Showing papers by "Ho Won Jang published in 2020"
TL;DR: In this paper, the synthesis methods of GQDs and CQDs have been summarized and their characterization methods also been analyzed, and issues and challenges of the carbon-based QDs were analyzed for their further development.
Abstract: Neuro-transmitters have been considered to be essential biochemical molecules, which monitor physiological and behavioral function in the peripheral and central nervous systems. Thus, it is of high pharmaceutical and biological significance to analyze neuro-transmitters in the biological samples. So far, researchers have devised a lot of techniques for assaying these samples. It has been found that electro-chemical sensors possess features of robustness, selectivity, and sensitivity as well as real-time measurement. Graphene quantum dots (GQDs) and carbon QDs (CQDs) are considered some of the most promising carbon-based nanomaterials at the forefront of this research area. This is due to their characteristics including lower toxicity, higher solubility in various solvents, great electronic features, strong chemical inertness, high specific surface areas, plenty of edge sites for functionalization, and versatility, in addition to their ability to be modified via absorbent surface chemicals and the addition of modifiers or nano-materials. Hence in the present review, the synthesis methods of GQDs and CQDs has been summarized and their characterization methods also been analyzed. The applications of carbon-based QDs (GQDs and CQDs) in biological and sensing areas, such as biological imaging, drug/gene delivery, antibacterial and antioxidant activity, photoluminescence sensors, electrochemiluminescence sensors and electrochemical sensors, have also been discussed. This study then covers sensing features of key neurotransmitters, including dopamine, tyrosine, epinephrine, norepinephrine, serotonin and acetylcholine. Hence, issues and challenges of the GQDs and CQDs were analyzed for their further development.
267 citations
21 Feb 2020
TL;DR: Palladium has been the key element for several C-C bond-forming reactions, especially the Nobel-acclaimed Suzuki, Heck, and Sonogashira cross-coupling reactions, among others.
Abstract: Palladium (Pd) has been the key element for several C–C bond-forming reactions, especially the Nobel-acclaimed Suzuki, Heck, and Sonogashira cross-coupling reactions, among others. This review arti...
176 citations
28 Jan 2020
TL;DR: The favorable design of FC-based biosensors and general sensors needs adequate control of their chemical and physical characteristics in addition to their surface immobilization and functionalization.
Abstract: This study is on current developments concerning ferrocene (FC) and its derivatives on the basis of electrochemical biosensors and sensors. The distinct physiochemical characteristics of FC have enabled the development of new sensor devices, specifically electrochemical sensors. Several articles have focused on the implementation of FC as an electrode constituent while discussing its electrochemical behavior. Furthermore, typical FC-design-based biosensors and sensors are considered as well as practical examples. The favorable design of FC-based biosensors and general sensors needs adequate control of their chemical and physical characteristics in addition to their surface immobilization and functionalization.
109 citations
TL;DR: In this paper, a review article explores typical recent applications of conductive polymers (2016-2020) as active electrode materials for energy storage applications, electrochemical sensing, and conversion fields such as electrochemical supercapacitors, lithium-ion batteries, fuel cells, and solar cells.
Abstract: Scientists have categorized conductive polymers as materials having strongly reversible redox behavior and uncommon combined features of plastics and metal. Because of their multifunctional characteristics, e.g., simplistic synthesis, acceptable environmental stability, beneficial optical, electronic, and mechanical features, researchers have largely considered them for diverse applications. Therefore, their capability of catalyzing several electrode reactions has been introduced as one of their significant features. A thin layer of the conducting polymer deposited on the substrate electrode surface can augment the electrode process kinetics of several solution species. Such electrocatalytic procedures with modified conducting polymer electrodes can create beneficial utilization in diverse fields of applied electrochemistry. This review article explores typical recent applications of conductive polymers (2016–2020) as active electrode materials for energy storage applications, electrochemical sensing, and conversion fields such as electrochemical supercapacitors, lithium-ion batteries, fuel cells, and solar cells.
107 citations
TL;DR: In this paper, a general approach for the photoreduction of CO2 to mimic natural photosynthesis, in which the H2 source is provided directly during the photocatalytic water splitting, is proposed and verified to generate value-added organic products successfully.
106 citations
TL;DR: This review has summarized COFs employed for electrochemical applications, such as batteries and capacitors, water splitting, solar cells, and sensors, with an emphasis on the structural design and resulting performance of the targeted electrochemical system.
