an energy efficient Fenton-like system. Experimental results showed that the system could achieve 99.6% carbamazepine removal with kobs of 0.355 min−1, while the decomposition of PMS was mild (0.0988 and 0.00917 min−1 in 0–2 and 2–30 min, respectively). Mechanistic studies revealed the reaction of Co(IV) = O to 1O2, which moderated the reduction of Co sites, thus slowing the decomposition rate of PMS. But the synergistic effect of 1O2 and Co(IV) = O maintained the high activity of the system. Combined with first-principles calculations, the optimal evolution path of PMS was PMS → OH*→Co(IV) = O → OO*→1O2, accompanied by the Co(II)/Co(III)/Co(IV) redox cycle. The work proposed a new interfacial reaction in term of Co(IV) = O triggered 1O2 generation, resulting in the construction of an energy-efficient Fenton-like system and provided a novel idea for the development of efficient and low consumption water purification technology.