Noncovalent Functionalization of Graphene and Graphene Oxide for Energy Materials, Biosensing, Catalytic, and Biomedical Applications

This Review focuses on noncovalent functionalization of graphene and graphene oxide with various species involving biomolecules, polymers, drugs, metals and metal oxide-based nanoparticles, quantum dots, magnetic nanostructures, other carbon allotropes (fullerenes, nanodiamonds, and carbon nanotubes), and graphene analogues (MoS2, WS2). A brief description of pi-pi interactions, van der Waals forces, ionic interactions, and hydrogen bonding allowing noncovalent modification of graphene and graphene oxide is first given. The main part of this Review is devoted, to tailored functionalization for applications in drug delivery, energy materials, solar cells, water splitting, biosensing, bioimaging, environmental, catalytic, photocatalytic, and biomedical technologies. A significant part of this Review explores the possibilities of graphene/graphene oxide-based 3D superstructures and their use in lithium-ion batteries. This Review ends with a look at challenges and future prospects of noncovalently modified graphene and graphene oxideope

Electrochemical reduction of carbon dioxide and carbon monoxide for the production of green fuels and chemicals.

It has become apparent that closing the carbon cycle on this planet in order to mitigate disastrous consequences of runaway global warming has become one of the most pressing issues of our civilization. One of the ways we need to accomplish this goal is by finding news methods to generate fuels that will be carbon neutral. Renewable fuels and green chemicals will be a major component of closing the carbon cycle and restoring our planet’s ecosystem into a sense of balance. A method that can help achieve this goal is the reduction of CO2. If CO2 can be a desirable reactant on a large enough scale to produce fuels and chemicals, many industries will greatly benefit from the implementation of CO2 reduction technologies. This would in turn make removing CO2 from the atmosphere a worthy and realistic endeavor while reducing the concentration of CO2 in the atmosphere. Reducing CO2 concentrations in the atmosphere will help mitigate global warming. In the following dissertation, several methods are discussed that aid in the development of CO2 electroreduction. The goal of which is to improve the overall efficiency of current CO2 electroreduction technology. The first major effort assesses the contaminants emanating from the membrane component of the CO2 electroreduction vii device, alleviating the issue of spurious product detection. The second effort involves the tuning of product selectivity on oxide-derived copper catalyst by pulsing the bias. The third effort details the pursuit of a stand-alone “artificial leaf” technology for the reduction of carbon monoxide. The electrochemical investigations undertaken in this dissertation discuss in detail the metrics and principles used to accomplish these works

