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 CoMoS 4 and NiMoS 4 were synthesized by a one-step reaction, and further CoMoS 4 -H and NiMoS 4 -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 CoMoS 4 -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 H 2 SO 4 . NiMoS 4 -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 H 2 SO 4 . In 1   M phosphate buffer solution, CoMoS 4 -H and NiMoS 4 -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.