Surface Engineering Approach to Maximize the Potential of Prussian Blue Analog Nanostructures for Electroreduction of CO ₂

Electroreduction of CO2 is a desirable approach to carbon capture, with the advantage of fixing CO2 to valuable chemicals. Transition-metal-coordinated metal–organic frameworks (MOFs) are progressively evolving as potential CO2 reduction reaction (CO2RR) electrocatalysts, but their low intrinsic conductivity limits their performance. This study addresses the limitations through a two-step surface-engineering strategy: etching and surface decoration with molybdenum disulfide (MoS2). The etchant selectively removes interior domains of redox-active Co–Fe Prussian blue analogue (PBA) MOFs via defect-assisted penetration, forming hollow nanostructures with enhanced conductivity and surface roughness. The catalytically active, edge-exposed 1T phase of MoS2 nanosheets is further anchored on etched PBAs, creating robust interfacial heterojunctions that promote electronic coupling and charge redistribution. The nanocomposite shows excellent electrochemical performance, with a low onset potential (−0.18 V vs RHE) and high reduction current (−20 mA cm–2 at −0.65 V vs RHE), superior to most MOF-based materials. The composite converts CO2 into multiple hydrogenated commodity products: gas products, confirmed by gas chromatography, and liquid products, confirmed by 1H NMR analysis. The maximum FE of 66.86% was observed for ethanol at −0.21 V vs RHE. Our findings propose that surface engineering via heterojunction formation can overcome the intrinsic limitations of MOF-based electrocatalysts, offering scope to further tune selectivity and maximize the utilization of non-Cu transition-metal-based MOFs for efficient CO2 conversion.