Dual-porphyrin architecture <i>via</i> post-modification: cobalt-porphyrin/guest-porphyrin hybrid POPs for synergistic hydrogen evolution catalysis

Developing electrocatalysts with synergistic active sites is a powerful strategy for enhancing hydrogen evolution reaction (HER) efficiency, yet achieving precise control over site interactions remains challenging. In this work, we introduce a cobalt-porphyrin/guest-porphyrin hybrid porous organic polymer (POP) synthesized <i>via</i> a post-modification strategy, enabling the construction of a dual-porphyrin architecture with tailored catalytic synergy. By incorporating cobalt-porphyrin (CoTPPOH) as additional active sites into the POP framework, the resulting material (CoTAPPHIPA-CoTPPOH) achieves strong electronic coupling and optimized spatial arrangement between Co(II) centers. This synergistic integration facilitates faster charge transfer, lowers the energy barrier for proton reduction, and significantly accelerates HER kinetics. As a result, the catalyst delivers a low overpotential of 123 mV at 10 mA cm^-2 in alkaline media, surpassing single-porphyrin analogs (CoTAPPHIPA, TAPPHIPA) and outperforming benchmark electrocatalysts. Furthermore, the robust POP framework provides exceptional long-term stability, maintaining HER performance without obvious degradation. This study pioneers a post-synthetic strategy to engineer cooperative catalytic sites, offering a novel design paradigm for next-generation HER electrocatalysts.