Three dimensional graphene based materials: Synthesis and applications from energy storage and conversion to electrochemical sensor and environmental remediation

Evaluating the simultaneous electrochemical determination of antineoplastic drugs using LaNiO3/g-C3N4@RGH nanocomposite material

A novel electrochemical sensor based on LaNiO3/g-C3N4@RGH nanocomposite material was developed to simultaneously determine Ribociclib (RIBO) and Alpelisib (ALPE). Ribociclib and Alpelisib are vital anticancer medications used in the treatment of advanced breast cancer. The sensor exhibited excellent electrocatalytic activity towards the oxidation of RIBO and ALPE, enabling their simultaneous detection. The fabricated sensor was characterized using various techniques, including energy dispersive X-ray (EDX), Fourier-transform infrared spectroscopy (FTIR), X-ray diffraction (XR), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS), which confirmed the successful synthesis of the LaNiO3/g-C3N4@RGH composite material. Electrochemical characterization revealed enhanced conductivity and lower resistance of the modified electrode compared to the bare electrode. The developed sensor exhibited high repeatability, reproducibility, stability, and selectivity toward RIBO detection. Furthermore, the sensor displayed high sensitivity with low detection limits of 0.88 nM for RIBO and 6.1 nM for ALPE, and linear ranges of 0.05-6.2 μM and 0.5-6.5 μM, respectively. The proposed electrochemical sensor offers a promising approach for simultaneously determining RIBO and ALPE in pharmaceutical formulations and biological samples with recovery data of 98.7-102.0 %, providing a valuable tool for anticancer drug analysis and clinical research.

Enhanced degradation of nitrate by a combined electrolysis precipitation process

Nitrate can be electrolyzed mainly into N2, but the generated ammonia, as its secondary intermediate, is soluble and remained in the wastewater yet, which affects negatively the degradation of nitrate and total nitrogen. In this work, an electrolytic reactor constructed with Ti/RuSn anode and Fe cathode, was applied to electrolyze nitrate, and magnesium chloride was used as electrolyte and precipitant simultaneously, while disodium hydrogen phosphate (DSP) was added only as precipitant of ammonia. The results indicated that, most part of generated ammonia could be precipitated as magnesium ammonium phosphate (MAP) and some residual ammonia may be transformed into N2 by breakpoint chlorination. Thus, the nitrate and total nitrogen (TN) degradation efficiencies could be enhanced obviously by the combined electrolysis precipitation process.

Recent advances in graphene-based electroanalytical devices for healthcare applications

Graphene, with its outstanding mechanical, electrical, and biocompatible properties, stands out as an emerging nanomaterial for healthcare applications, especially in building electroanalytical biodevices. With the rising prevalence of chronic diseases and infectious diseases, such as the COVID-19 pandemic, the demand for point-of-care testing and remote patient monitoring has never been greater. Owing to their portability, ease of manufacturing, scalability, and rapid and sensitive response, electroanalytical devices excel in these settings for improved healthcare accessibility, especially in resource-limited settings. The development of different synthesis methods yielding large-scale graphene and its derivatives with controllable properties, compatible with device manufacturing - from lithography to various printing methods - and tunable electrical, chemical, and electrochemical properties make it an attractive candidate for electroanalytical devices. This review article sheds light on how graphene-based devices can be transformative in addressing pressing healthcare needs, ranging from the fundamental understanding of biology in in vivo and ex vivo studies to early disease detection and management using in vitro assays and wearable devices. In particular, the article provides a special focus on (i) synthesis and functionalization techniques, emphasizing their suitability for scalable integration into devices, (ii) various transduction methods to design diverse electroanalytical device architectures, (iii) a myriad of applications using devices based on graphene, its derivatives, and hybrids with other nanomaterials, and (iv) emerging technologies at the intersection of device engineering and advanced data analytics. Finally, some of the major hurdles that graphene biodevices face for translation into clinical applications are discussed.

