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Initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments

Chinese Journal of Aeronautics 2022年第1期35卷 277-289页

作者： Yangguang ZHANG Yueliang CHEN Yong ZHANG Guixue BIAN Chenguang WANG Andong WANG Naval Aviation University Qingdao Campus Qingdao 266041China

The initial corrosion behavior and mechanism of 7B04 aluminum alloy under acid immersion and salt spray environments(pH=3.5)are studied by Scanning Electron Microscope(SEM),optical microscope,Fourier Transform Infrared Spectroscopy(FT-IR),X-Ray Diffraction(XRD),potentiodynamic polarization,Electrochemical Impedance Spectroscopy(EIS),and Scanning Kelvin Probe(SKP).The results show that pitting corrosion occurs at the initial corrosion stage,and the potential difference between the second phase particles is the main cause of pitting.Pitting pits on different locations gradually expand and coalesce with the proceeding of corrosion.The main components of corrosion products are Al_(2)O_(3),Al(OH)_(3),and AlCl_(3),and the generation rate of the corrosion product layer under the salt spray environment is larger than that under acid immersion environment.Under both environments,the Volta potential distribution first disperses and then concentrates,while the charge transfer resistance first decreases and then increases with the corrosion time.The Volta potential gradually shifts in a positive direction,indicating that corrosion products have an inhibitory effect on corrosion.After the same corrosion time,the corrosion product layer resistance and the expectation of the Volta potential of the salt spray sample are higher than those of the immersion sample.Comparatively,the corrosion current density for the salt spray sample is significantly lower than the immersion sample,which indicates that the thicker the corrosion product layer,the stronger the inhibition of corrosion reaction.

关键词： 7B04 aluminum alloy Acid salt spray Corrosion mechanism Corrosion products electrochemistry Scanning Kelvin probe

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Immobilization of cobalt oxide nanoparticles on porous nitrogen-doped carbon as electrocatalyst for oxygen evolution

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Chinese Journal of Chemical Engineering 2022年第12期52卷 10-18页

作者： Shusheng Li Rui Kuang Xiangzheng Kong Xiaoli Zhu Xubao Jiang College of Chemistry and Chemical Engineering University of JinanJinan 250022China College of Traffic Civil Engineering Shandong Jiaotong UniversityJinan 250357China

Highly efficient and robust electrocatalysts have been in urgent demand for oxygen evolution reaction(OER).For this purpose,high-cost carbon materials,such as graphene and carbon nanotubes,have been used as supports to metal oxides to enhance their catalytic activity.We report here a new Co_(3)O_(4)-based catalyst with nitrogen-doped porous carbon material as the support,prepared by pyrolysis of porous polyurea(PU) with Co(NO_(3))_(2)immobilized on its surface.To this end,PU was first synthesized,without any additive,through a very simple one-step precipitation polymerization of toluene diisocyanate in a binary mixture of H2O-acetone at room temperature.By immersing PU in an aqueous solution of Co(NO_(3))_(2)at room temperature,a cobalt coordinated polymer composite,Co(NO_(3))_(2)/PU,was obtained,which was heated at 500℃ in air for 2 h to get a hybrid,Co_(3)O_(4)/NC,consisting of Co_(3)O_(4)nanocrystals and sp2-hybridized N-doped carbon.Using this Co_(3)O_(4)/NC as a catalyst in OER,a current density of10 mA·cm^(-2)was readily achieved with a low overpotential of 293 mV with a Tafel slope of87 mV·dec^(-1),a high catalytic activity.This high performance was well retained after 1000 recycled uses,demonstrating its good durability.This work provides therefore a facile yet simple pathway to fabrication of a new transition metal oxides-based N-doped carbon catalyst for OER with high performance.

关键词： Porous polyurea N-doped carbon-Co_(3)O_(4)hybrid Oxygen evolution Catalyst Electrolysis electrochemistry

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Exploring the degradation behavior of MgXAg alloys by in vitro electrochemical methods

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Bioactive Materials 2022年第1期7卷 441-452页

作者： Yuqiuhan Zhang Tycho Zimmermann Wolf-Dieter Mueller Frank Witte Florian Beuer Andreas Schwitalla Charit´e-Universit¨atsmedizin Berlin corporate member of Freie Universit¨at Berlin and Humboldt-Universit¨at zu BerlinDental Materials and Biomaterial ResearchDepartment of ProsthodonticsGeriatric Dentistry and Craniomandibular DisordersAßmannshauser Str.4-614197BerlinGermany