비공유 화학적 도핑을 이용한 단일층 그래핀 소자의 전자특성 최적화

학위논문(박사) -- 서울대학교대학원 : 자연과학대학 화학부, 2022. 8. 홍병희.2004년 그래핀은 테이프를 이용한 (고배향 열분해성) 흑연(highly oriented pyrolytic graphite; HOPG)으로부터의 박리를 통해 최초 발견되었다. 이후 수많은 연구들에 의해 그래핀이 우수한 열적, 기계적, 전기적, 광학적 특성을 지녔음이 알려졌다. 2009년에 이르러 화학기상증착(chemical vapor deposition; CVD) 방식을 이용한 다결정 그래핀의 대면적 합성이 실험적으로 가능해졌고, 이로써 그래핀이 다양한 분야에 응용될 수 있는 발판이 마련되었다. 특히 그래핀의 응용분야 중 전기전자특성을 이용한 분야가 각광을 받고 있다. 그래핀은 높은 전자이동도, 전기전도도 및 열전도도를 지닌 재료이며, 밀접결합(tight-binding; TB) 근사 모형을 이용하여 계산한, 결함이 없는 단결정 단층 그래핀의 밴드갭(band gap)은 0임이 밝혀졌다. 재료의 전자특성 조절은 전자소자로의 응용에 필수적 공정이고, 도핑은 전자특성 조절에 주로 쓰이는 방법 중 하나이다. 그래핀에 도핑 처리를 함으로써 밴드갭, 전기전도도 및 일함수와 같은 전기전자특성을 조절할 수 있다. 그래핀에 대한 도핑 방법으로는 원자 치환, 전계 인가, 분자나 금속 나노입자 등의 물리적 흡착 등이 있다. 이 중 물리적 흡착 방식은 결함 없이 간단하고 우수한 도핑 효과를 얻을 수 있어 그래핀 도핑 방법으로 널리 사용되고 있다. 본 논문에서는 화학기상증착 방식으로 합성한 그래핀의 전자특성 최적화 방법 및 전자소자로의 응용에 관한 연구를 다루었다. 그래핀의 전자특성 최적화 방식으로 물리적 흡착을 통한 비공유 화학적 도핑을 택하였으며, 도핑된 그래핀의 전자소자로의 응용 가능성에 대하여 확인하였다. 제1장에서는 그래핀의 물리적 특성 중 전기전자특성에 초점을 맞춰 설명하였다. 또한, 연구에 사용한 도핑 방법과 도핑된 그래핀의 전하 이동현상에 관하여 소개하였다. 제2장에서는 그래핀의 합성, 전사 및 도핑 방법에 관하여 서술하였다. 연구에 사용된 그래핀은 화학기상증착 방식으로 합성되었으며, 합성된 그래핀은 구리 식각 및 전사 공정을 통해 소자 연구를 위한 시편으로 제작되었다. 그래핀은 자기조립단층(self-assembled monolayer; SAM)을 형성하는 분자 외 다양한 나노물질을 이용한 물리적 흡착 방식에 의해 화학적 도핑된다. 라만 분광분석을 통해 합성 및 도핑 직후의 그래핀 시편의 품질을 평가하였고, 3 전극 시스템을 이용한 전계효과 트랜지스터를 제작하여 그래핀의 전자특성을 분석하였다. 제3장에서는 화학기상증착 방식으로 합성한 그래핀에 다양한 나노물질을 차례로 제공함으로써 화학적 도핑 효과의 변화를 나타낸 전자소자 연구를 기술하였다. 그래핀 표면에 금 나노입자를 물리적 흡착 방식으로 도핑하여 비공유 기능화하고, 이를 이용한 그래핀을 전계효과 트랜지스터 소자로 제작하였다. 제작된 소자에 존재하는 금 나노입자에 4-머캅토벤조산(4-mercaptobenzoic acid; 4-MBA) 분자를 흡착시킴으로써 자기조립단층을 형성케 한다. 이때 수은 이온을 주입하면 자기조립단층을 형성한 4-MBA 분자의 카복시기(carboxyl group)가 리간드로 작용하여 수은 이온을 포획하면서 킬레이트(chelate) 복합체를 구성한다. 각 단계의 그래핀 전계효과 트랜지스터 소자의 전자특성 분석을 통해, 각 나노물질 요소에 의해 그래핀 표면의 도핑 효과가 미세 조정됨을 알 수 있다. 본 연구를 통해 그래핀 전계효과 트랜지스터의 화학적 기능화에 대한 가능성을 확인하였다. 제4장에서는 화학기상증착 방식으로 합성한 그래핀에 n-알킬아민(n-alkylamine; H2NCn) 분자를 도입함으로써, n형 도핑된 그래핀을 이용한 열전소자 성능의 향상에 관하여 기술하였다. n-알킬아민 분자는 그래핀 표면에서 자기조립단층을 형성하고 비공유 기능화를 통해 전자를 그래핀에 제공한다. 탄소사슬 길이가 각기 다른 n-알킬아민 분자를 이용하여 도핑한 그래핀을 3 전극 시스템을 통해 분석함으로써, 서로 다른 길이의 분자를 통해 그래핀 시편의 전하운반자 농도의 조절이 가능함을 확인하였다. n-알킬아민 분자의 자기조립단층이 형성된 각 그래핀 시편 위로 산화갈륨(Ga2O3) 박막층 및 갈륨-인듐 공융합금(eutectic Ga-In alloy; EGaIn) 벌크층을 차례로 적층하여 열전소자를 제작하였다. n-알킬아민 분자의 비공유 접합에 의해 유도 갭 상태(induced-gap state)가 그래핀 열전소자(SLG//H2NCn//Ga2O3/EGaIn)에 도입되었다. 금 박막층과 n-알케인싸이올레이트(n-alkanethiolates; SCn) 분자의 접합으로 구성된 종래의 열전소자(Au/SCn//Ga2O3/EGaIn)와의 비교를 통해, 상기한 방식으로 제작된 그래핀 열전소자가 우수한 열전특성을 지니고 있음을 증명하였다.Since its first discovery as a flake-form from mechanical exfoliation of highly-oriented pyrolytic graphite (HOPG) using tape in 2004, numerous studies have shown that graphene has outstanding and extraordinary thermal, mechanical, electrical, electronic and optical properties. In 2009, large-area synthesis of polycrystalline graphene using a chemical vapor deposition (CVD) method became experimentally possible, thereby establishing a foothold for the graphene to be applied to various fields. In particular, the