A coupled electrocatalytic system with reduced energy input for CO2 reduction and biomass valorization

Coupling the cathodic electrochemical CO2 reduction (eCO2RR) with the anodic electrochemical 5-hydroxymethylfurfural oxidation reaction (HMFOR) is an appealing approach to co-produce value-added chemicals and simultaneously lower the energy input, while the main challenge is to develop effective electrocatalysts for eCO2RR and HMFOR. Inspired by the techno-economic analysis, we herein report a coupling system for economical formate generation and biomass valorization by concurrent cathodic eCO2RR and anodic HMFOR. Single Cu atom doped Bi (Cu1Bi) and NiCo layer doubled hydroxides (NiCo LDHs) are used as the cathodic and anodic catalysts, respectively. Due to the accelerated water dissociation, the Cu1Bi cathode catalyst demonstrated remarkably high activity (jformate > 1 A cm−2) for formate conversion as well as robust stability (200 mA cm−2 for 45 h). Meanwhile, the NiCo LDH anode displays high activity for HMF electrooxidation to 2,5-furandicarboxylic acid with a faradaic efficiency of over 95% at low potential. Consequently, the paired eCO2RR-HMFOR system reduces the electricity input for the eCO2RR-to-formate conversion to ∼3493 kW h per tonne of formate, corresponding to 22.9% in energy saving compared to the conventional eCO2RR (∼ 4528 kW h per tonne of formate). This study offers an appealing route for CO2 reduction and biomass valorization with low energy consumption.