Peroxymonosulfate as inducer driving interfacial electron donation of pollutants over oxygen-rich carbon–nitrogen graphene-like nanosheets for water treatment

Abstract

Herein, a novel metal-free catalyst consisting of multiporous oxygen-rich carbon–nitrogen graphene-like nanosheets (OLAA-CN NSs) is first developed through a staged temperature-programmed calcination of l-ascorbic acid (LAA)-modified dicyandiamide precursor. It is found that the oxygen species from l-ascorbic acid (OLAA) are introduced into the graphene-like basic matrix and replace partial N atoms to form the COC-R structure, leading to the non-uniform distribution of electrons on the catalyst surface, and the formation of electron-rich centers around the COC microareas according to a series of characterization techniques. As a result, OLAA-CN NSs exhibits excellent performance for refractory pollutant removal in the presence of peroxymonosulfate (PMS) and dissolved oxygen. Some pollutants with complex structures are even completely degraded within only 1 min. The interface reaction mechanism is further revealed that PMS mainly acts as an active inducer to drive the electron donation of pollutants over OLAA-CN NSs. These electrons are finally utilized by dissolved oxygen to generate reactive oxygen species (ROS) through the interface process. This reaction system results in pollutants that can either be cleaved directly by surface oxidation process or degraded by the attack of the generated ROS, such as singlet oxygen (1O2) and superoxide radicals (O2•−), through oxygen activation, which significantly reduces the resource and energy consumption in advanced wastewater treatment by harnessing the energy of pollutants and dissolved oxygen in the water.