Hui Wang,Hongyuan Chuai,Xiaoyi Chen,Jianlong Lin,Sheng Zhang,Xinbin Ma
Single-atom catalysts within M-N-C structures are efficient for electrochemical CO2 reduction. However, most of them are powdered and require a coating process to load on the electrode. Herein, we developed a facile approach to the synthesis of large-scale self-supported porous carbon nanofiber electrodes directly decorated with atomically dispersed nickel active sites using facile electrospinning, where poly(methyl methacrylate) was employed to tune well the distributions of pores located in carbon nanofibers. The above self-supported carbon nanofibers were applied as a gas diffusion electrode to achieve 94.3% CO Faraday efficiency and 170 mA cm–2 current density, which can be attributed to the effects of rich mesoporous structures favorable for adsorption and mass transfer of CO2 and single nickel catalysts effectively converting CO2 to CO. This work provides an efficient strategy to fabricate self-supported electrodes and may accelerate the progress toward industrial applications of single-atom catalysts in the field of CO2 electroreduction.
Jun Ma,Feng Zhang,Ya Tan,Song Wang,Hui Chen,Lirong Zheng,Hongbo Liu,Run Li
The preparation of imines has drawn increasing attention as they are fundamental intermediates in the production of pharmaceuticals, agricultures, and fine chemicals. Nevertheless, current approaches for imines synthesis mainly focus on thermally driven reactions which always involve the consumption of high price noble metal catalysts, expensive ligands, strong base, and harsh reaction conditions. Herein, we demonstrate single atom nickel anchored on polymeric carbon nitride (Ni-SA@PCN) in Ni–N4 structure for visible light-promoted crossed coupling between aromatic alcohols and aliphatic amines. As expected, the Ni atoms dispersed carbon nitride demonstrates an obviously improved charge separation and transfer as reflected in UV–vis, fluorescence intensity and lifetime, photocurrent density, and electrochemical impedance characterizations. More impressively, the density functional theory (DFT) calculations also reveals that the presence of Ni atoms can dramatically accelerate the absorption of reactive substrates on the surface of PCN. The decreased absorption energy from −0.51 to −3.35 eV, associated with increased O═O bond length from 1.226 to 1.371 Å indicates a huge advantage of single Ni atom on oxygen activation. As a result, the obtained Ni-SA@PCN photocatalyst shows a prominent catalytic efficiency in imines formation with a reaction conversion of 73% and selectivity of >99%. Lastly, the photocatalytic reactions displays an excellent compatibility with various imines being achieved with high yield.
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