CNTs Coordination-Embedded into Copper–Pyrazole MOFs for Selective Electrocatalytic CO2 to C2H4

Abstract

Selective electrolytic CO₂ to C₂H₄ is a meaningful pathway to alleviate both energy and environmental concerns. Copper–pyrazole MOFs (CuPz) has emerged as a highly promising and ideal catalytic material for C₂H₄ production from electrocatalytic CO₂ reduction. Here, short carbon nanotubes (CNTs) or functionalized CNTs were in situ embedded into CuPz to enhance its electrical conductivity and to regulate the direct coordination microenvironment of the Cu active center. Following a pre-reduction at − 1.3 V vs. reversible hydrogen electrode (RHE), a further increase in low-valent Cu was observed on the surface of CuPz, particularly in the case of CuPz@FCNT-A, with Cu⁺ accounting for over 50%. This resulted in the highest C₂H₄ selectivity (55.3% FE_C2H4) at − 1.1 V vs. RHE and excellent stability. The embedding of short CNTs or functionalized CNTs exposed more active sites, and, at the same time, enhanced the catalysts’ electron transfer ability. Notably, functionalized CNTs exhibited a more pronounced positive impact than pristine CNTs. The reaction mechanism responsible for C₂H₄ production was elucidated through in situ attenuated total reflection-fourier transform infrared spectroscopy (ATR-FTIR) analysis, which revealed that *CO dimerization was the primary pathway and *CO–*COH coupling was the secondary one.

Graphical Abstract