NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators o...NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators on the size of Ni_(2)P particles over wrinkle silica nanoparticles(WSNs)by introducing chelating agents EDTA and NTA during impregnation process.The characterization results show that chelators modified cata-lysts possess smaller size of Ni_(2)P particles than the unmodified Ni_(2)P catalysts.Among all the synthesized catalysts,the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst possesses smallest average particle size of Ni_(2)P,only 2.6 nm.Moreover,the Ni_(2)P catalysts with the assistance of EDTA exhibits better catalytic activity than that of NTA under high reaction temperature,which can be ascribed to the strong bonding between EDTA and Ni.And the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst shows highest hydrogenation ability,almost reaching 100%decalin selectivity.展开更多
氢气(H_(2))具有能量密度高、环境友好等优点,是一种很有前景的清洁能源载体.目前,电催化水裂解大规模制氢被认为是一种理想可行的方法.析氢反应(HER)涉及多个步骤,首先形成吸附的氢(Volmer步骤),然后是脱附步骤(Heyrovsky步骤)或两个...氢气(H_(2))具有能量密度高、环境友好等优点,是一种很有前景的清洁能源载体.目前,电催化水裂解大规模制氢被认为是一种理想可行的方法.析氢反应(HER)涉及多个步骤,首先形成吸附的氢(Volmer步骤),然后是脱附步骤(Heyrovsky步骤)或两个相邻的吸附氢形成H_(2)(Tafel步骤).与酸性介质相比,碱性介质中的HER可与现有的析氧反应(OER)催化剂偶合,降低电解水的设备成本,因此研究碱性条件下HER更具应用价值.但是,HER在碱性介质中不可避免地需要打破较强的共价键H–O–H,动力学缓慢,导致需要高过电位驱动反应.因此,开发适用于广泛的pH范围,特别是碱性介质高催化活性的催化剂,成为当务之急.金属铂是最高效的HER催化剂,但昂贵的价格严重阻碍了其在电解水中的大规模商业化应用.因此,开发过电位低和稳定性持久的非贵金属催化剂,特别是可以在大电流密度(>500 mA cm^(-2)的质子交换膜和碱性电解槽)下稳定工作的催化剂,对实际工业应用至关重要.过渡金属磷化物(TMPs),尤其是CoP和Ni_(2)P在HER中表现出了较好的催化活性,引起广泛关注.但是,有限的电子结构、低电导率和大电流密度测试过程中的团聚仍然是限制其实际应用的瓶颈.近年来,具有金属可调性、多孔型结构、高比表面积和多交叉开放通道的金属有机骨架(MOFs)已被证明是制备TMPs的理想前驱体.但是,在高温煅烧过程中无法避免MOF结构坍塌,导致开放通道和电导率降低,限制了电子/离子的传输以及在高电流密度下的电催化活性.本文通过TMPs和Co-MOF之间的简单拓扑化学转化制备了一种自支撑结构的N掺杂二元TMPs电催化剂(N-CoP_(x)/Ni_(2)P),以Co-MOF作为模板和前驱体,一部分泡沫镍原位磷化成Ni_(2)P,形成异质结构的双金属磷化物.扫描电镜和透射电镜结果表明,该催化剂呈三维多孔结构,有利于充分暴露活性位点.通过X射线光电子能谱分析了催化剂表面化学状态,发现形成了Co–N键,说明N掺杂成功.通过电化学测试结果表明,N-CoP_(x)/Ni_(2)P在全pH范围内表现出较好的HER活性,尤其在碱性介质中,当电流密度为650 mA cm^(-2)时,仅需要152 mV过电位.催化剂转化率为3.2 s^(-1),法拉第效率接近100%,该催化剂在200 mA cm^(-2)电流密度下连续工作24 h无明显衰减.密度泛函理论计算表明,N-CoP_(x)/Ni_(2)P催化活性的增强归因于氮掺杂及双金属磷化物的协同作用提高了催化剂的本征活性位点,从而优化了氢吸附能和水结合能.综上,本文为廉价电催化剂的工业化应用提供了一种有前景的策略.展开更多
In this study,different loadings of x%Ni_(2)P/γ-Al_(2)O_(3)(x=6%,9%,12%,15%,18%)catalysts with aluminum oxide(Al_(2)O_(3))as the carrier,nickel chloride(NiCl2)as the nickel(Ni)source,and ammonium hypophosphite(NH_(4)...In this study,different loadings of x%Ni_(2)P/γ-Al_(2)O_(3)(x=6%,9%,12%,15%,18%)catalysts with aluminum oxide(Al_(2)O_(3))as the carrier,nickel chloride(NiCl2)as the nickel(Ni)source,and ammonium hypophosphite(NH_(4)H_(2)PO_(2))as the phosphorus(P)source were prepared by the equal volume impregnation method to investigate the effects of different loadings on the performance of the selective hydrogenation of diolefins and thiol etherification in LPG.The physicochemical properties of the catalysts were characterized by XRD,BET,SEM,TEM,H_(2)-TPR,and XPS,and the catalytic activity of the catalysts was evaluated in a fixed-bed microreactor.The results showed that a change in the loading affected the catalyst crystalline phase structure and size,specific surface area,P coverage,active phase dispersion,and catalytic activity.At 6%,9%,and 12%loadings the catalysts had an Ni phase but there was no obvious Ni_(2)P phase in the nickel phosphide;at 15%loading a single Ni_(2)P phase was obtained,and at 18%loading both Ni_(2)P and Ni1_(2)P_(5) phases appeared.There was a P enrichment on the catalyst surface,and the higher the loading the more P species were enriched on the surface,but some of the P was lost during the catalyst reduction process due to the production of phosphine(PH3)gas.