Abstract: Covalent organic frameworks (COFs), materials constructed from organic building blocks joined by robust covalent bonds, have emerged as attractive materials in the context of electrochemical applications because of their high, intrinsic porosities and crystalline frameworks, as well as their ability to be tuned across two- and three-dimensions by the judicious selection of building blocks. Because of the recent and rapid development of this field, we have summarized COFs employed for electrochemical applications, such as batteries and capacitors, water splitting, solar cells, and sensors, with an emphasis on the structural design and resulting performance of the targeted electrochemical system. Overall, we anticipate this review will stimulate the design and synthesis of the next generation of COFs for use in electrochemical applications and beyond.
103 citations
TL;DR: In this paper, metal-organic frameworks (MOFs), a versatile class of porous materials that exhibit high specific surface areas, controllable structures, and tunable pores, have been identified as a promising plat.
Abstract: Metal–organic frameworks (MOFs), a versatile class of porous materials that exhibit high specific surface areas, controllable structures, and tunable pores, have been identified as a promising plat
100 citations
13 Apr 2020
TL;DR: The incorporation of renewable and sustainable energy sources in electric grids has been acknowledged as a potential strategy to solve the evergrowing environmental issues that result from the use of renewable energy sources as mentioned in this paper.
Abstract: The incorporation of renewable and sustainable energy sources in electric grids has been acknowledged as a potential strategy to solve the ever-growing environmental issues that result from the use...
70 citations
09 Mar 2020
TL;DR: The proposed nanocatalyst and co-catalyst 2,2,6,6-tetramethylpiperidine-N-oxyl substantially enhance the catalytic performance for the aerobic oxidation under very mild and sustainable reaction conditions.
Abstract: Fabrication of a nanocomposite catalyst via a novel and efficient strategy remains a challenge; Fe3O4 nanoparticles anchored on graphene oxide (GO) sheet-supported metal-organic frameworks (MOFs). ...
61 citations
TL;DR: In this article, a review summarizes the progress that has been made in the past ten years in the field of electrochemical sensing using nanomaterial-based carbon paste electrodes, and summarizes the status, addresses future challenges, and gives an outlook on potential trends.
Abstract: This review summarizes the progress that has been made in the past ten years in the field of electrochemical sensing using nanomaterial-based carbon paste electrodes. Following an introduction into the field, a first large section covers sensors for biological species and pharmaceutical compounds (with subsections on sensors for antioxidants, catecholamines and amino acids). The next section covers sensors for environmental pollutants (with subsections on sensors for pesticides and heavy metal ions). Several tables are presented that give an overview on the wealth of methods (differential pulse voltammetry, square wave voltammetry, amperometry, etc.) and different nanomaterials available. A concluding section summarizes the status, addresses future challenges, and gives an outlook on potential trends.
58 citations
TL;DR: In this article, a facile method for the fabrication of WS2 hollow spheres and used the spheres as efficient catalysts for hydrogen evolution reaction was introduced and compared with WS2 nanoflowers.
01 Nov 2020
TL;DR: Four types of memristive devices, namely, resistive switching, phase‐change, spintronics, and ferroelectric tunnel junction memristors, are explored and the application of these devices to a crossbar array (CBA), which is a novel concept of integrated architecture, is a step toward the realization of ultradense electronics.
Abstract: In complementary metal–oxide–semiconductor (CMOS)‐based von Neumann architectures, the intrinsic power and speed inefficiencies are worsened by the drastic increase in information with big data. With the potential to store numerous values in I–V pinched hysteresis, memristors (memory resistors) have emerged as alternatives to existing CMOS‐based computing systems. Herein, four types of memristive devices, namely, resistive switching, phase‐change, spintronics, and ferroelectric tunnel junction memristors, are explored. The application of these devices to a crossbar array (CBA), which is a novel concept of integrated architecture, is a step toward the realization of ultradense electronics. Exploiting the fascinating capabilities of memristive devices, computing systems can be developed with novel computing paradigms, in which large amounts of data can be stored and processed within CBAs. Looking further ahead, the ways in which memristors could be incorporated in neuromorphic computing systems along with various artificial intelligence algorithms are established. Finally, perspectives and challenges that memristor technology should address to provide excellent alternatives to existing computing systems are discussed. The infinite potential of memristors is the key to unlock new computing paradigms, which pave the way for next‐generation computing systems.
TL;DR: The oxygen evolution reaction (OER) of LaNiO3 (LNO) is reported by changing the NiO6 structure using compositional change and strain to increase the Ni-O-Ni bond angle and an expansion of bandwidth, enhancing the charge transfer ability.
