Tuning Carbon-Supported Metal Single-Atom Catalysts toward Hydrogen Isotope Separation by Water Electrolysis

Water electrolysis is an attractive technique for hydrogen isotope separation in liquid water, and the development of hydrogen evolution reaction (HER) catalysts with a high separation factor and high activity is of crucial importance to minimize energy consumption. Herein, we prepare four kinds of single-atom catalysts (SACs) with different metal centers (Pt, Pd, Ni, and Co) on Ar plasma-treated graphite foil (AGF) via one-step plasma processing and compared their performance toward hydrogen separation during HER. The resultant Pt₁/AGF electrode exhibits a high catalytic activity toward HER with a low overpotential of 0.032 V at 10 mA cm^-2 and a high separation factor of 6.21 for hydrogen and deuterium separation, superior to other SAC counterparts or Pt/C catalysts. DFT calculations ascribe the high separation performance to the lower difference of zero-point energies of adsorbed hydrogen isotopes on the Pt-C₄ structure, which leads to a larger difference between hydrogen and deuterium adsorption free energies. This work paves the way for the design and application of SACs for hydrogen isotope separation via water electrolysis.