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the largest Ni/Al ratio and the best dispersion.The Ni_(2)P active phase size was small at about 4.25 nm and Ni_(2)P was uniformly dispersed on the catalyst surface without agglomeration.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the best catalytic activity at a pressure of 2.0 MPa,a liquid hourly space velocity(LHSV)of 3.0 h-1,and a hydrogen to hydrocarbon ratio of 12.The 1,3-butadiene conversion was 97.45%and the methanethiol removal was 100%at a temperature of 140℃.展开更多
Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect an...Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni_(2)P nanoarrays inside nickel foam(PNF).Uniform Ni_(2)P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni_(2)P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^(-2) and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO_(4) battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.展开更多
Electrochemical catalysts for the hydrogen evolution reaction(HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni_(2)...Electrochemical catalysts for the hydrogen evolution reaction(HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni_(2)P/MoS_(2) cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni_(2)P and MoS_(2) improved the catalytic performance for the HER. Compared with pure Ni_(2)P catalyst and MoS_(2) catalyst, the prepared Ni_(2)P/MoS_(2) cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide p H range and low onset potential values of 280, 350 and40 m V in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec^(-1),respectively. Density functional theory(DFT) was adopted to calculate the hydrogen adsorption free energy(ΔG_(H)^(*)). The results showed that the interface between Ni_(2)P and MoS_(2) reduced ΔG_H^(*), which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.展开更多
基金supported by the National Natural Science Foundation of China(No.21878330)Key Research and Development Program of Ministry of Science and Technology of China(No.2019YFC1907602)Scientific Research and Technology Development Program of China National Petroleum Corporation(2020B-2116).
文摘NizP supported catalysts exhibit high catalytic activities in hydrogenation reaction,of which the particle sizes of Ni_(2)P active phases are the key influential factor.This research focus on the effect of chelators on the size of Ni_(2)P particles over wrinkle silica nanoparticles(WSNs)by introducing chelating agents EDTA and NTA during impregnation process.The characterization results show that chelators modified cata-lysts possess smaller size of Ni_(2)P particles than the unmodified Ni_(2)P catalysts.Among all the synthesized catalysts,the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst possesses smallest average particle size of Ni_(2)P,only 2.6 nm.Moreover,the Ni_(2)P catalysts with the assistance of EDTA exhibits better catalytic activity than that of NTA under high reaction temperature,which can be ascribed to the strong bonding between EDTA and Ni.And the EDTA modified Ni_(2)PE(1.5)/WSNs catalyst shows highest hydrogenation ability,almost reaching 100%decalin selectivity.