field of application using electrical and electronic characteristics of graphene is in the spotlight. Graphene is a remarkable material with high electron mobility, electrical conductivity and thermal conductivity. Furthermore, the pristine single-layer graphene (SLG) has zero gap, a theoretical value calculated by a tight-binding (TB) approximation model. Engineering the electronic properties of materials is an essential process for application to electronic devices, and doping is one of the methods mainly used to control electronic properties. By doping graphene, electrical and electronic characteristics such as band gap, electrical conductivity, and work function (WF) can be modified and controlled. Doping methods for graphene include atomic substitution, applying electric field, physisorption (physical adsorption) of molecules and metal nanoparticles, etc. Among those methods, the physisorption is widely used as a graphene doping method because it can obtain a simple and superior doping effect without crystallographic defects. This paper describes researches on optimization methods of the electronic properties of graphene synthesized by CVD method and its applications of electronic devices. Noncovalent chemical doping by the physisorption was selected as the optimization method of the electronic properties of graphene, and the possibility of application of the doped graphene to an electronic device was verified. Chapter 1 delineates the physical properties of graphene, focusing on the electrical and electronic properties. In addition, the doping method used in the study and the charge transfer phenomenon of doped graphene were introduced. Chapter 2 gives a detailed description of the procedure such as the synthesis, transfer, and doping methods of graphene. Graphene used in these researches was synthesized by CVD method, and the synthesized graphene was manufactured as electronic device specimens through copper etching and transfer processes. Graphene is chemically doped by the physisorption method using various nanomaterials such as molecules forming self-assembled monolayers (SAM). Through Raman spectroscopy, the quality of graphene specimens immediately after synthesis and doping process was evaluated. Moreover, the electronic properties of graphene were analyzed by a 3-electrode system using field-effect transistor (FET) devices Chapter 3 depicts a study on electronic devices showing changes in chemical doping effects by sequentially providing various nanomaterials to graphene synthesized by CVD method. Gold nanoparticles were used as dopants on the surface of graphene by physisorption for a noncovalent functionalization, and the doped graphene was manufactured as FET devices. SAM is formed by adsorbing 4-mercaptobenzoic acid (4-MBA) molecules onto gold nanoparticles on the manufactured graphene device. And then, if mercury ions are injected, a carboxyl group of 4-MBA molecules constructing SAM acts as a