Synergistic effect of cobalt boride nanoparticles on MoS2 nanoflowers for a highly efficient hydrogen evolution reaction in alkaline media.

The development of efficient, stable and low-cost electrocatalysts for the alkaline hydrogen evolution reaction (HER) is critical for large-scale, economically viable water splitting. In this work, we successfully prepared non-precious metal CoB@MoS2 hybrid electrocatalysts for the HER in alkaline media by the reductive growth of cobalt boride nanoparticles (CoB NPs) on the surface of MoS2 nanoflowers (MoS2 NFs). The CoB@MoS2-0.5-300 hybrid showed an HER overpotential of only 146 mV at a current density of 10 mA cm-2 and a Tafel slope of 80.9 mV dec-1 in 1.0 M KOH solution. The significantly enhanced HER activity of the hybrid is primarily attributable to the ability of CoB to drive the OER in alkaline solution and improved electrical conductivity of the hybrid electrocatalyst relative to the pristine MoS2. Furthermore, the synthetic strategy used to prepare the CoB@MoS2 electrocatalyst was successfully applied to prepare NiB@MoS2 and FeB@MoS2 hybrid electrocatalysts, which similarly showed very good HER activity in 1.0 M KOH solution. Thus, this work conclusively demonstrates that the introduction of transition metal borides is an effective approach for enhancing the HER performance of MoS2 in alkaline media.