Abstract: As the BO6 octahedral structure in perovskite oxide is strongly linked with electronic behavior, it is actively studied for various fields such as metal–insulator transition, superconductivity, and...
TL;DR: In this article, the authors compared the resistive switching characteristics of ReRAM devices based on a quasi-two-dimensional (2D) halide perovskite, (PEA)2Cs3Pb4I13, to those based on 3D CsPbI3.
Abstract: Resistive random-access memory (ReRAM) devices based on halide perovskites have recently emerged as a new class of data storage devices, where the switching materials used in these devices have attracted extensive attention in recent years. Thus far, three-dimensional (3D) halide perovskites have been the most investigated materials for resistive switching memory devices. However, 3D-based memory devices display ON/OFF ratios comparable to those of oxide or chalcogenide ReRAM devices. In addition, perovskite materials are susceptible to exposure to air. Herein, we compare the resistive switching characteristics of ReRAM devices based on a quasi-two-dimensional (2D) halide perovskite, (PEA)2Cs3Pb4I13, to those based on 3D CsPbI3. Astonishingly, the ON/OFF ratio of the (PEA)2Cs3Pb4I13-based memory devices (109) is three orders of magnitude higher than that of the CsPbI3 device, which is attributed to a decrease in the high-resistance state (HRS) current of the former. This device also retained a high ON/OFF current ratio for 2 weeks under ambient conditions, whereas the CsPbI3 device degraded rapidly and showed unreliable memory properties after 5 days. These results strongly suggest that quasi-2D halide perovskites have potential in resistive switching memory based on their desirable ON/OFF ratio and long-term stability. A type of computer memory that stores data by changing the resistance of insulating crystals can be made more durable with organic chemical additives. Resistive memory devices constructed from inorganic crystals known as halide perovskites are inexpensive and have minimal power requirements. However, they can degrade quickly in humid conditions. Hyojung Kim from Seoul National University in South Korea and colleagues now report that these stability issues can be improved by sandwiching thin layers of aromatic hydrocarbons between halide perovskite crystals. The water-repelling nature of the organic molecules helps double the lifespan of the new hybrid compared to an unmodified halide perovskite device. In addition, the organic layers augment the differences between ‘ON’ and ‘OFF’ resistive memory states, making device operation more reliable. ReRAM devices based on halide perovskites have recently emerged as a new class of data storage device, where the switching materials used in these devices have attracted huge attention in recent years. In this study, we compare the resistive switching characteristics of ReRAM devices based on a quasi-2D halide perovskite, (PEA)2Cs3Pb4I13, to those based on 3D CsPbI3. Astonishingly, the ON/OFF ratio of the (PEA)2Cs3Pb4I13-based memory devices was much higher than that of the CsPbI3 device. Also this device retained a high ON/OFF current ratio for two weeks under ambient conditions, whereas the CsPbI3 device degraded rapidly and showed unreliable memory properties after five days. We strongly believe that quasi-2D halide perovskites have potential in resistive switching memory based on their high ON/OFF ratio and long-term stability.
05 Mar 2020
TL;DR: The use of noble-free materials to convert atmospheric CO2 into energy-rich fuels has gained a significant amount of attention in an effort toward decreasing global warming due to high concentrations of CO2 as mentioned in this paper.
Abstract: The use of noble-free materials to convert atmospheric CO2 into energy-rich fuels has gained a significant amount of attention in an effort toward decreasing global warming due to high concentrations of CO2. Metallic catalysts, two-dimensional materials (such as graphene and graphene based), metal oxides, and metal-organic frameworks have been used as catalysts in the CO2 reduction reaction and recently recognized as promising platforms due to their excellent electrical and thermal conductivity, outstanding mechanical properties, and good chemical stability. This review summarizes the progress made related to the electrochemical and photoelectrochemical CO2 reduction reaction over the past few decades. In addition, the fundamentals and principles that govern both electrocatalytic and photocatalytic CO2 reduction are discussed. Then, a detailed discussion of the different electrocatalysts, photocatalysts, and strategies used to improve the performance is provided.
27 Jul 2020
TL;DR: In this article, nonaqueous rechargeable rechargeable aluminum batteries (RABs) have emerged as a promising class of battery materials and been intensively used in the last few decades.
Abstract: Owing to their high theoretical capacity and reliable operational safety, nonaqueous rechargeable aluminum batteries (RABs) have emerged as a promising class of battery materials and been intensive...
TL;DR: The calculated thermally-assisted ion-hopping activation energy and the results of the time-of-flight secondary ion mass spectroscopy demonstrated that the 2D perovskite layer could efficiently prevent the Ag ion migration into the 3D perOVskite film and control the rupture of the Ag conductive filament.