ligand to capture mercury ions, thereby assembling a chelate complex. Through the analyses of the electronic properties of the graphene FET devices in each step, it can be seen that the doping effect of the graphene surface is finely adjusted by each nanomaterial element. Through this study, the possibility of chemical functionalization of graphene FET devices was exactly clarified. Chapter 4 describes the improvement in the performance of graphene thermoelectric devices using n-type doping by introducing n-alkylamine (H2NCn) molecules onto SLG film synthesized by CVD method. The n-alkylamine molecules form SAM on the surface of graphene and provide electrons to graphene through noncovalent functionalization. Graphene doped by n-alkylamine molecules with different lengths of carbon chain was manufactured as FET devices and analyzed by a 3-electrode system. Graphene FET devices were proved clearly that the concentration of charge carriers of graphene specimens could be regulated by chemical doping method using each molecule. Graphene thermoelectric devices was manufactured by sequentially stacking a gallium oxide (Ga2O3) thin film layer and a eutectic gallium-indium alloy (EGaIn) bulk layer onto the n-alkylamine SAM formed on each graphene specimen. An induced-gap state was introduced into the graphene layer in graphene thermoelectric devices (SLG//H2NCn//Ga2O3/EGaIn) by noncovalent junctions of n-alkylamine molecules. Through comparison with thermoelectric devices with a conventional structure (Au/SCn/Ga2O3/EGaIn) composed of the junction of gold thin film layer and n-alkanethiolates (SCn) molecules, it was shown that the graphene thermoelectric devices produced by the above method have improved and outstanding thermoelectric properties.Cover 1 Abstract 3 Table of Contents 6 List of Tables 8 List of Figures 9 Chapter 1. Introduction to Graphene 12 1. 1. Discovery and Advancement of Graphene 12 1. 2. Crystal Structure of Graphene 16 1. 3. Band Structure of Graphene 25 1. 4. Group Theory to Analyze Graphene 40 1. 5. Chemical Doping of Graphene 47 1. 6. Properties of Doped Graphene 50 Chapter 2. Experimental 54 2. 1. Graphene Synthesis by Chemical Vapor Deposition 54 2. 2. Pre-treatment Process for Graphene Transfer 65 2. 3. Graphene Transfer Process 66 2. 4. Graphene Doping by Physisorption 69 2. 5. Raman Spectroscopic Analyses for Graphene 70 2. 6. Electronic Analyses for Graphene Field-effect Transistor 80 Chapter 3. Gold Nanoparticle-Mediated Noncovalent Functionalization of Graphene for Field-Effect Transistors 94 3. 1. Abstract 94 3. 2. Introduction 95 3. 3. Experimental 96 3. 4. Results and Discussion 101 3. 5. Conclusion 123 Chapter 4. Enhanced Thermopower of Saturated Molecules by Noncovalent Anchor-Induced Electron Doping of Single-Layer Graphene 124 4. 1. Abstract 124 4. 2. Introduction 125 4. 3. Experimental 128 4. 4. Results and Discussion 138 4. 5. Conclusion 157 Bibliography 158 Abstract in Korean 178박

