Dramatically enhanced photoelectrochemical properties and transformed p/n type of g-C3N4 caused by K and I co-doping

Graphitic carbon nitride (g-C 3 N 4 ) usually shows amphoteric property in a neutral solution. In this work, a K&I co-doped g-C 3 N 4 is prepared by simply sintering the mixture of dicyandiamine, KI and I 2 . The K&I co-doping modulates the band structure of g-C 3 N 4 with pulling the Fermi level toward its conduction band minimum. The obtained K&I co-doped g-C 3 N 4 (K&I-C 3 N 4 ) generates positive photocurrents over the whole investigated potential range, exhibiting a typical n-type semiconductor characteristic. Therefore, the K&I co-doping transforms the g-C 3 N 4 from amphoteric to n-type semiconductor. Also, the prepared K&I-C 3 N 4 shows widened light absorption range and enhanced separation efficiency of the photogenerated charge carriers, which results in the dramatically enhanced photoelectrochemical performance.