P, K doped crystalline g-C3N4 grafted with cyano groups for efficient visible-light-driven H2O2 evolution

Abstract

Graphitic carbon nitride (g-C3N4), especially in heptazine forms, has long been considered as a promising non-toxic, benign and sustainable photocatalyst for producing the important chemical and potential green energy H2O2. However, bulk g-C3N4 shows moderate activity originated from its intrinsic drawbacks such as restricted visible-light harvesting ability and sluggish charge separation. Herein, a co-modified crystalline g-C3N4 by P, K ions and cyano group was successfully synthesized via co-thermal polymerization of precursors followed by molten salt treatment. The advanced g-C3N4 exhibits an outstanding photocatalytic H2O2 generation yield of 4424 μmol g−1h−1, more than 81-fold of the pristine counterpart, also superior than that of g-C3N4 processed by single modification treatment. This superior photocatalytic H2O2 evolution efficiency is attributed to the rational design of crystalline g-C3N4, enabling super visible photons capture, more efficient charge carries separation and substantially reduced charge recombination. The current work may furnish an integratable strategy for solar fuel production.