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g‐C3N4 (g‐CN) with edge grafting of 4‐(1H‐imidazol‐2‐yl) benzoic acid (IBA) and NiS cocatalysts is fabricated via a one‐pot chemical condensation of monomers with urea and subsequent photodeposition. The successful copolymerization of the IBA in g‐CN (g‐CN/IBA) is easily identified by 13C NMR spectra, Fourier transformed infrared spectra, and UV–vis absorption spectra. As a result, the acquired copolymer composites exhibit greatly enhanced visible‐light photocatalytic performance for H2 evolution, in comparison with the undoped g‐CN. The g‐CN‐IBA photocatalyst with the optimal loading amounts of NiS displays an outstanding hydrogen‐evolution rate of 2948.52 µmol g‐1 h‐1 under visible light (λ > 420 nm). The maximum apparent quantum efficiency of g‐CN/IBA‐3%NiS is 3.20% at 450 nm. The enhanced activity can be attributed to the synergism of edge grafting of 4‐(1H‐Imidazol‐2‐yl) benzoic acid and loading of NiS cocatalysts, which not only shows a remarkable redshift of the optical‐absorption compared to g‐CN, effectively improving the absorption in the visible range, but also effectively avoids recombination and drives the favorable separation of photogenerated carriers in plane. This work provides a protocol for simultaneously increasing the active sites of light absorption and surface reactions of g‐CN‐based photocatalysts to maximize photocatalytic hydrogen production activity.

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Conjugated organic polymers (COPs) have recently attracted intense interest in photocatalytic hydrogen evolution (PHE) due to their easily tuned properties, high stability, and processability. However, most COPs photocatalysts displayed poor...

Direct photocatalytic hydrogen and oxygen evolution from water splitting is an attractive approach for producing chemical fuels. In this work, a novel fluorenone‐based covalent organic framework (COF‐SCAU‐2) is successfully exfoliated into ultrathin three‐layer nanosheets (UCOF‐SCAU‐2) for photocatalytic overall water splitting (OWS) under visible light. The ultrathin structures of UCOF‐SCAU‐2 greatly enhance carrier separation, utilization efficiency, and the exposure of active surface sites. Surprisingly, UCOF‐SCAU‐2 exhibits efficient photocatalytic OWS performance, with hydrogen and oxygen evolution rates reaching 0.046 and 0.021 mmol h−1 g−1, respectively, under visible‐light irradiation, whereas bulk COF‐SCAU‐2 shows no activity for photocatalytic OWS. Charge‐carrier kinetic analysis and DFT calculations confirm that reducing the thickness of the COF nanosheets increases the number of accessible active sites, reduces the distance for charge migration, prolongs the lifetimes of photogenerated carriers, and decreases the Gibbs free energy of the rate‐limiting step compared to nonexfoliated COFs. This work offers new insights into the effect of the layer thickness of COFs on photocatalytic OWS.

Covalent organic framework (COF) has been emerged as an extremely promising material for photocatalytic splitting from water for hydrogen production. However, its photocatalytic performance is seriously affected by the properties...