Kui Wang,Bin Chen,Yimin Xuan,Wenjun Fan,Nan Sun,Sheng Chang,Guowen Meng
The CO 2 electroreduction (CO 2 RR) is extensively deemed as a promising route to reach carbon neutralization, while the single-atom catalysts (SACs) are proved to be effective in CO 2 RR. However, most SACs cannot further amplify performance due to their powdery feature. Herein, we present numerous isolated nickel single atoms anchored on 3D interconnected N-doped carbon tubes (NiSAs@3D-INCT) network as a self-supported electrode. The NiSAs@ 3D-INCT has truly interconnected and highly ordered vertical and lateral carbon tube-channels, which promote the CO 2 interaction and electrolyte transmission. The NiSAs@3D-INCT exhibits a superior CO 2 RR performance with an appreciable CO partial current density of 51.8 mA cm −2 at − 0.96 V versus the reversible hydrogen electrode (RHE). X-ray absorption fine structure spectroscopy and theoretical computations reveal the NiSAs are loaded on the 3D-INCT network with Ni-N 4 configuration as highly active sites for CO 2 RR. This work will shed a new light on opening up high performance SACs for CO 2 RR.
Baochun Wang,Haorong Chen,Zilong Wang,Zhaoqing Jin,Anbang Wang,Yaqin Huang,Weikun Wang
Lithium-sulfur batteries (LSBs) are promising candidates as next-generation secondary batteries due to their advantages with respect to cost and energy density. However, their practical application is hindered by their slow kinetics and the shuttle behavior of soluble polysulfide ions. Herein, we successfully prepared a three-dimensional porous conductive catalyst material with an atomic-level Ni–N 4 structure. The results showed that a strong adsorption of lithium polysulfides (LiPSs) by the Ni–N 4 catalytic active sites and a strong catalytic effect on the conversion of LiPSs in the sulfur reduction reaction (SRR) as well as the lithium sulfide oxidation reaction (SOR) were achieved, effectively inhibiting the shuttle effect of polysulfide ions and promoting the sulfur cathode kinetics process. Thus, the LSBs exhibited an excellent performance with a specific capacity of 829.8 mAh g –1 and an average coulombic efficiency of 98.8 % after 420 cycles at a high rate of 1 C. Our work provides new insights and novel efforts to solve the shuttle effect in LSBs.
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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