Xuefang Lan

Three-dimensional (3D) photocatalysts can overcome the serious aggregation exhibited by two-dimensional (2D) nanosheets caused by unavoidable van der Waals forces. However, the water splitting efficiency needs further improvement, which can be achieved by boosting the exciton dissociation and charge transfer. Herein, a gelatin-confined strategy is developed to construct 3D tube-assembled g-C₃N₄ open frameworks. The gelatin plays multiple roles in the thermal polymerization. It not only engineers the grain growth of g-C₃N₄, but also supplies in situ external C and O sources. Experimental and density functional theory (DFT) calculation results indicate that the self-integration effects of the unique 3D architecture and bridging electron delocalization channels lead to prompt exciton production and dissociation, and subsequent carrier transfer. Consequently, the g-C₃N₄ open framework achieves a hydrogen evolution rate of 99.4 μmol h⁻¹ and an apparent quantum efficiency of 7.43% at 450 nm, significantly superior to previously reported C and (or) O-doped 2D g-C₃N₄ and other 3D g-C₃N₄ materials. These findings provide promising guidance for designing efficient 3D architectures to drive photocatalysis and support the broader application of cost-effective biopolymers.

Enhanced photocatalytic H ₂ evolution by bimetal cocatalyst of NiCoP@C.

Graphitic carbon nitride (CN) is a promising candidate for use in photocatalytic pollutant degradation, but it only shows moderate activity because of its sluggish photocarrier transfer and insufficient light absorption. Herein, CN@DMAP-X (DMAP is 4-dimethylaminopyridine and X is the amount of DMAP) samples were synthesized using a simple polycondensation strategy via grafting DMAP onto the edge of a g-C₃N₄ framework. The nucleophilic pyridine ring induces the delocalization of the local electrons of the large number of π-bonds, which alters the electron distribution and avoids in-plane carrier recombination. The steric hindrance effects of the 4-dimethylamino groups on DMAP limit the random growth of the g-C₃N₄ framework and contribute more layered structures, which can enhance visible light absorption via providing more scattering of light, and this can also provide more accessible active sites for the sunset yellow (SY) macromolecule. CN@DMAP-200 showed optimum visible light degradation efficiency toward SY, up to 2.51 times that of pristine g-C₃N₄. ¹O₂ was determined to be the dominant active species for SY degradation, whereas ˙O₂ ⁻ and h⁺ played secondary roles in photodegradation.

A magnetically recyclable Ni/NiO/g-C₃N₄ photocatalyst with significantly enhanced H2 evolution efficiency was successfully synthesized by a simple ethanol-solvothermal treatment. The presence of electronegative g-C₃N₄ is found to be the key factor for Ni⁰ formation in ternary Ni/NiO/g-C₃N₄, which provides anchoring sites for Ni²⁺ absorption and assembling sites for Ni⁰ nanoparticle formation. The metallic Ni⁰, on one side, could act as an electron acceptor enhancing carrier separation and transfer efficiency, and on the other side, it could act as active sites for H₂ evolution. The NiO forms a p–n heterojunction with g-C₃N₄, which also promotes carrier separation and transfer efficiency. The strong magnetic property of Ni/NiO/g-C₃N₄ allows a good recyclability of catalyst from aqueous solution. The optimal Ni/NiO/g-C₃N₄ showed a full-spectrum efficiency of 2310 μmol·h⁻¹·g⁻¹ for hydrogen evolution, which is 210 times higher than that of pure g-C₃N₄. This ethanol solvothermal strategy provides a facile and low-cost synthesis of metal/metal oxide/g-C₃N₄ for large-scale application.

Application of lead halide perovskites in CO₂ photoreduction in pure H₂O medium is restricted, owing to the inherent instability and high toxicity of lead. Herein, 3D melamine foam (MF) with an interconnected porous structure is selected as a multifunctional assistance to solve these problems. Three‐dimensionality of MF can avoid direct touches of CsPbX₃ (X = Br, I) with liquid H₂O, preventing damage of H₂O. Porosity of MF can accelerate H₂O evaporation by its strong adsorption and photothermal effects, which will overcome the drawback of low CO₂ solubility in aqueous solution, achieving a quick and sufficient mixture of CO₂ with H₂O vapor. These functions contribute to realize highly efficient CO₂ reduction by CsPbX₃ in pure H₂O medium. The best products and electron consumption yields of the composite reach 42.08 and 161.84 μmol g⁻¹ h⁻¹, respectively, which surpass most of the other CsPbX₃‐related works in H₂O or organic reaction media. MF/CsPbBr₃ also presents long‐term stability, with product yields not showing any obvious decrease after continuous reaction for 104 h. Moreover, strong adherence of MF toward perovskites allows a good recoverability of CsPbX₃, avoiding pollution of lead leakage to the environment.