Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis....Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis.Substantial studies on processes including methane reforming,oxidative coupling of methane,non-oxidative coupling of methane,etc.have been conducted for many years.However,owing to the intrinsic chemical inertness of CH4,harsh reaction conditions involving either extremely high temperatures or highly oxidative reactants are required to activate the C–H bonds of CH4 in such thermocatalytic processes,which may cause the target products,such as ethylene or methanol,to be further converted into coke or CO and CO2.It is desirable to adopt a new strategy for direct CH4 conversion under mild conditions.Herein,we report that efficient electrocatalytic oxidation of methane to alcohols at ambient temperature and pressure can be achieved using a NiO/Ni hollow fiber electrode.This work opens a new avenue for direct catalytic conversion of CH4.展开更多
The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance ...The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics were studied. The results show that the samples mainly consist of NiO and NiFe2O4 when content of CaO is less than 4%(mass fraction), bending strength increases obviously by CaO doping. Bending strength of the samples doped with 2% CaO is above 185 MPa, but that of the samples without CaO is only 60 MPa. Fracture toughness is improved obviously by CaO doping, the samples doped with 2% CaO have the maximum fracture toughness of 2.12 MPa ·m1/2 , which is about two times of that of the undoped ceramics. CaO doping is bad to thermal shock resistance of 10NiO-NiFe2O4 composite ceramics.展开更多
The recovery of nickel from spent nickel catalyst for the preparation of nickel hydroxide was studied. Nickel was extracted from the spent catalyst by acid leaching with 1 mol/L sulfuric acid at 90 ℃. Purified nickel...The recovery of nickel from spent nickel catalyst for the preparation of nickel hydroxide was studied. Nickel was extracted from the spent catalyst by acid leaching with 1 mol/L sulfuric acid at 90 ℃. Purified nickel solution was used in the preparation of nickel hydroxide. Three different methods, namely urea hydrolysis, conventional, and hydrothermal methods, of precipitation using NaOH were employed to get various nickel hydroxides samples named as Ni（OH）E-U, Ni（OH）2-C, and Ni（OH）E-H, respectively. Hydrothermal treatment induced better crystallinity in the Ni（OH）2 compared with conventional method. Both Ni（OH）2-C and Ni（OH）E-H samples have mixed phases of fl-Ni（OH）2 and a＊-Ni（OH）E.0.75H20 phases, whereas Ni（OH）2-U has only a＊-Ni（OH）2.0.75H20. TEM image of Ni（OH）E-U sample shows rod-like Ni（OH）2 structures. Among all, Ni（OH）2-U shows the best electrochemical activity.展开更多
There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,a...There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.展开更多
Exploring and designing bi-functional catalysts with earth-abundant elements that can work well for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline medium are of significance f...Exploring and designing bi-functional catalysts with earth-abundant elements that can work well for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline medium are of significance for producing clean fuel to relieve energy and environment crisis.Here,a novel Ni/NiO monolithic electrode was developed by a facile and cost-effective acid promoted activation of Ni foam.After the treatment,this obtained monolithic electrode with a layer of NiO on its surface demonstrates rough and sheet-like morphology,which not only possesses larger accessible surface area but also provides more reactive active sites. Compared with powder catalysts,this monolithic electrode can achieve intimate contact between the electrocatalyst and the current collector,which will alleviate the problem of pulverization and enable the stable function of the electrode. It can be served as an efficient bi-functional electrocatalyst with an overpotential of 160 mV for HER and 290 mV for OER to produce current densities of 10 mA cm^（-2） in the alkaline medium. And it maintains benign stability after 5,000 cycles,which rivals many recent reported noble-metal free catalysts in 1.0mol L^（-1） KOH solution. Attributed to the easy,scalable methodology and high catalytic efficiency,this work not only offers a promising monolithic catalyst but also inspires us to exploit other inexpensive,highly efficient and self-standing noble metalfree electrocatalysts for scale-up electrochemical water-splitting technology.展开更多
文摘Natural gas and shale gas,with methane as the main component,are important and clean fossil energy resources.Direct catalytic conversion of methane to valuable chemicals is considered a crown jewel topic in catalysis.Substantial studies on processes including methane reforming,oxidative coupling of methane,non-oxidative coupling of methane,etc.have been conducted for many years.However,owing to the intrinsic chemical inertness of CH4,harsh reaction conditions involving either extremely high temperatures or highly oxidative reactants are required to activate the C–H bonds of CH4 in such thermocatalytic processes,which may cause the target products,such as ethylene or methanol,to be further converted into coke or CO and CO2.It is desirable to adopt a new strategy for direct CH4 conversion under mild conditions.Herein,we report that efficient electrocatalytic oxidation of methane to alcohols at ambient temperature and pressure can be achieved using a NiO/Ni hollow fiber electrode.This work opens a new avenue for direct catalytic conversion of CH4.
