Nanoscience and Nanotechnology Commons^™

Rational Design Of Highly Efficient Electrocatalysts Using Atomic Layer Deposition: From Nanoparticle To Single Atom, Junjie Li

Electronic Thesis and Dissertation Repository

Polymer electrolyte membrane fuel cells (PEMFCs) have been attracted significant attention due to their high energy efficiency. The electrocatalyst is one of the most important parts. However, state-of-the-art electrocatalysts suffer from several challenges, including 1) low stability under harsh working conditions; 2) low atomic utilization efficiency, especially for noble metals. This thesis, therefore, focuses on the design of highly efficient and stable electrocatalysts from nanoparticles down to single atoms using atomic layer deposition (ALD) and further understand the insight mechanisms.

Firstly, Pt nanoparticles are selectively deposited on the TiO₂ modified N-doped carbon nanotubes. The strong metal-support interactions between Pt …

Synthesis And Electrochemical Study Of Cuau Nanodendrites For Co2 Reduction, Siltamaki Dylan, Chen Shuai, Rahmati Farnood, Lipkowski Jacek, Chen Ai-Cheng

Journal of Electrochemistry

The conversion of carbon dioxide (CO₂) to carbon monoxide (CO) and other value-added products is an interesting approach for carbon-containing fuel synthesis using renewable and clean energy. The electrochemical reduction of CO₂ is one of the promising strategies for the storage of intermittent renewable energy resources. The development of electrocatalysts with high activity and stability is vital in the electrochemical CO₂ reduction process. In this study, copper and gold alloyed (CuAu) electrodes with nanodendritic structures were synthesized using a facile electrodeposition method. The CuAu nanodendrites with the atomic ratio of Cu to Au being approximately 1:1 …

Application Of Atomically Precise Metal Nanoclusters In Electrocatalysis, Zhi-Hua Zhuang, Wei Chen

Journal of Electrochemistry

Metal nanoclusters (M NCs) consist of only several to a few hundred of metal atoms and possess core sizes less than 2 nm. Owing to the quantum size effect, the electronic states of M NCs evolve to discrete levels similar to the molecule energy gaps, other than a continuous density of states to produce plasmon characteristic of bulk metal nanoparticles (M NPs). In comparison with the conventional M NPs, M NCs exhibit dramatically unique electronic and optical properties, such as molecule-like energy gaps, strong photoluminescence and high catalytic properties, which make them promising for potential application in numerous fields, such …

Preparation Of Pdcoir Tetrahedron Nanocatalysts And Its Performance Toward Ethanol Oxidation Reaction, Zhi-Yuan Yu, Rui Huang, Jie Liu, Guang Li, Qian-Tong Song, Shi-Gang Sun

Journal of Electrochemistry

As a new energy conversion device, direct ethanol fuel cells (DEFCs) are widely concerned because of their remarkable advantages such as high theoretical energy density and wide fuel sources. However, the rapid development of DEFCs has been severely impeded due to the sluggish kinetic process and toxic intermediates especially in their anodic reactions. Palladium (Pd)-based materials are considered to be excellent anode catalysts for DEFCs, especially under alkaline conditions. And further improving their performance is an important direction to promote the development of DEFCs. Surface structure and composition are the key factors affecting the performance of catalysts which can be …

Investigation Of Iron-Nickel Based Nanoparticles As Catalysts For Oxygen Evolution Reaction (Oer), Prashant Acharya

Graduate Theses and Dissertations

Hydrogen fuel is increasingly seen as an appealing alternative by both the scientific and the industrial communities in the drive towards a clean energy future. Hydrogen, unlike fossil-based fuels, does not release carbon dioxide, a chief component of greenhouse gases, upon combustion. However, more than 95% of the hydrogen in the world is still produced by burning fossil fuels as this method is currently the only economically feasible option at a large industrial scale.