Flake-like structure of SrTiO3 nanoparticles dispersed on graphene oxide: A selective and sensitive electrochemical sensor for determination of chloramphenicol in milk and honey samples

The use of Chloramphenicol (CAP), a potent antibiotic with broad-spectrum capabilities in food-producing animals has been restricted by the European Union and several other countries due to its severe side effects. Thus, CAP must be detected quickly and sensitively. In this investigation, the preparation of SrTiO3 nanoparticles was carried out utilizing a hydrothermal technique. The as-synthesized strontium titanate was decorated on the graphene oxide (SrTiO3/GO) using an ultrasonication method. An electrochemical sensor was developed by employing a modified electrode consisting of SrTiO3/GO, which can accurately detect CAP in food samples. The synergistic effect of SrTiO3 and GO could improve the peak current response. Remarkably, the SrTiO3/GO-modified glassy carbon electrode has a LOD and sensitivity of 6.08 µM nM and 2.771 µA·μM-1·cm-2, respectively. This modified electrode was evaluated in food samples and had an outstanding reaction with a high percentage of recovery, which makes it a potential electrocatalyst for CAP detection.

MXene Key Composites: A New Arena for Gas Sensors

With the development of science and technology, the scale of industrial production continues to grow, and the types and quantities of gas raw materials used in industrial production and produced during the production process are also constantly increasing. These gases include flammable and explosive gases, and even contain toxic gases. Therefore, it is very important and necessary for gas sensors to detect and monitor these gases quickly and accurately. In recent years, a new two-dimensional material called MXene has attracted widespread attention in various applications. Their abundant surface functional groups and sites, excellent current conductivity, tunable surface chemistry, and outstanding stability make them promising for gas sensor applications. Since the birth of MXene materials, researchers have utilized the efficient and convenient solution etching preparation, high flexibility, and easily functionalize MXene with other materials to prepare composites for gas sensing. This has opened a new chapter in high-performance gas sensing materials and provided a new approach for advanced sensor research. However, previous reviews on MXene-based composite materials in gas sensing only focused on the performance of gas sensing, without systematically explaining the gas sensing mechanisms generated by different gases, as well as summarizing and predicting the advantages and disadvantages of MXene-based composite materials. This article reviews the latest progress in the application of MXene-based composite materials in gas sensing. Firstly, a brief summary was given of the commonly used methods for preparing gas sensing device structures, followed by an introduction to the key attributes of MXene related to gas sensing performance. This article focuses on the performance of MXene-based composite materials used for gas sensing, such as MXene/graphene, MXene/Metal oxide, MXene/Transition metal sulfides (TMDs), MXene/Metal-organic framework (MOF), MXene/Polymer. It summarizes the advantages and disadvantages of MXene composite materials with different composites and discusses the possible gas sensing mechanisms of MXene-based composite materials for different gases. Finally, future directions and inroads of MXenes-based composites in gas sensing are presented and discussed.

Recent advances and perspectives in solar photothermal conversion and storage systems: A review

Developing high-efficiency solar photothermal conversion and storage (SPCS) technology is significant in solving the imbalance between the supply and demand of solar energy utilization in time and space. Aiming at the current research status in the field of SPCS, this review thoroughly examines the phase change materials and substrates in SPCS systems. It elucidates the design principles and methods of SPCS integrated composites. Comparatively, it analyzes the parameters of various types of SPCS composites in terms of photothermal conversion, thermal conductivity, energy density, and cycling stability. Additionally, the review discusses the trade-offs between each parameter to achieve the most optimal effect of SPCS. By sorting out the current status of the application of SPCS technology in solar thermal/photovoltaic, aerospace, buildings, textile, and other industries, this analysis clarifies the requirements for various latent heat, phase change temperature, and other properties under different environmental conditions. Through a comprehensive discussion of SPCS technology, this paper accurately captures the development trend of efficiently and comprehensively utilizing solar energy by analyzing existing scientific problems. It identifies bottlenecks in SPCS technology and suggests future development directions that need focused attention. The insights gained from this analysis may provide a theoretical basis for designing strategies, enhancing performance, and promoting the application of SPCS.

