Bifunctional template-mediated synthesis of porous ordered g-C3N4 decorated with potassium and cyano groups for effective photocatalytic H2O2 evolution from dual-electron O2 reduction

The photocatalytic method to produce hydrogen peroxide (H2O2) as a substitute for fossil fuels has become a hot research topic. We herein propose cyano defect and potassium intercalation modified g-C3N4 photocatalysts in which the porous structure and crystallinity can be maintained relatively well. Simultaneously, the photocatalysts possess adjustable band structure, enhanced carrier transfer efficiency and highly selective dual-electron O2 reduction. The physicochemical properties and reaction mechanisms are well studied through the effective combination of experiments and theoretical calculations. The H2O2 yield of KDCN-0.2 (278.9 μmol L-1h−1) is approximately 4.3 times higher than that of original CN (65.2 μmol L-1h−1), and the energy conversion efficiency is also higher than many current CN-based photocatalysts. This work deepens the understanding of the mechanism of photocatalytic O2 reduction for H2O2 production and points out the promising direction for the design of novel CN-based photocatalysts with ideal properties in energy conversion and environmental applications.