Controllable Fabrication Of Transition Metal / Ru And Biomass Carbon Composites With Their Application In Electrochemistry Catalysis

Hydrogen has the advantages of wide source,high energy density,no pollution,easy storage and transportation.It is considered to be one of the best choices to replace traditional energy sources,and it also provides an effective solution to environmental pollution problems.Hydrogen production from electrolyzed water is considered to be the most efficient way to convert renewable resources into hydrogen energy.Among them,the noble metal Pt-based catalyst has the highest hydrogen evolution activity,but it is expensive,has small reserves,and has poor stability,which limits its large-scale use.Therefore,Ru-based catalysts have been widely concerned as low-cost precious metals,and the development of inexpensive,high-efficiency non-precious metal-based catalysts has also been favored by researchers.Due to the variety specials,green renewable,special macromolecular structure and controllable chemical composition of biomass carbon,they are often applied as good conductive substrates for metal catalysts.Therefore,developing biomass carbon-based catalytic materials also have a practical value in clean energy field.In this paper,combined with the low-cost precious metal Ru and transition metals and biomass carbon-based materials,the advantages of cheap and easy to obtain,abundant reserves,and controllable electronic structure,the use of chemical modification techniques such as phosphorylation,N,P in-situ doping,selenization,etc.A biomass carbon-based electrocatalytic material having high catalytic activity and stability is prepared.The main findings of this paper are as follows:(1)In this study,a cobalt ruthenium-doped nitrogen phosphide porous carbon electrocatalyst(CoRu@NPC)was prepared by using chitosan as a biomass carbon raw material via chemical modification,metal coordination chelation and high temperature carbonization.The hydrogen evolution performance of the catalysts in different pH electrolyte solutions was investigated.The synergistic reaction between Co and Ru nanoparticles,the surface controlled pore structure and the nitrogen-phosphorus co-doping promotes the electrochemical activity of the catalysts.The results show that the catalytic activity of CoRu@NPC-800 was comparable to commercial Pt/C in 0.5 M H2SO4(pH=0),0.1 M KOH(pH=13)and 1 M PBS phosphate buffer solution(pH=7),the overpotential at current density of 10 mA cm-2 was 66 mV,66 mV and 104 mV,respectively,the tafel slope under acidic conditions was only 57 mV dec"1.In addition,better HER performance can be achieved with only 0.06 mmol of Ru.It is worth noting that new phase Co2P appeared when the carbonization temperature reached 900?.(2)In order to save cost and further increase the electrochemical active area,we substituted the precious metal Pt and Ru-based catalysts with non-precious metal catalytic materials,and in-situ embedding polyoxophosphate into the fibers by electrospinning technology.The nanosized molybdenum carbide-molybdenum nitride heterostructure was embedded in nitrogen-phosphorus-doped flexible carbon fiber membrane(Mo2C-MoN@NPFCF)after low temperature pre-oxidation and carbonization process in high temperature.We applied it as self-supporting membrane electrodes for hydrogen evolution in acidic,basic and neutral solutions as well as the oxygen evolution in alkaline solution.It is found that the synergy between Mo2C and MoN,the fibrous structure and the in-situ doping of heteroatoms N and P all contributed to the electrocatalytic activity of the catalyst.The results show that Mo2C-MoN@NPFCF-900 has a low overpotential(?10=27 mV)as well as good stability in 0.5 M H2SO4 solution,the overpotential was close to commercial Pt/C,and it also performed well in both 0.1 M KOH and 1 M PBS solutions.In addition,the catalyst was also suitable for oxygen evolution reaction,and the overpotential and tafel slope(356 mV@10 mA Cm-2,54 mV dec-1)were superior to commercial RuO2(360 mV@10 mA Cm-2,85 mV/dec).Finally,the flexibility test showed that the lignin-added fiber membrane had a distinct bendable and foldable feature.(3)In order to avoid the use of adhesives and conductive additives,carbon cloth is applied as the conductive substrate,and carbon cloth-loaded cobalt-nickel selenide nanowires(CoNiSe2 NWs/CC)was prepared by one-step hydrothermal and selenization,which was used as a self-supporting working electrode for hydrogen evolution reaction(HER)and oxygen evolution reaction(OER).It is found that the special nanowire structure and the synergy between CoSe2 and NiSe2 accelerates CoNiSe2 NWs/CC-600 to exhibit good HER performance,and the overpotential at a current density of 10 mA cm-2 was 176 mV as well as high stability and durability.In addition,the oxygen evolution overpotential(?20=0.419)of CoNiSe2 NWs/CC-600 was superior to that of commercial RuO2(?20=0.449).