Selective Zero-Gap CO₂ Reduction in Acid

The electrochemical CO 2 reduction reaction (CO 2 RR) is a promising method of converting CO 2 into valuable chemicals and fuels, thereby contributing to carbon neutrality. This study explores the CO 2 RR under acidic conditions using a zero-gap electrolyzer, which minimizes ohmic losses by optimizing the electrode proximity. We assessed the performance of the CO 2 RR using a Ni single-atom catalyst, a porous diaphragm, and various ion-exchange membranes. Our findings show that the porous diaphragm enhances the CO Faraday efficiency (FE) and prevents salt formation, which are crucial for maintaining high selectivity and system durability. Comparative analyses demonstrate that, while traditional ion-exchange membranes can be faced with considerable salt buildup and/or reduced CO FE, the implementation of a zero-gap electrolyzer with a porous diaphragm offers a robust solution, enabling higher efficiency and stability, even at increased current densities. These developments can help optimize CO 2 electrolyzer technologies and enhance their operational and economic viability.