Chong Min Koo

• PhD
• Professor at Sungkyunkwan University

Aqueous hydrofluoric acid (HF)‐based solutions are widely used for etching MAX phases to synthesize high‐purity 2D molybdenum carbides (MXenes). However, their applicability is limited to selected MAX phases, and the production of certain MXenes, such as Mo‐based MXenes, remains challenging owing to low quality, low yield, and the time‐intensive pr...

The structural design of lightweight MXene-polymer composites has attracted significant interest for enhancing both electromagnetic interference (EMI) shielding performance and mechanical strength, which are critical for practical applications. However, a...

Polymerase chain reaction (PCR) is a critical tool for nucleic acid amplification in molecular diagnosis and genetic analysis. Point‐of‐care (POC) devices are essential for controlling the spread of infectious diseases, but developing cost‐effective chip‐based PCR systems remains a challenge. This study introduces a photonic PCR chip featuring a pe...

Lithium metal batteries are considered highly promising candidates for the next-generation high-energy storage system. However, the growth of lithium dendrites significantly hinders their advance, particularly under high current densities, due to the formation of unstable solid electrolyte interphase (SEI) layers. In this study, we demonstrate that...

Metal batteries have captured significant attention for high-energy applications, owing to their superior theoretical energy densities. However, their practical viability is impeded by severe dendrite formation and poor cycling stability. To alleviate these issues, a 3D-structured bimetallic-Mo2Ti2C3Tx based fiber electrode was fabricated in this s...

Despite significant progress in developing artificial synapses to emulate the human nervous system for bio‐signal transmission, synapses with thermo‐adaptive coloration and soft actuators driven by temperature change have seldom been reported. Herein, a photonic neuro‐actuating synaptic skin is presented enabling thermoresponsive synaptic signal tr...

The fabrication of durable and high anticorrosion hydrogel composite materials composed of multi‐walled carbon nanotubes (MCNTs) and crosslinked polyacrylic acid (PAA) for EMI shielding application is reported. The MCNTs contribute to the generation of 3D porous structures and enhance the mechanical properties of composite hydrogel. The 3D porous s...

Developing a single‐component epoxy system is challenging but crucial for advanced thermoset applications. Unfortunately, conventional latent curing agents using chemical or physical passivation do not provide satisfactory storage stability and the necessary property requirements. Here, it is demonstrated that all‐in‐one epoxy/MXene nanocomposite s...

Advanced electronics and telecommunication devices rely on electromagnetic (EM) waves of a wide frequency range during their operation, thereby necessitating the development of efficient and ultrathin materials for electromagnetic interference (EMI) shielding across multispectral EM waves, particularly those exceeding 100 GHz, equivalent to millime...

Multifunctional, flexible, and robust thin films capable of operating in demanding harsh temperature environments are crucial for various cutting-edge applications. This study presents a multifunctional Janus film integrating highly-crystalline Ti 3 C 2 T x MXene and mechanically-robust carbon nanotube (CNT) film through strong hydrogen bonding. Th...

Molybdenum carbide MXenes have garnered considerable attention in electronics, energy storage, and catalysis. However, they are prone to oxidative degradation, but the associated mechanisms have not been systematically explored. Therefore, the oxidation mechanisms of Mo-based single-metallic/bimetallic carbide MXenes including Mo2CTx, Mo2TiC2Tx, an...

Surface plasmons in 2D materials such as graphene exhibit exceptional field confinement. However, the low electron density of majority of 2D materials, which are semiconductors or semimetals, has limited their plasmons to mid‐wave or long‐wave infrared regime. This study demonstrates that a 2D Ti3C2Tx MXene with high electron density can not only s...

Heterointerface engineering, which plays a pivotal role in developing advanced microwave‐absorbing materials, is employed to design zeolitic imidazolate framework (ZIF)–MXene nanocomposites. The ZIF–MXene composites are prepared by electrostatic self‐assembly of negatively charged titanium carbide MXene flakes and positively charged Co‐containing Z...

