Tubular Carbon Nitride with Hierarchical Network: Localized Charge Carrier Generation and Reduced Charge Recombination for High‐Performance Photocatalysis of H₂ and H₂O₂ Production

Polymeric carbon nitride (PCN), as an appealing metal‐free and low‐cost photocatalyst for solar‐to‐fuel conversion, is still suffering from insufficient light‐harvesting efficiency and short excited state lifetime of electron–hole pairs. Herein, a 3D hierarchical network of carbon nitride tubes (NCNT) with intercrossing few‐layer tubes of uniform diameter, synthesized by a synergistic strategy of tailoring the chemical and hydrogen bond, is reported. This hollow network structure facilitates the internal light reflection, thus promoting the light‐induced electron–hole pair generation. Moreover, the few‐layer NCNT with nitrogen defects effectively decreases the undesired electron–hole recombination. These advantages are disclosed by experimental spectra and finite difference time domain (FDTD) simulations and density functional theory (DFT) calculations. Impressively, the optimized NCNT exhibits almost 32 times the photocatalytic hydrogen evolution ability (8.6 mmol h⁻¹ g⁻¹) and 4 times (485.7 μmol h⁻¹ g⁻¹) the hydrogen peroxide production of those of bulk PCN, respectively. This work provides a new strategy to construct a hierarchical nanostructure of a high‐performance carbon nitride photocatalyst through enhancing the solar‐light capture and conversion.