Physical Sciences and Mathematics Commons^™

Fuel Cells Reactor For Chemicals And Electric Energy Cogeneration, Zhi-Lin Heng, Xiao-Zi Yuan, Yi-Mei Yin, Zi-Feng Ma

Journal of Electrochemistry

As an energy conversion device, fuel cells can efficiently convert chemical energy into electrical energy. With the developing of technology, it is used as a reactor to conduct the synthesis of high value-added chemicals while generating electrical energy. Having benefits such as mild reaction conditions, controllability of the reaction process, high selectivity of the product, as well as high efficiency of energy utilization, it is widely used in many fields such as preparation of high value-added industrial products, gas separation, water treatment, etc. This paper introduces the current trends and statuses of fuel cell reactors in the cogeneration of chemicals …

Fuel Cell Performance Curve After Mea Optimization Structural Optimization Of Low Pt Membrane Electrode Assembly, Yan Rao, Shang Li, Fen Zhou, Tian Tian, Qing Zhong, Zhao-Hui Wan, Jin-Ting Tan, Mu Pan

Journal of Electrochemistry

Membrane electrode assemblies (MEAs) are the key component of proton exchange membrane fuel cell. For a long time, much attention has been paid to develop MEA technology. At present, the research, development and industrialization of fuel cell has entered a new era. More strict requirements for MEA, especially for the reduction of Pt loading with a challenging target of 0.125 mg·W^-1 have to be met. In this paper, the performance losses under low Pt loading are analyzed in terms of activation polarization, ohm polarization and mass-transfer polarization. It is proposed that research should be focused on the activity of …

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 …

Morphological Control Of Ptcu2 Octahedron And Oxygen Reduction Electrocatalytic Performance Of Ptcu For Fuel Cell, Long-Sheng Cao, Lei Wan, Zhi-Gang Shao, Hong-Mei Yu, Ming Hou, Bao-Lian Yi

Journal of Electrochemistry

Platinum acetylacetonate (Pt(acac)₂) and copper acetylacetonate (Cu(acac)₂) were co-reduced to prepare PtCu₂ octahedron alloy catalyst in N,N-dimethylformamiade by solvothermal method. The PtCu₂ showed lattice compression, and high ratio of non-oxidized Pt with high electronic binding energy. All those structural features contributed to weak adsorption strength of oxygen species on Pt and lower d-band centre position. The influence of structure-directing agent on morphology of PtCu alloy was systematically studied. In the half cell test, as a result of the uniform morphology and regular octahedron of PtCu₂ formed, the mass activity and area specific activity …

Effects Of So2 In Air On Performance Of Direct Methanol Fuel Cell, Bin Qin, Fen-Ning Jing, Xue-Jing Sun, Gong-Quan Sun, Hai Sun

Journal of Electrochemistry

Direct methanol fuel cells (DMFC) generally use oxygen as an oxidant. Contaminants such as sulfides and nitrides in the air can affect the performance of the DMFC. In this work, the effects of SO₂ on the performance of DMFC were investigated and the mechanism of poisoning was analyzed, by means of constant current discharge curve, polarization performance curve, cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS). In the CV scan, the permeated methanol was oxidized at a low potential to eliminate its effect on the SO₂ poisoning behavior test. The results showed that the SO₂ poisoning resulted …

Acid Treated Carbon As Anodic Electrocatalysts Toward Direct Ascorbic Acid Alkaline Membrane Fuel Cells, He-Mu Chen, Chen-Xi Qiu, Yuan-Yuan Cong, Hui-Yuan Liu, Zi-Hui Zhai, Yu-Jiang Song

Journal of Electrochemistry

In order to improve the hydrophilicity and electrocatalytic activity, commercial carbon black (BP 2000) was subjected to acid treatment to obtain acid-treated carbon (ATC). The generation of rich oxygen-containing groups on the surface of the ATC was proved by X-ray photoelectron spectra (XPS), Fourier transform-infra red spectra (FTIR), thermogravimetric analysis (TG) and contact angle measurement. UV-vis spectra were firstly recorded to calculate activation energy (Ea) of ascorbic acid (AA) chemical oxidation in alkaline conditions by oxygen in air and the Ea value was determined to be 37.1 kJ·mol^-1. Additionally, electrochemical impedance spectra (EIS) were used to evaluate unprecedented …