Progress of Research on Conductive Hydrogels in Flexible Wearable Sensors

Conductive hydrogels, characterized by their excellent conductivity and flexibility, have attracted widespread attention and research in the field of flexible wearable sensors. This paper reviews the application progress, related challenges, and future prospects of conductive hydrogels in flexible wearable sensors. Initially, the basic properties and classifications of conductive hydrogels are introduced. Subsequently, this paper discusses in detail the specific applications of conductive hydrogels in different sensor applications, such as motion detection, medical diagnostics, electronic skin, and human-computer interactions. Finally, the application prospects and challenges are summarized. Overall, the exceptional performance and multifunctionality of conductive hydrogels make them one of the most important materials for future wearable technologies. However, further research and innovation are needed to overcome the challenges faced and to realize the wider application of conductive hydrogels in flexible sensors.

Magnetite nanoparticles decorated on cellulose aerogel for p-nitrophenol Fenton degradation: Effects of the active phase loading, cross-linker agent and preparation method

Magnetite nanoparticles (Fe3O4 NPs) are among the most effective Fenton-Like heterogeneous catalysts for degrading environmental contaminants. However, Fe3O4 NPs aggregate easily and have poor dispersion stability because of their magnetic properties, which seriously decrease their catalytic efficiency. In this study, a novel environmentally friendly method for synthesising Fe3O4@CA was proposed. Fe3O4 NPs were immobilized on the 3D cellulose aerogels (CAs) in order to augment the degradation efficiency of p-nitrophenol (PNP) treatment and make the separation of the catalyst accessible by vacuum filtration method. Besides, CAs were fabricated from a cellulose source extracted from water hyacinth by using different cross-linking agents, such as kymene (KM) and polyvinyl alcohol-glutaraldehyde system (PVA-GA), and other drying methods, including vacuum thermal drying and freeze drying, were evaluated in the synthesis process. As-synthesized samples were analysed by various methods, including Powder X-ray diffraction, Fourier transform infrared spectroscopy, field emission scanning electron microscopy, energy dispersive X-ray analysis and Brunauer-Emmett-Teller. Then, using ultraviolet-visible spectroscopy, the difference in the degradability of PNP of the obtained material samples was also investigated to determine their potential applications. Results highlighted that the Fe3O4-3@CA-KF catalyst with an Fe3O4 loading of 0.40 g/gCA used KM as a cross-linker and the freeze-drying method demonstrated the highest PNP removal efficiency (92.5 %) in all Fe3O4@CA samples with a H2O2 content of 5 g/L. The degradation kinetics and well-fitted pseudo-first-order model were investigated. Notably, after five successive PNP degradation experiments, this catalyst retained ∼80 % of the ability to degrade PNP, indicating its outstanding reusability. In environmental remediation, this study provides valuable insights into the development of simply separated and high-efficiency catalysts for heterogeneous catalytic reactions.

Environmental biotechnology and the involving biological process using graphene-based biocompatible material

Biotechnology is a promising approach to environmental remediation but requires improvement in efficiency and convenience. The improvement of biotechnology has been illustrated with the help of biocompatible materials as biocarrier for environmental remediations. Recently, graphene-based materials (GBMs) have become promising materials in environmental biotechnology. To better illustrate the principle and mechanisms of GBM application in biotechnology, the comprehension of the biological response of microorganisms and enzymes when facing the GBMs is needed. The review illustrated distinct GBM-microbe/enzyme composites by providing the GBM-microbe/enzyme interaction and the determining factors. There are diverse GBM modifications for distinct biotechnology applications. Each of these methods and applications depends on the physicochemical properties of GBMs. The applications of these composites were mainly categorized as pollutant adsorption, anaerobic digestion, microbial fuel cells, and organics degradation. Where information was available, the strategies and mechanisms of GBMs in improving application efficacies were also demonstrated. In addition, the biological response, from microbial community changes, extracellular polymeric substances changes to biological pathway alteration, may become important in the application of these composites. Furthermore, we also discuss challenges facing the environmental application of GBMs, considering their fate and toxicity in the ecosystem, and offer potential solutions. This research significantly enhances our comprehension of the fundamental principles, underlying mechanisms, and biological pathways for the in-situ utilization of GBMs.