Abstract: Hybrid organic-inorganic halide perovskites (HPs) have garnered significant attention for use in resistive switching (RS) memory devices due to their low cost, low operation voltage, high on/off ratio, and excellent mechanical properties. However, the HP-based RS memory devices continue to face several challenges owing to the short endurance and stability of the HP film. Herein, two-dimensional/three-dimensional (2D/3D) perovskite heterojunction films were prepared via a low-temperature all-solution process and their RS behavior was investigated for the first time. The 2D/3D perovskite RS devices exhibited excellent performance with an endurance of 2700 cycles, a high on/off ratio of 106, and an operation speed of 640 μs. The calculated thermally assisted ion hopping activation energy and the results of the time-of-flight secondary ion mass spectroscopy demonstrated that the 2D perovskite layer could efficiently prevent the Ag ion migration into the 3D perovskite film. Moreover, we found that owing to its high thermal conductivity, the 2D perovskite can control the rupture of the Ag conductive filament. Thus, the 2D perovskite layer enhances endurance by controlling both Ag migration and filament rupture. Hence, this study provides an alternate strategy for improving endurance of HP-based RS memory devices.
Kerman Medical University1, Graduate University of Advanced Technology2, Payame Noor University3, Shahid Sadoughi University of Medical Sciences and Health Services4, Seoul National University5, Duy Tan University6, National Institute for Materials Science7, University of Queensland8, Kyung Hee University9
TL;DR: In this paper, a critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used hydrazine in water resources with desirable recovery is presented.
Abstract: The detection of hydrazine (HZ) is an important application in analytical chemistry There have been recent advancements in using electrochemical detection for HZ Electrochemical detection for HZ offers many advantages, eg, high sensitivity, selectivity, speed, low investment and running cost, and low laboriousness In addition, these methods are robust, reproducible, user-friendly, and compatible with the concept of green analytical chemistry This review is devoted to the critical comparison of electrochemical sensors and measuring protocols used for the voltammetric and amperometric detection of the most frequently used HZ in water resources with desirable recovery Attention is focused on the working electrode and its possible modification which is crucial for further development
TL;DR: In this paper, a facile hydrothermal method was used to synthesize transition metal carbide/chalcogenide composites for the hydrogen evolution reaction (HER) without using any complex structure of carbon or polymer source for carbonization.
TL;DR: Diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA are critically evaluated.
Abstract: In recent years, several studies have focused on environmental pollutants. Bisphenol A (BPA) is one prominent industrial raw material, and its extensive utilization and release into the environment constitute an environmental hazard. BPA is considered as to be an endocrine disruptor which mimics hormones, and has a direct relationship to the development and growth of animal and human reproductive systems. Moreover, intensive exposure to the compound is related to prostate and breast cancer, infertility, obesity, and diabetes. Hence, accurate and reliable determination techniques are crucial for preventing human exposure to BPA. Experts in the field have published general electrochemical procedures for detecting BPA. The present timely review critically evaluates diverse chemically modified electrodes using various substances that have been reported in numerous studies in the recent decade for use in electrochemical sensors and biosensors to detect BPA. Additionally, the essential contributions of these substances for the design of electrochemical sensors are presented. It has been predicted that chemically modified electrode-based sensing systems will be possible options for the monitoring of detrimental pollutants.
TL;DR: In this article, a graphene oxide (GO) based nitrogen dioxide (NO2) gas sensor with extremely low limit of detection (LOD), which is far below the WHO and EU annual standards, is presented.
TL;DR: In this article, a review of surface modification of zirconia incorporating hydroxyapatite (HAp) is presented, where the advantages, disadvantages, biocompatibility, strength, and osseointergration and biointegration properties of the presented composites are explored.
Abstract: Zirconia has garnered significant attention as a new ceramic material for dental implant due to its excellent biocompatibility, strength, and promoting the oral rehabilitation with high aesthetic, biological and mechanical properties. It also expedites the amelioration of bone minerals surface by its bio-integrative ingredients which are naturally close to ceramic intrinsic of bone. Alternatively, hydroxyapatite (HAp) has prevalently been used in dental implant due to its high biocompatibility. However, it generally shows weak strength and mechanical properties. Consequently, incorporating zirconia and HAp produces appropriate composites for dental implant having improved physiochemical properties. This review provides discussions addressing the methodologies and exemplars for the designed composites used in dental implant applications. The representative methods for surface modification of zirconia incorporating HAp (i.e. sol-gel, hot isostatic pressing, plasma spraying, electrophoretic deposition, etc.) is highlighted. The advantages, disadvantages, biocompatibility, strength, and osseointergration and biointegration properties of the presented composites are explored.
