Construction of self-supporting bimetallic sulfide arrays as a highly efficient electrocatalyst for bifunctional electro-oxidation

Hydrogen production by water splitting is considered to be a feasible and energy-conserving way to develop renewable energy. Compared with water electrolysis which involves oxygen/hydrogen evolution reaction (OER/HER), the introduction of urea not only improves the energy conversion efficiency of water electrolysis but also involves the urea-rich wastewater treatment. In this work, a promising and novel bifunctional electrocatalytic material, bimetal nickel–cobalt sulfide nanosheet arrays on Ni Foam (NCS/NF), is developed as an electrocatalyst for water splitting. Benefiting from the sulfuration effect, which facilitates the formation of the high-valence states of Ni and Co during the oxidation process, the NCS/NF demonstrates a low potential of 1.46 V for the OER and 1.31 V for the UOR at 10 mA cm−2. When utilized in a water-splitting system with urea, the voltage is further reduced to 1.397 V at 10 mA cm−2. The result lays the foundation for exploring the feasibility of low energy-intensive and large-scale hydrogen production in the future.