基金Project(2005CB623703) supported by the National Basic Research Program of China
文摘The CaO doped 10NiO-NiFe2O4 composite ceramics were prepared by the cold isostatic pressing-sintering process, and the effects of CaO content on the phase composition, mechanical property and thermal shock resistance of 10NiO-NiFe2O4 composite ceramics were studied. The results show that the samples mainly consist of NiO and NiFe2O4 when content of CaO is less than 4%(mass fraction), bending strength increases obviously by CaO doping. Bending strength of the samples doped with 2% CaO is above 185 MPa, but that of the samples without CaO is only 60 MPa. Fracture toughness is improved obviously by CaO doping, the samples doped with 2% CaO have the maximum fracture toughness of 2.12 MPa ·m1/2 , which is about two times of that of the undoped ceramics. CaO doping is bad to thermal shock resistance of 10NiO-NiFe2O4 composite ceramics.
文摘The recovery of nickel from spent nickel catalyst for the preparation of nickel hydroxide was studied. Nickel was extracted from the spent catalyst by acid leaching with 1 mol/L sulfuric acid at 90 ℃. Purified nickel solution was used in the preparation of nickel hydroxide. Three different methods, namely urea hydrolysis, conventional, and hydrothermal methods, of precipitation using NaOH were employed to get various nickel hydroxides samples named as Ni（OH）E-U, Ni（OH）2-C, and Ni（OH）E-H, respectively. Hydrothermal treatment induced better crystallinity in the Ni（OH）2 compared with conventional method. Both Ni（OH）2-C and Ni（OH）E-H samples have mixed phases of fl-Ni（OH）2 and a＊-Ni（OH）E.0.75H20 phases, whereas Ni（OH）2-U has only a＊-Ni（OH）2.0.75H20. TEM image of Ni（OH）E-U sample shows rod-like Ni（OH）2 structures. Among all, Ni（OH）2-U shows the best electrochemical activity.
文摘There remains a challenge in designing electrocatalysts for water oxidation to create highly efficient catalytic sites for the oxygen evolution reaction(OER)while maintaining their robustness at large outputs.Herein,an etching-assisted synthesis approach was developed to integrate highly active NiFe2O4 nanoparticles with a robust and active NiOOH scaffold directly on commercial stainless steel.A precise selenization strategy was then introduced to achieve selective Se doping of NiFe2O4 to further enhance its intrinsic OER activity while maintaining a three-dimensional NiOOH nanosheet array as a robust scaffold for prompt mass transfer and gas evolution.The resulting NiFe2O4-xSex/NiOOH electrode exhibited superior electrocatalytic activity with low overpotentials of 153 and 259 mV to deliver benchmark current densities of 10 and 500 mA cm^(−2),respectively.More importantly,the catalyst exhibited remarkable durability at a stable current output of 100 mA cm^(−2)for hundreds of hours.These findings may open up opportunities for exploring efficient and robust electrocatalysts for scalable hydrogen production with practical materials.
基金supported by the National Natural Science Foundation of China (21571073 and 21673090)the National Basic Research Program of China (2015CB932600)+2 种基金Hubei Provincial Natural Science Foundation of China (2016CFA031)the Program for HUST Interdisciplinary Innovation Team (2015ZDTD038)the Fundamental Research Funds for the Central Universities
文摘Exploring and designing bi-functional catalysts with earth-abundant elements that can work well for both hydrogen evolution reaction（HER） and oxygen evolution reaction（OER） in alkaline medium are of significance for producing clean fuel to relieve energy and environment crisis.Here,a novel Ni/NiO monolithic electrode was developed by a facile and cost-effective acid promoted activation of Ni foam.After the treatment,this obtained monolithic electrode with a layer of NiO on its surface demonstrates rough and sheet-like morphology,which not only possesses larger accessible surface area but also provides more reactive active sites. Compared with powder catalysts,this monolithic electrode can achieve intimate contact between the electrocatalyst and the current collector,which will alleviate the problem of pulverization and enable the stable function of the electrode. It can be served as an efficient bi-functional electrocatalyst with an overpotential of 160 mV for HER and 290 mV for OER to produce current densities of 10 mA cm^（-2） in the alkaline medium. And it maintains benign stability after 5,000 cycles,which rivals many recent reported noble-metal free catalysts in 1.0mol L^（-1） KOH solution. Attributed to the easy,scalable methodology and high catalytic efficiency,this work not only offers a promising monolithic catalyst but also inspires us to exploit other inexpensive,highly efficient and self-standing noble metalfree electrocatalysts for scale-up electrochemical water-splitting technology.
