Hydrophobicity Graded Gas Diffusion Layer for Stable Electrochemical Reduction of CO₂

Abstract

To mitigate flooding associated with the gas diffusion layer (GDL) during electroreduction of CO 2 , we report a hydrophobicity-graded hydrophobic GDL (HGGDL). Coating uniformly dispersed polytetrafluoroethylene (PTFE) binders on the carbon fiber skeleton of a hydrophilic GDL uniformizes the hydrophobicity of the GDL and also alleviates the gas blockage of pore channels. Further adherence of the PTFE macroporous layer (PMPL) to one side of the hydrophobic carbon fiber skeleton was aided by sintering. The introduced PMPL shows an appropriate pore size and enhanced hydrophobicity. As a result, the HGGDL offers spatial control of the hydrophobicity and hence water and gas transport over the GDL. Using a nickel-single-atom catalyst, the resulting HGGDL electrode provided a CO faradaic efficiency of over 83 % at a constant current density of 75 mA cm À 2 for 103 h operation in a membrane electrode assembly, which is more than 16 times that achieved with a commercial GDL.

Promoting CO2Dynamic Activation via Micro‐Engineering Technology for Enhancing Electrochemical CO2Reduction

“…in the next work to optimize the resistance of water invasion and improve the high current stability of the flow cell. [ 42 ]…”

“…in the next work to optimize the resistance of water invasion and improve the high current stability of the flow cell. [42] Based on the electrocatalytic performance order of I-Ni SA/NHCRs > O-Ni SA/NHCRs > Ni-NC, the difference in electrocatalytic activity between I-Ni SA/NHCRs, O-Ni SA/NHCRs and Ni-NC (similar content of Ni, Table S3, Supporting Information) might be caused by the diverse Ni catalytic environ ment, thus the critical role of the structure of support in electrocatalysis is first discussed. COMSOL Multiphysics finite-element method was used to computationally simulate the mass transport behavior in solid sphere structure (model I, e.g., Ni-NC) and hollow nano-reactor structure (model II, e.g., I-Ni SA/NHCRs), the designed simulation model was based on the size and morphology of the original sample to maximize the real reaction situation, as detailed shown in Figures S31-S33, Supporting Information (Figure 2b; Figures S13, S15 and Equations S7, S8, Supporting Information).…”

Stability Issues in Electrochemical CO2Reduction: Recent Advances in Fundamental Understanding and Design Strategies

“…In another work by Li et al., the hydrophobicity‐upgrading treatment by PTFE dipping and coating endowed commercial GDE with substantial resistance to flooding under flowing electrolyte conditions. [ 141 ] When equipped in MEA, the hydrophobicity‐graded GDE system demonstrated a 103 h of lifetime for CO production, which was ≈16 times longer than that of commercial GDE counterpart. In addition to the electrode modification, the morphology engineering of catalyst layer is also meaningful to upgrade hydrophobicity and inhibit flooding, especially for those catalysts in situ electrodeposited in the GDE.…”

Advances and challenges in membrane electrode assembly electrolyzers for CO2 reduction

“…73 In general, the factors inuencing the hydrophobicity of the GDE can be categorized as electrowetting effects, 66,67 hydrophilic carbonate salt precipitation, 74,75 pressure uctuations, 73 and defects or cracks in the GDE, 76 as summarized by Ramdin et al 77 Therefore, based on the above analysis and recent studies in the literature, the following solutions are summarized to address cathode ooding: (1) construct GDEs with improved intrinsic hydrophobicity. [78][79][80][81] For instance, Vermaas et al 64 Fig. 7 The water transport process inside the MEA.…”