The rational design of single atom catalysts (SACs) with tailored electronic and geometric structures is essential for optimizing electrocatalytic performance in carbon dioxide reduction reactions (CO2RR). In this work, we report a highly effective strategy to engineer the atomic-scale environment of copper atoms on MXene supports through selective etching of quaternary MAX phases. The synthesis involves the controlled removal of aluminum from Ti3(Al1−xCux)C2 via molten ZnCl2 treatment at 600 °C, where AlCl3 sublimates selectively, leaving behind isolated Cu atoms anchored onto the Ti3C2Clx surface. This process not only preserves the structural integrity of the MXene but also ensures uniform dispersion of Cu atoms without aggregation.
Advanced characterization techniques confirm the successful formation of single atom Cu sites. Aberration-corrected high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM) reveals numerous bright dots corresponding to individual Cu atoms distributed across the MXene layers. X-ray absorption near-edge structure (XANES) analysis shows that Cu exhibits an intermediate oxidation state between Cu⁺ and Cu²⁺, indicating charge transfer from Cu to the surrounding oxygen ligands. Extended X-ray absorption fine structure (EXAFS) fitting confirms three-coordinate O–Cu bonding with a bond length of 1.92 Å, with no evidence of Cu–Cu scattering, proving the absence of clustering.
Surface-sensitive techniques such as X-ray photoelectron spectroscopy (XPS) further support these findings. The Cu 2p₃/₂ peak appears at 933.7 eV, consistent with Cu⁺ species stabilized by oxygen coordination. O 1s spectra show contributions from Ti–O and surface hydroxyl groups, confirming the presence of oxygen-rich functionalization on the MXene surface.HLA-F Antibody supplier The Ti 2p and Cl 2p spectra indicate the retention of dominant surface Cl termination, which enhances the stability of the MXene framework under electrochemical conditions.137234-62-9 Formula
Electrocatalytic evaluation demonstrates that SA-Cu-MXene achieves a Faradaic efficiency of 59.1% for methanol production at −1.4 V vs RHE, among the highest reported for SACs in CO2RR.PMID:34319926 The current density reaches 21.3 mA cm⁻² under identical conditions, significantly higher than that of Cu-particles-MXene (9.6 mA cm⁻²) and pristine MXene (3.7 mA cm⁻²). Chronoamperometry tests over a range of potentials reveal a volcano-shaped trend in methanol selectivity, peaking at −1.4 V. Notably, the catalyst maintains >58% Faradaic efficiency after 30 hours of operation, highlighting its robustness.
DFT calculations elucidate the origin of enhanced activity. The Cu–O₃ configuration creates a highly unsaturated electronic structure that facilitates the adsorption and activation of CO2 molecules. The rate-determining step—conversion of HCOOH* to CHO*—is thermodynamically favorable due to a low energy barrier (0.15 eV), attributed to the optimized binding strength of key intermediates. In contrast, nanoparticle Cu surfaces exhibit higher barriers (0.27 eV), leading to less efficient methanol formation. Moreover, the suppression of C–C coupling pathways due to isolated Cu sites favors the selective production of CH3OH over ethylene or ethanol.
This study establishes a clear correlation between atomic-scale structure and catalytic function in SACs. By combining selective etching with precise control over surface chemistry, we demonstrate a powerful approach to engineering single metal atom catalysts with superior activity, selectivity, and stability. The methodology can be extended to other transition metals and layered materials, offering broad potential for next-generation electrocatalysts in renewable energy conversion.MedChemExpress (MCE) offers a wide range of high-quality research chemicals and biochemicals (novel life-science reagents, reference compounds and natural compounds) for scientific use. We have professionally experienced and friendly staff to meet your needs. We are a competent and trustworthy partner for your research and scientific projects.Related websites: https://www.medchemexpress.com