Magnesium as biodegradable biomaterial could serve as bone augmentation material in implant dentistry.The knowledge about the predictability of the biodegradation process is essential as this process needs to go hand in hand with the formation of new bone to gradually replace the augmentation material.Therefore,this work aimed to assess if the electrochemistry(EC)measurements of the corrosion process correlate with the surface features at various time points during the surface degradation,in order to describe the degradation process of Mg and Mg alloys more reliably,under the assumption that differences in EC behavior can be detected and related to specific patterns on the surface.In this test setup,a special optical chamber was used for electrochemical measurements on Mg and Mg-alloys(Mg2Ag,Mg4Ag,and Mg6Ag).Specimens were investigated using different circulating cell culture solutions as electrolytes,these were minimum essential medium(MEM),Hank’s Balanced Salt Solution(HBSS),and MEM+(MEM with added sodium hydrogen carbonate)at 37℃.Open circuit potential measurements(OCP)over 30 min followed by cyclic polarization were performed.The electrochemistry data,including OCP,exchange current density and corrosion potential,were compared with visible changes at the surface during these treatments over time.The results show that the addition of silver(Ag)leads to a“standardization”of the degradation regardless of the selected test medium.It is currently difficult to correlate the visible microscopic changes with the data taken from the measurements.Therefore,further investigations are necessary.

关键词： Biodegradable magnesium Magnesium silver alloys electrochemistry Hydrogen evolution

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Effect of Gd on neutron absorption properties and electrochemical corrosion behavior of Zr-Gd alloy in boiling concentrated HNO3

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Nuclear Science and Techniques 2023年第3期34卷 40-51页

作者： Cheng-Jie Du Xiao-Gang Hu Ping-Yi Guo Xiao-Long Pan Jin-Ping Wu School of Materials Science and Engineering Jiangsu University of Science and TechnologyZhenjiang 212100China Xi’an Rare Metal Materials Institute Co. LtdXi’an 710016China

A Zr-Gd alloy with neutron poisoning properties and resistance to boiling concentrated HNO3 corrosion was developed based on a corrosion-resistant Zr-702 alloy to meet the demand for neutron shielding in the closed-loop treatment of spent fuel and the nuclear chemical industry.In this study,1 wt.%,3 wt.%,5 wt.%,7 wt.%,and 9 wt.%Zr-Gd alloys were designed and fabricated with Zr-702 as the control element.The electrochemical behavior of the Zr-Gd alloys in boiling concentrated HNO3 was investigated,and the neutron shielding effect on plate thickness and Gd content was simulated.The experimental results demonstrate that the corrosion resistance of the alloy decreased slightly before~7-9 wt.%with increasing Gd content;this is the inflection point of its corrosion resistance.The alloy uniformly dissolved the Gd content that could not be dissolved in the Zr lattice,resulting in numerous micropores on the passivation coating,which deteriorated and accelerated the corrosion rate.The MCNP simulation demonstrated that when the Gd content was increased to 5 wt.%,a 2-mm-thick plate can shield 99.9%neutrons;an alloy with a Gd content≥7 wt.%required only a 1-mm-thick plate,thereby showing that the addition of Gd provides an excellent neutron poisoning effect.Thus,the corrosion resistance and neutron shielding performance of the Zr-Gd alloy can meet the harsh service requirements of the nuclear industry.

关键词： Zr-Gd alloy Boiling concentrated HNO3 electrochemistry Neutron shielding MCNP

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Molten salt electrochemical modulation of Ni/Co nanoparticles onto N-doped carbon for oxygen reduction

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Journal of Energy Chemistry 2022年第11期31卷 212-217,I0007页

作者： Xinxin Liang Jialin Chen Biao Hong Tingting Wan Wei Weng Wei Xiao College of Chemistry and Molecular Sciences Hubei Key Laboratory of Electrochemical Power SourcesWuhan UniversityWuhan 430072HubeiChina Zijin School of Geology and Mining Fujian Key Laboratory of Green Extraction and High-value Utilization of Energy MetalsFuzhou UniversityFuzhou 350108FujianChina Queen Marry University of London Engineering School Northwestern Polytechnical UniversityXi’an 710129ShaanxiChina

Activation of oxygen over non-precious materials has been an imperative task to develop efficient electrochemical energy storage and conversion such as fuel cells and metal-air batteries.Herein,a molten salt electrochemical modulation of metal-nitrogen-carbon based compounds(M–N–C)is achieved.By electrochemical treatment of polydopamine-coated NiCo_(2)O_(4)(NiCo_(2)O_(4)@PDA)in molten Li_(2)CO_(3)-Na_(2)CO_(3)-K_(2)CO_(3)at 500℃,Ni/Co bimetal-nitrogen-carbon catalyst(denoted as Ni/Co@NC)consisting of Ni-Co nanoparticles anchoring on porous nitrogen-doped carbon is constructed and evaluated as electrocatalysts towards the oxygen reduction reaction(ORR).Experimental and calculation results confirm that alloying of Ni-Co and nitrogen doping to carbon enhances the rate-determining transformation of*OH intermediate during ORR.The Ni/Co@NC hence shows an ORR activity comparable with the commercial Pt/C.

