Zn−Co−S Colloidal Nanocrystal Clusters as Efficient and Durable Bifunctional Electrocatalysts For Full Water Splitting

Abstract The synthesis of efficient, cost‐effective, and non‐toxic bifunctional electrocatalysts for oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) is highly needed for renewable energy related processes (conversion and storage). In the present work, we report a simple and straightforward one‐step hydrothermal strategy to prepare Zn−Co−S colloidal nanocrystal clusters (CNCs) for total water splitting (OER and HER activity) for the first time. The Zn−Co−S CNCs consist of a large number of interconnected nanoparticles forming spherical structures, which is very helpful for the electrochemical activity. Under alkaline conditions, the Zn−Co−S electrocatalyst demonstrates an excellent electrocatalytic activity by driving 10 mA cm⁻² at 157 mV HER and 320 mV OER overpotentials, respectively. The Zn−Co−S catalyst electrode maintained the catalytic activity for 12 h exhibiting a good electrochemical stability. Furthermore, as fabricated two‐electrode alkaline water‐splitting system of Zn−Co−S//Zn−Co−S affords 10 mA cm⁻² at a voltage of 1.64 V.