Comprehensive investigation on robust photocatalytic hydrogen production over C3N5

Abstract

Carbon nitride has drawn numerous eyes in the past decade, whereas the photocatalytic performance is significantly limited by its wide band-gap (∼2.7 eV for C 3 N 4 ) simultaneously. Recently, C 3 N 5 with narrower band-gap has been reported, however, a systematically investigation on its photoactivity for H 2 production has not been reported. The present work demonstrates the synthesis of C 3 N 5 by thermal treatment of 3-amino-1,2,4-triazole, and the photocatalytic performance for H 2 production of C 3 N 5 is investigated comprehensively. Photocatalytic H 2 production rate of C 3 N 5 is ∼2.2 times higher than that of C 3 N 4 with 1.0 wt% Pt as co-catalyst, and series of experiments are carried out to explore the behind elements accounting for the high photoactivity. Combining the results of DRS, PL and photocurrent, it is found that C 3 N 5 possesses wider visible light absorption region, lower band-gap and quicker photogenerated e - /h + separation efficiency. Moreover, characterizations including in-situ DRIFTS are adopted to monitor the adsorption property of H 2 O on C 3 N 5 , which plays a significant role in surface water reduction reaction, and higher amount of adsorbed H 2 O molecules on C 3 N 5 is confirmed. The present work exhibits new insights into the high photocatalytic performance of N-rich carbon nitride catalysts. As a new type of carbon nitride, C 3 N 5 exhibits much higher photocatalytic H 2 production activity than conventional C 3 N 4 , which represents a new direction for designing materials for photocatalytic applications.