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Substrate mediated dissolution of redox active nanoparticles;electron transfer over long distances

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Nano Research 2022年第1期15卷 429-437页

作者： Ruo-Chen Xie Christopher Batchelor-McAuley Minjun Yang richard g.compton Department of Chemistry Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxford OXl 3QZUK

Reflective dark field microscopy is used to observe the decrease in the light scattered from Ag nanoparticles immobilised on differing solid *** nanoparticles are exposed to solutions containing halide ions,both at open circuit and under potentiostatic control,leading to the loss of the *** coupling optical and electrochemical techniques the physical origin of this transformation is demonstrated to be the electrochemical dissolution of the metal nanoparticles driven by electron transfer to ultra-trace dissolved *** dissolution kinetics of the surface-supported metal nanoparticles is compared on four substrate materials(i.e.,glass,indium titanium oxide,glassy carbon and platinum)with different electrical *** three conductive substrates catalyse the redox-driven dissolution of Ag nanoparticles with the electrons transferred from the nanoparticles,via the macroscopic electrode to the dioxygen electron acceptor.

关键词： substrate electrocatalysis oxidative dissolution metal nanoparticles optical microscopy electrochemistry

荧光胺电化学检测水溶液中的氨:荧光检测与伏安分析比较(英文)

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电化学 2012年第5期18卷 437-449页

作者： Janjira Panchompoo richard g.compton 牛津大学化学系物理化学与理论化学实验室

荧光胺是一种非荧光剂,易与伯胺反应形成荧光产物,被普遍用于伯胺的荧光光谱定量分析.本文利用荧光胺与伯胺反应发展了一种新型灵敏的伏安法用于检测水溶液中的伯胺.首先,在有、无伯胺的0.1 mol.L-1PBS(pH 9.0)缓冲液中,研究了玻碳电极... 详细信息

荧光胺是一种非荧光剂,易与伯胺反应形成荧光产物,被普遍用于伯胺的荧光光谱定量分析.本文利用荧光胺与伯胺反应发展了一种新型灵敏的伏安法用于检测水溶液中的伯胺.首先,在有、无伯胺的0.1 mol.L-1PBS(pH 9.0)缓冲液中,研究了玻碳电极表面荧光胺的循环伏安电化学行为.荧光胺的不可逆氧化峰出现在0.70 V(***),当加入伯胺时,在0.46 V(***)出现另一不可逆的氧化峰,为荧光胺与伯胺反应的产物.继续加入氨水,荧光胺的氧化峰变弱,反应产物的氧化峰则由于荧光胺按反应化学计量比随氨消耗增多而随之增大.上述两个阳极峰分别对应于荧光胺及其反应产物,采用方波伏安和荧光光谱技术可实现水溶液中伯胺的定量检测.在0～60μmol.L-1氨浓度范围内,该反应产物方波伏安检测成线性响应.S/N=3或3σ时检测下限分别为0.71μmol.L-1和3.17μmol.L-1,与荧光法检测的结果相近.

关键词：电化学检测循环伏安方波伏安荧光光谱氨荧光胺

Au（111）电极上砷沉积的电化学反应机理（英文）

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Au（111）电极上砷沉积的电化学反应机理（英文）

Complementary fruiting phenologies facilitate sharing of one pollinator fig wasp by two fig trees

第十三次全国电化学会议

作者：贾铮 Andrew O．Simm richard g.compton 哈尔滨工业大学应用化学系牛津大学物理和理论化学实验室牛津大学物理和理论化学实验室

＜正＞The arsenic contamination of groundwater and soil in various parts of the world has been well reported. In Bangladesh alone, an estimated SO million people are at risk in the threat which WHO calls the world’s worst mass human poisoning disaster. The electrochemical methods have been effectively applied in arsenic removal and quantitative analysis of arsenic. Especially, many researches have revealed that anodic stripping voltammetry （ASV） on different forms of gold electrodes provided a low-cost, rapid and portable detection of arsenic for routine in-field monitoring of large numbers of samples. Therefore, the study of electrochemical

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Journal of Plant Ecology 2015年第2期8卷 197-206页

作者： gui-Xiang Liu Da-Rong Yang Yan-Qiong Peng Stephen g.compton Key Laboratory of Tropical Forest Ecology Xishuangbanna Tropical Botanical GardenChinese Academy of Sciences88 Xuefu RoadKunming 650223China University of Chinese Academy of Science 19 Yuquan roadBeijing 100049China School of Biology University of LeedsWoodhouse LaneLeeds LS29JTUK Department of Zoology and Entomology Rhodes UniversityLower University RoadGrahamstown 6140South Africa

