Surfactant‐modified electrode–electrolyte interface for steering CO 2 electrolysis on Cu electrodes

Recent progresses have highlighted the enormous potentials of renewable electricities driven carbon dioxide (CO2) electrolysis in achieving carbon neutrality. However, its further industrial application is limited by low liquid product concentrations, which requires energy‐intensive downstream separation processing. Herein we report a CO2 and methanol co‐electrolysis strategy to produce formate at both electrodes and collect highly concentrated formate in zero‐gap CO2 electrolyzers. An anion exchange membrane was employed to enable formate product crossover from cathode to anode. A bismuth silicate derived nanofiber electrocatalyst with rich grain boundaries was synthesized and exhibited excellent formate selectivity (Faradaic efficiency >95%), high activity (partial current density >500 mA cm−2), as well as good stability (>120 h). Coupled with NiOX anode catalyst for methanol selective oxidation to formate in a zero‐gap electrolyzer, we demonstrate a ~180% of formate Faradaic efficiency and a full‐cell voltage of 2.43 V at an industrially relevant current density of 0.2 A cm−2. By decoupling product generation and collection, our electrolyzer produced a highly concentrated formate of 3.24 M, which could be directly used as anode fuel for fuel cells.

Section: Introductionmentioning

confidence: 99%

Concentrated formate produced through co‐electrolysis of CO₂ and methanol in a zero‐gap electrolyzer

Lin,

Chi,

Liu

et al. 2024

Insights into hydrophobicity‐tuned catalyst microenvironment in gas diffusion electrode for boosting CO₂ electrolysis

Dong,

Yu,

Sheng

et al. 2024

Self Cite

CO2 electrolysis to value‐added chemicals and fuels shows tremendous potential to store renewable electricity. It features with H2O as the hydrogen source of CO2 electroreduction. Here, we aim at the effect of the hydrophobicity‐tuned catalyst microenvironment in gas diffusion electrode (GDE) on boosting CO2 electrolysis. The hydrophobic polytetrafluoroethylene (PTFE) nanoparticles are introduced in the Sn catalyst layer of GDE. The PTFE‐modified GDE compared to the non‐PTFE electrode delivers a higher HCOOH Faraday efficiency and lower overpotential at current densities of 50–250 mA cm−2. A two‐dimensional axisymmetric model jointly with electrochemical impedance spectroscopy is developed to provide mechanistic insights into the hydrophobicity regulation. The simulated polarization current densities are in keeping with experimental results. The boosted CO2 electrolysis is attributed to the decrease of the distance from the gas–liquid phase boundary to the electrocatalyst. The understanding of the catalyst microenvironment established here can be generalized to other gas‐involved electrocatalytic reactions.

Sol–gel pore‐confined strategy to synthesize atomically dispersed metal sites for enhanced CO₂ electroreduction

Li,

Wang,

Liu

et al. 2024

Excavating highly efficient and cost‐effective non‐noble metal single‐atom catalysts for electrocatalytic CO2 reduction reaction (CO2RR) is of paramount significance. However, the general and universal strategy for designing atomically dispersed metals as accessible active sites is still in its infancy. Herein, we reported a general sol–gel pore‐confined strategy for preparing a series of isolated transition metal single atoms (Fe/Co/Ni/Cu) anchored on nitrogen‐doped carbon matrix. Benefiting from synergistic effect of M‐N4 coordination and neighboring N doping, the Fe‐N4‐C catalyst exhibited superior capability with a Faradaic efficiency of 96.9%, achieving highly stable electrocatalytic activity for more than 20 h. Density functional theory (DFT) calculations further revealed the changes in the dxz orbital of Fe, with a decrease in the out‐of‐plane component. Thus, a lower free energy barrier (ΔG) in thermodynamic pathway and the accelerated proton transfer to *COOH in kinetic pathway both enhanced electrocatalytic process.