Enhanced reduction of nitrate by TDER packed with surface-modified plastic particles electrodes

Based on Iron cathodes, nitrate could be selectively decomposed into other lower-valence nitrogen compounds, including ammonia, nitrogen gas, nitrite and nitric oxide, but the removal efficiencies of nitrate and total nitrogen (TN), are affected significantly by the synergistic effects of anodes, chloride electrolyte and conductive plastic particles electrodes. In this work, the base material Titanium (Ti) metal plates and plastic particles which surfaces were mainly coated with Ru-Sn oxidizing compounds, were applied as plates anodes and conductive particles electrodes in Three Dimensional Electrode Reactors (TDER). The Ti/RuSn plate anodes showed excellent performance on degrading nitrate, more nitrogen gas (83.84%) and less ammonia (15.51%) was produced, less TN and Iron ion (0.02 mg/L) was left in the wastewater, and less amount of chemical sludge (0.20 g/L) was produced. Furthermore, the removal efficiencies of nitrate and TN were further increased by the surface-modified plastic particles, which were cheap, reusable, corrosion-resistance, easy to obtain as manufactured materials and light to be suspended in waters. The degradation of nitrate and its intermediates was enhanced possibly by the continuous synergistic reactions initiated by hydrogen radicals, which was generated on the countless surficial active Ru-Sn sites of Ti/RuSn metal plate anodes and plastic particles electrodes, among residual nitrogen intermediates, most of ammonia was selectively converted to gaseous nitrogen by hypochlorite from chloride ion reaction.

In situ preparation of MOF-199 into the carrageenan-grafted-polyacrylamide@Fe3O4 matrix for enhanced adsorption of levofloxacin and cefixime antibiotics from water

In this research study, a novel method, an in-situ growth approach, to incorporate metal-organic framework (MOF) into carrageenan-grafted- polyacrylamide-Fe3O4 substrate was introduced. Carrageenan-grafted-polyacrylamide-Fe3O4/MOF nanocomposite (kC-g-PAAm@Fe3O4-MOF-199) was fabricated utilizing three stages. In this way, the polyacrylamide (PAAm) was grafted onto the carrageenan (kC) backbone via free radical polymerization in the presence of methylene bisacrylamide (MBA) as cross-linker and Fe3O4 magnetic nanoparticles. Next, the kC-g-PAAm@Fe3O4 was modified by MOF-199 via an in-situ solvothermal approach. Several analyses such as Fourier transform infrared spectroscopy (FT-IR), X-Ray diffraction (XRD), field emission scanning electron microscopy (FESEM), energy-Dispersive X-ray Spectroscopy (EDX), thermogravimetric analysis (TGA), vibrating sample magnetometer (VSM), Brunauer-Emmett-Teller (BET) demonstrated the successful synthesis of kC-g-PAAm@Fe3O4-MOF-199 magnetic hydrogel nanocomposite. The XRD pattern of magnetic hydrogel nanocomposite illustrated characteristic peaks of Fe3O4, neat kC, and MOF-199 with enhanced crystallinity in comparison with kC-g-PAAm@Fe3O4. TGA showed it has a char yield of 24 wt% at 800 °C. VSM confirmed its superparamagnetic behavior (with Ms of 8.04 emu g-1), and the BET surface area of kC-g-PAAm@Fe3O4-MOF-199 was measured at 64.864 m2 g-1, which was higher than that of kC-g-PAAm@Fe3O4 due to the highly porous MOF-199 incorporation with a BET surface area of 905.12 m2 g-1). The adsorption effectiveness of kC-g-PAAm@Fe3O4-MOF-199 for eliminating cephalosporin and quinolones antibiotics, i.e., Cefixime (CFX) and Levofloxacin (LEV) from the aquatic area was considered. Several experimental setups were used to evaluate the efficacy of adsorption, such as solution pH, amount of adsorbent, contact duration, and initial concentration. The maximum adsorption capacity (Qmax) of the prepared magnetic hydrogel nanocomposite was found to be 2000 and 1666.667 mg-1 for LEV and CFX using employing 0.0025 g of adsorbent. The Freundlich isotherm model well described the experimental adsorption data with R2CFX = 0.9986, and R2LEV = 0.9939. And the adsorption kinetic data were successfully represented by the pseudo-second-order model with R2LEV = 0.9949 and R2CFX = 0.9906. Hydrogen bonding, π-π interaction, diffusion, and entrapment in the hydrogel network all contributed to the successful adsorption of both antibiotics onto the kC-g-PAAm@Fe3O4-MOF-199 adsorbent. Other notable physicochemical properties include the three-dimensional structure and availability of the reactive adsorption sites. Moreover, the adsorption/desorption efficacy of magnetic hydrogel nanocomposites was not significantly diminished after four cycles of recovery.

