Preparation Of The Highly Active Crystal Co/Ni-Fe Sulfides And Its Electrocatalytic Activity Exploration

Facing the increasing concerns on severe environmental pollution caused by the byproducts?e.g.CO_x,NO_x?of consuming fossil fuel,it is necessary to develop renewable and sustainable energy sources.Hydrogen,a renewable clean and abundant energy vector,is well recognized as one of the most ideal candidates to replace conventional fossil fuels in the future.Currently,electrochemical or photoelectrochemical water electrolysis are the two important protocols for producing ultrapure H₂.Although,photovoltaic or photoelectrochemical approaches are very environmentally friendly,and the efficiency of sunlight-driven water splitting also reaches 12.3%for generating H₂,widespread implementation of these approaches is still hampered by the high expenses of the necessary apparatus.Thus,searching for cost-efficient bifunctional catalysts with high activity for overall water splitting are thus critically needed.Transition metal foam is a commercial metal material with three-dimensional openings,porosity and metal skeleton interconnection.It is widely used in Ni-MH battery electrode materials,catalyst of fuel cells and other fields.These materials have a large electrochemical reaction interface,and it shows potential application in the field of HER and OER.A facile and effective strategy for fabricating a three-dimensionally?3-D?structured nanocomposite catalyst based on nonprecious metals for water splitting in alkaline electrolyzer is reported in this paper.The Ni-Fe foam?NFF?,for the first time,was pretreated by the dielectric barrier discharge?DBD?plasma under ambient conditions?PNFF?,and many microtrenches were generated on the NFF surface.Moreover,some NiO and Fe₂O₃ flecks occurred on the NFF frame under the function of hot filaments generated in air-DBD plasma which will take an important role in the HER and OER processes.Further more,the sakura-like CoS/Ni₃S₂-FeS flowers were fabricated on the PNFF surface by vukanizing the Co nanosheets electrodeposited on the PNFF surface,and the CoS/Ni₃S₂-FeS/PNFF exhibts a high elctrocatalytic activiy for the overall water splitting.Benefiting from the 3D hierarchical nanoarchitecture of CoS/Ni₃S₂-FeS/PNFF with large surface areas,fast electron transport,and smaller adsorption free energy value,a current density of 10 m A cm^-2 can be achieved for the HER and OER with small overpotentials of 75 mV and 136 mV respectively.Especially,the H₂ and O₂ amount of CoS/Ni₃S₂-FeS/PNFF pushed with 10 mA cm^-2 in 1 M KOH is about 680?mol h^-1 and 1230?mol h^-1,and the generating efficiency of H₂ or O₂ is far higher than those of freshly reported noble metal free electrodes in alkline media.