Hybrid Materials Based on Carbon Nanotubes and Graphene: Synthesis, Interfacial Processes, and Applications in Chemical Sensing

Development of hybrid nanostructures based on two or more building blocks can significantly expand the complexity and functionality of nanomaterials. For the specific objective of advanced sensing materials, single-walled carbon nanotubes and graphene have been recognized as ideal platforms, because of their unique physical and chemical properties. Other functional building blocks include polymers, metal and metal oxide nanostructures, and each of them has the potential to offer unique advances in the hybrid systems. In any case of constructing hybrid nanostructures, challenges exist in the controlling of composition, morphology and structure of different nanoscale building blocks, as well as the precise placement of these building blocks in the final assembly. Both objectives require systematical exploration of the synthetic conditions. Furthermore, there has been an increasing recognition of the fundamental importance of interface within the nanohybrid systems, which also requires detailed investigation. We have successfully developed several innovative synthetic strategies to regulate the assembly of nanoscale building blocks and to control the morphology of the hybrid systems based on graphitic carbon nanomaterials. We demonstrate the importance of surface chemistry of each building block in these approaches. Moreover, interfacial processes in the hybrid system have been carefully investigated to elucidate their impacts on the functions of the hybrid products. Specifically, we explored the synthesis and characterization of hybrid nanomaterials based on single-walled carbon nanotubes and graphene, with other building blocks including conducting polymers, metal, metal oxide and ceramic nanostructures. We demonstrated the development of core/shell morphology for polyaniline and titanium dioxide functionalized single-walled carbon nanotubes, and we showed a bottom-up synthesis of metal nanostructures that involves directed assembly and nanowelding of metal nanoparticles on the graphitic surfaces. Through electrical, electrochemical and spectroscopic characterizations, we further investigated their surface chemistry, interfacial interaction/processes, as well as their fundamental influence on the performance of the hybrid systems. We showed improved or even synergic properties for each hybrid system. Their chemical sensitivities, material stabilities, and charge separation efficiency were superior to individual components. These properties hold great promise in the real-world sensor applications, and can potentially benefit other research fields such as catalysis and green energy

Nanomaterials for Healthcare Biosensing Applications

In recent years, an increasing number of nanomaterials have been explored for their applications in biomedical diagnostics, making their applications in healthcare biosensing a rapidly evolving field. Nanomaterials introduce versatility to the sensing platforms and may even allow mobility between different detection mechanisms. The prospect of a combination of different nanomaterials allows an exploitation of their synergistic additive and novel properties for sensor development. This paper covers more than 290 research works since 2015, elaborating the diverse roles played by various nanomaterials in the biosensing field. Hence, we provide a comprehensive review of the healthcare sensing applications of nanomaterials, covering carbon allotrope-based, inorganic, and organic nanomaterials. These sensing systems are able to detect a wide variety of clinically relevant molecules, like nucleic acids, viruses, bacteria, cancer antigens, pharmaceuticals and narcotic drugs, toxins, contaminants, as well as entire cells in various sensing media, ranging from buffers to more complex environments such as urine, blood or sputum. Thus, the latest advancements reviewed in this paper hold tremendous potential for the application of nanomaterials in the early screening of diseases and point-of-care testing

Inorganic—Carbon Nanomaterial Composites for Chemical Sensing

Carbon nanomaterials have been demonstrated to be excellent transducer materials for chemical sensing. Their high surface to volume ratio, high conductivity, and nanoscale dimensions allow them to be incorporated into miniaturized, low power consumption devices. The attachment of receptors to carbon nanomaterials as an analyte recognition layer is crucial for achieving selective and sensitive chemical sensing. The hybridization of carbon nanomaterials with metals, metal oxides, and other inorganic materials has created a new class of materials, inorganic—carbon nanomaterial composites. These composites seek to combine the properties of inorganic materials with the aforementioned properties of carbon nanomaterials. The surface chemistry and electronic structure of these composites are important for various applications, including chemical sensing. In this work we describe the synthesis and characterization of novel inorganic—carbon nanomaterial composites. Attachment of the inorganic materials to the carbon nanomaterial layer was achieved through both covalent and noncovalent methods. Characterization of these composites was performed with electron microscopy, X-ray diffraction, photoelectron spectroscopy, fluorescence spectroscopy, Raman spectroscopy, electrical measurements, and gas adsorption measurements. Most of the described inorganic—carbon nanomaterial composites were incorporated into chemiresistor devices for chemical gas sensing. The indium oxide/single-walled carbon nanotube composite was found to be sensitive to volatile organic compounds such as ethanol and acetone, while the carbon nitride/reduced graphene oxide composite was sensitive to inorganic gases such as oxygen and carbon dioxide. The sensing mechanisms for these inorganic—carbon nanomaterial composites are explored and discussed. A new photoredox sensing mechanism was demonstrated for the carbon nitride/reduced graphene oxide composite. Tuning the electronic structure of carbon nitride/reduced graphene oxide with copper nanoparticles was found to change the sensor sensitivity toward carbon dioxide. Through hybridization of carbon nanomaterial with new inorganic materials like zeolitic imidazolate frameworks (ZIF) and carbon nitride, we have shown that carbon nanomaterial composites can achieve new properties such as microporosity and photoexcited charge carriers, respectively. Combining these properties with those of carbon nanomaterials will benefit a variety of applications including chemical sensors, (photo)electrocatalysts, and energy storage devices, among others