Development of metal free carbon catalyst derived from Parthenium hysterophorus for the electrochemical detection of dopamine

Parthenium hysterophorus, one of the seven most hazardous weeds is widely known for its allergic, respiratory and skin-related disorders. It is also known to affect biodiversity and ecology. For eradication of the weed, its effective utilization for the successful synthesis of carbon-based nanomaterial is a potent management strategy. In this study, reduced graphene oxide (rGO) was synthesized from weed leaf extract through a hydrothermal-assisted carbonization method. The crystallinity and geometry of the as-synthesized nanostructure are confirmed from the X-ray diffraction study, while the chemical architecture of the nanomaterial is ascertained through X-ray photoelectron spectroscopy. The stacking of flat graphene-like layers with a size range of ∼200-300 nm is visualized through high-resolution transmission electron microscopy images. Further, the as-synthesized carbon nanomaterial is advanced as an effective and highly sensitive electrochemical biosensor for dopamine, a vital neurotransmitter of the human brain. Nanomaterial oxidizes dopamine at a much lower potential (0.13 V) than other metal-based nanocomposites. Moreover, the obtained sensitivity (13.75 and 3.31 μA μM-1 cm-2), detection limit (0.6 and 0.8 μM), the limit of quantification (2.2 and 2.7 μM) and reproducibility calculated through cyclic voltammetry/differential pulse voltammetry respectively outcompete many metal-based nanocomposites that were previously used for the sensing of dopamine. This study boosts the research on the metal-free carbon-based nanomaterial derived from waste plant biomass.

Electrochemical-Based Sensing Platforms for Detection of Glucose and H2O2 by Porous Metal-Organic Frameworks: A Review of Status and Prospects

Establishing enzyme-free sensing assays with great selectivity and sensitivity for glucose and H₂O₂ detection has been highly required in biological science. In particular, the exploitation of nanomaterials by using noble metals of high conductivity and surface area has been widely investigated to act as selective catalytic agents for molecular recognition in sensing platforms. Several approaches for a straightforward, speedy, selective, and sensitive recognition of glucose and H₂O₂ were requested. This paper reviews the current progress in electrochemical detection using metal-organic frameworks (MOFs) for H₂O₂ and glucose recognition. We have reviewed the latest electrochemical sensing assays for in-place detection with priorities including straightforward procedure and manipulation, high sensitivity, varied linear range, and economic prospects. The mentioned sensing assays apply electrochemical systems through a rapid detection time that enables real-time recognition. In profitable fields, the obstacles that have been associated with sample preparation and tool expense can be solved by applying these sensing means. Some parameters, including the impedance, intensity, and potential difference measurement methods have permitted low limit of detections (LODs) and noticeable durations in agricultural, water, and foodstuff samples with high levels of glucose and H₂O₂.

Metal-organic frameworks-derived layered double hydroxides: From controllable synthesis to various electrochemical energy storage/conversion applications

Over the past years, metal-organic frameworks (MOF) have been directly used as electrodes or as a precursor for MOF-derived materials in energy storage and conversion systems. In the wide range of existing MOF derivatives, MOF-derived layered double hydroxides (LDHs) are determined to be promising materials due to their unique structure and features. However, MOF-derived LDHs (MDL) materials can suffer from insufficient intrinsic conductivity and agglomeration during formation. Various techniques and approaches were designed and applied to tackle these problems, such as using ternary LDHs, ion-doping, sulphurization, phosphorylation, selenization, direct growth, and conductive substrates. All the mentioned enhancement techniques aim to create the ideal electrode materials with maximum performance. In this review, we gathered and discussed the most recent progressive advances, different synthesis methodologies, unsolved challenges, applications, and electrochemical and electrocatalytic performance of MDL materials. We hope this work will be a reliable source for future progress and synthesis of these materials.