Water electrolysis shows a lot of potential in both hydrogen generation and in the storage of energy from renewable sources such as wind and sunlight. Likewise, …

Core-Shell Structured Ru@Ptru Nanoflower Electrocatalysts Toward Alkaline Hydrogen Evolution Reaction, Xue-Liang Wang, Yuan-Yuan Cong, Chen-Xi Qiu, Sheng-Jie Wang, Jia-Qi Qin, Yu-Jiang Song

Journal of Electrochemistry

Water electrolysis for hydrogen production is beneficial for solving the problem of energy crisis and environmental issues. It is necessary to study highly active and cost-effective catalysts toward hydrogen evolution reaction (HER) to reduce the consumption of noble metals. Herein, we report the synthesis of core-shell structured Ru@Pt_0.24Ru nanoflowers electrocatalyst by stepwise reduction of Ru and Pt precursors in the mixture of oleylamine and benzyl alcohol at 160 oC. The average diameter of the resultant Ru@Pt_0.24Ru was 16.5±4.0 nm with a bulk atomic ratio between Pt and Ru of 0.24:1 and a surface ratio of 3.3:1 …

Recent Progress On Enhancing Effect Of Nanosized Metals For Electrochemical Co2 Reduction, Yu-Ning Zhang, Dong-Fang Niu, Shuo-Zhen Hu, Xin-Sheng Zhang

Journal of Electrochemistry

The electrochemical conversion of CO₂ to chemical raw material for further utilization shows promising future to alleviate global warming and realize carbon cycle in nature, which is of great significance to the green chemistry and sustainable development. This review briefly introduces the advantages of CO₂ electrochemical reduction (CO₂ER) and its basic reaction principles, and summarizes the recent progress in a series of activity enhancement strategies based on nanosized metal catalysts. The influences of alloy effect, interface engineering, synergistic effect, surface defect engineering and support effect on the catalytic performance of nanosized metals for CO₂ER …

Optimization Of Nitrate Removal From Aqueous Solution By Acid-Activated Rice Straw Supported Nano Zero-Valent Iron Using Response Surface Methodology, Dalia A. Ali Eng, Nagwa Mahmoud Al-Mansi Prof, Mohamed Amin Sadek Prof., Ahmad Wafiq Abolnasr Dr.

Chemical Engineering

Rice straw is one of the most common agricultural wastes due to its large production amounts. Energy valorization of rice straw is a technology used for nitrate removal as the produced ashes used to generate the adsorbent by means of an alkali dissolution followed by acid precipitation. The novelty of the proposed process is that the production of the nano zero-valent iron supported acid-activated rice straw (AARS-nZVI) adsorbent is carried out without the energy valorization process but, through an acid activation for rice straw followed by precipitation of nZVI particles on its surface. The new adsorbent synthesis, characterization and application …

Manufacturing Of Carbon-Based Hybrid Nanocomposites With Engineered Functionalities Via Laser Ablation Synthesis In Solution (Lasis) Techniques, Erick Leonardo Ribeiro

Doctoral Dissertations

Carbon-based composite materials have long been fabricated and extensively used in our daily lives. In the past decades, with rapid development of nanotechnology, these class of material have gained even more attention owing to their outstanding properties which directly results in their prospects to revolutionize technological development in many fields, ranging from medicine to electronics. Nevertheless, for certain applications, including electrochemical energy storage/conversion devices, the chemically inert nature of these materials creates obstacles and thus requires their coupling with other active species. This thesis explores the use of Laser Ablation Synthesis in Solution (LASiS) in tailoring promising strategies and pathways …

Preparations Of Nano-MnoX/Ti Electrocatalytic Membrane Electrode For Catalytic Oxidation Of Cyclohexane Using Intermittent Electrodeposition, Xue Zhou, Hong Wang, Zhen Yin, Yu-Jun Zhang, Jian-Xin Li

Journal of Electrochemistry

Cyclohexanone and cyclohexanol (KA oil) obtained from highly selective oxidation of cyclohexane (CHA) show important industrial value and application prospects. In this work, the intermittent electrodeposition was developed to prepare nano-MnO_x catalyst loading porous tubular titanium membrane electrode (MnO_x/Ti), which was employed to constitute an electro-catalytic membrane reactor (ECMR) for the oxidation of cyclohexane to produce cyclohexanol and cyclohexanone. The surface morphology, crystal structure and electrochemical property of the catalysts were characterized by FESEM, XRD and electrochemical workstation, respectively. The results show that the catalyst prepared by the intermittent electrodeposition displayed nano-flower-like γ-MnO₂. Compared …

