Immobilized molecular catalysts (IMCs) with well-defined active sites and tunable coordination environments are promising candidates for catalyzing the electrochemical CO₂ reduction reaction (CO₂RR) with high activity and selectivity. With substantial progress in catalyst development, IMCs are being transitioned from batch cells (e.g., H-cells) where activity is limited by CO₂ solubility in aqueous electrolyte, to flow electrolyzers equipped with gas diffusion electrodes (GDEs) that can achieve commercially relevant CO₂RR current densities. This transition is challenged by the drastic differences in the microenvironment (e.g., local pH, CO₂ concentration, GDE wetting) between batch cells and flow electrolyzers, and a poor understanding of the implications of these microenvironment changes on CO₂RR performance of IMCs. In this perspective, we highlight recent studies that probe the IMC-microenvironment interactions in GDE configurations, and we suggest strategies to understand better microenvironment effects using electrochemical measurements, in situ spectroelectrochemical measurements, and post-mortem catalyst characterization.

具有明确活性位点和可调配位环境的固定化分子催化剂（IMC）是催化高活性和选择性电化学CO ₂还原反应（CO _{2 RR）的有希望的候选者。随着催化剂开发的实质性进展，IMC 正在从活性受到水性电解质中 CO 2}溶解度限制的间歇式电池（例如 H 电池）过渡到配备气体扩散电极 (GDE) 的流动电解槽，可实现商业相关的 CO ₂ RR 电流密度。这种转变受到微环境（例如当地 pH、CO ₂批处理电池和流动电解槽之间的浓度、GDE 润湿），并且对这些微环境变化对IMC 的CO ₂ RR 性能的影响了解甚少。从这个角度来看，我们重点介绍了最近探索 GDE 配置中 IMC-微环境相互作用的研究，并提出了使用电化学测量、原位光谱电化学测量和事后催化剂表征来更好地了解微环境影响的策略。