A Pair-Electrosynthesis for Formate at Ultra-Low Voltage Via Coupling of CO2 Reduction and Formaldehyde Oxidation

Abstract

Formate can be synthesized electrochemically by CO2 reduction reaction (CO2RR) or formaldehyde oxidation reaction (FOR). The CO2RR approach suffers from kinetic-sluggish oxygen evolution reaction at the anode. To this end, an electrochemical system combining cathodic CO2RR with anodic FOR was developed, which enables the formate electrosynthesis at ultra-low voltage. Cathodic CO2RR employing the BiOCl electrode in H-cell exhibited formate Faradaic efficiency (FE) higher than 90% within a wide potential range from − 0.48 to − 1.32 VRHE. In flow cell, the current density of 100 mA cm−2 was achieved at − 0.67 VRHE. The anodic FOR using the Cu2O electrode displayed a low onset potential of − 0.13 VRHE and nearly 100% formate and H2 selectivity from 0.05 to 0.35 VRHE. The CO2RR and FOR were constructed in a flow cell through membrane electrode assembly for the electrosynthesis of formate, where the CO2RR//FOR delivered an enhanced current density of 100 mA cm−2 at 0.86 V. This work provides a promising pair-electrosynthesis of value-added chemicals with high FE and low energy consumption.

Simultaneous Anodic and Cathodic Formate Production in a Paired Electrolyzer by CO2 Reduction and Glycerol Oxidation

“…In contrast to recent works reporting simultaneous production of formate in paired electrolyzers, [14,15,19,20,22] our proposed system exhibits selectivity for formate of ∼141 % (45 % anode and 96 % cathode) at a current density of 200 mA cm −2 . Hence, the present paired electrolysis approach provides substantially increased formate production, reaching up to 282.8 mA cm −2 (Figure S10 and Table S8).…”

“…[10][11][12][13] The simultaneous production of valuable products from both anodic and cathodic half-cell reactions in a two-compartment reactor separated by a membrane is referred to as a paired electrolyzer. [12] Few reports showed results of a paired electrolyzer performing CO 2 RR on the cathode side combined with the methanol, [14,15] ethanol, [16] octylamine, [17] hydroxymethylfurfural (HMF), [18] PET, [19] glycerol, [11,20,21] or formaldehyde [22] oxidation as the anodic half-cell reaction. These studies showed that a paired electrolyzer can lower the cell voltage with concomitant increased production of valuable products.…”

Identification of Dynamic Active Sites Among Cu Species Derived from MOFs@CuPc for Electrocatalytic Nitrate Reduction Reaction to Ammonia

“…2 c) has a low signal-to-noise ratio, which can be attributed to the low Cu content. The peaks of Cu1.5/NTC at 955.0 and 934.7 eV can be described as Cu 2 p 1/2 and Cu 2 p 3/2 of Cu 2+ [ 31 ], and the peaks of Cu3.2/NTC samples at 953.5 and 933.3 eV are Cu 2 p 1/2 and Cu 2 p 3/2 of Cu 0 or Cu + [ 32 ]. The high-resolution XPS of Cu 2 p spectra for both Cu1.5/NTC and Cu3.2/NTC display a large half-peak width, indicating mixed valence states of Cu with 0, + 1, and + 2.…”

Formate Over‐Oxidation Limits Industrialization of Glycerol Oxidation Paired with Carbon Dioxide Reduction to Formate

“…Paired electrolysis for simultaneous production of formate at both anode and cathode is reported by CO 2 reduction coupled with oxidation of glycerol [5,6] or formaldehyde. [7] In this paper we optimize reaction conditions for the oxidation of glycerol to formate in flow cell electrolysis to pair this reaction with the reduction of CO 2 (Figure 1).…”

“…Since the costs of electrochemical cells is of great significance on the formate production costs, [4] paired electrolysis to produce formate at both electrodes can strongly reduce the formate production costs. Paired electrolysis for simultaneous production of formate at both anode and cathode is reported by CO 2 reduction coupled with oxidation of glycerol [5,6] or formaldehyde [7] . In this paper we optimize reaction conditions for the oxidation of glycerol to formate in flow cell electrolysis to pair this reaction with the reduction of CO 2 (Figure 1).…”