Molybdenum disulfide nanosheets rich in edge sites for efficient hydrogen isotope separation by water electrolysis

Electrolysis of water offers an efficient and eco-friendly route to separate hydrogen isotopes and cathode electrocatalysts featuring high separation factors coupled with high activity and stability are increasingly in demand. In this work, we propose MoS2 rich in edge sites (MoS2-RS) as a promising hydrogen isotope separation electrocatalyst for the first time. MoS2-RS cathode exhibits high activity and hydrogen isotope selectivity with a low overpotential of 182.4 mV at 10 mA cm−2, a small Tafel slope of 61 mV dec−1 and a high hydrogen-deuterium separation factor (SH/D) of 10.22 in contrast to 6.33 for the commercial Pt/C catalyst. Density functional theory calculations ascribe the high selectivity of MoS2-RS to the H/D zero-point energy difference. Moreover, MoS2-RS demonstrates much higher values of SH/D compared with Pt/C catalyst under all test conditions and good long-term stability under acidic conditions. This work not only provides a promising catalytic material for efficient electrolytic separation of hydrogen isotopes but also indicates the direction of rational design of it.