文摘氢气(H_(2))具有能量密度高、环境友好等优点,是一种很有前景的清洁能源载体.目前,电催化水裂解大规模制氢被认为是一种理想可行的方法.析氢反应(HER)涉及多个步骤,首先形成吸附的氢(Volmer步骤),然后是脱附步骤(Heyrovsky步骤)或两个相邻的吸附氢形成H_(2)(Tafel步骤).与酸性介质相比,碱性介质中的HER可与现有的析氧反应(OER)催化剂偶合,降低电解水的设备成本,因此研究碱性条件下HER更具应用价值.但是,HER在碱性介质中不可避免地需要打破较强的共价键H–O–H,动力学缓慢,导致需要高过电位驱动反应.因此,开发适用于广泛的pH范围,特别是碱性介质高催化活性的催化剂,成为当务之急.金属铂是最高效的HER催化剂,但昂贵的价格严重阻碍了其在电解水中的大规模商业化应用.因此,开发过电位低和稳定性持久的非贵金属催化剂,特别是可以在大电流密度(>500 mA cm^(-2)的质子交换膜和碱性电解槽)下稳定工作的催化剂,对实际工业应用至关重要.过渡金属磷化物(TMPs),尤其是CoP和Ni_(2)P在HER中表现出了较好的催化活性,引起广泛关注.但是,有限的电子结构、低电导率和大电流密度测试过程中的团聚仍然是限制其实际应用的瓶颈.近年来,具有金属可调性、多孔型结构、高比表面积和多交叉开放通道的金属有机骨架(MOFs)已被证明是制备TMPs的理想前驱体.但是,在高温煅烧过程中无法避免MOF结构坍塌,导致开放通道和电导率降低,限制了电子/离子的传输以及在高电流密度下的电催化活性.本文通过TMPs和Co-MOF之间的简单拓扑化学转化制备了一种自支撑结构的N掺杂二元TMPs电催化剂(N-CoP_(x)/Ni_(2)P),以Co-MOF作为模板和前驱体,一部分泡沫镍原位磷化成Ni_(2)P,形成异质结构的双金属磷化物.扫描电镜和透射电镜结果表明,该催化剂呈三维多孔结构,有利于充分暴露活性位点.通过X射线光电子能谱分析了催化剂表面化学状态,发现形成了Co–N键,说明N掺杂成功.通过电化学测试结果表明,N-CoP_(x)/Ni_(2)P在全pH范围内表现出较好的HER活性,尤其在碱性介质中,当电流密度为650 mA cm^(-2)时,仅需要152 mV过电位.催化剂转化率为3.2 s^(-1),法拉第效率接近100%,该催化剂在200 mA cm^(-2)电流密度下连续工作24 h无明显衰减.密度泛函理论计算表明,N-CoP_(x)/Ni_(2)P催化活性的增强归因于氮掺杂及双金属磷化物的协同作用提高了催化剂的本征活性位点,从而优化了氢吸附能和水结合能.综上,本文为廉价电催化剂的工业化应用提供了一种有前景的策略.