Construction of superhydrophobic graphene-based coating on steel substrate and its ultraviolet durability and corrosion resistance properties

For the first time, a facile and environmentally friendly approach for producing high-quality graphene from the biomass of banana leaves is described in this paper. Two rough coats of Ni-graphene, Ni@G, and Ni-graphene doped with chromium, Ni@Cr-G, were created on steel substrates by electrostatic deposition. These coatings were then submerged in an ethanolic solution of myristic acid, MA, to produce a superhydrophobic, SHP, surface. The Raman spectra demonstrated that the generated graphene was of high quality. Fourier transform infrared spectroscopy findings confirm the modification of the Ni@G coating by MA, Ni@G@MA, and the modification of the Ni@Cr-G composite with MA, Ni@Cr-G@MA. The results of the scanning electron microscope revealed that the created SHP coatings have nanoscale features. The wettability results showed that the water contact angle values for Ni@G@MA and Ni@Cr-G@MA coatings are 158° and 168°, while the water sliding angle values for both coatings are 4.0 ^o and 1.0°, respectively. The atomic force microscopy results show that both Ni@G and Ni@Cr-G coatings increase the roughness of the steel. The chemical and mechanical stability of the Ni@Cr-G@MA coating was higher than those of the Ni@G@MA coating. The coated steel by Ni@Cr-G@MA exhibits UV stability up to 110 h, while the SHP-coated steel by Ni@G@MA exhibits UV stability for 60 h. The potentiodynamic polarization results show that the value of the corrosion current density for bare steel is 13 times that of steel coated with Ni@G@MA, and 21 times that of coated steel with Ni@Cr-G@MA. The electrochemical impedance spectroscopy, EIS, results show that the charge transfer resistance for steel coated with Ni@G@MA is 38 times that of bare steel, while steel coated with Ni@Cr-G@MA is 57 times that of bare steel. Potentiodynamic polarization and EIS results show that the SHP Ni@Cr-G@MA film exhibits higher corrosion resistance than Ni@G@MA film.

Core-shell alginate beads as green reactor to synthesize grafted composite beads to efficiently boost single/co-adsorption of dyes and Pb(II)

A series of sodium alginate (SA) grafted polymer composite beads were synthesized by a solution free-radical graft polymerization reaction performed in a surface crosslinked alginate bead reactor. The outer surface of the precursor droplet containing reactants including SA, acrylamide (AM), N,N'-methylene-bis-acrylamide (MBA), ammonium persulfate (APS), sepiolite (SP) and gelatin (GE) was instantly crosslinked with Ca²⁺ ions to form a capsule-like bead when it was dropped into aqueous solution of calcium chloride, and simultaneously the reactants inside the capsule-like "bead reactor" were polymerized in-situ to form new composite beads with crosslinked network structure, abundant functional groups, single or co-adsorption ability and easily separable advantages. The optimal composite bead shows high adsorption capacity of 390.78, 1425.65 and 533.91 mg/g towards Methylene Blue (MB), Basic Fuchsin (BF) and Pb(II), respectively. After adsorption by the composite bead, 99.71% of MB, 99.99% of BF and 99.97% of Pb(II) were removed from original dye or Pb(II) solutions. Moreover, above 99.22% of BF and 95.33% of Pb(II) was co-removed from their binary mixture (BF concentration, 100 mg/L; Pb(II) concentration, 50 mg/L). This paper provides a simple green way to synthesize efficient and recyclable biopolymer-based adsorbents capable of purifying dyes and heavy metal ions in water.