MXenes are a promising class of two‐dimensional transition metal carbides, nitrides, and carbonitrides, widely utilized in diverse fields such as energy storage, electromagnetic shielding, electrocatalysis, and sensing applications. Their potential in chemical sensing is particularly noteworthy, where optimizing surface chemistry for strong interac...

Polyurethane foam (PUF)’s porous structure, light weight, flexibility, and low‐cost properties make it useful in various cutting‐edge technologies. However, time‐consuming, costly, and complicated surface modification methods severely hinder its commercial applications. Herein, an ultrafast, simple, and cost‐effective surface modification method ba...

Rechargeable all-solid-state batteries (ASSBs) comprising solid electrodes and electrolytes have attracted significant interest as next-generation battery systems because of their high energy density and enhanced safety, as compared to conventional lithium-ion battery (LIBs). However, numerous challenges, such as poor ionic conductivity of the soli...

Surface chemistry of MXenes is of significant interest due to its potential to control their final optoelectronic and physicochemical properties, and address the oxidation and dispersion stabilities of MXenes. Surface chemistry of MXenes can be manipulated by either MXene synthesis via chemical etching or post surface functionalization method. Alth...

MXene, an ultra-thin two-dimensional conductive material, has attracted considerable interest in various fields due to its exceptional material properties. In particular, Ti 3 C 2 T x MXene exhibits distinct optical properties, enabling it to support surface plasmons in the shortwave infrared (SWIR) region. However, it is challenging to enhance the...

Two-dimensional (2D) MXenes have attracted significant attention in electromagnetic interference (EMI) shielding applications due to their unique properties, such as excellent metallic conductivity, high surface area, 2D geometry, tunable surface chemistry, and solution processability. In this study, we present a simple and versatile way for introd...

Surface chemistry influences not only physicochemical properties but also safety and applications of MXene nanomaterials. Fluorinated Ti3C2Tx MXene, synthesized using conventional HF‐based etchants, raises concerns regarding harmful effects on electronics and toxicity to living organisms. In this study, well‐delaminated halogen‐free Ti3C2Tx flakes...

MXenes are an emerging class of 2D materials with unique properties including metallic conductivity, mechanical flexibility, and surface tunability, which ensure their utility for diverse applications. However, the synthesis of MXenes with high crystallinity and atomic stoichiometry in a low‐cost process is still challenging because of the difficul...

Shape‐Deformable Locomotive MXene In article number 2210385, Cheolmin Park and co‐workers develop a MXene‐encapsulated magnetic liquid metal with shape deformable, locomotive, and self‐healing abilities. The liquid metal composite can be integrated as an electrical component of a device, with magnetic field‐induced performance tunability. Such char...

Lightweight electromagnetic interference (EMI) shielding materials for portable and highly compact electronics are required to have robust mechanical strength as well as excellent shielding efficiency. In the recent years, although 1D/2D nano carbons and 2D MXenes have been explored as electromagnetic shield in place of highly conductive yet dense...

Owing to their unique surface chemistry, room‐temperature pseudoliquidity, and high electrical conductivity, gallium‐based liquid metals (LMs) exhibit multifunctionality. To grant deformable and self‐flowing characteristics to LMs, magnetic particles are incorporated for precisely controlling the LM motion and shape deformability. However, LM surfa...

Ligands can control the surface chemistry, physicochemical properties, processing, and applications of nanomaterials. MXenes are the fastest growing family of two-dimensional (2D) nanomaterials, showing promise for energy, electronic, and environmental applications. However, complex oxidation states, surface terminal groups, and interaction with th...

With the rapid development of electronic technology, mobile communication and satellite communication, electromagnetic interference (EMI) or Radio Frequency Interference (RFI) has received global scientific attention to ensure unperturbed performance of electronic items and to avoid any adverse effect on human health. EMI is one of the main factors...

