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

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.