Electronic modulation influenced by interfacial Pd-O-Mo for enhanced acidic hydrogen evolution kinetics

Efficient electrocatalytic water splitting demands precise hetero-interface engineering. This work synthesizes Pd-anchored MoO₂@carbon hollow nanospheres (Pd/MoO₂@C HNSs) via a facile one-step polymerization, leveraging automatic Pd-O-Mo bonding to immobilize Pd nanoparticles on MoO₂ nanoclusters. X-ray absorption near-edge structure (XANES) analysis confirms enhanced electron transfer from Pd to oxygen, enabling exceptional acidic hydrogen evolution reaction (HER) performance: an ultralow overpotential of 28 mV at 10 mA cm^-2, a mass activity of 4.82 A mg^-1 (34-fold higher than Pt/C), and a turnover frequency of 2.53 s^-1 (18-fold higher than Pt_20%/C). The Pd integration effectively compensates the intrinsic low active-sites density on MoO₂ while accelerating H₂ desorption and HER kinetics. Assembled into an asymmetric-electrolyte electrolyzer harvesting electrochemical neutralization energy (ΔG = 0.83 eV), this system achieves hydrogen production at 10 mA cm^-2 with only 0.63 V applied voltage. This work highlights hetero-interface modulation as a universal strategy to activate inert electrocatalysts for sustainable energy conversion.