关键词： Oxygen reduction Metal-nitrogen-carbon electrochemistry Molten salt Bimetal modulation

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The synergism of sequential paired electrosynthesis with halogen bonding activation for the cyclization of organochlorides with olefins

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Science China Chemistry 2023年第2期66卷 540-547页

作者： Fei Lian Kun Xu Chengchu Zeng Faculty of Environment and Life Beijing University of TechnologyBeijing100124China

Reported herein is the design of a new catalytic paradigm by synergistically combining sequential paired electrosynthesis with halogen-bonding(XB)activation for the cyclization of organochlorides with olefins.This dual activation strategy enables rapid access to densely functionalized 2-alkylidene-tetrahydrofurans with exclusive Z-selectivities,which are challenging to be synthesized by other methods.4,4′-Di-tert-butyl-2,2′-bipyridine(dtbbpy)showed an unprecedented reactivity as a XB acceptor to activate C-Cl bond by shifting its reduction potential positively by 220 m V.Distinctly different from previous electroreductions of C-Cl bonds relying upon high electrode potentials or matched redox properties between mediators and organochlorides,the XB activator employed herein has no limit on the abovementioned redox property matching but can lower the applied electrode potentials.The decreased operating potential allows broad functional group tolerance,which was highlighted by the late-stage functionalization of 11 examples of drugs and natural products-derived alkenes.

关键词： electrochemistry cross-electrophile coupling electrocatalysis paired electrolysis

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PtCo-based nanocatalyst for oxygen reduction reaction:Recent highlights on synthesis strategy and catalytic mechanism

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Chinese Journal of Chemical Engineering 2023年第1期53卷 101-123页

作者： Wenjuan Yan Puhua Sun Chen Luo Xingfan Xia Zhifei Liu Yuming Zhao Shuxia Zhang Liang Sun Feng Du State Key Laboratory of Heavy Oil Processing Center for Chemical Engineering Experimental TeachingOil Industry Training CenterChina University of PetroleumQingdao 266580China Petrochemical Research Institute PetroChinaBeijing 102200China

Oxygen reduction reaction over Pt-based catalyst is one of the most significant cathode reactions in fuel cells.However,low reserves and high price of Pt have motivated researchers worldwide seeking enhanced utilization efficiency and durability by doping non-noble metals to form Pt-based alloy catalysts.Alloying Pt with Co has been recognized as one of the most effective approaches to achieve this goal.PtCo bimetal combination is one of the most promising candidates to synthesize highly efficient catalysts for oxygen reduction reaction(ORR)applications,owing to its relatively more suitable oxygen binding energy for four-electron transfer reactions.Recently,impressive strategies have been developed to fabricate more active and stable PtCo-based multimetallic alloys with tailorable size and morphology.This paper aims to summarize the most recent highlights on the study of the relationship between preparation strategies,morphologies,electroactivities of the PtCo-based catalyst at atomic level and further the relevant reaction mechanism.The challenges and opportunities on the further development of electrocatalysts for fuel cells are included to provide reference for the practical application.

关键词： electrochemistry Catalysis Oxygen reduction reaction Fuel cells PtCo nanoalloy Multimetallic

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Activating Inert Sites in Cobalt Silicate Hydroxides for Oxygen Evolution through Atomically Doping

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Energy & Environmental Materials 2022年第2期5卷 655-661页

作者： Jiexin Zhu Lixue Xia Wenxuan Yang Ruohan Yu Wei Zhang Wen Luo Yuhang Dai Wei Wei Liang Zhou Yan Zhao Liqiang Mai State Key Laboratory of Advanced Technology for Materials Synthesis and Processing Wuhan University of TechnologyWuhan 430070China International School of Materials Science and Engineering Wuhan University of TechnologyWuhan 430070China Foshan Xianhu Laboratory of the Advanced Energy Science and Technology Guangdong Laboratory Xianhu Hydrogen ValleyFoshan 528200China

Metal silicate hydroxides have been recognized as efficient oxygen evolution reaction(OER)electrocatalysts,yet tailoring of their intrinsic activity remains confused.Herein,Fe had been incorporated into cobalt silicate hydroxide nanosheets and the resulted material achieves a competitive OER catalytic activity.It is found that the doping state obviously affects the electrical transport property.Specifically,highly dispersed Fe atoms(low-concentration Fe doping)trigger slight electron transfer to Co atoms while serried Fe(highconcentration Fe doping)attract vast electrons.By introducing 6 at.%Fe doping,partial relatively inert Co sites are activated by atomically dispersed Fe,bearing an optimal metal 3d electronic occupation and adsorption capacity to oxygen intermediate.The introduced Co-O-Fe unit trigger the p-donation effect and decrease the number of electrons in p*-antibonding orbitals,which enhance the Fe-O covalency and the structural stability.As a result,the sample delivers a low overpotential of 293 mV to achieve a current density of 10 mA cm^(-2).This work clarifies the superiority of atomically dispersed doping state,which is of fundamental interest to the design of doped catalyst.

