Porous blade. like cobalt disulfide electrocatalyst boosting hydrazine.assistance energy-efficient hydrogen production

Here, we report a three-dimensional blade-like nanosheet cobalt disulfide electrocatalyst with CoS2 as the main crystal phase with a small amount of the mixed NiO phase, which is fabricated in situ on nickel foam (NF) by one-step hydrothermal synthesis. When the molar ratio of cobalt and sulfur in the solution was 1:5, the crystalline CoS2/NF electrocatalyst with a three-dimensional porous blade-like structure composed of 10 nm nanosheets was obtained at 140 degrees C for 18 h. During hybrid water electrolysis in an alkaline medium containing hydrazine hydrate, CoS2/NF electrode merely need 83 mV overpotential to deliver -10 mA.cm(-2) towards hydrogen evolution reaction (HER), while 51 mV (vs RHE) oxidation potential to drive 50 mA.cm(-2) towards hydrazine oxidation reaction (HzOR). Integrated into a hybrid cell towards hydrazine hydrate assisted water electrolysis, the CoS2/NF couple required a cell voltage of only 0.550 V to afford 100 mA.cm(-2) current density, far lower than that of overall water splitting (2.075 V), giving rise to the significant decrease of power consumption and the great improvement of hydrogen-producing efficiency. As-prepared CoS2/NF displayed excellent stability and durability towards HER or HzOR both in three-electrode and two-electrode systems. The formation of a nanoporous blade-like structure created a large number of micropores on the electrode surface, which led to the nearly 24-fold increased electrochemical active area (ECSA), and provided a huge amount of active sites and material transfer channels for the catalytic reaction. The formation of cobalt disulfide and nickel oxide phase synergically improved the intrinsic hydrogen evolution activity to a certain extent. The composition and structural characteristics of CoS2/NF contribute to superior catalytic performance, and the structural advantage played the predominant role in outstanding catalytic performances. Using mechanism research, the reaction paths of CoS2/NF in HER and HzOR are proposed, respectively.