Mechanistic analysis of multiple processes controlling solar-driven H2O2 synthesis using engineered polymeric carbon nitride

Abstract

Solar-driven hydrogen peroxide (H₂O₂) production presents unique merits of sustainability and environmental friendliness. Herein, efficient solar-driven H₂O₂ production through dioxygen reduction is achieved by employing polymeric carbon nitride framework with sodium cyanaminate moiety, affording a H₂O₂ production rate of 18.7 μmol h ⁻¹ mg⁻¹ and an apparent quantum yield of 27.6% at 380 nm. The overall photocatalytic transformation process is systematically analyzed, and some previously unknown structural features and interactions are substantiated via experimental and theoretical methods. The structural features of cyanamino group and pyridinic nitrogen-coordinated soidum in the framework promote photon absorption, alter the energy landscape of the framework and improve charge separation efficiency, enhance surface adsorption of dioxygen, and create selective 2e⁻ oxygen reduction reaction surface-active sites. Particularly, an electronic coupling interaction between O₂ and surface, which boosts the population and prolongs the lifetime of the active shallow-trapped electrons, is experimentally substantiated.

Solar-driven H₂O₂ production presents a renewable approach to chemical synthesis. Here, authors perform a mechanistic analysis on the contribution of the sodium cyanaminate moiety to the 2-electron oxygen reduction reaction performance of polymeric carbon nitride frameworks.