Implementation and applications of density-fitted symmetry-adapted perturbation theory

Noncovalent interactions play a vital role throughout much of chemistry. The understanding and characterization of these interactions is an area where theoretical chemistry can provide unique insight. While many methods have been developed to study noncovalent interactions, symmetry-adapted perturbation theory (SAPT) stands out as one of the most robust. In addition to providing energetic information about an interaction, it provides insight into the underlying physics of the interaction by decomposing the energy into electrostatics, exchange, induction and dispersion. Therefore, SAPT is capable of not only answering questions about how strongly a complex is bound, but also why it is bound. This proves to be an invaluable tool for the understanding of noncovalent interactions in complex systems. The wavefunction-based formulation of SAPT can provide qualitative results for large systems as well as quantitative results for smaller systems. In order to extend the applicability of this method, approximations to the two-electron integrals must be introduced. At low-order, the introduction of density fitting approximations allows SAPT computations to be performed on systems with up to 220 atoms and 2850 basis functions. Higher-orders of SAPT, which boasts accuracy rivaling the best theoretical methods, can be applied to systems with over 40 atoms. Higher-order SAPT also benefits from approximations that attempt to truncate unneccesary unoccupied orbitals.PhDCommittee Chair: Sherrill, C. David; Committee Member: Bongiorno, Angelo; Committee Member: Brown, Kenneth R.; Committee Member: Harvey, Stephen C.; Committee Member: Liotta, Charles L.; Committee Member: Whetten, Robert L

Materials and interfaces for electrocatalytic hydrogen production and utilization.

