The Synthesis Of Transition Metal S/P Nanocrystalline And Its Electrocatalytic Activity Exploration

Energy and environmental issues are two crucial themes for the sustainable development of human society.At present,with the rapid growth of population,social development,the problem of environmental pollution caused by fossil energy consumption becomes more and more serious,and human beings must continue to seek for novel,efficient and environmental friendly renewable energy sources.Because of merits of H₂ energy?e.g.abundant,clean,efficient and sustainable?,it has great potential application in new-energy field for resolving the energy crisis and environmental pollution.The development of efficient and low-cost hydrogen production technology will be great scientific and applicable value in the future.Electrochemical water splitting is one of the promising method to produce hydrogen.Currently,the noble metals such as Pt-group based metals are still the most robust electrocatalysts for HER,nevertheless,the scarcity of these noble catalysts and high cost restrict their wide practical applications in hydrogen production.Therefore,the development of catalyst with rich reserves,low price,easy preparation and good catalytic activity has become the hot research topic.In recent years,transition metal compounds have become crucial electrocatalytic materials because of their rich reserves,strong controllability and high catalytic activity.In this work,the nanoscale transition metal dichalcogenides?TMDs?and transition metal phosphides?TMPs?were fabricated on the surface of three-dimensional transition metal foam?Ni-Fe-Co?by the dielectric barrier discharge?DBD?plasma and hydrothermal method.The intrinsic relationships among the preparation conditions,the physicochemical structure of nanocrystals,and the activity and stability in their hydrogen evolution?HER?and oxygen evolution?OER?processes were investigated,the detail works are listed as follows:?1?Using nickel foam?NF?as substrate,the Ni_1.8Cu_0.2-P/NF heterojunction phosphite wafers were prepared by hydrothermal syntheisi of nickel-copper layered double hydroxide?NiCu LDH/NF?and then by chemical vapor deposition method.The results show that the Ni_1.8Cu_0.2-P porous wafers are intersected on the foam surface.This structure greatly improves the active reaction area and the electrocatalytic stability of the catalyst material.In 1 M KOH solution,a current density of 10 mA cm^-2 can be achieved for the HER with small overpotential of 78 mV,and the hydrogen evolution amount could reach 1.91 mmol h^-1,indicating nearly 100%Ferrari efficiency.The electrocatalytic performances are obviously superior to most of the reported state-of-the-art electrocatalysts.In addition,Ni_1.8Cu_0.2-P/NF also exhibits strong electrochemical stability.The change of morphology and crystal structure for Ni_1.8Cu_0.2-P/NF can be nearly neglected after 10,000 cycles and 30 hours of continuous scanning and has great potential for industrial application.?2?The Ni-Fe-Co foam?NFCF?,for the first time,was pretreated by the dielectric barrier discharge?DBD?plasma under ambient conditions?PNFCF?,and many microsized cracks were formed on the PNFCF frame.Moreover,some NiO,Fe₂O₃,and Co₃O₄ flecks occurred on the NFCF surface under the function of hot filaments generated in air-DBD plasma which will take an important role in OER processes.The Ni₃S₂-FeS-CoS/PNFCF electrode was fabricated on the PNFCF surface by a facile in-situ method.Based on the characteristics of large surface areas,fast electron transport and in-situ growth,the overpotentials of Ni₃S₂-FeS-CoS/PNFCF pushed with a current density of 10 mA cm^-2 for the HER and OER are 82 mV and 170 mV respectively.Especially,the H₂ and O₂ amount of Ni₃S₂-FeS-CoS/PNFCF stimulated with 10mA cm^-2 in 1 M KOH is about 0.78 and 0.68 mmol h^-1.In addition,the Ni₃S₂-FeS-CoS nanosheets sprouted from metal NFCF foam exhibits ultrastable electrocatalytic performances,and after the test for 50 h,the current density of HER and OER is not deviated greatly,which indicate that the Ni₃S₂-FeS-CoS/PNFCF electrode material has super electrocatalytic stability.