S-scheme enhanced photocatalysis on graphitic carbon nitride functionalized with perylene tetracarboxylic diimide

Abstract

It is a challenge to realize the catalytic conversion of ammonia by photocatalysis under mild conditions, because it is limited by the high photoinduced carrier recombination rate and low photo-absorption efficiency. Herein, we perform the condensation reaction of 3,4,9,10-perylenetetracarboxylic diimide (PTCDA) with graphitic carbon nitride (g-C3N4) nanosheets to obtain a novel organic semiconductor perylene tetracarboxylic diimide (PTCDI) modified g-C3N4 S-scheme heterostructure (named PTCDI@g-C3N4) via thermal-etching and bath process. The obtained PTCDI@g-C3N4 composite shows an obvious improvement in photocatalytic nitrogen reduction rate of 7308.9 μmol L−1 g−1h−1 with methanol under the Xe lamp irradiation, higher than g-C3N4 nanosheets (1215.3 μmol L−1 g−1 h−1). The excellent photocatalytic performance of PTCDI@g-C3N4 heterostructure is ascribed to two advantages: (1) The S-scheme heterojunction between organic semiconductor PTCDI and g-C3N4 nanosheets is profit to suppress carrier recombination and enhance electron utilization efficiency; (2) The utilization rate of g-C3N4 nanosheets to light was promoted due to the existence of PTCDI with broad visible light absorption. This work may help to provide a possibility to realize efficient photocatalytic nitrogen fixation by preparing organic-nonmetallic heterostructure through facile methods.