Aims most pollinator fig wasps are host plant specific,with each spe-cies only breeding in the figs of one fig tree species,but increasing numbers of species are known to be pollinated by more than one fig wasp,and in rare instances host switching can result in Ficus species sharing *** this study,we examined factors facilitating observed host switching at Xishuangbanna in southwestern(sW)China,where Ficus squamosa is at the northern edge of its range and lacks the fig wasps that pollinate it elsewhere,and its figs are colonized by a Ceratosolen pollinator that routinely breeds in figs of *** We recorded the habitat preferences of *** and ***-yla at Xishuangbanna,and compared characteristics such as fig size,location and colour at receptive ***,the vegetative and reproductive phenologies in the populations of *** and *** were recorded weekly at Xishuangbanna Tropical botanical garden for 1 *** Findings Ficus squamosa is a shrub found near fast-flowing rivers,*** is a small tree of disturbed forest *** preferring different habitats,they can be found growing close *** species have figs located at or near ground level,but they differ in size when *** production in *** was concentrated in the colder *** produced more figs in summer but had some through-out the *** absence of its normal pollinators,in combination with similarly located figs and partially complementary fruiting patterns appear to have facilitated colonization of *** by the routine pollinator of *** figs probably also share similar attractant *** host switching suggests one mechanism whereby fig trees can acquire new pollinators and emphasizes the likely significance of edges of ranges in the genesis of novel fig tree-fig wasp relationships.

关键词： agaonidae edge of range Ficus host specificity host switching

Electro-oxidation of hydrazine shows marcusian electron transfer kinetics

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Science China Chemistry 2021年第2期64卷 322-329页

作者： Ruiyang Miao Lifu Chen richard g.compton Department of Chemistry Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxfordOX13QZUK

Although hydrazine(N2 H4) oxidation in an electrochemical environment has been of great interest for years,its intrinsic electron transfer kinetics remain *** report that the phenomenological Butler-Volmer(BV) theory is not appropriate for interpreting the process of hydrazine oxidation for which an astonishingly wide range of transfer coefficients,Tafel slopes and diffusion coefficient have been previously *** Tafel analysis for voltammetry recorded at glassy Carbon(gC)electrodes reveals a strong potential dependence of the anodic transfer coefficient,consistent with the symmetric Marcus-Hush(sMH) *** to the relationship β=λ+FEf^0/2λ-F/2λ E,the reorganization energy(0.35±0.07 eV) and an approximate formal potential of the rate-determining first electron transfer were successfully extracted from the voltammetric responses.

关键词： hydrazine electrode kinetics transfer coefficient Butler-Volmer theory Marcus-Hush theory

Magnetic control： Switchable ultrahigh magnetic gradients at Fe3O4 nanoparticles to enhance solution-phase mass transport

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Nano Research 2015年第10期8卷 3293-3306页

作者： Kamonwad Ngamchuea Kristina Tschulik richard g. compton DepartmentofChemistry Physical&TheoreticalChemistryLaboratoryUniversityofOxfordSouthParksRoadOxfordOX13QZUK

Enhancing mass transport to electrodes is desired in almost all types of electrochemical sensing, electrocatalysis, and energy storage or conversion. Here, a method of doing so by means of the magnetic gradient force generated at magnetic-nanoparticle-modified electrodes is presented. It is shown using Fe3O4-nanoparticle-modified electrodes that the ultrahigh magnetic gradients （〉10^8 T·m^- 1） established at the magnetized Fe3O4 nanoparticles speed up the transport of reactants and products at the electrode surface. Using the Fe（Ⅲ）/ Fe（Ⅱ）-hexacyanoferrate redox couple, it is demonstrated that this mass transport enhancement can conveniently and repeatedly be switched on and off by applying and removing an external magnetic properties of magnetite nanoparticles field, owing to the superparamagnetic Thus, it is shown for the first time that magnetic nanoparticles can be used to control mass transport in electrochemical systems. Importantly, this approach does not require any means of mechanical agitation and is therefore particularly interesting for application in micro- and nanofluidic systems and devices.

