Hantzsch ester as hole relay significantly enhanced photocatalytic hydrogen productionElectronic supplementary information (ESI) available: Experimental section, TEM images, cyclic voltammogram, UV-vis absorption spectrum, comparison of photocatalytic hydrogen evolution rates under different sacrificial reagents. See DOI: 10.1039/c8cy01922c

• Main Authors: Ma, Liu-Bo, Liu, Ya-Nan, Liang, Kuang, Fang, Xiao-Xiang, Sahar, Shafaq, Kombo, Miza, Xu, An-Wu
• Format: Journal Article
• Published: 26.11.2018
• DOI: 10.1039/c8cy01922c
• ISSN: 2044-4753

Polymeric graphitic carbon nitride (g-C 3 N 4 ) has emerged as a promising semiconductor photocatalytic material, which can convert solar energy into chemical energy under visible-light irradiation. However, because of the issue of recombination of photogenerated electron-hole pairs, the photocatalytic efficiency of g-C 3 N 4 is dissatisfactory. Herein, we constructed a novel system of graphitic-C 3 N 4 composite photocatalyst (C 3 N 4 /DHPE) through π-π interactions and hydrogen bonds for efficient visible light-driven H 2 evolution. The Hantzsch ester (diethyl 1,4-dihydro-2,6-3,5-pyridine dicarboxylate, denoted as DHPE) not only speeds up the transfer rate of photogenerated charge carriers, but also retards the recombination of electron-hole pairs through extracting holes from g-C 3 N 4 . C 3 N 4 /DHPE hybrid photocatalyst exhibits efficient spatial separation of photogenerated electrons and holes and thus, more electrons can be released for hydrogen production. When 4% DHPE was introduced, the hydrogen production rate of C 3 N 4 /DHPE photocatalyst drastically increased up to 1345.0 μmol h −1 g −1 , which is 4.7 times higher than that of pure g-C 3 N 4 (286.0 μmol h −1 g −1 ). Moreover, there is no significant decrease in H 2 production after a long time reaction (20 h, five test cycles), confirming that the C 3 N 4 /DHPE photocatalyst has excellent stability. Our study offers a simple, cost-effective, and powerful route to promoting efficient separation of photogenerated charge carriers and a novel strategy to design other highly efficient photocatalytic systems for solar energy conversion. Hantzsch ester (DHPE) retards the recombination of electron-hole pairs through extracting holes from g-C 3 N 4 , thus dramatically improving visible photocatalytic hydrogen production.