Coupling Value‐Added Anodic Reactions with Electrocatalytic CO₂ Reduction

Abstract

Electrocatalytic CO2 reduction features a promising approach to realize carbon neutrality. However, its competitiveness is limited by the sluggish oxygen evolution reaction (OER) at anode, which consumes a large portion of energy. Coupling value‐added anodic reactions with CO2 electroreduction has been emerging as a promising strategy in recent years to enhance the full‐cell energy efficiency and produce valuable chemicals at both cathode and anode of the electrolyzer. This review briefly summarizes recent progresses on the electrocatalytic CO2 reduction, and the economic feasibility of different CO2 electrolysis systems is discussed. Then a comprehensive summary of recent advances in the coupled electrolysis of CO2 and potential value‐added anodic reactions is provided, with special focus on the specific cell designs. Finally, current challenges and future opportunities for the coupled electrolysis systems are proposed, which are targeted to facilitate progress in this field and push the CO2 electrolyzers to a more practical level.

Single-Pass Electrooxidation of Glycerol on Bismuth-Modified Platinum Electrodes as an Anodic Process Coupled to the Continuous CO2 Electroreduction toward Formate

“…However, the sluggish kinetics of the OER and the low industrial value of the O 2 produced at the anode significantly reduce the competitiveness and economic feasibility of this process. In this way, coupling more valuable anodic reactions with CO 2 electroreduction has been the subject of recent and valuable contributions − and has emerged as a promising approach to lower the overall cell voltage, and consequently the energy efficiency of the system, and also to simultaneously produce high-added-value products both at the cathode and anode. Among the different anodic processes used as paired reactions with CO 2 RR, the electrooxidation of glycerol (GOR, glycerol oxidation reaction) to high-added-value products is one of the most interesting alternatives. ,,,,− Glycerol is the major waste product from biodiesel production and can be electrochemically oxidized into a variety of valuable chemicals. − In this sense, Verma et al demonstrated that coupling CO 2 RR with the electrooxidation of glycerol reduced the power consumption of the system by 53% compared to use of the OER as anodic process.…”

Stable Operation of Paired CO2 Reduction/Glycerol Oxidation at High Current Density

“…The other option is noble metals as electrocatalysts, such as Pt, ,− Au, Pd, , and their multimetallic derivatives, PtRu, , and PdAu . GOR can be driven at several hundred mVs less positive potentials compared to the OER. , A major general issue with using noble metals in GOR is that, mostly, a complex mixture of C1–C3 products forms, mandating the addition of separation/purification step(s). For example.…”

“… 27 GOR can be driven at several hundred mVs less positive potentials compared to the OER. 7 , 31 A major general issue with using noble metals in GOR is that, mostly, a complex mixture of C1–C3 products forms, mandating the addition of separation/purification step(s). For example.…”