Linkage effect in the bandgap-broken V₂O₅-GdCrO₃ heterojunction by carbon allotropes for boosting photocatalytic H₂ production

Refining carrier transfer in bandgap-broken heterojunctions, which consist of two semiconductors with broken bandgaps, is crucial yet highly challenging for photocatalysis. Herein, we incorporated amorphous carbons (AC) into the bandgap-broken V2O5/GdCrO3 heterojunctions, inducing a linkage effect to facilitate photoexcited carrier transfer. The created V-O-C and Cr-O-C bonds in V2O5-AC-GdCrO3 interfaces show almost identical orbital energies to overcome the broken-gap energy barriers at interfaces. The holes at GdCrO3's valence band and electrons at V2O5's conduction band tent to migrating toward the carbon ring of amorphous carbon via Cr-O-C and V-O-C bonds, thereby enhancing carrier separation of bandgap-broken V2O5-GdCrO3 heterojunction. By controlling the relative amount of metal-O-C bonds in the interface, the modulation of charge transfer kinetics was also achieved on V2O5/AC/GdCrO3, resulting in similar to 7 times higher of H-2 generation than V2O5/GdCrO3. The concept could be expanded to the other carbon allotropes, including graphene, carbon nanotube, and graphdiyne conjugated structures, demonstrating a universal strategy in reaching optimal charge transfer of broken-bandgap heterojunctions for photocatalytic H-2 production.