Selective formaldehyde condensation on phosphorus-rich copper catalyst to produce liquid C3+ chemicals in electrocatalytic CO2 reduction

Abstract

Recent advancements in the CO2 reduction reaction (CO2RR) target multicarbon chemical production and scalable electrode designs for industrial applications. Here we introduce a zero-gap cell utilizing humidified gas-phase CO2 and circulated alkaline media, achieving a Faradaic efficiency of 66.9% for C3+ products and a current density of −1,100 mA cm−2. In situ spectroscopic analyses revealed formaldehyde as a key intermediate formed on copper oxide/hydroxide interfaces derived from a phosphorus-rich copper catalyst. Unlike conventional pathways based on dimerization of CO intermediates, our study selectively produces liquid-phase multicarbon products because of autonomous local pH variations under a weak alkaline microenvironment, with allyl alcohol as the dominant C3+ product. The high selectivity and efficiency for liquid products provide a substantial advantage for storage and transport, highlighting the scalability and practical feasibility of our approach, which offers a potential economically viable solution for CO2 utilization. This development encourages the adoption of CO2RR technologies in iron–steel and petrochemical industries to mitigate greenhouse gas emissions. (Figure presented.) © The Author(s) 2025.