Graphitic carbon nitride/few-layer graphene heterostructures for enhanced visible-LED photocatalytic hydrogen generation
Résumé
Few-layer graphene (FLG, 2–7 nm thickness) prepared by catalytic chemical vapour deposition (c-CVD), and bulk graphitic carbon nitride (g-C3N4; GCN) were assembled to develop novel 2D/2D xFLGy/GCN heterostructures. The impact of FLG loading and morphology on the activity of GCN has been evaluated towards H2 generation from water splitting under visible-LED irradiation. The heterostructures, characterised by UV–vis DRS, photoluminescence, EPR, Raman, AFM, XRD, XPS, SEM/TEM/STEM and photocurrent, present strong interfacial interaction and show higher photocatalytic activity than pure GCN. The best performing material, 2FLG10/GCN, generated 1274 g−1 h−1 of H2, i.e., 4-times higher than pure GCN. The improved photoactivity was ascribed to a synergistic effect between GCN and FLG, owing to: i) efficient charge separation of photoinduced electron-hole pairs through electron transfer from GCN to FLG, ii) increased surface area, and iii) enhanced visible light absorption. Moreover, the best performing composite presents high stability after four successive cycles with no significant change in its activity.