Cobalt-incorporated tellurium-nanostructured electrocatalysts for hydrogen evolution reaction in acidic electrolyte

In recent years, transition metal dichalcogenides (TMDs) have attracted immense interest as new electrocatalysts in water splitting applications. Cobalt has often been incorporated into chalcogenides to form bifunctional electrocatalysts due to its abundance, catalytic activity, and environmentally friendly nature. Nanostructured tellurium is an emerging electrocatalyst support that can accelerate electron transportation while serving as a host to many active sites. This study focuses on exploring the effects of using different and low amounts of cobalt-incorporated tellurium nanostructured composites (CoTe₂/Te) as electrocatalysts in hydrogen evolution reactions (HER) with 0.5 M H₂SO₄ electrolyte. The electrocatalysts were prepared via a facile hydrothermal route. The highest HER activity was revealed for the CoTe₂/Te (Co:Te = 4:20) composite electrode, achieving overpotentials of 312 and 421 mV at 10 and 100 mA cm⁻², respectively, with a Tafel slope of 69.2 mV dec⁻¹. The optimal CoTe₂/Te (Co:Te = 4:20) electrode retains an analogous polarization curve with almost zero attenuation of the cathodic current after 2000 cyclic voltammetry curves (CVs). The electrode remained highly active even after constant current density was maintained in the stability testing over 20 h. The HER performance of the CoTe₂/Te (Co:Te = 4:20) electrode was observed to be superior to those of Te (commercial powder), Te (fabricated), and CoTe₂ electrocatalysts.