Achieving Efficient Electrocatalytic CO<sub>2</sub>-Involved N-Methylation on Cu–Ni–Al Heterostructured Catalysts
Xiaodong Ma, Xinning Song, Xingxing Tan, Libing Zhang, Shunhan Jia, Limin Wu, Ruhan Wang, Weixiang Li, Chaofeng Zheng, Lihong Jing, Xinchen Kang, Qinggong Zhu, Xiaofu Sun, Buxing Han
Abstract
Using CO 2 as the carbon source for electrocatalytic C–N coupling with organic amino compounds to achieve N-methylation reactions offers an appealing route for synthesizing valuable N-containing chemicals, mitigating CO 2 emissions, and storing renewable energy but is challenging. Herein, we report the first work to design heterostructured Cu–Ni–Al electrocatalysts for N-methylation. Using 4-hydroxypiperidine (PD) as a substrate, high electrocatalytic performance with a 1-methyl-4-piperidinol (MPD) faradaic efficiency (FE) of 29.3%, a N-methylation selectivity of 100%, a C-selectivity of 78.3%, and a formation rate of 15.4 mmol g –1 h –1 was achieved in the H-cell. It also showed remarkable recycling stability. Control experiments and in situ measurements confirmed the key role of the CuO/NiAl 2 O 4 heterostructure for the N-methylation reaction. Moreover, a combination of experimental and density functional theory (DFT) calculations demonstrated that CO 2 converted to the *H 2 CO intermediate on the CuO/NiAl 2 O 4 heterostructure, which underwent chemical condensation and subsequent reduction with nucleophilic amino compounds on the CuO/NiAl 2 O 4 heterostructure, leading to high efficiency toward N-methylation. Further investigation showed that this system could also be extended to other amino compounds.