Synthesis And Raman Study Of Hollow Core-Shell Ni1.2Co0.8P@N-C As An Anode Material For Sodium-Ion Batteries, Jia-Hui Chen, Xiao-Bin Zhong, Chao He, Xiao-Xiao Wang, Qing-Chi Xu, Jian-Feng Li

Journal of Electrochemistry

With the increasing demand for large-scale energy storage, great progress has been made in discovering new advanced energy storage materials. Sodium-ion batteries (SIBs) have attracted much attention in recent years due to their use of abundant sodium resources and their comparable electrochemical capacity to lithium-ion batteries (LIBs). In this paper, we developed novel hollow core-shell Ni-Co bimetallic phosphide nanocubes with N-doped carbon coatings (Ni_1.2Co_0.8P@N-C) as the anode material for SIBs. The material was synthesized through a low-temperature phosphorization method using resorcinol formaldehyde (RF) resin coating with a Ni-Co Prussian blue analogue (PBA) as a template and …

The Artificial Leaf: An Investigation Into The Sociotechnical Integration Of New Solar Energy Innovations, Alexandra K. Treml, Jamie M. Mears

Senior Honors Projects, 2020-current

Increasing global demand, combined with the volatility of fossil fuels, has called for a large-scale increase in renewable energy production. Photovoltaics hold significant potential, but by nature, solar energy is intermittent and lacks dispatchability. Researchers around the world are working to create innovative solutions that utilize semiconductors found in solar cell technologies in new ways. This project harnesses photoelectrochemical water-splitting, which uses light energy to dissociate water molecules into hydrogen and oxygen. When the water-splitting device is submerged in saltwater and illuminated by sunlight, oxygen and hydrogen gas are produced on opposite surfaces, and can be either released or stored …

Nio@Rgo Supported Palladium And Silver Nanoparticles As Electrocatalysts For Oxygen Reduction Reaction, Shuo Yao, Tai-Zhong Huang, Rizwan Haider, Heng-Yi Fang, Jie-Mei Yu, Zhan-Kun Jiang, Dong Liang, Yue Sun, Xian-Xia Yuan

Journal of Electrochemistry

For pervasive applications of fuel cells, highly efficient and economical materials are required to replace Pt-based catalysts for oxygen reduction reaction (ORR). In this study, the NiO@rGO, Pd-NiO@rGO and Ag-NiO@rGO nanoparticles were synthesized, and their catalytic performances toward ORR were investigated. The results revealed that all the three materials were capable of catalyzing ORR, but both the Pd-NiO@rGO and Ag-NiO@rGO showed the better performances compared with the NiO@rGO in terms of the reaction pathway being 4-electron process, the increases of the onset potential and the intermediate yielding rate, as well as the extended stability. Moreover, the effect of Pd modification …

Engineered Nanoparticles For Site-Specific Bioorthogonal Catalysis: Imaging And Therapy, Riddha Das

Doctoral Dissertations

Bioorthogonal catalysis offers a strategy for chemical transformations complementary to bioprocesses and has proven to be a powerful tool in biochemistry and medical sciences. Transition metal catalysts (TMCs) have emerged as a powerful tool to execute selective chemical transformations, however, lack of biocompatibility and stability limits their use in biological applications. Incorporation of TMCs into nanoparticle monolayers provides a versatile strategy for the generation of bioorthogonal nanocatalysts known as “nanozymes”. We have fabricated a family of nanozymes using gold nanoparticles (AuNPs) as scaffolds featuring diverse chemical functional groups for controlled localization of nanozymes in biological environments, providing unique strategies for …

Electrochemical Preparations And Applications Of Nano-Catalysts With High-Index Facets, Chi Xiao, Na Tian, Zhi-You Zhou, Shi-Gang Sun

Journal of Electrochemistry

The performance of catalysts highly depends on their surface structure and composition. Nanocrystals bounded by high-index facets usually exhibit high catalytic activity due to their high-density low-coordinated step atoms with high reactivity. In this paper, we have reviewed the preparations of noble metals (e.g., Pt, Pd and Rh) nanocatalysts with high-index facets by electrochemical square-wave potential method developed in our group. The square-wave potential method includes a nucleation procedure to generate nuclei, followed by a square-wave potential procedure for a certain period of time for the growth of nuclei into nanocrystals. The formation mechanism of high-index facets is also discussed. …

