| Due to the growing influence of energy shortage and environment pollution,it is urgent to find clean and renewable energy.Hydrogen energy which has a great potential for mitigating energy problems is widely used in many fields.The product of hydrogen energy combustion is water,and hydrogen can be produced from water,so it fully complies with the principles of energy recycling and sustainable development.Electrolysis of water for hydrogen production has attracted the attention of many researchers with the advantages of simple operation,non-pollution,and high product purity.However,there is a large-scale power consumption in current industrial water electrolysis because of the high potential using(1.8?2.0 V).Therefore,it is urgently to develop an efficient electrocatalyst for reducing the power consumption in the process.Currently Pt metal is considered as the most efficient catalysts,while the large-scale industrial application is greatly hindered by its scarcity and high price.Thus,it is necessary to find a highly active and inexpensive non-precious metal electrocatalyst.At present,many non-noble metal electrocatalysts have been reported.Among them,transition metals have received widespread attention due to their special orbital structures and unpaired d electrons.Cellulose and its derivatives,which are abundant in nature can be used in energy catalysis because of its high flexibility,environmental friendliness,and rich active groups on the surface.Based on this,the main research contents of this paper can be summarized as the following three parts:(1)With poplar powder as a precursor,lignocellulose is prepared by benzene alcohol extraction,acidification and alkalization treatment.And then the carbon fiber derived from lignocellulose was prepared by freeze drying and high temperature carbonization.The chemical compositions and surface morphologies of lignocellulose carbon fiber were studied and analyzed by X-ray diffraction(XRD),Raman spectra and scanning electron microscope(SEM).The results show that the lignocellulose carbon fiber sample was successfully prepared,and the diameter of the prepared carbon fiber is about 100 ?m.(2)Carbon fibers-supported cobalt nanoparticles(Co/CFs)electrocatalyst was prepared by impregnating and then carbonized at high temperature.X-ray diffraction(XRD),X-ray photoelectron spectroscopy(XPS),scanning electron microscopy(SEM),and transmission electron microscopy(TEM)were performed to investigate the compositions and micromorphology of the samples.And the electrocatalytic activities were tested by a CHl workstation.The results exhibited that the usage of CFs alleviates the problem of easy agglomeration of Co nanoparticles(Co NPs),which is conducive to achieve maximum exposure of active sites.When used as a hydrogen evolution catalyst,only a low overpotential of 250 mV is required for obtaining a current density of 10 mA cm-2 and the catalyst could also maintain a long stability for up to 15 h.(3)Transition metal Ni supported by lignocellulose carbon fiber(Ni CFs)was prepared by impregnation and carbonization.The experimental results exhibited that the usage of CFs alleviates the problem of easy agglomeration of Ni nanoparticles(Ni NPs),which facilitates to the increase of specific surface area and active sites.The study of its HER performance showed that Ni/CFs exhibited excellent catalytic activities in alkaline conditions.Specifically,only a low overpotential of 428 mV is required for obtaining a current density of 10 mA cm-2,the electric double layer capacitance value is 18.06 mF cm-2.The curves before and after 5000 cycles of CV scan are almost coincident and the catalyst could also maintain a long stability for up to 10 h.In addition,Ni/CFs composites also displayed good HER performances in neutral conditions. |
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