Roles of alkali metal dopants and surface defects on polymeric carbon nitride in photocatalytic peroxymonosulfate activation towards water decontamination

Minshu Cui; Kangping Cui; Xueyan Liu; Xing Chen; Yihan Chen; Zhi Guo

doi:10.1016/j.jhazmat.2021.127292

Roles of alkali metal dopants and surface defects on polymeric carbon nitride in photocatalytic peroxymonosulfate activation towards water decontamination

J Hazard Mater. 2022 Feb 15;424(Pt A):127292. doi: 10.1016/j.jhazmat.2021.127292. Epub 2021 Sep 25.

Authors

Minshu Cui¹, Kangping Cui², Xueyan Liu¹, Xing Chen¹, Yihan Chen¹, Zhi Guo¹

Affiliations

¹ School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China; Key Laboratory of Nanominerals and Pollution Control of Higher Education Institutes, Hefei University of Technology, Hefei 230009, China.
² School of Resources and Environmental Engineering, Hefei University of Technology, Hefei 230009, China; Key Laboratory of Nanominerals and Pollution Control of Higher Education Institutes, Hefei University of Technology, Hefei 230009, China. Electronic address: cuikangping@hfut.edu.cn.

PMID: 34583168
DOI: 10.1016/j.jhazmat.2021.127292

Abstract

Polymeric carbon nitride (PCN) has been extensively employed in peroxymonosulfate (PMS) activation for water decontamination. However, limited photocatalytic efficiency can be achieved by pristine PCN due to its intrinsic deficiencies like high electron-hole recombination rate and resistance to charge transfer. Herein, in a two-stage thermal treatment process, the nontoxic and stable Na and K were successfully anchored among the PCN skeleton with surface defects created, leading to an elevated photocatalytic activity for PMS activation. The SO₄·^- and ¹O₂ were identified as the dominant reactive oxygen species, which were generated from electron transfer processes between PMS and catalyst. Experimental and theoretical analyses suggested that the defective structures and metal dopants improved the optical properties of catalyst, endowing it a wider light absorption range and a lower energy barrier for electron transitions. The modified structures were also beneficial to electron transfer processes due to the weaker electron confinement effect, accelerating the production of SO₄·^- on the defective sites and ¹O₂ on the metal sites. The synergy of radical and non-radical species weakened the influence of side reactions between radicals from PMS and coexisting inorganic anions in practical water, hence to promote the resistance of modified catalysts in complex water matrices.

Keywords: DFT calculations; Electron localization function; Excited state; Photocatalysis; Water treatment.