Altering the Interfacial Microenvironment of the Photocatalytic System for Boosted H2O2 Generation from Biomass Waste

Abstract

The catalytic and environmentally friendly synthesis of H2O2 is crucial in green chemistry. Many researchers are dedicated to its study, and various methods have been proposed, but these methods usually require organic solvents or dissipative reagents. It has been reported recently that different biomass could be converted to hydrothermal carbonaceous carbon (HTCC) photocatalysts capable of producing H2O2 with high efficiency. Herein, we report a method to further increase the catalytic efficiency of HTCC, from 0.53 mmol gcat -1 h-1 to 1.35 mmol gcat -1 h-1 under air, by simply changing the neutral solution to basic (pH = 11) where the contact environment between HTCC and the solvent is changed. The radical trap experiment and electron paramagnetic resonance (EPR) spectroscopy confirmed a two-step oxygen reduction reaction as the primary catalytic pathway. The mechanism study indicates that OH- in the solution could react with the acidic terminal functional groups of HTCC originating from the synthesis and hole-induced oxidation within HTCC during photocatalysis, thus enhancing the generation of active species and electron transfer. This study paves a new way to improve the photocatalytic efficiency of HTCC by altering the microenvironment of solvent and photocatalysts.