Multiple ordered porous honeycombed g-C₃N₄ with carbon ring in-plane splicing for outstanding photocatalytic H₂ production

Morphology regulation and electronic structure modulation are very important means to improve the photocatalytic H₂ evolution capability of the metal-free graphitic carbon nitride (g-C₃N₄) photocatalyst. Herein, we constructed a multiple ordered porous honeycomb structure g-C₃N₄via a one-step chemical vapor deposition (CVD) method with the co-pyrolysis of melamine and glucose, involving the in-plane seamless splicing of the carbon ring (C_r) into the g-C₃N₄ lattice network (denoted as C_r-PHCN). The as-prepared C_r-PHCN exhibits a periodic honeycomb structure with a ∼300 nm inner diameter and ∼20 nm wall thickness. The multi-dimensional honeycomb architecture provides the concomitant advantages of enhanced light-harvesting ability, abundant active sites and short electron transport paths. Simultaneously, the seamless in-plane C_r splicing in triazine@C_r extends the π-conjugated systems, which contributes to a narrow band gap, improved electrical conductivity and a low electron-hole recombination rate. Accordingly, the average hydrogen evolution rate (HER) of C_r-PHCN reaches 7581 μmol h⁻¹ g⁻¹, around 47.4 times that of pure CN (160 μmol h⁻¹ g⁻¹), and its remarkable apparent quantum efficiency (AQE) reaches 10.62% at 420 nm. This work has successfully achieved the simultaneous morphology control and in-plane modification of high-performance g-C₃N₄ with high yield.