Nanoscale Colocalization Of Fluorogenic Probes Reveals The Role Of Oxygen Vacancies In The Photocatalytic Activity Of Tungsten Oxide Nanowires, Meikun Shen, Tianben Ding, Steven T. Hartman, Fudong Wang, Christina Krucylak, Zheyu Wang, Che Tan, Bo Yin, Rohan Mishra, Matthew D. Lew, Bryce Sadtler

Electrical & Systems Engineering Publications and Presentations

Defect engineering is a strategy that has been widely used to design active semiconductor photocatalysts. However, understanding the role of defects, such as oxygen vacancies, in controlling photocatalytic activity remains a challenge. Here, we report the use of chemically triggered fluorogenic probes to study the spatial distribution of active regions in individual tungsten oxide nanowires using super-resolution fluorescence microscopy. The nanowires show significant heterogeneity along their lengths for the photocatalytic generation of hydroxyl radicals. Through quantitative, coordinate-based colocalization of multiple probe molecules activated by the same nanowires, we demonstrate that the nanoscale regions most active for the photocatalytic generation of …

Nanostructured Metal Thin Films As Components Of Composite Membranes For Separations And Catalysis, Michael J. Detisch

Theses and Dissertations--Chemical and Materials Engineering

Novel metallic thin film composite membranes are synthesized and evaluated in this work for improved separations and catalysis capabilities. Advances in technology that allow for improved membrane performance in solvent separations are desirable for low molecular weight organic separation applications such as those in pharmaceutical industries. Additionally, the introduction of catalytic materials into membrane systems allow for optimization of complex processes in a single step. By adding a nanostructured metallic thin film to its surface, a polymer membrane may be modified to exhibit these improved properties. Using magnetron sputtering, thin metal films may be deposited on commercially available membranes to …

Transient Electrochemical Surface-Enhanced Raman Spectroscopic Study In Electrochemical Reduction Of P-Nitrothiophenol, Yun Ling, Jing Tang, Guo-Kun Liu, Cheng Zong

Journal of Electrochemistry

P-nitrothiophenol (PNTP) is one of the most common probe molecules studied by surface-enhanced Raman spectroscopy (SERS). The research in electrochemical reduction behavior of PNTP will help understanding the mechanism for the nitrobenzene reduction. In this paper, we used transient electrochemical surface-enhanced Raman spectroscopy (TEC-SERS) to study the SERS of PNTP with cyclic voltammetry and chronoamperometry on gold electrodes. The results show that the TEC-SERS provide a time resolution that equals the transient electrochemical methods, and we concluded that the reaction was so quick that we did not observe the spectral information of intermediate species described in the literatures with a …

Electrochemical Sensor Based On Magnetic Electrode Modified With Magnetic Molecularly Imprinted Nanoparticles Immobilized Hemoglobin For Determination Of Hydrogen Peroxide, Yang Yuan, Jia-Xin Wang, Yu-Hua Cao

Journal of Electrochemistry

In this work, the surface-imprinted technique was used to prepare magnetic hemoglobin (Hb) imprinted nanoparticles, using Fe₃O₄@SiO₂ NPs as the carrier, Hb as the template molecule, and tetraethyl orthosilicate (TEOS) as the imprinted polymer monomer. The nanoparticles had a core-shell structure, with magnetic Fe₃O₄ NPs as the core and Hb imprinted polymers as the shell. Therefore, Hb could be concentrated and fixed on the surface of the magnetic imprinted nanoparticles (MMIPs NPs). Furthermore, MMIPs NPs were immobilized with chitosan (CS) on the surface of a magnetic electrode to constitute Hb enzyme-like biosensor …

A Facile Route To Synthesize Pt-Wo3 Nanosheets With Enhanced Electrochemical Performance For Her, Peng-Jie Jiang, Yi Lv, Chang-Miao Chen, Hong-Cheng He, Yong Cai, Ming Zhang

Journal of Electrochemistry

Platinum-tungsten trioxide (Pt-WO₃) nanosheets were synthesized on nickel foams (NFs) directly. As great conductive networks, NFs substrates could greatly improve the electrode performance of WO₃. The modified platinum nanoparticles not only enhanced the electron transformation of catalysts, but also increased the active sites for hydrogen evolution reaction (HER). Pt-WO₃/NF revealed a better catalytic activity than WO₃/NFs with a smaller Tafel slope (80 mV·dec^-1) and a lower overpotential of 72 mV at the current density of 10 mA·cm^-2. In addition, Pt-WO₃/NF showed great durability and stability during …