MXene Synthesis In article number 2203767, Chong‐Min Koo and co‐workers show that a high temperature non‐aqueous synthesis of Ti3C2Tx can significantly enhance the reaction rate and yield of delaminated MXene flakes with high quality. Additionally, Ti3C2Tx prepared by this method is covered with more F‐terminations and exhibits high tensile strengt...

Texture regulation of metal–organic frameworks (MOFs) is essential for controlling their electromagnetic wave (EMW) absorption properties. This review systematically summarizes the recent advancements in texture regulation strategies for MOFs, including etching and exchange of central ions, etching and exchange of ligands, chemically induced self‐a...

While two-dimensional (2D) Ti3C2Tx MXene in aqueous dispersions spontaneously oxidizes into titanium dioxide (TiO2) nanocrystals, the crystallization mechanism has not been comprehensively understood and the resultant crystal structures are not controlled among three representative polymorphs: anatase, rutile, and brookite. In this study, such cont...

Two-dimensional transition metal carbide/nitride (MXene) conductive inks are promising for scalable production of printable electronics, electromagnetic devices, and multifunctional coatings. However, the susceptible oxidation and poor rheological property seriously impede the printability of MXene inks and the exploration of functional devices. He...

Controlling the orientation of two-dimensional materials is essential to optimize or tune their functional properties. In particular, aligning MXene, a two-dimensional carbide and/or nitride material, has recently received much attention due to its high conductivity and high-density surface functional group properties that can easily vary based on...

2D transition metal carbides or nitrides (MXenes) have attracted considerable attention from materials scientists and engineers owing to their physicochemical properties. Currently, MXenes are synthesized from MAX‐phase precursors using aqueous HF. Here, in order to enhance the production of MXenes, an anhydrous etching solution is proposed, consis...

Lithium metal batteries (LMBs) have attracted increasing attention owing to their high theoretical capacity and low reduction potential. However, safety concerns and their low coulombic efficiencies (CE) arising from the nonuniform and irreversible formation of Li dendrites on their anodes hinder their practical application. Here, we demonstrate th...

The development of electrodes with high conductivity, optical transparency, and reliable mechanical flexibility and stability is important for numerous solution-processed photoelectronic applications. Although transparent Ti3C2TX MXene electrodes with high conductivity are promising, their suitability for displays remains limited because of the hig...

MXenes have recently attracted significant interest owing to their outstanding properties and performance. However, their hydrophilic and metastable surfaces make most MXenes prone to oxidation, which can greatly degrade their properties and hinder their practical applications. Here, we enhanced the stability of Ti3C2Tx MXene films by coating a con...

Sendust/expanded graphite and Sendust/boron nitride binary composite fillers adhered through surface silane modification and their non-modified, simply mixed, polymer composites were fabricated for optimization of multifunctional EMI shielding and thermal conduction properties. The effect of filler type, filler content, surface modification, and di...

High-tech electronic and communication devices require advanced materials for their protection against electromagnetic interference (EMI). Electrically conductive solid materials, such as metals, are typically employed as EMI shields owing to their high shielding performance caused by their high electronic conductivity. Herein, electrically insulat...

MXene SPR, which is more sensitive than the conventional gold SPR at SWIR regime, is advantageous for measuring the refractive index of thin materials, was theoretically and experimentally confirmed.

Light localization with plasmons in 2D material is restricted to mid- or long-wave infrared. Here, we demonstrate plasmons in 2D MXene, covering whole mid-infrared range. MXene plasmon exhibits wavelength 20 times shorter than vacuum wavelength.

Electrically-insulative ionic solutions of KBr, NaCl, and CaCl 2 salts are employed as effective electromagnetic interference (EMI) shielding materials. Debye-Drude theoretical models is applied for illuminating the EMI shielding mechanism of ionic solution.

