Interface-engineered Cu–Co₃O₄ catalysts for efficient plasma-catalytic CO₂ hydrogenation

Nonthermal plasma (NTP) catalysis enables CO₂ hydrogenation to methanol under mild conditions, yet achieving high selectivity remains challenging. Here, we report an interface-engineered Cu₇Co₃ catalyst reduced at 300 °C (Cu₇Co₃–300) that delivers a CO₂ conversion of 15.3 % and a methanol space–time yield (STY) of 2.6 g·kg_cat⁻¹·h⁻¹, doubling that of the monometallic counterparts. Structural characterizations reveal intimately coupled metallic Cu and Co₃O₄ phases, with XPS evidencing interfacial electron transfer from Cu to Co₃O₄. This electronic modulation weakens H* adsorption on Cu and promotes hydrogen spillover to Co₃O₄, where H* adsorption is strengthened. In-situ diffuse reflectance infrared Fourier-transform spectroscopy (DRIFTS) shows that this hydrogen migration enables the Cu–Co₃O₄ interfacial structure to efficiently hydrogenate formate (HCOO*) and CO* intermediates, thereby increasing the flux of both reaction pathways. This work highlights interfacial electron engineering as a powerful strategy to synergistically activate dual hydrogenation routes for efficient plasma-catalytic CO₂-to-methanol conversion.