Exploration of the g-C3N4 Heterostructure with Ag-In Sulfide Quantum Dots for Enhanced Photocatalytic Activity

Photocatalysisis an effective technology to convert solar energyinto chemical energy, which has attracted great attention for thedegradation of water pollutants and the hydrogen production by watersplitting. The nonmetallic polymer g-C3N4 (GCN)can meet the thermodynamic conditions of photocatalytic water splitting,but its performances are not satisfying due to its narrow light absorptionrange and high recombination rate of photogenerated charge carriers.Among metal sulfide semiconductors, Ag-In sulfide quantum dots(AIS QDs), such as AgInS2, show excellent visible lightabsorption and promising photoactivity. In this work, AIS QDs-modifiedGCN is synthesized by an in situ growth method in mild conditions.The photocatalytic activity of the AIS-QDs/GCN nanocomposite is notablyhigher than that of the pure phase g-C3N4. Especially,the sample containing 10 wt % AIS QDs has the best activity in bothtetracycline degradation and hydrogen generation, reaching 48.5% degradationefficiency in 1 h of visible light exposure (3.2 times that of GCN)and a hydrogen evolution rate of 62.3 & mu;mol & BULL;g(-1)& BULL;h(-1) (that of bare GCN being negligible).The optical and photoelectrochemical characterization highlights theinterplay between the two components, suggesting that the enhancedphotocatalytic activity of AIS-QDs/GCN is mainly due to the broadeningof the light absorption range, the acceleration of charge transfer,and the reduction of the carrier pair recombination rate due to theformation of a type-II heterojunction inside the composite catalyst.This work is among the first attempts to modify g-C3N4 with polysulfide quantum dots to improve its catalytic performance,and the results provide an important step for advances in the applicationof these systems.

Automated summary

The AIS-QDs/GCN nanocomposite, obtained by modifying nonmetallic polymer g-C3N4 with Ag-In sulfide quantum dots (AIS QDs), exhibits higher photocatalytic activity compared to pure g-C3N4, with significantly improved tetracycline degradation and hydrogen generation. The enhanced photocatalytic activity of AIS-QDs/GCN is attributed to the broadening of the light absorption range, acceleration of charge transfer, and reduction of the carrier pair recombination rate. This study provides an important step towards enhancing the catalytic performance of g-C3N4 and has potential applications in water pollutant degradation and hydrogen production.