Benzenesulfonyl chloride-incorporated g-C3N4 for photocatalytic hydrogen generation by using the hydrolysate of poly(lactic acid) as sacrificial reagent

To overcome the shortcomings of insufficient absorption of visible light and rapid recombination of photoexcited electron-hole pairs of g-C3N4, we synthesized benzenesulfonyl chloride incorporated g-C3N4 (BS-CN) with narrower bandgap and stronger absorption in visible light region thanks to extension of π-electron delocalization. A quick intramolecular electron transfer was realized via intramolecular donor-acceptor conjugation in BS-CN. Different from commercial sacrificial reagents, lactate, hydrolyzed by poly(lactic acid) (PLA) in KOH solution, was used as sacrificial reagent in this work. The optimal H2 production rate over Pt-loaded (1 wt%) BS5-CN was 1890 µmol h−1g−1 under visible light illumination (λ > 420 nm), roughly 2.8 times as high as pure g-C3N4. 1H NMR spectrum indicated that lactate was oxidized into formate and acetate. Our work manifests that the abandoned PLA plastic can be transformed into hydrogen energy and valuable organic chemicals simultaneously via photocatalytic reaction, thus inhibiting “white pollution”. [Display omitted] •Benzenesulfonyl chloride incorporated g-C3N4 (BS-CN) is synthesized.•Lactate hydrolyzed by poly(lactic acid) acts as sacrificial agent for H2 evolution.•Lactate is transformed into formate and acetate meanwhile H2 is produced.•The H2 evolution rate of the optimal BS-CN is 2.8 times of that of pure g-C3N4.