Harnessing Electrocatalytic Coupling of Carbon Dioxide and Methanol for High-Efficiency Formic Acid Production.

The coupling of electrocatalytic CO2 reduction (ECR) and methanol oxidation reaction (MOR) presents a promising strategy for simultaneous cogeneration of formic acid (FA) at both cathode and anode. However, sluggish kinetics, low selectivity and efficiency hinder practical application. Herein, we demonstrate an integrated ECR||MOR system employing CuBi cathode and NiCo anode for energy-efficient FA cogeneration. The CuBi alloy achieves high Faradaic efficiencies (FE > 90%) for FA generation over an extensive potential range (>400 mV), attributed to the accelerated formation of HCOO* intermediates in facilitating FA production. Meanwhile, the NiCo alloy reached a remarkable FE of 97.5% for FA generation at 1.4 V versus reversible hydrogen electrode, benefiting from rapid HCOO* intermediate formation that effectively mitigates CO toxicity. This unique system delivered a current density of 10 mA cm-2 at a voltage of 2.07 V, representing a substantial reduction of 320 mV compared to water electrolysis. Across a wide operational voltage window (2.0-2.8 V), the system consistently delivered total Faradaic efficiencies ranging between 189% and 192%, alongside exceptional FA production capacities surpassing 400 g kWh-1, which significantly outperformed traditional methods (∼220 g kWh-1). This work provides an efficient pathway for low-energy CO2 utilization and sustainable FA production.