Understanding and preventing oxidative degradation of MXene suspensions is essential for fostering fundamental academic studies and facilitating widespread industrial applications. Owing to their outstanding electrical, electrochemical, optoelectronic, and mechanical properties, MXenes, an emerging class of two-dimensional (2D) nanomaterials, show...

High-performance EMI shielding of a core-shell nanocomposite of Ni-Co MOF (core) wrapped by a heterogeneous layer of FeBTC MOF and polymeric polypyrrole (PPy) (shell) named Ni-Co/[email protected] is reported. Herein, the spherical structure Ni-Co MOF was firstly prepared and employed as nucleation sites for polymerization of pyrrole monomer utiliz...

Lightweight shielding materials that can protect devices against undesirable multispectral electromagnetic waves are critical in electronic, medical, military, and aerospace applications. However, the existing shielding materials are heavyweight and work only in a narrow frequency-range. In this work, we developed metal–metal oxide Ag-WO3 decorated...

Discover a cutting-edge reference on 2D EMI shielding materials for both industrial and academic audiences Two-Dimensional Materials for Electromagnetic Shielding delivers a thorough and comprehensive examination of all aspects of electromagnetic interference (EMI) shielding and microwave absorption, including fundamentals and applications, as wel...

Lithium Metal Batteries In article number 2101261, Seon Joon Kim, Young Soo Yun, and co-workers study lithiophilic surface-guided lithium metal nucleation and growth behaviors using a large-area Ti3C2Tx MXene electrode containing a large number of oxygen and fluorine dual heteroatoms. The lithiophilic MXene substrate significantly affects the surfa...

In article number 2010897, Yong Jin Jeong, Tae Kyu An, Insik In, Se Hyun Kim, and co-workers propose a clever strategy of engineering MXene inks for electrohydrodynamic jet printing to produce all printed logic circuits. This work could inspire further practical printed electronics by providing an option to manufacture electrodes in complex circuit...

MXenes occupy a leading position among materials capable of providing lightweight shielding against electromagnetic interference (EMI) owing to their outstanding metallic conductivity, low density, tunable surface chemistry, and easy solution processing. In this work, we demonstrate that multiple interfaces of segregated structures in MXene composi...

All electrical and electronic devices receive or transmit electromagnetic waves (EMWs), which cause a type of pollution called electromagnetic interference (EMI). This phenomenon affects the performance of electronic circuits, shortening their lifespan, and it is injurious to human health. For safe exposure limits to EMWs, different operating frequ...

The selection of appropriate instruments and measurement methods is vital for precise measurements of the electromagnetic interference (EMI) shielding effectiveness. This chapter describes common measurement techniques and standards for determining the electromagnetic shielding performance. Different measurement techniques, such as the coaxial tran...

Electromagnetic interference (EMI) shielding mechanisms and scattering parameter conversion theory are essential for understanding the shielding performance of materials. This chapter primarily discusses the basic EMI shielding mechanisms, including reflection, absorption, and multiple reflections. Moreover, scattering parameter conversion techniqu...

The large surface area, ballistic electron transport properties, and tunable surface chemistry of graphene make this material suitable for electromagnetic interference (EMI) shielding applications. In this chapter, the physical and chemical properties of graphene are discussed along with the shielding properties of graphene variants such as graphen...

Shielding materials with absorption‐dominant properties have been explored for many civilian and defense applications. Various 2D materials, including transition metal dichalcogenides (TMDCs; e.g. MoS2, WS2, and TaS2), black phosphorus (BP), hexagonal boron nitride (h‐BN), and metal–organic frameworks (MOFs), have been explored for electromagnetic...

Two‐dimensional (2D) MXenes are a newly discovered family of transition metal carbides, nitrides, and carbonitrides. Their outstanding electrical conductivities of >104 S cm−1 and 2D morphology offer an efficient alternative to highly conductive metals in applications requiring high electrical conductivity. In addition, the low density, mechanical...

