Molecular-scale CO spillover on a dual-site electrocatalyst enhances methanol production from CO2 reduction.

Cobalt phthalocyanine (CoPc) is recognized for catalysing electrochemical CO2 reduction into methanol at high Faradaic efficiency but is subject to deactivation. Cobalt tetraaminophthalocyanine (CoPc-NH2) shows improved stability, but its methanol Faradaic efficiency is below 30%. This study addresses these limitations in selectivity, reactivity and stability by rationally designing a dual-site cascade catalyst. Here we quantify the local concentration of CO, a key intermediate of the reaction, near a working CoPc-NH2 catalyst and show that co-loading nickel tetramethoxyphthalocyanine (NiPc-OCH3) with CoPc-NH2 on multiwalled carbon nanotubes increases the generation and local concentration of CO. This dual-site cascade catalyst exhibits substantially higher performance than the original single-site CoPc-NH2/carbon nanotube catalyst, reaching a partial current density of 150 mA cm-2 and a Faradaic efficiency of 50% for methanol production. Kinetic analysis and in situ sum-frequency generation vibrational spectroscopy attribute this notable performance improvement to molecular-scale CO spillover from NiPc-OCH3 sites to methanol-active CoPc-NH2 sites.