Catalytic resins are advanced functional materials that integrate ion-exchange properties with embedded catalytic centers, typically metal complexes, to drive specific chemical transformations . These resins consist of a polymeric matrix functionalized with ion-exchange groups (Figure & b), which selectively bind or release ions in response to the surrounding environment. This ion-exchange capacity ensures a controlled and efficient supply of protons or other reactants to the catalytic centers, making them particularly effective for hydrogen evolution reactions (HER). The combination of high surface area, mechanical stability, and selective ion transport enables catalytic resins to achieve exceptional turnover numbers (TON) and turnover frequencies (TOF), all while maintaining durability under harsh electrochemical conditions. The synergy between ion-exchange dynamics and the catalytic activity of embedded metal complexes enhances both reaction kinetics and product yield .