High performance, 3D-hierarchical CoS2/CoSe@C nanohybrid as an efficient electrocatalyst for hydrogen evolution reaction

Electrolysis, driven by renewables, is ideally a direct and clean route to generate the hydrogen. However, for the efficient H2 generation designing active, stable and low cost electrocatalyst system to replace expensive Pt is of paramount importance. Here, a hetero-structured system composed of CoS2 and CoSe nanostructures on carbon matrix (CoS2/CoSe@C) is proposed as an active electrocatalyst for hydrogen evolution reaction (HER) in acid medium. The composition of sulfur and selenium in the derived CoS2/CoSe@C electrocatalyst is analytically controlled for the enhanced HER performance. The prepared electrocatalyst offers the low overpotential of 164 mV at the current density of 10 mA cm−2 with a small Tafel slope of 42 mV dec−1 as a result of proper synergy between the active components CoS2 and CoSe. Moreover, the interconnected network in the carbon matrix of CoS2/CoSe@C provides better conductivity ensured by adequate contact area between the electrocatalyst and electrolyte. Besides the convincing electrochemical activity, catalyst demonstrates the good stability for at least 10 h. This work highlights importance of composite materials for HER via synchronizing catalytically active materials (Ni, Co, Mo) and highly conductive supports (CNT, C, rGO).