Pd/C Catalysts For Co2 Electroreduction To Co:Pd Loading Effect, Dun-Feng Gao, Cheng-Cheng Yan, Guo-Xiong Wang, Xin-He Bao

Journal of Electrochemistry

Nanostructured heterogeneous catalysts have been widely used in the electrochemical carbon dioxide (CO₂) reduction reaction (CO₂RR), which can simultaneously achieve the electrocatalytic conversion of CO₂ to fuels and the storage of renewable energy sources. Carbon supported palladium nanoparticles (Pd/C) catalysts have been previously reported to show excellent CO₂RR performance. However, the crucial role of the metal loading in supported electrocatalysts has been rarely reported. In this work, we study the Pd loading effect on the structure of Pd/C catalysts as well as their activity and selectivity of CO₂RR to CO. The …

Voltage Distribution Of Self-Humidifying Air-Cooled Pemfc, Kai-Feng Tan, Wei-Rong Chen, Ming Han, Xue-Xia Zhang

Journal of Electrochemistry

In this work, the self-adaptive characteristics of self-humidifying air-cooled PEMFC stack was investigated. The performance and the unit-cell voltage distribution of the stack were measured and analyzed through the unit-cell I-V curve fitting. The operating conditions for this experimental study were set as follows: hydrogen pressure at the anode was 2 bar, the fan power used for the reactant oxygen feed and stack cooling was at 0.3 W, and the duration and time gap of water purged from hydrogen chamber were 1 s and 10 s, respectively. The experimental results showed that the self-humidifying air-cooled PEMFC stack used for this …

Durability Performance Of The High-Power Fuel Cell System, Ke-Yong Wang, Wei-Yu Shi, Ren-Fang Wang, Jia Liu, Zhong-Jun Hou

Journal of Electrochemistry

Fuel cell durability is the crucial challenge in fuel cell vehicle, and the lifetime of more than 5000 hours is believed to be necessary for vehicle application. Few works on durability test of the full fuel cell system have been reported. In this work, the long lifetime HySYS-30 fuel cell system was developed in Sunrise Power based on the improved MEA durability and system control strategy. The durability performance of the system was investigated under vehicle duty cycle for more than 6000 hours, and only 8.1% performance loss was observed, implying that the durability of HySYS-30 fuel cell system could …

Caging Porous Co-N-C Nanocomposites In 3d Graphene As Active And Aggregation-Resistant Electrocatalyst For Oxygen Reduction Reaction, Lu-Yang Xiu, Meng-Zhou Yu, Peng-Ju Yang, Zhi-Yu Wang, Jie-Shan Qiu

Journal of Electrochemistry

Oxygen reduction reaction (ORR) is the cornerstone reaction of many renewable energy technologies such as fuel cells and rechargeable metal-air batteries. The Pt-based electrocatalysts exhibit the highest activity toward ORR, but their large implementation is greatly prohibiting by unaffordable cost and inferior durability. During electrode manufacturing and electrochemical reaction, severe aggregation of catalyst nanoparticles induced by size effect further limits the operational performance of electrocatalysts. We report a new strategy for fabrication of active and aggregation-resistant ORR electrocatalyst by caging metal-organic frameworks derived Co-N-C nanocomposites in permeable and porous 3D graphene cages via sprayed drying the mixed colloids of ZIF-67 …

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 …

Progress Of Self-Humidifying Membrane Electrode Assembly For Low Temperature Proton Exchange Membrane Fuel Cell, Bin Chi, Yue-Kun Ye, Shi-Jie Jiang, Shi-Jun Liao