TL;DR: In this article, the current status of lead-free, all-inorganic halide perovskite quantum dots (LFAIHP QDs) is discussed, and the limitations of these materials, possible methods to overcome them and prospects for these materials in the future are provided.
Abstract: Halide perovskite is attracting significant attention in optoelectronic because of its unique properties. Lead-free halide perovskites, in particular, have been studied intensively for their nontoxicity. In addition to the attention given to lead-free halide perovskites, the manufacture of these materials on a quantum scale has also received considerable attention due to the quantum confinement effect. This review discusses the current status of lead-free, all-inorganic halide perovskite quantum dots (LFAIHP QDs). First, synthetic methods for producing quantum dots are introduced; then materials are discussed with a focus on tin, bismuth, antimony, copper-based and double perovskite quantum dots. The properties of these materials-such as their physical structure, optical properties, electrical properties, and stability-are discussed. The application of these materials for solar cells, light-emitting diodes, photodetectors, photocatalysts, and memory devices are also examined. Finally, the limitations of LFAIHP QDs, possible methods to overcome them and prospects for these materials in the future are provided.
06 Jan 2020
TL;DR: The development of a carbon-free hydrogen production method by photoelectrochemical water splitting is a promising pathway to deal with the increased energy demands and deleterious environmental is... as mentioned in this paper.
Abstract: The development of a carbon-free hydrogen production method by photoelectrochemical water splitting is a promising pathway to deal with the increased energy demands and deleterious environmental is...
TL;DR: In this article, a combinatory approach for the assembly of PBA-supported heterogeneous nanocatalysts was proposed. But the PBA framework structure suffers from poor electronic conductivity, which limits the catalytic efficiency for this class of materials.
TL;DR: In this article, a composite structure composed of vertically grown molybdenum disulfide (MoSx) nanosheets supported by conductive carbon nanotube-reduced graphene oxide (CNT-rGO) on Vietnamese traditional paper was reported for a high-performance electrochemical hydrogen evolution reaction (HER).
TL;DR: In this paper, a photoelectrochemical (PEC) water splitting method was proposed to solve the photocorrosion in the electrolyte and high overpotential at the interface with the electrolytes.
Abstract: Silicon for photoelectrochemical (PEC) water splitting suffers from severe photocorrosion in the electrolyte and high overpotential at the interface with the electrolyte, although it is an earth-ab...
TL;DR: In this paper, an extensive investigation in the field of optical applications of nanocomposite materials has been conducted, where an optically functional phase is embedded in a transparent, processable matrix.
Abstract: There has been an extensive investigation in the field of optical applications of nanocomposite materials. To prepare photosensitive nanocomposites, an optically functional phase is embedded in a transparent, processable matrix. This provides the opportunity to utilize the optical properties in other forms including fibers and films, which are more technologically important. Due to expansion of optical materials applications, novel transparent materials and optically functional are required. Recent optical nanocomposites and their applications in different areas especially catalysis and drug delivery have been addressed in this paper.
TL;DR: This work provides a promising material strategy for lead-free all-inorganic HP-based nonvolatile memory devices for practical applications through the use of a closed-loop pulse switching method.
Abstract: Organometallic and all-inorganic halide perovskites (HPs) have recently emerged as promising candidate materials for resistive switching (RS) nonvolatile memory due to their current-voltage hysteresis caused by fast ion migration. Lead-free and all-inorganic HPs have been researched for non-toxic and environmentally friendly RS memory devices. However, only HP-based devices with electrochemically active top electrode (TE) exhibit ultra-low operating voltages and high on/off ratio RS properties. The active TE easily reacts to halide ions in HP films, and the devices have a low device durability. Herein, RS memory devices based on an air-stable lead-free all-inorganic dual-phase HP (AgBi2 I7 -Cs3 Bi2 I9 ) are successfully fabricated with inert metal electrodes. The devices with Au TE show filamentary RS behavior by conducting-bridge involving Ag cations in HPs with ultra-low operating voltages ( 107 ), multilevel data storage, and long retention times (>5 × 104 s). The use of a closed-loop pulse switching method improves reversible RS properties up to 103 cycles with high on/off ratio above 106 . With an extremely small bending radius of 1 mm, the devices are operable with reasonable RS characteristics. This work provides a promising material strategy for lead-free all-inorganic HP-based nonvolatile memory devices for practical applications.