Electrocatalytic regeneration of atmospherically aged MoS₂ nanostructures via solution-phase sulfidation

The performance of MoS₂ as a hydrogen evolution catalyst is diminished by exposure to air. We demonstrate a solution phase technique to resulfidate MoS_xO₂−x using Na₂S₂O₃. The success of the method was judged by performance as a H+ reduction catalyst. Following sulfidation samples displayed a favourable decrease in both onset potential and Tafel slope, with the best decreasing from −0.23 V to −0.18 V (vs. SHE), and 282 mV dec^-1 to 87 mV dec^-1 respectively. Ageing studies indicate that this method may be used to recycle the MoS₂ repeatedly without losing catalytic performance, although repeated sulfidation did result in homogenisation of the nanostructure.