Highly dispersive and stable chelated Fe active sites on 2D graphitic carbon nitride nanosheets exhibit effective N2 molecule capture capacity for improving visible-light photocatalytic N2 fixation performance.

Amphiphilic two-dimensional graphitic carbon nitride nanosheets exhibit improved performance for visible-light-driven phase-boundary photocatalytic reduction of nitrobenzene to aniline.

Photocatalytic reduction of p‐nitrophenol to p‐aminophenol is important because of the high toxicity of p‐nitrophenol and the wide application of p‐aminophenol. Graphitic carbon nitride (g‐CN) is an excellent photocatalyst for various photo‐reduction reactions, but inefficient for photo‐reduction of p‐nitrophenol due to the electrostatic exclusion. In this work, we control the morphology and surface property of g‐CN and achieve significantly enhanced activity. The obtained protonated g‐CN nanosheet (pg‐CNNS) material has positively charged surface that can adsorb p‐nitrophenolate anions, therefore facilitating the transfer of photo‐generated electrons from catalyst to p‐nitrophenol. Its reaction rate is 1626 times higher than that of the pristine g‐CN. Besides the surface charge, the morphology of photocatalyst also has important effect on activity, which is demonstrated by the relatively low activity of protonated g‐CN in comparison to pg‐CNNS. The pg‐CNNS photocatalyst has an excellent stability and superior catalytic universality for photo‐reduction of various nitroaromatic compounds. This work does not only expand the application of a well‐known material, but also highlights the importance of understanding photocatalytic mechanism for designing photocatalyst.

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Composite hydrogels of graphitic carbon nitride nanosheets (CNNS) and polyacrylamide (PAM) with superior UV absorption and visible transparence capabilities are reported. CNNS is employed not only as a photocatalytic initiator to trigger the polymerization of acrylamide, but also as a cross‐linker to 3D connected PAM chains via hydrogen bonds. The obtained CNNS/PAM hydrogels are highly moldable for preparing various forms, and have good mechanical properties, self‐healing ability, and photo‐stability. Furthermore, the composite hydrogels have a wide spectral range for UV absorption compared to conventional UV protective materials. Besides the complete screening of UVB (280–315 nm) in sun radiation, the CNNS/PAM hydrogel film can also filter >95% UVA radiation (315–400 nm) by regulating the coating thickness, meanwhile retaining a high visible transmittance. Therefore, the CNNS/PAM hydrogels have potential applications for shielding UV radiation. Additionally, this strategy provides a common and facile route to fabricate functional composite hydrogels via photo‐induced polymerization.