Journal of Electrochemistry

The self/non-humidification membrane electrode assembly（SH-MEA）is an important pathway towards the self- humidification fuel cell and plays a crucial role for the large scale commercialization of low temperature proton exchange membrane fuel cell (LT-PEMFC), because it not only can reduce the volume and complexity of fuel cell system, resulting in the decrease of the cost, but also can improve the output power density of the fuel cell system. Currently, the researches on the self-humidifying MEA of LT-PEMFC mainly focus on three aspects: the preparation of self-humidification proton exchange membrane, the construction of self-humidification catalyst layer, and the construction of composite self-humidifying …

A Review Of Proton Exchange Membrane Fuel Cell Catalyst Layer By Electrospinning, Yong Liu, Han Ding, De-Chun Si, Jie Peng, Jian-Bo Zhang

Journal of Electrochemistry

The limitation of catalyst layer for proton exchange membrane fuel cell (PEMFC) in cost, durability and performance constitutes the bottleneck for the commercialization of fuel cell vehicles. Electrospun catalyst layer, with high catalyst utilization, increased triple phase boundary (TPB) and triple phase channel (TPC), has been developed by many researchers. This paper reviews the research progress in the electrospun catalyst layer for PEMFC, combined with the author’s work. Firstly, the development progress of catalyst layer is summarized, and the catalyst layer is classified and analyzed based on its fabrication method and structure character. Next, the fabrication process, physical property characterization, …

Palladium Adatoms On Gold Nanoparticles As Electrocatalysts For Ethanol Electro-Oxidation In Alkaline Solutions, Hui-Mei Chen, Shang-Qian Zhu, Jia-Le Huang, Min-Hua Shao

Journal of Electrochemistry

Palladium (Pd) is a good catalyst for ethanol electro-oxidation in alkaline solutions. The activity of Pd is further improved in this study by modifying the gold (Au) nanoparticles with Pd adatoms using a simple spontaneous deposition process. The Pd overlayer on the Au core (Au@Pd) is un-uniform with some Au atoms exposed to the electrolyte. The activity of Au@Pd/C toward ethanol oxidation reaction (EOR) is much higher than that of Pd/C in an alkaline solution. The peak current density of Au@Pd/C is 4.6 times higher than that of Pd/C with a 100 mV lower onset potential. The enhanced activity may …

Stabilization Strategies Of Pt Catalysts Forproton Exchange Membrane Fuel Cells, Da-Ping He, Shi-Chun Mu

Journal of Electrochemistry

The low service lifetime of proton exchange membrane fuel cells (PEMFCs) is the main bottleneck for their commercial applications. One of the main factors is that the expensive metal Pt catalyst is easy to degradation under the harsh working environment of PEMFC (such as variable voltage, strong acidity, gas-liquid two-phase flow), which leads to the inevitable decay of the catalytic performance, thus, seriously restricting the lifetime of PEMFC. Therefore, the electrochemical stability of Pt-based electrocatalysts has become an important and hot topic to improve the PEMFC lifetime. In this paper, we review the recent development in enhancing the stability of …

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 …

2018 Fall Engr333 Project Final Report (Section B), Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten

ENGR 333

What is the largest possible reduction in Calvin College’s annual energy costs from a $5M initial investment in renewable energy? Renewable energy systems are essential for Calvin College to reduce greenhouse gas emissions and achieve carbon neutrality to meet the Carbon Commitment that President Le Roy signed in December 2017. Also, a significant cost reduction could be a positive result of transitioning to renewable energy sources such as geothermal, wind, solar, and biomass. Four renewable energy sources were studied throughout the semester to determine a feasible renewable energy plan for Calvin with a $5M investment.

2018 Fall Engr333 Project Final Report (Section A), 2018 Fall Engr333 Section A

ENGR 333

Calvin College currently spends 2.35 million dollars on energy every year. Physical Plant is under pressure to reduce the amount of energy that Calvin purchases from the electrical grid since the college is facing many budget constraints. In addition, President Le Roy signed the President’s Carbon Commitment to achieve carbon neutrality by 2057. With this need to save money on energy and reduce the college’s carbon footprint, the objective of this project was to determine the largest possible reduction in Calvin’s annual energy costs given a five-million-dollar investment in renewable energy.

