Zheng Hu’s group reports the Oxygen-Bridged Cu Binuclear Sites for Efficient Electrocatalytic CO2 Reduction to Ethanol at Ultralow Overpotential on JACS


Electrocatalytic CO2 reduction (CO2RR) to fuels and chemicals using renewable electricity is a viable approach to achieving global carbon neutrality and sustainable development. Among the C2+ products from CO2RR, ethanol is a versatile organic reagent that can be utilized as a high-energy-density fuel, as well as a raw material for the production of organic chemicals and disinfectants.Copper-based catalysts, as the only catalyst capable of deep reduction of CO2, have attracted widespread attention. However, there are still problems such as poor selectivity for single products, large overpotential, unstable active site structure, and difficulty in explaining the mechanism. Therefore, it is crucial to develop efficient, stable, and structurally clear copper-based catalysts.

Recently, the research group of professor Zheng Hu at the Key Laboratory of Mesoscopic Chemistry of MOE took Cu2O as the precursor and hNCNC as the support, and successfully constructed the highly dispersive Cu catalyst, which is composed of the unique CuOCu-N4 binuclear sites with a Cu···Cu distance of 3.0−3.1 Å and the conventional Cu-N4 sites, thanks to the suitable micropores (0.6 nm) and high-content N dopants of the hNCNC. The DFT calculations reveal that the CuOCu-N4 binuclear sites enable the C−C coupling to become a spontaneous exothermic process at low overpotentials. And the CO produced at the coexisting Cu-N4 sites and hNCNC support could easily migrate to the adjacent CuOCu-N4 sites to increase the local CO concentration and promote the formation of C2+ products. Thus, the catalyst demonstrates a state-of-the-art low overpotential of 0.19 V for ethanol production and achieves a high C2+ FE (65.7%) in CO2RR with an ethanol FE of 56.3% at the low applied potential of −0.3 V via the tandem electrocatalysis. This study sheds new light on the convenient construction of the advanced Cu binuclear site catalysts, achieves the production of ethanol by CO2RR at ultralow overpotential, reveals the reaction mechanism by combined experimental and theoretical results and provides new ideas for the development of copper-based catalysts to prepare high added value C2+products.

 Figure 1. Morphology and structure characterizations of Cu−1/hNCNC. (a) TEM image. (b, c) HAADF-STEM image showing twinned Cu atoms (circled) and isolated Cu atoms (b) and corresponding enlargement of the sites 1−4 and intensity profiles (c). (d) Cu K-edge XANES spectra of Cu−1/hNCNC and the references. (e) FT-EXAFS spectra of Cu−1/hNCNC and the references. (f) FT-EXAFS fitting curve of the Cu K-edge in R-space for Cu−1/hNCNC and the corresponding structure diagram.

Figure 2. Electrocatalytic CO2RR performance and determination of active sites of Cu−1/hNCNC. (a) FE, j, and product distribution at different polarization potentials. (b, c) Operando XAFS of Cu−1/hNCNC at the OCP and −0.30 V: Cu K-edge XANES spectra (b) and FT-EXAFS spectra (c).

The related paper entitled “Oxygen-Bridged Cu Binuclear Sites for Efficient Electrocatalytic CO2 Reduction to Ethanol at Ultralow Overpotential” has been published on Journal of the American Chemical Society on March 12, 2024 (Paper link: https://doi.org/10.1021/jacs.4c01610, DOI: 10.1021/jacs.4c01610). Ph.D. student Fengfei Xu is the first author. Assoc. Prof. Lijun Yang, Prof. Qiang Wu and Prof. Zheng Hu from our department are co-corresponding authors. This work was jointly supported by the National Key Research and Development Program of China (No. 2021YFA1500900), the National Natural Science Foundation of China (Nos.21832003, 21972061, 52071174), and the Natural Science Foundation of Jiangsu Province, Major Project (BK20212005).