Boosted Scavenger-Free Photocatalytic H2o2 Production Over Alkali-Doped Poly(Heptazine Imide) Under Controlled Solution Conditions

Abstract

Photocatalysis renders appealing mechanisms for synthesizing hydrogen peroxide (H2O2) from water and oxygen under ambient conditions; however, it still suffer from low efficiency due to the high kinetic barriers, low reaction selectivity, and severe recombination of photo-generated charge carriers. This study contributes to establishing a foundational understanding on the influence of the solution environment, specifically the solution pH in the photocatalytic performance of H2O2 production. By adjusting the solution from neutral to alkaline conditions, the photocatalytic system exhibited a 9-fold increased, unprecedented rate of 7.68 mmol gcat-1 h-1 for producing H2O2 over the prototype photocatalyst of alkali-doped poly(heptazine imide). Mechanistic studies demonstrate that alkaline condition plays threefold roles in promoting H2O2 production by regulating the oxygen reduction reaction pathway, balancing the rate of charge carrier consumption, and alleviating the photocatalytic decomposition of H2O2. These fundamental insights may serve as guidelines for the development of superior photocatalytic systems.

Keywords: Photocatalysis, Carbon nitride, scavenger-free H2O2 production, poly(heptazine imide)