Optimal Placement Of Distributed Energy Storage Systems In Distribution Networks Using Artificial Bee Colony Algorithm, Choton K. Das, Octavian Bass, Ganesh Kothapalli, Thair S. Mahmoud, Daryoush Habibi

Research outputs 2014 to 2021

The deployment of utility-scale energy storage systems (ESSs) can be a significant avenue for improving the performance of distribution networks. An optimally placed ESS can reduce power losses and line loading, mitigate peak network demand, improve voltage profile, and in some cases contribute to the network fault level diagnosis. This paper proposes a strategy for optimal placement of distributed ESSs in distribution networks to minimize voltage deviation, line loading, and power losses. The optimal placement of distributed ESSs is investigated in a medium voltage IEEE-33 bus distribution system, which is influenced by a high penetration of renewable (solar and wind) …

Nanopower Analog Frontends For Cyber-Physical Systems, Kenji Aono

McKelvey School of Engineering Theses & Dissertations

In a world that is increasingly dominated by advances made in digital systems, this work will explore the exploiting of naturally occurring physical phenomena to pave the way towards a self-powered sensor for Cyber-Physical Systems (CPS). In general, a sensor frontend can be broken up into a handful of basic stages: transduction, filtering, energy conversion, measurement, and interfacing. One analog artifact that was investigated for filtering was the physical phenomenon of hysteresis induced in current-mode biquads driven near or at their saturation limit. Known as jump resonance, this analog construct facilitates a higher quality factor to be brought about without …

Design, Layout, And Testing Of Sige Apds Fabricated In A Bicmos Process, Dane Laurence Gentry

UNLV Theses, Dissertations, Professional Papers, and Capstones

This Thesis is concerned with the design, layout, and testing of avalanche photodiodes (APDs). APDs are a type of photodetector and, thus, convert light signals into electrical signals (current or voltage). APDs can be fabricated using silicon (Si). In this Thesis, however, three integrated circuit (IC) chips containing various silicon-germanium (SiGe) APDs with different sizes, structures, and geometries were designed, laid out, and fabricated using the Austriamicrosystems (AMS) 0.35μm SiGe BiCMOS (S35) process. This was done in order to compare SiGe APDs to Si only APDs and investigate the hypothesis that SiGe APDs are capable of detecting longer wavelengths than …

Optical Micro-Seismometer Based On Evanescent Field Perturbation Of Whispering Gallery Modes, Jaime Da Silva

Mechanical Engineering Research Theses and Dissertations

This thesis proposes a light-weight, compact, and accurate optical micro-seismometer that could be used in many applications, such as planetary exploration. The sensor proposed here is based on the principle of whispering gallery optical mode (WGM) resonance shifts of a dielectric micro-resonator due to disturbances of its evanescent field. The micro-seismometer could be used in place of the traditional bulky seismometers. The design of a waveguide-resonator and mechanical structure to disturb the evanescent field are presented. A proof-of-concept a seismometer model that uses a 5µm ring resonator is numerically tested with actual seismic data. The results show that a WGM-based …

College Of Engineering Senior Design Competition Fall 2018, University Of Nevada, Las Vegas

Fred and Harriet Cox Senior Design Competition Projects

Part of every UNLV engineering student’s academic experience, the senior design project stimulates engineering innovation and entrepreneurship. Each student in their senior year chooses, plans, designs, and prototypes a product in this required element of the curriculum. A capstone to the student’s educational career, the senior design project encourages the student to use everything learned in the engineering program to create a practical, real world solution to an engineering challenge. The senior design competition helps focus the senior students in increasing the quality and potential for commercial application for their design projects. Judges from local industry evaluate the projects on …

2018 Fall Engr333 Poster, Alexander Cooper, Katie Diekema, Grace Fasipe, Daniella Sugijanto, Alec Dejonge, Timothy Dykhuis, Breanna Kooiman, Samuel Olson, Brennan Boice, Tyler Gustman, Daniel Norton, Christopher Vanwhye, Robert Capozzoli, Jared Minderhoud, Clark Richeson, Nathan Schuyten, 2018 Fall Engr333 Section A