关键词： superparamagneficmagnetite nanoparficles nanoparticle-modifiedelectrodes magnetic field effects magnetoelectrochemistry

Chemical interactions between silver nanoparticles and thiols: a comparison of mercaptohexanol against cysteine

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Science China Chemistry 2014年第9期57卷 1199-1210页

作者： TOH Her Shuang BATCHELOR-MCAULEY Christopher TSCHULIK Kristina compton richard g Department of Chemistry Physical and Theoretical Chemistry LaboratoryUniversity of OxfordSouth Parks RoadOxford OX1 3QZUK

The interaction between citrate capped silver nanoparticles and two different thiols, mercaptohexanol （MH） and cysteine, was investigated. The thiols interacted with silver nanoparticles in a significantly contrasting manner. With MH, a sparingly soluble silver（1） thiolate complex AgSRm （Rm = -（CH2）6OH） was formed on the silver nanoparticle surface. Cyclic voltammograms and UV-vis spectra were used to infer that the AgSRm complex on the nanoparticle surface undergoes a phase transition to give a mixture of AgSRm and Ag2S-like complexes. In contrast, when silver nanoparticles were exposed to cysteine, the citrate cap- ping agent on the silver nanoparticles was replaced by cysteine to give cysteine capped nanoparticles. As cysteine capped nanoparticles form, the electrochemical data displayed a decrease in oxidative peak charge but the UV-vis spectra showed a constant signal. Therefore, cysteine capped nanoparticles were suggested to have either inactivated the silver surface or else pro- moted detachment from the electrode surface.

关键词： silver nanoparticles interaction thiol

Koutecky-Levich analysis applied to nanoparticle modified rotating disk electrodes： Electrocatalysis or misinterpretation？

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Nano Research 2014年第1期7卷 71-78页

作者： Justus Masa Christopher Batchelor-McAuley Wolfgang Schuhmann richard g. compton Department of Chemistry Physical and Theoretical Chemistry Laboratory University of Oxford South Parks Road Oxford OX13QZ UK Analytische Chemie and Center for Electrochemical Sciences-CES Ruhr-Universitat Bochum Universitatsstr 150 D-44780 Bochum Germany

The application of naive Koutecky-Levich analysis to micro- and nano-particle modified rotating disk electrodes of partially covered and non-planar geometry is critically analysed. Assuming strong overlap of the diffusion fields of the particles such that transport to the entire surface is time-independent and one-dimensional, the observed voltammetric response reflects an apparent electrochemical rate o constant koapp, equal to the true rate constant ko describing the redox reaction of interest on the surface of the nanoparticles and the ratio,ψ, of the total electroactive surface area to the geometric area of the rotating disk surface. It is demonstrated that Koutecky-Levich analysis is applicable and yields the expected plots of I-1 versus ω-1 where I is the current and ω is the rotation speed but that the values of the electrochemical rate constants inferred are thereof koapp, not ko. Thus, for ψ 〉 1 apparent electrocatalysis might be naively but wrongly inferred whereas for ψ 〈 1 the deduced electrochemical rate constant will be less than ko. Moreover, the effect of ψ on the observed rotating disk electrode voltammograms is significant, signalling the need for care in the overly simplistic application of Koutecky-Levich analysis to modified rotating electrodes, as is commonly applied for example in the analysis of possible oxygen reduction catalysts.

关键词： rotating disk electrodes nanoparticles electrocatalysis electrode kinetics electro-reduction ofoxygen Koutecky-Levich analysis

Coulometric sizing of nanoparticles： Cathodic and anodic impact experiments open two independent routes to electrochemical sizing of Fez04 nanoparticles

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Nano Research 2013年第11期6卷 836-841页

作者： Kristina Tschulik Baptiste Haddou Dario Omanovi Neil V. Rees richard g. compton Department of Chemistry Physical & Theoretical Chemistry Laboratory Oxford University South Parks Road Oxford OXI 3QZUnited Kingdom Center for Marine and Environmental Research Ruder Boskovic Institute P. O. Box 180 I0001 Zagreb Croatia

Anodic particle coulometry （APC） is a recently established method of sizing individual metal nanoparticles by oxidising them during their impact on a micro electrode. Here it is demonstrated that the application of APC can be extended to sizing of metal oxide nanoparticles, such as Fe304 magnetite nanoparticles. Additionally, a new route to electrochemical nanoparticle sizing is introduced-- cathodic particle coulometry （CPC）. This method uses the reduction of impacting nanoparticles, e.g., metal oxide nanoparticles, and is demonstrated to yield correct size information for Fe304 nanoparticles. The combination of these two independent electrochemical methods of nanoparticle sizing, allows for purely electrochemical sizing of single nanoparticles and simultaneous verification of the obtained results.

关键词： nanoparticle sizing Fe3O4 anodic particle coulometry cathodic particle coulometry impact experiments metal oxide nanoparticles