Engineering ultrathin g-C3N4 nanosheets via a solvent-tailored bottom-up strategy for efficient boosting photocatalytic H2 evolution

Graphitic carbon nitride (g-C3N4) has emerged as a promising metal-free photocatalyst for renewable hydrogen (H2) evolution, yet its efficiency is limited by the rapid charge recombination and insufficient active sites. Herein, we reported a feasible solvent-tailored bottom-up strategy to engineer ultrathin g-C3N4 nanosheets (GCN-NS) by using isopropanol as solvent and melamine (MA) as raw material. Isopropanol can facilitate the nanosheet formation, resulting in the improving charge transfer of GCN-NS, which may be caused by the synergistically optimized electronic and morphological properties of as-formed precursor through the solvothermal treatment. Compared to the bulk g-C3N4 (GCN-B) directly derived from MA, the as-obtained GCN-NS with an average thickness of ∼3.5 nm could accelerate the charge transfer, enlarge the specific surface area, and promote the electrical conductivity. Consequently, the GCN-NS showed a boosting visible-light-driven photocatalytic H2 activity (461.6 μmol/h/g), which was over 2-folds higher than that of GCN-B (227.8 μmol/h/g) under the same conditions. Moreover, the H2 generation performance of GCN-NS also obviously improved both under blue light with λ = 450 nm and green light with λ = 550 nm, respectively. This work establishes alcohol solvent engineering as a facile approach to fabricate the g-C3N4-based photocatalysts for sustainable photocatalytic solar-to-H2 fuel conversion.