Synergistic effects between Mo and Pd supported on carbon for enhanced deuterium evolution performance

Deuterium (D 2 ) is a strategic material essential to the nuclear, fiber optic, and semiconductor industries. Proton exchange membrane (PEM) electrolysis of heavy water (D 2 O) is a robust and environmentally friendly method for D 2 production, but its energy efficiency is limited by the sluggish deuterium evolution reaction (DER). While being a promising DER catalyst, Pd still suffers from suboptimal DER kinetics due to strong adsorption of active deuterium (D∗). Herein, synergistic interactions between Pd and Mo/MoO x on carbon black are introduced to modulate the adsorption of active deuterium/hydrogen, leading to outstanding deuterium/hydrogen evolution performance. In 0.5 M D 2 SO 4 (H 2 SO 4 ), the optimal PdMo/C catalyst exhibits a record low overpotential of 19.1 mV (13.3 mV) at 10 mA cm −2 and a mass activity 10 times higher than that of commercial Pt/C. Furthermore, PdMo/C outperforms Pt/C in PEM electrolysis of D 2 O at 1.5–3.0 A cm −2 . X-ray photoelectron spectroscopy, DFT calculation, and D∗ underpotential deposition experiments show decreased electron density of Pd and reduced adsorption energy of D∗ in the presence of Mo that lead to enhanced intrinsic activity. This work offers valuable insights into the development of high-performance Pd-based electrocatalysts and demonstrates their potential in industrial production of D 2 .