The positive effects of a lithiophilic substrate on the electrochemical performance of lithium metal anodes are confirmed in several reports, while the understanding of lithiophilic substrate‐guided lithium metal nucleation and growth behavior is still insufficient. In this study, the effect of a lithiophilic surface on lithium metal nucleation and...

MXenes are interesting 2D materials that have been considered as attractive frontier materials for potential applications in the fields of energy and electronic devices due to their excellent optoelectronic properties including metallic conductivity and high optical transparency. However, it is still challenging to achieve compatibility for the as‐...

Two-dimensional graphene is of great interest for electromagnetic interference (EMI) shielding owing to its inherent electrical conductivity, lightweight, and excellent mechanical flexibility even at minor thicknesses. However, the complex synthesis and quality-control difficulties limit its application. In this study, we demonstrate that electroch...

MXenes are two-dimensional (2D) transition metal carbides, nitrides, and carbonitrides with unique intrinsic properties, including excellent electrical conductivity, 2D sheet morphology, lightweight, flexibility, tunable surface chemistry, and easy solution processability, thus attracting considerable attention as electromagnetic interference (EMI)...

A nanostructured composite composed of reduced graphene oxide (rGO) and NiO/ZnO hollow spheres was prepared via an in situ reaction involving pyrolysis and surface modification of a heterobimetallic Ni-Zn metal-organic framework with amine-functional group. The rGO sheet was successfully grafted on the surface of NiO/ZnO. The hybrid displayed excel...

Nano-hydroelectric technology utilizes hydraulic flow through electronically conducting nanomaterials to generate electricity in a simple, renewable, ubiquitous, and environmentally friendly manner. Up to date, several designs of nano-hydroelectric devices have...

A composite of reduced graphene oxide (rGO) coated with metal-organic framework (MOF) HKUST-1 was synthesized using a facile hydrothermal method. The micro-frame of HKUST-1 was retained with the well-decorated octahedral framework on the surface of rGO sheets, resulting in the production of a scabrous, thorny trunk structure. The as-prepared compos...

A novel inorganic–organic hybrid crosslinker was prepared through synthesis of a fully condensed, high molecular weight ladder-like poly(methacryloxypropyl)silsesquioxane (LPMASQ) in one pot with a facile, base-catalysed system. The fully condensed LPMASQ revealed good thermal (∼380 °C) and electrochemical stability (∼5.0 V) due to the absence of u...

In article number 2000883, Chong Min Koo, Aamir Iqbal, and Pradeep Sambyal comprehensively review the recent advancements in MXene‐based electromagnetic interference shielding materials with different structural morphologies and provides an insight into future challenges and guideline for finding material solutions for the next‐generation shielding...

Since their discovery in 2011, 2D transition metal carbides, nitrides, and carbonitrides, known as MXenes, have attracted considerable global research interest owing to their outstanding electrical conductivity coupled with light weight, flexibility, transparency, surface chemistry tunability, and easy solution processability. Here, the promising a...

2-dimensional (2D) MXene has enlightened enormous potentials in scientific fields, including energy storage and electromagnetic interference (EMI) shielding. Unfortunately, MXene based material structures generally suffer from mechanical fragility and vulnerability to oxidation. Herein, mussel-inspired dopamine successfully addresses those weakness...

In article number 2001224, Chong Min Koo, Cheolmin Park, and co‐workers demonstrate a solution‐processed, large‐area, flexible, transparent MXene electrode suitable for a high‐performance polymer light emitting diode (PLED). The PLED with the MXene electrode exhibits a light‐emission performance superior to that of previously reported flexible PLED...

Lightweight, ultrathin, and flexible electromagnetic interference (EMI) shielding materials are needed to protect electronic circuits and portable telecommunication devices and to eliminate cross-talk between devices and device components. Here, we show that a two-dimensional (2D) transition metal carbonitride, Ti3CNT x MXene, with a moderate elec...