Issue 15, 2024

Steady Cu+ species via magnesium and boron co-modification for enhanced CO2 electroreduction to C2+ products: an in situ Raman spectroscopic study

Abstract

The electrochemical carbon dioxide reduction reaction (CO2RR) to produce high-value multi-carbon (C2+) compounds holds significant practical importance in realizing carbon neutrality. Copper-based electrocatalysts are promising for CO2-to-C2+ conversion. However, the labile Cu valence at high current densities impedes C2+ product generation. Here, we present an electrocatalyst derived from CuO, featuring a heterostructure of Cu/Cu2O/CuO/Mg(OH)2via the co-addition of Mg and B during the preparation (referred to as Cu5(B0.02 M)Mg1). The Cu5(B0.02 M)Mg1 shows an impressive C2+ yield, with a Faraday efficiency (FEC2+) of 79.59% at −1.57 V vs. RHE (reversible hydrogen electrode). Additionally, the partial current density of C2+ on the Cu5(B0.02 M)Mg1 catalyst is −317.03 mA cm−2, 2.7 and 3.5 times higher than those catalysts lacking B (Cu5Mg1 catalyst) or Mg (Cu(B0.02 M) catalyst), respectively. Over a wide potential range of 600 mV between −1.17 and −1.77 V vs. RHE, the overall FEC2+ surpasses 60% on the Cu5(B0.02 M)Mg1 catalyst. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS) and high-resolution transmission electron microscopy (HRTEM) characterization studies indicate the NaBH4 reactant could promote the formation of crystalline Mg(OH)2 in the catalyst structure, which is found to better stabilize Cu+ at negative potentials compared to the amorphous phase. Further in situ Raman spectroscopy reveals that at increasingly negative potentials, the higher copper species (Cu2+) is inevitably reduced to the lower copper species (Cu0/Cu+). However, the synergy of Mg and B prolongs the presence of Cu+ on the catalyst surface across a broad potential range, and *CO and *CO2 could still be recorded at quite negative reduction potentials. This suggests enhanced binding strength of *CO intermediates on the catalyst surface, promoting the C–C coupling process.

Graphical abstract: Steady Cu+ species via magnesium and boron co-modification for enhanced CO2 electroreduction to C2+ products: an in situ Raman spectroscopic study

Supplementary files

Article information

Article type
Research Article
Submitted
02 Apr 2024
Accepted
16 Mai 2024
First published
17 Mai 2024

Inorg. Chem. Front., 2024,11, 4770-4779

Steady Cu+ species via magnesium and boron co-modification for enhanced CO2 electroreduction to C2+ products: an in situ Raman spectroscopic study

H. Yang, X. Mu, J. Guan, B. Ouyang, H. Li and Y. Deng, Inorg. Chem. Front., 2024, 11, 4770 DOI: 10.1039/D4QI00842A

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