文摘In this study,different loadings of x%Ni_(2)P/γ-Al_(2)O_(3)(x=6%,9%,12%,15%,18%)catalysts with aluminum oxide(Al_(2)O_(3))as the carrier,nickel chloride(NiCl2)as the nickel(Ni)source,and ammonium hypophosphite(NH_(4)H_(2)PO_(2))as the phosphorus(P)source were prepared by the equal volume impregnation method to investigate the effects of different loadings on the performance of the selective hydrogenation of diolefins and thiol etherification in LPG.The physicochemical properties of the catalysts were characterized by XRD,BET,SEM,TEM,H_(2)-TPR,and XPS,and the catalytic activity of the catalysts was evaluated in a fixed-bed microreactor.The results showed that a change in the loading affected the catalyst crystalline phase structure and size,specific surface area,P coverage,active phase dispersion,and catalytic activity.At 6%,9%,and 12%loadings the catalysts had an Ni phase but there was no obvious Ni_(2)P phase in the nickel phosphide;at 15%loading a single Ni_(2)P phase was obtained,and at 18%loading both Ni_(2)P and Ni1_(2)P_(5) phases appeared.There was a P enrichment on the catalyst surface,and the higher the loading the more P species were enriched on the surface,but some of the P was lost during the catalyst reduction process due to the production of phosphine(PH3)gas.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the largest Ni/Al ratio and the best dispersion.The Ni_(2)P active phase size was small at about 4.25 nm and Ni_(2)P was uniformly dispersed on the catalyst surface without agglomeration.The 15%Ni_(2)P/γ-Al_(2)O_(3) catalyst had the best catalytic activity at a pressure of 2.0 MPa,a liquid hourly space velocity(LHSV)of 3.0 h-1,and a hydrogen to hydrocarbon ratio of 12.The 1,3-butadiene conversion was 97.45%and the methanethiol removal was 100%at a temperature of 140℃.
基金financial supported by the National Natural Science Foundation of China(Grant Nos.51874361 and 51904343)the Science and technology program of Hunan Province(2019RS3002)。
文摘Lithium(Li)metal is the most potential anode material for the next-generation high-energy rechargeable batteries.However,intrinsic surface unevenness and‘hostless’nature of Li metal induces infinite volume effect and uncontrollable dendrite growth.Herein,we design the in-situ grown lithiophilic Ni_(2)P nanoarrays inside nickel foam(PNF).Uniform Ni_(2)P nanoarrays coating presents a very low nucleation overpotential,which induces the homogeneous Li deposition in the entire spaces of three-dimensional(3D)metal framework.Specifically,the lithiophilic Ni_(2)P nanoarrays possess characteristics of electrical conductivity and structural stability,which have almost no expansion and damage during repeating Li plating/stripping.Therefore,they chronically inhibit the growth of Li dendrites.This results in an outstanding Coulombic efficiency(CE)of 98% at 3 mA cm^(-2) and an ultra long cycling life over 2000 cycles with a low overpotential.Consequently,the PNF-Li||LiFePO_(4) battery maintains a capacity retention of 95.3% with a stable CE of 99.9% over 500 cycles at 2 C.
基金financial support of the National Natural Science Foundation of China (No. 21872119,22072127)the Natural Science Foundation of Hebei Province(No. B2021203016)+1 种基金the Science and Technology Project of Hebei Education Department (No. ZD2022147)the Special Project for Local Science and Technology Development Guided by the Central Government of China (No.216Z1301G)。
文摘Electrochemical catalysts for the hydrogen evolution reaction(HER) have attracted increasing attentions. Noble metal-free cocatalysts play a vital role in HER applications. Herein, a novel strategy to prepare a Ni_(2)P/MoS_(2) cocatalyst through a simple hydrothermal-phosphorization method was reported, and the prepared cocatalyst was then loaded on an N-doped carbon substrate with excellent conductive performance. The large surface area of the carbon substrate provided many active sites, and the interface between Ni_(2)P and MoS_(2) improved the catalytic performance for the HER. Compared with pure Ni_(2)P catalyst and MoS_(2) catalyst, the prepared Ni_(2)P/MoS_(2) cocatalyst exhibited enhanced catalytic performance. In addition, the results indicate that the prepared cocatalyst has a wide p H range and low onset potential values of 280, 350 and40 m V in acidic, phosphate-buffered saline and alkaline solutions, respectively, and the corresponding Tafel slopes are 75, 121 and 95 mV dec^(-1),respectively. Density functional theory(DFT) was adopted to calculate the hydrogen adsorption free energy(ΔG_(H)^(*)). The results showed that the interface between Ni_(2)P and MoS_(2) reduced ΔG_H^(*), which was beneficial to the adsorption of hydrogen. Present preparation of cocatalysts with unique interfaces provides a new strategy for improving the catalytic performance of HER.
