| Large-scale use of fossil fuels has caused grievous pollution of the environment,and its limited reserves have also caused energy crisis.The development and research of clean energy have attracted extensive attention.Hydrogen(H2)is expected to become the most promising substitute for fossil fuels because of its high energy storage and low environmental pollution.Hydrogen production by electrolysis of water has the advantages of high hydrogen production efficiency,simple process and no pollution in the production process.It is one of the best ways to convert clean energy such as wind energy and solar energy into hydrogen energy.The efficiency of hydrogen production by electrolysis of water mainly depends on electrolysis of water catalyst,so the research and development of high-performance electrolysis of water catalyst has become the focus of current research.In this paper,three kinds of Ru-based transition metal compounds were prepared by chemical oxidation and potentiostatic electrodeposition on copper foam with excellent electrical conductivity,and their HER properties and stability under alkaline,neutral and acid conditions were investigated.The specific research results are as follows:1.Cu(OH)2 nanorod array was prepared by chemical oxidation method on copper foam substrate.a layer of Ru(OH)x was deposited on Cu(OH)2 nanorod array by potentiostatic electrodeposition,and then Cu@RuO2/CF nanorod array electrocatalyst was obtained by high temperature calcination,etching treatment and electric reduction.Electrocatalytic test shows that Cu@RuO2/CF has excellent HER performance.in alkaline electrolyte,it only needs HER overvoltage of 24 mV,64 mV and 159 mV to generate of 10 mA/cm2,100 mA/cm2 and 700 mA/cm2,which is superior to Pt/C catalyst.And its Tafel slope is only 52.1mV/dec;In addition,the catalyst also has good HER performance in neutral electrolyte,and the current densities of 50,100 and 700 mA/cm2 can be generated by only 27,51 and 373 mV of HER overpotential.Its excellent HER activity can be attributed to its low electrochemical transfer resistance(1.6Ω),high electric double layer capacitance(105.6 mF/cm2)and large electrochemical active area(2640),which can fully expose the active sites,which is beneficial to electron transfer and mass transfer of electrolyte.The array of Cu@RuO2/CF nanorods also showed good stability.after 60 h potentiostatic hydrogen evolution stability test(the initial current density was 100 mA/cm2),its current density remained at 74 mA/cm2.2.NiRu hydroxide was electrodeposited on the surface of Cu(OH)2 nanorods by potentiostatic electrodeposition,and then a series of CuPOx@NiRuPOx/CF nanorod array electrocatalysts were obtained by high temperature roasting and phosphating.The research shows that the CuPOx@Ni0.5RuPOx/CF nanorod array electrocatalyst prepared with the molar ratio of Ni:Ru 1:2 has the best HER performance in alkaline electrolyte,which can drive the current density of 10,100 and 700 mA/cm2 respectively with only 25,53 and 124 mV of HER overpotential,and the Tafel slope is 37.5 mV/dec.At the same time,CuPOx@Ni0.5RuPOx/CF nanorod array electrocatalyst also has excellent acidic and neutral HER performance.when the current density reaches 10,100 and 700 mA/cm2 respectively in acidic electrolyte,only 36,92 and 154 mV of HER overpotential is needed,and only 23,45 and 297 mV of HER overpotential in neutral electrolyte can generate 50,100 and 700 mA/cm2 respectively The array of CuPOx@Ni0.5RuPOx/CF nanorods also has good stability,and its current density remains at 76 mA/cm2 after the constant potential HER stability test for 60 hours at the initial current density of 100 mA/cm2.The excellent HER performance of CuP@Ni0.5RuPOx/CF is attributed to the following aspects:(1)CuPOx/CF nanorod array substrate has good conductivity,which is beneficial to improve the electron conduction rate and ion mass transfer rate in HER process;(2)CuPOx@Ni0.5RuPOx/CF nanorod array structure has a large ESCA(2737.5),which can expose a large number of active sites;(3)RuO2 and Ni2P in CuPOx@Ni0.5RuPOx/CF nanorod array have synergistic effect,and Ni,Ru,P and O elements also have synergistic effect,which can effectively adjust the electronic structure of Ni and Ru elements and contribute to the improvement of HER performance.3.CoRu hydroxide was electrodeposited on the surface of Cu(OH)2 nanorods by potentiostatic electrodeposition,and a series of CuNOx@CoRuNOx/CF nanorod array electrocatalysts were prepared by high temperature calcination and urea nitridation.The research shows that the CuNOx@CoRuNOx/CF nanorod array electrocatalyst prepared with the molar ratio of Co:Ru 1:1 has the best electrocatalytic performance,and has excellent HER performance in acidic,neutral and alkaline electrolytes.When the current density in acidic electrolyte reaches 10,100 and 700 mA/cm2,it only needs 68,137 and 199 mV of HER overpotential,and the Tafel slope is 66.6 mV/dec.In neutral electrolyte,the current densities of 50,100 and 700 mA/cm2 can be generated only by HER overvoltage of 19,43 and 239 mV,respectively,as well as the Tafel slope is 64.3 mv/dec.In alkaline electrolyte,only HER overpotential of 26,63 and 133 mV can drive current density of 10,100 and 700 mA/cm2 respectively,and Tafel slope is 46.6 mV/dec.The array of CuNOx@CoRuNOx/CF nanorods also has good stability.when the initial current density is 100 mA/cm2,the current density of CuNOx@CoRuNOx/CF nanorod array remains at 78 mA/cm2 after 60 hours of potentiostatic HER stability test.The excellent HER performance of CuNOx@CoRuNOx/CF is attributed to:(1)the substrate of 1)CuNOx/CF nanorod array has good conductivity,which is beneficial to improve the electron conduction rate and ion mass transfer rate in HER process;(2)CuNOx@CoRuNOx/CF nanorod array structure has a large ESCA(2430),which can expose a large number of active sites;(3)RuO2 and CoN in CuNOx@CoRuNOx/CF nanorod array electrocatalyst have synergistic effect,and Co,Ru,N and O elements also have synergistic effect which can effectively adjust the electronic structure of Co and Ru elements and further enhance hydrogen evolution performance. |
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