Mass industrialization over the last few centuries has created a global economy which is dependent upon fossil fuels to satisfy an exponentially increasing demand for energy. Aside from the possible depletion of this finite resource, the combustion of fossil fuels releases greenhouse gases into the atmosphere which cause the global temperature to rise – a phenomenon which has already begun to create geologic and geopolitical instability and shows no signs of abatement. One proposed method to rid humanity of its dependence on fossil fuels is to use green hydrogen as an energy carrier. In this scheme, excess electricity from a robust renewable energy generation infrastructure is diverted to grid-scale electrolyzers which split water into hydrogen and oxygen. The hydrogen is in turn distributed via supply chain to end users who employ fuel cells to locally convert the energy stored in the chemical bond of hydrogen into electricity on-demand. This vision for an alternative global energy economy has been inhibited by several factors including the low utilization of renewable energy generating technologies, the considerable cost of precious metals required for electrolyzer electrodes, and the relatively low efficiency of the cathodic fuel cell reaction. This vi dissertation is a compilation of experimental work related to the development of materials and interfaces for enhanced electrocatalytic hydrogen evolution using non-precious materials and hydrogen utilization in highly-efficient proton exchange membrane fuel cells. Chapter 1 begins with an overview of the global energy diet and the problem of climate change followed by a discussion of renewable energy technologies, ending with a proposal of how the large-scale implementation of green hydrogen technologies may fit into the futuristic energy landscape. Chapter 2 presents a brief review of the mechanism of hydrogen evolution electrocatalysis including its thermodynamic, kinetic, and mass transport limitations. In Chapter 3, we demonstrate a simple and scalable fabrication process for highly-active non-precious molybdenum sulfide electrolyzer cathodes. Molybdenum sulfide and other transition metal dichalcogenides have received considerable attention in recent years as electrolyzer catalysts due to their environmental benignity, high stability, good catalytic activity, and low cost. Aside from the issue of low efficiency, industrial implementation of most reported molybdenum sulfide fabrication procedures is complicated by extreme and/or lengthy processing conditions. Our process is roll-to-roll amenable and produces a catalyst film in milliseconds without the use of harsh processing conditions or excessive chemicals. Ex-situ characterization of the resulting electrode confirms transformation of the precursor to molybdenum sulfide and reveals a hydrogen evolution reaction overpotential of 200 mV at 10 mA cm-2 which is comparable to that of other reported highly-active molybdenum sulfide catalysts. Chapter 4 deals with the development and ex-situ characterization of a novel non-precious electrocatalyst platform for hydrogen evolution based upon a nickel-centered thiosemicarbazone molecular framework. The enzyme hydrogenase, found in most forms of life, has served as a source of inspiration for researchers due to its ability to reversibly catalyze hydrogen evolution efficiently. However, efforts to translate the activity of the hydrogenase active site to an electrode have been limited in their success. We report a class of molecular catalysts inspired by previous work on hydrogenase active site analogues. Successful translation and retention of the catalyst to the electrode surface is confirmed, and ex-situ testing reveals a hydrogen evolution reaction overpotential of 450 mV at 10 mA cm-2 with remarkable stability – a promising milestone which lays the foundation for further development of this class of materials. Beginning in Chapter 5, the focus of the dissertation is shifted away from materials for hydrogen evolution and toward the development of highly-efficient proton exchange membrane fuel cell devices. Chapter 5 details the interplay between chemical transport, catalytic kinetics, thermodynamic considerations, and Ohmic losses which influence fuel cell efficiency. In Chapter 6, we introduce a structured proton exchange membrane fuel cell cathode which utilizes an array of bulk-like ionomer channels to improve the interface between the catalyst layer and membrane. The channels serve as conduits for rapid proton transport, dramatically decreasing the cathode sheet resistance and enabling a reduction in electrode ionomer content which attenuates active site inhibition from sulfonate adsorption. Using this approach, the mass activity of Vulcan carbon-based Pt viii catalyst is improved by up to 80 %, and the power density is improved by up to hundreds of mW cm-2 at benchmark cell potentials – particularly under arid conditions. Further performance gains may be realized by tuning the electrode geometry and/or applying this technology to other catalyst types including those based upon high-surface-area carbon. The results described in this dissertation 1) advance the understanding of materials and fabrication processes for hydrogen evolution electrodes and 2) provide a simple tool for mitigating chemical transport and catalyst poisoning limitations in the proton exchange membrane fuel cell cathode

Carbon Dioxide Capture Potential of Chitosan-Nanocrystalline Cellulose Aerogel Composite Materials: Synthesis, Functionalization, and Characterization

The carbon dioxide capture technology has been established as an invaluable player in the current global efforts to allay the warming of the planet and climate change. In this connection, the study centers on the valorization of waste organic materials for the application described herein. The sorbents, sourced from a combination of by-products of food processing and agricultural residue waste products, viz. seafood waste and sugarcane bagasse, showed prospects for selective carbon dioxide capture, adsorbing up to 5.78 mg/g of the gas at 273 K and 2.82 mg/g at 298 K, as observed on the Micromeritic ASAP 2020 surface area and porosity analyser. Further, thermogravimetric analysis (TGA) showed the materials to possess a decent level of thermal stability, making them fit for the purpose in an industrial setting. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), fourier transform infrared spectroscopy (FT-IR), energy dispersive X-ray spectroscopy (EDS), X-ray diffraction (XRD), and viscometry were used to elucidate the microstructure and physicochemical properties of the materials. Drawing on the sorption performance of the aerogels, the low cost of raw materials, potential for scaling up, this work further validates the adsorbent-based carbon capture technology toward curbing the slowly revealing cataclysmic aftermaths of carbon dioxide emissions