Dual-site synergy via interfacial engineering for enhanced CO₂ electroreduction to methanol

Electrocatalytic CO₂-to-methanol (MeOH) is hindered by the low efficiency of single-site catalysts, primarily due to insufficient local concentration of the key ^⁎CO intermediate. This work aims to construct a dual-site catalyst to synergistically boost ^⁎CO generation and its subsequent hydrogenation, thereby enhancing methanol production. Herein, a cooperative interface was designed by integrating single atoms Ni (SAs Ni) for CO₂-to-CO conversion and amino-functionalized cobalt phthalocyanine (CoPc-NH₂) for methanol formation on N-doped carbon nanotubes ((SAs Ni + CoPc-NH₂)/N-CNT). The dual-site catalyst achieves a remarkable methanol Faradaic efficiency (FE_MeOH) of 48.7% and a total current density of 45.6 mA cm^-2 at -1.05 V vs. RHE, outperforming single-component CoPc-NH₂/N-CNT (FE_max = 28.4%) and physically mixed SAs Ni/N-CNT + CoPc-NH₂/N-CNT (FE_max = 30.6%) in an H-cell. A peak FE_MeOH of 51.9% and a methanol partial current density of 103.8 mA cm^-2 are achieved in a flow cell. When tested in a membrane electrode assembly (MEA) electrolyzer fed with simulated flue gas (10% CO₂), the catalyst delivers a current density of 500 mA cm^-2, while maintaining a FE_MeOH of 67.1%. In situ attenuated total reflectance-surface-enhanced infrared absorption spectroscopy (ATR-SEIRAS) confirms the enhanced surface coverage of ^⁎CO and the emergence of the ^⁎CHO intermediate exclusively on the dual-site interface, revealing a synergistic mechanism wherein SAs Ni sites enrich the local ^⁎CO concentration and adjacent CoPc-NH₂ sites facilitate its selective hydrogenation to methanol. This work provides a catalyst design paradigm for efficient CO₂-to-methanol conversion and offers fundamental insights into constructing cooperative interfaces for multistep electrocatalytic reactions.