Nickel Based Selenide Nano Array For Highly Efficient Oxygen Evolution

Oxygen evolution reaction(OER)represents the core process of many electrochemical systems like metal-air batteries and water splitting.However,OER has been regarded as the bottleneck in improving the efficiency of these systems with its sluggish kinetics.Thus,finding a stable,active and low-cost OER catalyst has been highly required.The electrocatalytic performance is highly depended on the conductivity and active sites of catalyst.Therefore,catalysts directly grown on a conductive substrate with well-designed architecture can solve this problem.For nickel based selenides,the rich valance states,the unique electron states and conductivity make them become promising electrocatalysts.In this paper,we prepared nickel based selenides catalysts on conductive Ni foam to build 3D self-supported electrodes.Besides,we also discussed the relationship of structure,chemical composition and electrocatalytic activity of the catalysts.1.We develop a new way to fabricate the 3D Ni0.85Se nanosheet arrays on conductive nickel foam by hydrothermal synthesis and selenization treatment.The nickel hydroxides were firstly grown on the Ni foam by a simple hydrothermal synthesis.After subsequent selenization,the Ni0.85Se nanosheet arrys were obtained and showed a good OER performance and stability.2.We develop a new strategy to synthesize the three-dimensional hierarchical NiCoSe2/Ni foam.Introducing NH4F as surface controller during the hydrothermal synthesis,NiCo double hydroxide with different hierarchical architecture can be modulated.With further selenization treatment,nanorods-like,nanobrush-like and nanosheets-like NiCoSe2 can be obtained.The unique nanobrush-like NiCoSe2 possesses high surface with rich active sites,faster mass transfer.Compared with other electrocatalysts,The NiCoSe2 nanobrush/Ni foam shows the best OER performance with a low overpotential of 274 mV at the current density of 10 mA/cm2.The Tafel slope of the electrocatalyst is only 61.2 mv/dec.Moreover,the electrocatalyst also shows a good stability during the long-term electrochemical tests.This work highlights the nanoscale engineering and will open a new avenue to design promising transition metal electrocatalysts for future electrochemical water oxidation.