Pd Nanoparticles Supported On The Etched Ni Foams As High-Performance Electrocatalysts For Direct Ethanol Fuel Cells, Chi Zhang, Cheng-Fei Li, Gao-Ren Li

Journal of Electrochemistry

The development of non-Pt anode electrocatalysts with high activity and long-term durability at low cost for fuel cells still remains enormous challenge. Here we report the Pd nanoparticles supported on Ni foams etched by the mixed acids (HNO₃+H₂SO₄+H₃PO₄+CH₃COOH) (Pd/ME-NF) that are designed and fabricated as high-performance electrocatalysts for ethanol oxidation in alkaline media. Because of the advantages of large open space, fast electrolyte penetration/diffusion and rapid electron transfer process, the Pd/ME-NF catalysts exhibited significantly improved electrocatalytic activity and durability compared with the commercial Pd/C catalysts.

Regulation Of Copper Surface Via Redox Reactions For Enhancing Carbon Dioxide Electroreduction, Bao-Hua Hang, Jin-Tao Zhang

Journal of Electrochemistry

A large-scale application of fossil fuels has led to excessive emission of carbon dioxide (CO₂), resulting in serious environmental issues. A promising path to reducing CO₂ emissions is recycling CO₂ into valuable chemicals and fuels through an electrochemical process. Herein, the redox reactions between copper (Cu) and ferric chloride (FeCl₃) have been utilized to regulate the Cu surface composition and structure, aimed to improve the electrocatalytic activity toward CO₂ reduction. Typically, a series of samples (named Cu-1h, Cu-2h, Cu-3h and Cu-4h) were prepared via the redox reactions for various time from 1 to …

Effect Of Morphology Of Fe-N Codoped Carbon Nanomaterial On Electrochemical Reduction Reactions, Er-Ling Li, Fa Yang, Ming-Bo Ruan, Ping Song, Wei-Lin Xu

Journal of Electrochemistry

Graphene nanosheets (GS) and carbon nanotubes have been considered as good catalysts candidates for applications in energy conversion and storage. However, hybrids of GS and carbon nanotubes are always formed in transition metal-based nitrogen-doped system, making the system quite complex for exploring the structure-activity relationship. To prepare the catalysts with desired species controllably, we try to adjust the outcomes with the effect of nitrogen on the growth of carbon nanotubes. In this work, a series of Fe-N co-doped carbon hybrid catalysts containing N-doped GS or hybrids of GS/bamboo carbon nanotubes (BCNTs) or BCNTs were obtained with one-step pyrolyzed method. To …

A Study Of Protein And Peptide-Directed Nanoparticle Synthesis For Catalytic Materials, Abdollah Mosleh

Graduate Theses and Dissertations

Nanoparticles have received much attentions due to their unique properties that makes them suitable candidates for a broad range of applications. As the size of particles decreases, their surface area-to-volume ratio would increase which is the main cause of much attention. In addition to the size, their morphologies and compositions may also play important roles for defining unique properties. Nanoparticle synthesis include both bottom-up and top-down strategies. To control the process of inorganic nanoparticles synthesis one could follow the bottom-up approach to have atom-level control over their compositions, morphologies, phases, and sizes which is the subject of this work. Due …

Electrocatalytic Nanomaterials For Reduction Of Hydrogen Peroxide As Potential Radioprotectors, Rui-Hong Jia, Jin-Xuan Zhang, Xiao-Dong Zhang, Mei-Xian Li

Journal of Electrochemistry

Nanomaterials have shown many potential application prospects in the biomedical field, such as medical imaging, drug delivery and biosensing due to their unique physical and chemical properties. In this review we focus on nanomaterials that have shown not only abilities of radiation protection, but also good electrocatalytic activities toward reduction reactions of hydrogen peroxide and oxygen. We discuss the abilities of radiation protection of these nanomaterials that are ascribed to their enzyme-like activities because their catalytic properties provide an effective pathway for scavenging free radicals in vivo via rapid reactions with reactive oxygen species. We also provide insights into electrocatalytic …

