Highly dispersed nickel-copper bimetallic catalysts prepared by monolayer NiCu-layered double hydroxide nanocomposites for CO2 electrocatalytic reduction

Schematic illustration of the synthetic procedure of NiCu-CN/NiCuZn-CN. Based on solid phase exfoliation, single-layer LDH nanocomposite materials were obtained and mixed with an appropriate amount of melamine grinding, using the pyrolytic deposition strategy to anchor the metal in LDH on the carbon substrate. Meanwhile, Zn would volatilize when surrounding temperature exceeds 907°C, and the volatility of Zn would form mesoporous structures on the carbon skeleton, which was conducive to the exposure of catalytic active sites. [Display omitted] •Based on solid phase exfoliation, NiCu-LDH/ NiCuZn-LDH was exfoliated into monolayer by polyhydroxyl material.•The ultra-thin two-dimensional carbon substrate with homogeneous metals dispersion was formed by in-situ nitridation.•NiCuZn-CN catalyst shows an outstanding performance for CO2RR.•Provide new ideas for the design of highly dispersed metal catalysts. The design of novel electrocatalyst for CO2 reduction reaction to available chemical substance is a meaningful approach to mitigate the CO2 emission problem. However, it is challenging to achieve uniform dispersion of the metals in the carbon substrate to enhance catalytic performance. Surprisingly, layered double hydroxide nanosheets have uniform metal distribution, which are appropriate metal negative supports for CO2RR catalyst. Herein, we have successfully prepared a simple, green and efficient novel CO2RR metal catalyst using monolayer NiCu-LDH nanocomposites as precursor. Based on solid phase exfoliation, monolayer NiCu-LDH nanocomposite material was obtained, and then the ultra-thin two-dimensional carbon substrate with homogeneous metals dispersion was formed by in-situ nitridation. The obtained Ni2Cu1-CN shows excellent CO2RR performance with CO current density of 12.65 mA cm−2 and great CO faraday efficiency of 96.9 % at −0.8 V (vs. RHE). But metals formed nanoparticles due to vibration migration at high temperature, which caused active sites to be obscured. Surprisingly, introduction of Zn prevented Cu and Ni metals from agglomerating and exposed more active sites. The as‐prepared Ni2Cu1Zn1-CN shows excellent catalytic performance with the greatest CO faraday efficiency of 98.1 % and high CO current density of 16.6 mA cm−2 at −0.8 V (vs RHE) and remarkable stability.