Three-Dimensional Hierarchical g-C3N4 Architectures Assembled by Ultrathin Self-Doped Nanosheets: Extremely Facile Hexamethylenetetramine Activation and Superior Photocatalytic Hydrogen Evolution.

Photocatalytic hydrogen evolution has broad prospects as a clean solution for the energy crisis. However, the rational design of catalyst complex, the H2 evolution efficiency, and the yield are great challenge. Herein, three-dimensional hierarchical g-C3N4 architectures assembled by ultrathin carbon-rich nanosheets (3D CCNS) were prepared via an extremely facile hexamethylenetetramine activation approach at the bulk scale, indicating the validation of scale-up production process. The two-dimensional ultrathin carbon-rich nanosheets were several hundred nanometers in width but only 5-6 nm in thickness and gave rise to a unique 3D interconnected network. The unique composition and structure of the nanosheets endow them with a remarkable light absorption spectrum with the tunable band gap, high electrical conductivity, fast charge separation, and large surface areas with abundant reaction active sites, and thus significantly improved H2 production performance. As high as ∼7.8%, quantum efficiency can be achieved by irradiating 3D CCNS at 420 nm with a H2 evolution rate >2.7 × 104 μmol/g/h, which is ∼31.3 times higher than that of the pristine g-C3N4. Our work introduces an extremely facile route for mass production of doping modified 3D g-C3N4-based photocatalyst with excellent H2 evolution performances.