Low-cost and highly efficient CoMoS4/NiMoS4-based electrocatalysts for hydrogen evolution reactions over a wide pH range

Highly efficient and low-cost electrocatalysts are essential for producing hydrogen through water electrolysis. Here ternary compounds CoMoS4 and NiMoS4 were synthesized by a one-step reaction, and further CoMoS4-H and NiMoS4-H were obtained by heating the above two samples under Ar atmosphere. The above four materials both show uniformly small irregular nanoparticles. Each element of the four materials exhibits semblable valence without distinct difference of which S was −2, Mo was +6, Ni and Co were +2. We firstly use the above ternary materials as advanced electrocatalysts for HER over a wide pH range, of which CoMoS4-H displays the best performance with a low onset overpotential at 8 mV in 1.0 M KOH and 83 mV in 0.5 M H2SO4. NiMoS4-H also shows excellent performance with a low onset overpotential at 26 mV in 1.0 M KOH and 160 mV in 0.5 M H2SO4. In 1 M phosphate buffer solution, CoMoS4-H and NiMoS4-H exhibit onset overpotential at overpotential of 122 mV and 152 mV, respectively. These results indicate that the combination of earth-abundant sulfur, cobalt (or nickel) and molybdenum elements can provide highly active electrocatalysts for HER over a wide pH range.