Journal of Electrochemistry

Table of Contents

2017, 23(2): 0.

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The Journal of Electrochemistry is proud to publish this Special Issue Honoring Professor Zhaowu Tian, on the occasion of his 90th birthday, for his enormous contributions to and far-reaching impact in the field of electrochemistry. Professor Tian is one of the founders and pioneers of electrochemistry in China, and a well-known electrochemist in the world as well. He was born in 1927 in Fuzhou, and graduated from Xiamen University in 1949 majoring in physical chemistry. Prof. Tian directed his study to electrochemistry in 1955, and significantly advanced electrochemistry in both fundamental and application. Based on his sharp scientific views and outstanding creativity, Prof. Tian has made a series of systematic and original achievements in electrochemistry covering wide areas from methodologies and instrumentations to fundamental and applied electrochemistry, including autocatalysis, AC impedance analysis，porous electrode theory, photoelectrochemistry, secondary batteries, supercapacitor, corrosion electrochemistry, electroanalysis, microfluidics/microchip and microfabrication. He has published seven books and 193 papers in journals, and is the owner of 34 patents. Many of his research achievements have realized technical transfer, which greatly advanced the development of science and industrial applications. He received 20 important awards for his great scientific achievements and outstanding contributions. Prof. Tian became an academician of Chinese Academy of Science in 1980, president of Xiamen University during 1982-1989, and elected as vice president of the International Electrochemical Society in 1996-1999. We are particularly proud that currently he is still very active in his interests of scientific topics, social progress and students’ supervision. His scientific spirit of “determined, strived, innovative and realistic” has always guided and stimulated his numerous students over the world. Prof. Tian founded the Journal of Electrochemistry in 1995, when the 46th annual meeting of the International Electrochemical Society was held in Xiamen. Under his long-term cultivation and direction, the journal has become the official publication of Chinese Society of Electrochemical (CSE), and devoted great efforts to serve for the rapidly growing needs of electrochemistry in both fundamental and applied topics in China and to promote the international communication and collaboration as well. In this special issue, we collected 13 papers involving various topics in modern electrochemistry contributed by some of Prof. Tian’s close friends and former students in China and over the world to celebrate the 90th Birthday of Prof. Tian. We would like to take this opportunity to sincerely thank all the authors for submission of their excellent works to ensure the high standard of the special issue. The professional devotions from the reviewers and editorial staff of the Journal of Electrochemistry to the success of special issue are also highly appreciated.

Designing Pt-skin of Pt-based Bimetallic electrocatalysts for Oxygen Reduction Reaction

Binwei Zhang, Yunxiao Wang, Yanfei Xu, Huakun Liu, Shixue Dou

2017, 23(2): 102-109. doi:10.13208/j.electrochem.161244

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In the past decade, great advancement has been made in the development of nanocatalysts for energy conversion and storage. Pt-skin of Pt-based bimetallic has shown a great potential in the tuning the electronic structures of electrocatalytically active materials toward oxygen reduction reaction. Here, we offer a brief overview of the recent research on the design and preparation of catalysts. Our focus is paid on the systematic studies of preparation and performance of Pt-skin catalysts towards oxygen reduction reaction.

Recent Progress in Template-Assisted Synthesis of Nitrogen-Doped Porous Carbons for Oxygen Electroreduction

Wenhan Niu, Ligui Li, and Shaowei Chen

2017, 23(2): 110-122. doi:10.13208/j.electrochem.161242

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Nitrogen (N)-doped porous carbons are potential alternatives to precious metal catalysts for oxygen reduction reaction (ORR) at the cathodes of proton exchange membrane fuel cells and metal-air batteries. Template-assisted synthesis has been used extensively as a robust and versatile method in the preparation of such carbon catalysts, where the ORR activity has been found to be dependent on various structural parameters, such as the concentrations and molecular configurations of the dopants, and the porosity, surface accessibility and electrical conductivity of the carbon materials. In this review, we summarize recent progress in this area of research focusing on the design, preparation and engineering of N-doped porous carbons, as well as their ORR catalytic activity. Future trends in the development of N-doped porous carbons are also pointed out.

Electrochemical Methods in Clinical Immunoassays and Nucleic Acid Analyses

Yanbing Zu

2017, 23(2): 123-129. doi:10.13208/j.electrochem.161248

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The applications of electrochemical methods in immunoassays and nucleic acid analyses are discussed. Instead of a comprehensive literature review, this paper focuses on the techniques that have already been commercialized and used in clinical diagnoses. Learning from the success of these methods will help us to further understand the strengths and limitations of electroanalytical technology. A personal perspective of the research and development in these fields has been presented.

