A review of carbon material-based Z-scheme and S-scheme heterojunctions for photocatalytic clean energy generation

• Carbon materials (CNTs, graphene, CQDs, etc.) enhance photocatalytic efficiency when integrated into Z-scheme and S-scheme heterojunctions. • These heterojunctions promote charge separation, reduce recombination losses, and extend spectral response for solar energy conversion. • The review summarizes recent advances in carbon-based heterojunctions for photocatalytic H2 generation and CO2 reduction. • Current challenges and future directions for carbon-based photocatalysts are critically discussed.