Surface Polarity Induced Simultaneous Enhancement of Nanopore Accessibility and Metal Utilization in Metal and Nitrogen Co-Doped Carbon Electrocatalysts for CO₂ Reduction

The efficient utilization of active centers for the emerging class of metal (M) and nitrogen (N) co-doped carbon (M–N–C) catalysts remains a research hotspot for electrochemical synthesis such as the reduction reactions of CO 2, O 2, N 2, or functional groups in organic molecules. However, keeping sufficient accessibility to these active centers upon thermal treatment at high temperatures can be challenging due to possible nanopore blocking issues. To tackle this limitation, this work presents a precise surface modulation approach based on a kind of porous carbon support with an ultrapolar surface, over which the unusual enhancement of nanopore accessibility and metal utilization is achieved. The strategy is well applicable to transition metals, precious metals, and rare earth metals. Experimental evidence revealed that the ultrapolar pore walls can be spontaneously wetted by hydrated metal ions. The unprecedented wettability ensured a unique metal-support interaction, which not only warrants the anchoring metal species in a dispersed manner but also induces the development of transport nanopores by dynamical etching of the polar carbon walls during thermal treatment. By this way, this strategy addresses the trade-off issue between metal utilization efficiency and accessibility to the active centers for the M–N–C type catalysts.