Regulation of Active Site Accessibility Enables Efficient Electrocatalytic CO2 Methanation

Abstract

Electrocatalytic CO₂ Reduction Reaction (ECO₂RR) driven by renewable energy, which could convert CO₂ into fuels or value-added chemicals, has become an effective approach to address environmental issues and the energy crisis. However, due to the low selectivity, the inferior activity, and unmanageable reconstruction of catalysts, the path of ECO₂RR remains a significant challenge. In this study, a series of electrocatalysts composed of copper–lanthanum nanoparticles dispersed within a nitrogen-doped carbon framework (LaCu@NCF-x, where x represents the abbreviation of calcination temperatures) were synthesized by calcining the mixture of polymers and metal ions, in which thermal control is the key to the catalyst preparation process. Phase and morphological characterizations reveal that the degree of carbonization and the accessibility of active sites were modulated by the temperature of calcination. The study highlights the importance of the synergistic and confinement effects of the encapsulating carbon layer, which not only provides a favorable matrix for the nanoparticles but also mitigates the reconstruction of electrocatalysts, thereby significantly enhancing its performance in CH₄ production during ECO₂RR. In particular, the LaCu@NCF-3 catalyst demonstrates the maximum Faraday efficiency (FE) of CH₄ up to 64.6% at −1.177 V vs RHE and superior stability. Moreover, it also maintains a high selectivity (FE_CH4 ≥ 60%) over the wide potential range from −0.977 V to −1.577 V vs RHE. This study provides a novel approach to the fabrication of efficient and stable Cu-based electrocatalyst for ECO₂RR to CH₄.