ENGR 333

• $158k initial investment in Geothermal systems for various Calvin-owned residential buildings
• $3.34M initial investment in solar panels for Calvin’s rooftops
• The overall savings would be $233,850 per year
• Emissions would be reduced by 864 tons of CO2 emissions per year
• The recommended investment would be fully paid back in 11-15 years

2018 Fall Engr333 Seminar Presentation, Rachel Evans, Alex Gross, Daniella Sugijanto, Jake Shaarda

ENGR 333

File for student presentation, given by students in the Fall 2018 class of ENGR333.

Facepet: Enhancing Bystanders' Facial Privacy With Smart Wearables/Internet Of Things, Alfredo J. Perez, Sherali Zeadally, Luis Y. Matos Garcia, Jaouad A. Mouloud, Scott Griffith

Information Science Faculty Publications

Given the availability of cameras in mobile phones, drones and Internet-connected devices, facial privacy has become an area of major interest in the last few years, especially when photos are captured and can be used to identify bystanders’ faces who may have not given consent for these photos to be taken and be identified. Some solutions to protect facial privacy in photos currently exist. However, many of these solutions do not give a choice to bystanders because they rely on algorithms that de-identify photos or protocols to deactivate devices and systems not controlled by bystanders, thereby being dependent on the …

Eye Pressure Monitior, Andrea Nella Levy

Computer Engineering

The document describes a mobile application that takes information from an attached device which tests eye pressure. The device consists of an IOIO board connected to a custom device that measures the frequency of a given waveform. The device was designed by another student for their senior project, which I am taking over. This device is connected to an IOIO board which is a board designed by a Google employee which works with an android phone in order to create applications that work with embedded systems. The board comes with an API and connects to the phone via a micro-USB. …

Automatic Performance Optimization On Heterogeneous Computer Systems Using Manycore Coprocessors, Chenggang Lai

Graduate Theses and Dissertations

Emerging computer architectures and advanced computing technologies, such as Intel’s Many Integrated Core (MIC) Architecture and graphics processing units (GPU), provide a promising solution to employ parallelism for achieving high performance, scalability and low power consumption. As a result, accelerators have become a crucial part in developing supercomputers. Accelerators usually equip with different types of cores and memory. It will compel application developers to reach challenging performance goals. The added complexity has led to the development of task-based runtime systems, which allow complex computations to be expressed as task graphs, and rely on scheduling algorithms to perform load balancing between …

Optimizing The Plasmonic Enhancement Of Light In Metallic Nanogap Structures For Surface-Enhanced Raman Spectroscopy, Stephen Joseph Bauman

Graduate Theses and Dissertations

Technology based on the interaction between light and matter has entered something of a renaissance over the past few decades due to improved control over the creation of nanoscale patterns. Tunable nanofabrication has benefitted optical sensing, by which light is used to detect the presence or quantity of various substances. Through methods such as Raman spectroscopy, the optical spectra of solid, liquid, or gaseous samples act as fingerprints which help identify a single type of molecule amongst a background of potentially many other chemicals. This technique therefore offers great benefit to applications such as biomedical sensors, airport security, industrial waste …

Exfoliation, Synthesis, And Characterization Of Nanoscale Te, Takayuki Hironaka

Graduate Theses and Dissertations

Since the experimental discovery of graphene, two dimensional materials have enjoyed more attention and emphasis in academic research than nanowires, but the latter are an important area of study for creating 1D materials, or single atom chains, the next generation materials for advancing electronic devices. Atomically thin layers can be generated from 2D materials with weak bonds in one direction, and by applying this concept to one dimensional weakly bonded materials, we hypothesize that single atom chains with atomic-scale diameters may be produced. Tellurium (Te) and selenium (Se) have lattices consisting of spiral chains oriented along the c-axis, and each …