Synthesis of Au/Co₉S₈ composite aerogels by one-step sol–gel method as hydrogen evolution reaction electrocatalysts

The development of effective electrocatalysts for hydrogen evolution reaction (HER) with a high performance and low-cost is greatly desirable to meet the increasing demands for sustainable energy. In this work, we herein demonstrate Au nanoparticles (NPs)-coupled Co₉S₈ (Au/Co₉S₈) aerogels with a porous feature and high surface area via a simple sol–gel approach. Besides, the as-prepared complexes are supposed to generate synergistic effect to greatly promote the HER electrocatalysis in an alkaline electrolyte. The improved electric conductivity of the resulting composite can accelerate the HER kinetics. Notably, the as-prepared Au/Co₉S₈-10 aerogel displays a good electrocatalytic property for HER with an overpotential of 35 mV at 10 mA cm⁻² and a small Tafel slope of 64 mV dec⁻¹. The porous architecture not only improves the contact area at interfaces but also allows faster mass transportation during electrochemical process. Furthermore, the catalyst declares a promising electrochemical stability over 40 h of continuous HER catalysis with only 6% loss of its initial activity. Hence, this work offers a guiding strategy for synthesizing nanostructured earth abundant electrocatalyst with an enhanced HER performance.