CO2 and CH2 Adsorption on Copper-Decorated Graphene: Predictions from First Principle Calculations

Single-layer graphene decorated with monodisperse copper nanoparticles can support the size and mass-dependent catalysis of the selective electrochemical reduction of CO2 to ethylene (C2H4). In this study, various active adsorption sites of nanostructured Cu-decorated graphene have been calculated by using density functional theory to provide insight into its catalytic activity toward carbon dioxide electroreduction. Based on the results of our calculations, an enhanced adsorption of the CO2 molecule and CH2 counterpart placed atop of Cu-decorated graphene compared to adsorption at pristine Cu metal surfaces was predicted. This approach explains experimental observations for carbon-based catalysts that were found to be promising for the two-electron reduction reaction of CO2 to CO and, further, to ethylene. Active adsorption sites that lead to a better catalytic activity of Cu-decorated graphene, with respect to general copper catalysts, were identified. The atomic configuration of the most selective CO2 toward the reduction reaction nanostructured catalyst is suggested.

Electrochemical Sensors and Biosensors for the Analysis of Tea Components: A Bibliometric Review

Tea is a popular beverage all around the world. Tea composition, quality monitoring, and tea identification have all been the subject of extensive research due to concerns about the nutritional value and safety of tea intake. In the last 2 decades, research into tea employing electrochemical biosensing technologies has received a lot of interest. Despite the fact that electrochemical biosensing is not yet the most widely utilized approach for tea analysis, it has emerged as a promising technology due to its high sensitivity, speed, and low cost. Through bibliometric analysis, we give a systematic survey of the literature on electrochemical analysis of tea from 1994 to 2021 in this study. Electrochemical analysis in the study of tea can be split into three distinct stages, according to the bibliometric analysis. After chromatographic separation of materials, electrochemical techniques were initially used only as a detection tool. Many key components of tea, including as tea polyphenols, gallic acid, caffeic acid, and others, have electrochemical activity, and their electrochemical behavior is being investigated. High-performance electrochemical sensors have steadily become a hot research issue as materials science, particularly nanomaterials, and has progressed. This review not only highlights these processes, but also analyzes and contrasts the relevant literature. This evaluation also provides future views in this area based on the bibliometric findings.

Electronic and optical properties of hydrogen-terminated biphenylene nanoribbons: a first-principles study

The electronic structures and optical properties of novel 2D biphenylene and hydrogen-terminated nanoribbons of different widths which are cut from a layer of biphenylene were explored via first-principles calculations. The findings of phonon computations demonstrate that such a biphenylene is dynamically stable and shows metallic properties. The crystal orbital Hamilton population analysis indicates that the tetra-ring local structure results in anisotropic mechanical properties. For 1D nanoribbons, their band gaps shrink, and a direct-indirect transition occurs in the band gap as the width increases, transforming the nanoribbon to endow them with metallic characteristics at a certain width. This is attributed to the weak coupling between the tetra-ring atoms, shrinking the direct band gap at the Y point in the Brillouin zone. Finally, the contribution of interband transitions to the dielectric function in 6-, 9-, and 12-armchair biphenylene nanoribbons (ABNRs) was identified. The lowest peak in the imaginary part of the dielectric function ε₂ spectrum was mainly a contribution of a Γ-Γ transition. As the width of ABNR increases, the transitions in the x direction become stronger while the transition strength in the y direction is not significantly altered. This investigation extends the understanding of the electronic and optical properties of 2D biphenylene and 1D nanoribbons, which will benefit the practical applications of these materials in optoelectronics and electronics.

Recent Advancements in the Technologies Detecting Food Spoiling Agents

To match the current life-style, there is a huge demand and market for the processed food whose manufacturing requires multiple steps. The mounting demand increases the pressure on the producers and the regulatory bodies to provide sensitive, facile, and cost-effective methods to safeguard consumers' health. In the multistep process of food processing, there are several chances that the food-spoiling microbes or contaminants could enter the supply chain. In this contest, there is a dire necessity to comprehend, implement, and monitor the levels of contaminants by utilizing various available methods, such as single-cell droplet microfluidic system, DNA biosensor, nanobiosensor, smartphone-based biosensor, aptasensor, and DNA microarray-based methods. The current review focuses on the advancements in these methods for the detection of food-borne contaminants and pathogens.

