H2o2 Production: Microplastic-Derived Carbon Materials for Oxygen Reduction to Hydrogen Peroxide Under Visible-Light-Driven Photocatalysis

Abstract

Artificial photosynthesis of H2O2 using water and oxygen as raw material is a promising approach. Herein, a novel graphite-like carbon nitride/carbon (g-C3N4/C) heterojunction was prepared by one-step calcination of KOH, melamine and microplastics mixture, which could photocatalytic H2O2 production up to 6.146 mmol g-1 h-1 under visible light irradiation. By analyzing the energy band-structure of the catalyst, the photocatalytic production of H2O2 in this system consists of two single-electron reactions. The modification of KOH makes a large number of N-vacancies and N-defects caused by cyano-groups in g-C3N4, enhancing the electron absorption ability. Moreover, the introduction of graphitic carbon increases its specific surface area and porosity and improves the adsorption ability of O2. Simultaneously, their synergism reduces the band-gap of g-C3N4 and makes both the conduction-band and valence-band positions more negative, showing enhanced reduction ability, lowering the energy barrier for oxygen reduction, and greatly improving the photogeneration performance of H2O2.

Keywords: H2O2 production, Photocatalysis, Microplastics, KOH-doping, Stepwise single-electron reactions