Surface Nanojunction Enabled by Vapor-Assisted π-Conjugation Modification of Carbon Nitride for Enhanced Photocatalytic Water Splitting

The unsatisfied visible light harvesting, slow charge separation, and limited practical surface area of carbon nitride (CN) constrain its performance in photocatalytic water splitting and environmental remediation. Herein, the thermal vapor-assisted π-conjugation modification of CN by grafting with p-aminophenoxy groups was developed to tune the photophysical properties of CN to enhance its photocatalytic activity. Besides extending the light absorption, the surface modification constructed a nanojunction across the depth direction, which leads to facilitated charge separation and transfer. In addition, the thermal vapor modification process thermally etches and trims the pristine CN to be a highly holey structure, resulting to >10 times increase in specific surface area. Photocatalysis results showed that the obtained modified CN yielded hydrogen from photocatalytic water splitting at a rate of 7.82 mmol/g/h, over 7-folds as that of pristine CN, with a quantum yield of 3.28% at 400 nm. The π-conjugation modified CN also demonstrated enhanced photocatalytic environmental remediation application, exemplified by much faster photodegradation of tetracycline hydrochloride. This work provides the thermal vapor surface chemical modification of CN as a promising integrated pathway of multiple favorable photophysical properties toward efficient photocatalysis application.