Development Of A Ws2 Catalyst For Hydrogen Evolution And Improvement Via Platinum Nanoparticle Decoration, Alexander O'Brien

Chemical Engineering Undergraduate Honors Theses

In response to a growing global need to improve utilization of green energy, the concept of renewable energy storage via electrolytic hydrogen production has gained popularity in recent years. However, the prohibitive expense of the bulk platinum catalysts currently used for the hydrogen evolution reaction prevents such a concept from being widely adoptable. This research focuses on a possible alternative catalyst, nanolayer WS₂, which is capable of promoting the hydrogen evolution reaction while maintaining economic viability. Bulk WS₂ was prepared in semiconducting, nanolayer form through liquid phase exfoliation. Prepared catalyst inks consisting of this material demonstrated successful …

Recent Developments In Surface/Interface Modulation And Structure-Performance Relationship Of Cathode Catalysts For Li-Air Batteries, Rui Gao, Jun-Kai Wang, Zhong-Bo Hu, Xiang-Feng Liu

Journal of Electrochemistry

Lithium-air battery has been considered to be one of the most promising secondary battery systems because of its high energy density. However, the sluggish kinetics of the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) on the cathode, and the high overpotential, poor cycle stability and low rate capacity have severely blocked the development and application of Li-air battery. One of the effective strategies to alleviate these issues is to develop cathode catalysts for Li-air batteries. The design and development of bifunctional cathode catalysts with high activity and efficiency on both ORR and OER is highly desired for Li-air …

The Pilot Application Of Electrochemical Impedance Spectroscopy On Dynamic Proton Exchange Membrane Fuel Cell, Jian-Wei Guo, Jian-Long Wang

Journal of Electrochemistry

By analyzing Electrochemical Impedance Spectroscopy (EIS) in applications of dynamic proton exchange membrane fuel cell (PEMFC), bottlenecks which restrict EIS tool development have been pointed out in this paper. Though the high-frequency resistance in EIS is largely accepted as cell inner-resistance, this can only be applied for cell with low current. The low-frequency resistance is difficult to be realized due to its relation with mass transfer. Furthermore, the improved Randles equivalent circuits are built up preliminarily, thus, penetrating into studies for mass transfer reaction, cell operation/degeneration, and high temperature fuel cell. Inspiringly, EIS is becoming an analyzing tool for stack …

Fe-N Doped Hollow Carbon Nanospheres Linked By Carbon Nanotubes For Oxygen Reduction Reaction, Ya-Lin Zhang, Chi Chen, Liang-Liang Zou, Zhi-Qing Zou, Hui Yang

Journal of Electrochemistry

The development of non-precious metal catalysts for oxygen reduction reaction (ORR) is essential for large-scale application of proton exchange membrane fuel cells. Herein, we present the in situ formed Fe-N doped hollow carbon nanospheres linked by carbon nanotubes composite, synthesized by using ZIF-8 as sacrificed template to form polydopamine (PDA) hollow nanospheres, followed by complexing with FeCl₃, high temperature heat-treatment and NH₃-etching. ZIF-8 was gradually decomposed simultaneously with PDA coating due to the loss of Zn²⁺ grabbed by PDA. NH3 etching resulted in the improved surface area, while the reducibility of NH₃ resulted in …

Facile Synthesis Of Pt-Cu Alloy Nanodendrites As High-Performance Electrocatalysts For Oxygen Reduction Reaction, Liu-Xuan Luo, Guang-Hua Wei, Shui-Yun Shen, Feng-Juan Zhu, Chang-Chun Ke, Xiao-Hui Yan, Jun-Liang Zhang

Journal of Electrochemistry

Structures and compositions have significant effects on the catalytic properties of nanomaterials. Herein, a facile etching-based method was employed to synthesize Pt-Cu nanodendrites (NDs) with uniform and homogeneous alloy structures for enhancing oxygen reduction reaction (ORR). The formation of dendritic morphology was ascribed to the etching effect caused by the oxidative etchants of the Br^-/O₂ pair. The atomic ratio of Pt/Cu in Pt-Cu NDs could be easily tuned by altering the ratio of the Pt/Cu precursors, without deteriorating the dendritic morphology. The most active carbon-supported Pt₁Cu₁ NDs (Pt₁Cu₁ NDs/C) exhibited the …