Palladium-Conductive Metal Organic Framework Interaction Enhances the Electrochemical Hydrogen Evolution in Acidic Electrolyte.

Strong metal-metal-organic framework (MOF) interactions can markedly enhance electrocatalytic hydrogen evolution, yet the intrinsically poor conductivity of most MOFs constrains their performance. Here, we employ a conductive 2,3,6,7,10,11-hexaaminotriphenylene (HITP)-based MOF to anchor sub-5 nm Pd nanoparticles (<1.1 wt.%). The metal-node- and ligand-dependent interfacial interaction between Pd and M-HITP (M = Fe, Ni, Cu, Zn) endows Pd/M-HITP with markedly higher intrinsic activity than the pristine MOFs. Among the resulting hybrids, Pd/Fe-HITP exhibits outstanding activity, requiring only 15 mV to reach -10 mA cm⁻ ² and maintaining stability for over 100 h. Morphology modulation to Fe-HITP nanosheets further reduces overpotentials to 9 and 74 mV at -10 and -100 mA cm⁻ ², respectively, by mitigating mass transport limitations. Density functional theory calculations reveal that Fe sites, rather than Pd, serve as the true active centers, with the Pd-Fe-HITP interaction upshifting the Fe d-band center, enhancing *H adsorption, and lowering the free energy barrier to 0.044 eV. This work highlights conductive MOFs as promising platforms for interfacial design in advanced electrocatalysts.