Electrografting of Mono-N-Boc-Ethylenediamine from an Acetonitrile/Aqueous NaHCO₃Mixture

Hisham Hamzah,Guy Denuault,Philip Bartlett,Aleksandra Pinczewska,Jeremy Kilburn

2017, 23(2): 130-140. doi:10.13208/j.electrochem.161241

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The electrografting of primary amines to carbon electrodes is now widely employed for electrode modification. Using a mixture of acetonitrile and 0.1 mol•L^-1 aqueous sodium hydrogen carborate (NaHCO₃) in the ratio of 4:1, the efficiency for coupling of mono-N-Boc-ethylenediamine (EDA-Boc) on the surface of glassy carbon was significantly improved as compared with that obtained using acetonitrile alone. In the presence of NaHCO₃the initial current determined in the cyclic voltammogram became higher, and the layer of attached amine was formed more rapidly, accordingly, the electrode was passivated more rapidly. The resulting film of EDA-Boc was shown to be more severely blocking toward the electrochemical reaction of [Fe(CN)₆]^3-. Following removal of the Boc protecting group and coupling of the free amine to anthraquinone-2-carboxylic acid, a higher surface coverage of the anthraquinone was obtained. Modelling for the electrograftng reaction using a simple kinetic scheme, it was demonstrated that the simulated voltammograms agreed well with the experimentally measured voltammograms . Comparison between the model fitting parameters obtained from the acetonitrile alone and the acetonitrile/NaHCO₃ mixture showed that the competition between reaction of the amine radicals with the carbon surface and reaction in the homogeneous solution became more favourable for the surface reaction in the acetonitrile/NaHCO₃ mixture.

Reconstruction of Distributions of Nanoparticles or Electroactive Nano-Components in Electrochemical Arrays Based on Chronoamperometric Data

Alexander Oleinick, Oleksii Sliusarenko, Irina Svir, Christian Amatore

2017, 23(2): 141-158. doi:10.13208/j.electrochem.161245

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The main scope of this work was to elaborate and test a simple mathematical and numerical procedure for reconstructing the probability density distributions f(ρ) characterizing the distribution of electroactive or electrocatalytic nano-components present or deposited on the electrochemically-inert surface of a planar conductor based on the time-dependent chronoamperometric responses of the corresponding electrochemical array. The mathematical and numerical validity of the procedure was established for three types of arrays (one periodical, two involving random dispersions) involving near-spherical nano-components dispersed on a flat surface. Indeed, altogether, these three types represent most 2D-experimental electrochemical nano-arrays used for analytical or electrocatalytic purposes. This reconstruction procedure is easily implementable using most commercial mathematical programs. Albeit the simplicity of its implementation, it allowed recovering probability densities with an excellent precision, even when the available time-range experimentally accessible was too short for its rigorous application, being thus perfectly adequate to most experimental purposes.

Comparative Studies of Fe, Ni, Co and Their Bimetallic Nanoparticles for Electrochemical Water Oxidation

Maduraiveeran Govindhan, Brennan Mao, Aicheng Chen

2017, 23(2): 159-169. doi:10.13208/j.electrochem.161247

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The design of efficient, durable, and earth-abundant electrocatalysts via environmentally compatible strategies for the oxygen evolution reaction (OER) is a vital for energy conversion processes. Herein we report a facile approach for the fabrication of low-cost and earth abundant metal catalysts, including iron (Fe), nickel (Ni), cobalt (Co), CoNi, and CoFe nanoparticles (NPs) on titanium (Ti) substrates through a one-step electrochemical deposition. Field-emission scanning electron microscopy (FE-SEM), energy dispersive X-ray spectroscopy (EDX), X-ray diffraction (XRD) spectrocopy, X-ray photoelectron spectroscopy (XPS), and electrochemical techniques were employed to characterize these nanoparticles. Our electrochemical results revealed that among the five synthesized nanomaterials, the Ti/Co electrode exhibited the highest electrocatalytic activity toward OER in 0.l mol·L^-1 KOH with a current density of 10.0 mA·cm^-2 at 0.70 V vs. Ag/AgCl. The optimized Ti/Co electrode exhibited a small overpotential (η) of 0.43 V at 10.0 mA·cm^-2 and a high mass activity of 105.7 A·g^-1 with a turnover frequency (TOF) value of 1.63×10^-3 s^-1, which are comparable to the values obtained with the state-of-the-art Pt/C and RuO₂ electrocatalysts. In addition, the durability of the optimized Ti/Co electrode was tested using a chronopotentiometric technique, which revealed that the developed electrocatalyst possessed good stability for OER in an alkaline solution. The high catalytic activity, high stability, earth abundance, cost-effectiveness, and easy scale-up for mass production make the Co nanoparticles, which were electrochemically deposited on a Ti substrate, promising for industrial water splitting