关键词： atomically doping electrochemistry electron transfer metal silicate hydroxides oxygen evolution

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COF-derived Co nanoparticles@N-doped carbon electrocatalysts for high performance Zn-air batteries

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Chinese Journal of Chemical Engineering 2023年第11期63卷 43-50页

作者： Jie Wei Chengcai Zhao Ming Chen Fengying Liu Limin Zhao Hui Zhao Zhong-Yong Yuan School of Materials Science and Engineering Liaocheng UniversityLiaocheng 252000China College of Chemistry and Chemical Engineering Xinyang Normal UniversityXinyang 464000China Key Laboratory of Advanced Energy Materials Chemistry(Ministry of Education) School of Materials Science and EngineeringNankai UniversityTianjin 300350China

Precise modulation of the structure and composition of electrocatalysts is critical for promoting the kinetically sluggish process of oxygen reduction reaction(ORR)and oxygen evolution reaction(OER).Covalent organic frameworks(COF)offer a novel way to create highly efficient electrocatalysts due to their tunable composition,structure and surface area.Herein,we report a high-efficiency bifunctional electrocatalyst comprising Co nanoparticles embedded within N-doped carbons(Co@NCs)for Zn-air batteries(ZABs).The Co@NC is yielded via the coordination of a triazine COF with Co-containing precursors and subsequent calcination under inert atmosphere.The as-prepared Co@NC exhibits remarkable ORR/OER performance and great potential in rechargeable ZABs.The liquid ZAB constructed with Co@NC provides both high specific capacity and power density.Remarkably,the ZAB exhibits a voltage gap of 0.8 V during discharge and charge cycles and high stability for 220 h compared to the Pt/C-assembled battery.This strategy for regulating electrocatalytic activities of COF-derived carbon materials could be expanded for creating various carbon catalysts.

关键词： COF Co@NC Composites electrochemistry Catalysis Zn-air battery

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Engineering sphere-like porous FeF3@C cathode with rational interfacial designing towards high-power batteries

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Rare Metals 2023年第3期42卷 954-970页

作者： Ming-Jun Jing Jun-Chang Liu Shao-Hui Yuan Wen-Qing Zhao Min Liu Yan-Song Bai Peng Ge Tian-Jing Wu National Base for International Science&Technology Cooperation National Local Joint Engineering Laboratory for Key Materials of New Energy Storage BatteryKey Laboratory of Environmentally Friendly Chemistry and Application of Ministry of EducationCollege of ChemistryXiangtan UniversityXiangtan 411105China School of Resource Processing and Bioengineering Central South UniversityChangsha 410083China

Due to the high theoretical capacity and energy density,conversion-type metal fluorides have captured plenty of attentions but still suffer from the inferior kinetic behaviors and serious capacity fading.For addressing the issues above,the strategies of surface/interface engineering are utilized for the preparation of sphere-like porous FeF3@C materials,where the as-resulted sample displays the uniform particle size(~150 nm in radii)and the ultrathin carbon layers(thickness of~10 nm).Significantly,benefitting from the rich oxygen of precursor,the interfacial chemical bonds Fe-O-C are successfully constructed between carbon matrix and FeF3 materials,accompanying by the enhancements of ions/electrons(e-)conductivity and stability.When used as Li-storage cathodes,the initial lithium-ions storage capacity could reach up to~400mAh·g^(-1) at 0.1 A·g^(-1).Even at 1.0 A·g^(-1),the capacity could be still remained at about 210 mAh·g^(-1),with the retention of 85%after 400 cycles.Assisted by the detailed kinetic behaviors,the considerable electrochemical properties come from the enhanced diffusion-controlled contributions,whilst the segregation of Fe with LiF is effectively alleviated by unique architecture.Moreover,during cycling,solid electrolyte interface film is reversibly formed/decomposed.Thus,this work is expected to offer rational exterior/interfacial designing strategies for metalbased samples.

关键词： Conversion-type Iron fluoride electrochemistry Kinetic behaviors Secondary batteries

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