Regulating the bandgap of graphitic carbon nitride via Mn doping for boosting visible-light-driven water reduction

Abstract As a low-cost and promising photocatalyst, graphitic carbon nitride (g-C 3 N 4 ) has aroused major interest for accomplishing visible-light-driven H 2 evolution. Nevertheless, rapid recombination of photoexcited electron–holes largely restricts the applications of g-C 3 N 4 in photocatalytic fields. Therefore, metal Mn is introduced into g-C 3 N 4 to tune its bandgap through a simple co-calcination method, effectively improving its photocatalytic performance. Mn doping successfully generates NH–Mn Ⅱ bonds, thus enlarging the surface area and shortening the bandgap of g-C 3 N 4 by moving the valence band upwards, which promotes the migration of photogenerated electrons. Mn-doped materials display extensive photocatalytic performance for water reduction. The hydrogen evolution rate for an optimized CN–Mn-0.20 sample can reach 171 μ mol g −1 h −1 , which is eight times higher than that for pure g-C 3 N 4 . This finding is helpful for the bandgap modification of g-C 3 N 4 by introducing a transition metal to promote the visible-light-driven water reduction and other photocatalytic applications.