Impact of Nafion Loading and Anion Adsorption on the Synthesis of Pt Monolayer Core-shell Catalysts

Lijun Yang, Dustin Banham, Elod Gyenge, Siyu Ye

2017, 23(2): 170-179. doi:10.13208/j.electrochem.161243

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Carbon supported palladium (Pd) nanoparticles were used as a model core material for the synthesis of platinum (Pt) monolayer core-shell catalysts using rotating disk electrode method and a copper (Cu) under potential deposition technique. The impact of Nafion on the synthesis process was revealed by electrochemical testing with various Nafion contents. The existence of Nafion influenced the Cu under potential deposition, galvanic replacement and eventually the oxygen reduction reaction activity of the core-shell catalyst. However, as long as the Nafion content was less than 5 wt% in the test film, adding Nafion could help to bind catalyst onto the surface of electrode while maintaining promising catalytic activity. Unique anion adsorption/desorption peaks were observed on the surface of Pd in H₂SO₄ solution, which turned out to be a useful indicator to evaluate the impact of Nafion on the synthesis of the core-shell catalysts.

Green Electrochemical Ozone Production via Water Splitting: Mechanism Studies

Gregory Gibson, Wenfeng Lin

2017, 23(2): 180-198. doi:10.13208/j.electrochem.161252

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The green and energy-efficient water splitting reaction using electrocatalysis for O₃ formation provides a very attractive alternative to the conventional energy-intensive cold corona discharge (CCD) method. Among a large number of electrocatalysts explored for the electrochemical ozone production, β-PbO₂ and SnO₂-based catalysts have proven to be the most efficient ones at room temperature. In this study Density Functional Theory (DFT) calculations have been employed to investigate the possible mechanisms of ozone formation over these two types of catalysts. For both the β-PbO₂ and Ni/Sb-SnO₂ (nickel and antimony doped tin oxide) catalysts the (110) facet was found to be the most stable one. The possible water splitting mechanisms were modeled on both the β-PbO₂(110) and Ni/Sb-SnO₂(110) surfaces with particular attention given to the final two reaction steps, the formations of O₂ and O₃. For the β-PbO₂, the formation of O₃ was found to occur through an Eley-Rideal style mechanism as opposed to that on the Ni/Sb-SnO₂, the latter occurs through a Langmuir-Hinshelwood style interaction. Thermodynamic parameters such as the adsorption energies (E_ads), Gibbs free energies (ΔG) and activation energies (E_act) have also been obtained, compared and presented, with β-PbO₂being modelled primarily as solid-liquid phases and Ni/Sb-SnO₂ modelled as gas phase. These DFT findings have provided the basis for a tool to design and develop new electrochemical ozone generation catalysts capable of higher current efficiencies.

Comparison of Oxygen Reduction Reaction Activity of Pt-Alloy Nanocubes

Yongan Tang, Lin Dai, Shouzhong Zou

2017, 23(2): 199-206. doi:10.13208/j.electrochem.161249

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Alloying Pt with the first row non-noble transition metals has been demonstrated to increase the catalytic activity toward oxygen reduction reaction (ORR), which is the cathode reaction of the proton exchange membrane fuel cells (PEMFCs) and metal-air batteries. However, how much the ORR activity improvement comes from the alloying elements remains controversial. In this paper, the nanocubes of PtMn, PtFe, PtCo, and PtNi with the similar size and composition were prepared and their ORR activities were explored, in order to investigate the effects of alloying elements on the catalytic activity. The use of cubic shape particles minimizes the contribution to the activity from particle surface structural difference. The results showed that the ORR activity vs. Pt d-band center plot had a volcano shape and PtCo nanocube is the most active. These observations are in harmony with density functional theory calculations on well-defined surfaces in the framework of the d-band theory.

