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

Graphitic carbon nitride (g-C3N4) usually shows amphoteric property in a neutral solution. In this work, a K&I co-doped g-C3N4 is prepared by simply sintering the mixture of dicyandiamine, KI and I-2. The K&I co-doping modulates the band structure of g-C3N4 with pulling the Fermi level toward its conduction band minimum. The obtained K&I co-doped g-C3N4 (K&I-C3N4) 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-C3N4 from amphoteric to n-type semiconductor. Also, the prepared K&I-C3N4 shows widened light absorption range and enhanced separation efficiency of the photogenerated charge carriers, which results in the dramatically enhanced photoelectrochemical performance. (C) 2018 Elsevier Ltd. All rights reserved.