Porous Bilayer Electrode‐Guided Gas Diffusion for Enhanced CO₂ Electrochemical Reduction

Abstract

Comparing with the massive efforts in developing innovative catalyst materials system and technologies, structural design of cells has attracted less attention on the road toward high‐performance electrochemical CO2 reduction reaction (eCO2RR). Herein, a hybrid gas diffusion electrode‐based reaction cell is proposed using highly porous carbon paper (CP) and graphene aerogels (GAs), which is expected to offer directional diffusion of gas molecules onto the catalyst bed, to sustain a high performance in CO2 conversion. The above‐mentioned hypothesis is supported by the experimental and simulation results, which show that the CP + GA combined configuration increases the Faraday efficiency (FE) from ≈60% to over 94% toward carbon monoxide (CO) and formate production compared with a CP only cell with Cu2O as the catalyst. It also suppresses the undesirable side reaction–hydrogen evolution over 65 times than the conventional H‐type cell (H‐cell). By combining with advanced catalysts with high selectivity, a 100% FE of the cell with a high current density can be realized. The described strategy sheds an extra light on future development of eCO2RR with a structural design of cell‐enabled high CO2 conversion.

Electrocatalytic CO2 Reduction in Acetonitrile Enhanced by the Local Environment and Mass Transport of H2O

“…Others have also found that ionic liquid environments enhance the selectivity of CO 2 reduction toward CO as well as higher-order hydrocarbons . Additional examples of environmental engineering include selection of electrolyte molecules − and morphology of catalyst materials. − However, because CO 2 reduction usually involves protons, the effects of the local environment of the proton donor, such as H 2 O, require further scrutiny as even minute quantities of H 2 O in bulk solvent can play a crucial role in electrochemical CO 2 reduction. ,− One of the main challenges in probing the local environment of H 2 O during electrochemical CO 2 reduction in aqueous electrochemical systems is the competition between CO 2 reduction and the hydrogen evolution reaction (HER) from H 2 O reduction, reactions that occur over a similar potential range. Further, because of the significantly higher concentration of H 2 O compared to CO 2 in aqueous media, the HER can dominate and overwhelm the CO 2 reduction reaction. , …”

Polyhedral Carbon Anchored on Carbon Nanosheet with Abundant Atomic Fe‐Nx Moieties for Oxygen Reduction

“…These results indicate that PCCNS-20 has the highest active site volumetric density and strong mass/charge transport capability. [40] We further analyzed the rotating ringdisk electrode (RRDE) results to calculate the electron transfer number (n) and the peroxide species yield (H 2 O 2 %). In Figure 5d, the n value of the PCCNS-20 is identified between 3.98 and 4.00 at the potential range of 0.2-0.8 V, almost the same as the commercial Pt/C.…”

Advances in electrolyzer design and development for electrochemical CO2 reduction

“…COMSOL simulation on CO 2 molar concentration along the cathode catalyst layer for (N) CP‐cell, (O) GA‐cell, and (P) GACP‐cell. Reproduced with permission: Copyright 2021, John Wiley & Sons, Inc 64 …”

“…Liu et al 63 designed a porous hybrid bilayer GDEs that achieve the FE $ 94% of CO than H-cell $ 60%. Traditional GDEs consists of catalyst layer and gas diffusion layer that the catalysts uniformly coated on the carbon 64 paper with the average thickness of 10 μm (Figure 4H-J). However, the traditional GDEs structure will destroy after a long-term reaction and the electrolyte will block the CO 2 mass transfer pathway.…”