Resistive-Pulse Analysis of Single Phospholipid Vesicles Using Quartz Nanochannels

Jonathan T. Cox, Bo Zhang

2017, 23(2): 207-216. doi:10.13208/j.electrochem.161250

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We report the uses of resistive-pulse method and quartz nanochannels for the detection and size analysis of single vesicles. Cylindrical shape quartz nanochannels have been used to detect single phospholipid vesicles ranging from 100 to 300 nm and polystyrene nanoparticles ranging from 170 to 400 nm in diameter. Translocations of single vesicles and nanoparticle were detected as individual square current pulses, which could be used to determine particle size. Our results show excellent agreement between the particle/vesicle sizes obtained from nanochannels and those from dynamic light scattering (DLS) and scanning electron microscopy (SEM). This electronic-based method was found to be fast, simple, and used cheap and robust microsensors made in house. The application of a quartz channel might be combined with other analytical methods, such as amperometry and fluorescence microscopy, to yield more complete information about biological and artificial vesicles.

Novel Composites between Nano-Structured Nickel Sulfides and Three-Dimensional Graphene for High Performance Supercapacitors

Xiaomin Wang, Huanglin Dou, Zhen Tian, Jiujun Zhang

2017, 23(2): 217-225. doi:10.13208/j.electrochem.161246

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In this paper, a three-dimensional graphene (3DG) network grown on nickel foam was employed as a template for synthesizing graphene-based composite materials of supercapacitor electrode. The composites (crystal Ni₃S₂ nanorods on the surface of 3DG (abbreviated as Ni₃S₂/3DG)) were obtained through a one-step hydrothermal reaction. The morphological and structural evolution of the Ni₃S₂/3DG composites were investigated by SEM, TEM, XRD and Raman spectroscopy. Detailed electrochemical characterization showed that the Ni₃S₂/3DG-coated electrodes exhibited both a specific capacitance as high as 1825 F·g^-1 at 5 mV·s^-1 and a discharge capacitance as high as 517 F·g^-1 at 10 mA. Remarkably, a high cycling performance (~ 100% capacitance retention after 1000 cycles) is achieved at a current density of 20 mA.

Rutile TiO₂Nanosheet Arrays Planted on Magnetron Sputtered Ti Metal Layers for Efficient Perovskite Solar Cells

Nang Zhang，Meidan Ye, Xiaoru Wen, Changjian Lin

2017, 23(2): 226-237. doi:10.13208/j.electrochem.161251

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In this work, vertical rutile titanium oxide (TiO₂) nanosheet arrays (NSAs) were firstly hydrothermally grown on the top of thin titanium (Ti) metal layers which were loaded on fluorine doped tin oxide (FTO) substrates by the DF magnetron sputtering deposition method. After an annealing post-treatment, the Ti metal layers were transformed into the compact TiO₂ layers with a strong connection between the rutile TiO₂ NSAs and the FTO substrates. For comparison, the rutile TiO₂ NSAs were similarly planted over two compact TiO₂ layers fabricated through atomic layer deposition (ALD) and spin coating (SC) methods, respectively. When served as the scaffold layers in perovskite solar cells (PSCs), the Ti-based TiO₂ NSAs showed the best cell performance due to the high quality of the TiO₂ NSA nanostructure and excellent interface contacts among the TiO₂ NSAs/TiO₂ compact layers/FTO substrate interface. Significantly, a highest cell efficiency of 11.82% was obtained after careful modification on the organization procedures for the PSC devices.

Electrodeposition of RuO₂ Layers on TiO₂ Nanotube Array toward CO₂ Electroreduction

Bei Jiang, Lina Zhang, Xianxian Qin, Wenbin Cai

2017, 23(2): 238-244. doi:10.13208/j.electrochem.161253

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RuO₂/TiO₂ composite materials have multitude of electrocatalytic applications including but not limited to CO₂ reduction reaction (CO₂RR). RuO₂/TiO₂ electrodes were previously prepared by repetitive coating and thermal decomposition (TD) of a Ru(III) precursor solution on Ti substrate. In this work, electrochemical potential cycling is applied to deposit amorphous RuO₂ (α-RuO₂) layers onto TiO₂ nanotube array (TNA) (RuO₂^CV/TNA) preformed on Ti foil. SEM, GIXRD, and voltammetry are applied to characterize the structures of the resulting Ru_O2^CV/TNA. Ru loading on the RuO₂^CV/TNA electrode is ca. 1/30 of that on the conventional RuO₂^TD/TNA electrode. Although both electrodes yield similar faradaic efficiencies (FEs) for the reduction products, the RuO₂^CV/TNA electrode displays a much higher reduction current, a more positive initial reduction potential and a better durability than the RuO₂^TD/TNA one. In addition to higher FEs for formate and CH₄, the RuO₂^CV/TNA electrode yields the product of CO for the CO₂RR in 0.1 mo•lL^-1 KHCO₃, which is not available in a PBS solution with pH 7.