Chitosan based adsorbents for the removal of phosphate and nitrate: A critical review

The tremendous development in the industrial sector leads to discharging of the several types of effluents containing detrimental contaminants into water sources. Lately, the proliferation of toxic anions particularly phosphates and nitrates onto aquatic systems certainly depreciates the ecological system and causes a deadly serious problem. Chitosan (Cs) is one of the most auspicious biopolymer adsorbents that are being daily developed for removing of various contaminants from polluted water. This is due to its unparalleled benefits involving biocompatibility, non-toxicity, facile modifications and low-cost production. Nevertheless, chitosan displays considerable drawbacks including low adsorption capacity, low surface area and lack of reusability. Therefore, few findings have been established regarding the aptitude of modified chitosan-based adsorbents towards phosphate and nitrate anions. This review elaborates an overview for the current advances of modified chitosan based-adsorbent for phosphate and nitrate removal, in specific multivalent metals-modified chitosan, clays and zeolite-modified chitosan, magnetic chitosan and carbon materials-modified chitosan. The efforts that have been executed for enriching their adsorption characteristics as well as their possible adsorption mechanisms and reusability were well addressed. Besides, the research conclusions for the optimum adsorption conditions were also discussed, along with emphasizing the foremost research gaps and future potential trends that could motivate further research and innovation to find best solutions for water treatment problems facing the world.

Recent Progress in LDH@Graphene and Analogous Heterostructures for Highly Active and Stable Photocatalytic and Photoelectrochemical Water Splitting

Photocatalytic (PC) and photoelectrochemical (PEC) water splitting is a plethora of green technological process, which transforms copiously available photon energy into valuable chemical energy. With the augmentation of modern civilization, developmental process of novel semiconductor photocatalysts proceeded at a sweltering rate, but the overall energy conversion efficiency of semiconductor photocatalysts in PC/PEC is moderately poor owing to the instability ariseing from the photocorrosion and messy charge configuration. Particularly, layered double hydroxides (LDHs) as reassuring multifunctional photocatalysts, turned out to be intensively investigated owing to the lamellar structure and exceptional physico-chemical properties. However, major drawbacks of LDHs material are its low conductivity, sluggish mass transfer and structural instability in acidic media, which hinder their applicability and stability. To surmount these obstacles, the formation of LDH@graphene and analogus heterostructures could proficiently amalgamate multi-functionalities, compensate distinct shortcomings, and endow novel properties, which ensure effective charge separation to result in stability and superior catalytic activities. Herein, we aim to summarize the currently updated synthetic strategies used to design heterostructures of 2D LDHs with 2D/3D graphene and graphene analogus material as graphitic carbon nitride (g-C₃ N₄ ), and MoS₂ as mediator, or interlayer support, or co-catalyst or vice versa for superior PC/PEC water splitting activities along with long-term stabilities. Furthermore, latest characterization technique measuring the stability along with variant interface mode for imparting charge separation in LDH@graphene and graphene analogus heterostructure has been identified in this field of research with understanding the intrinsic structural features and activities.

Development of ESAT-6 Based Immunosensor for the Detection of Mycobacterium tuberculosis

Early secreted antigenic target of 6 kDa (ESAT-6) has recently been identified as a biomarker for the rapid diagnosis of tuberculosis. We propose a stable and reusable immunosensor for the early diagnosis of tuberculosis based on the detection and quantification of ESAT-6 via cyclic voltammetry (CV). The immunosensor was synthesized by polymerizing aniline dispersed with the reduced graphene oxide (rGO) and Ni nanoparticles, followed by surface modification of the electroconductive polyaniline (PANI) film with anti-ESAT-6 antibody. Physicochemical characterization of the prepared materials was performed by several analytical techniques, including FE-SEM, EDX, XRD, FT-IR, Raman, TGA, TPR, and BET surface area analysis. The antibody-modified Ni-rGO-PANI electrode exhibited an approximately linear response (R2 = 0.988) towards ESAT-6 during CV measurements over the potential range of -1 to +1 V. The lower detection limit for ESAT-6 was approximately 1.0 ng mL-1. The novelty of this study includes the development of the reusable Ni-rGO-PANI-based electrochemical immunosensor for the early diagnosis of tuberculosis. Furthermore, this study successfully demonstrates that electro-conductive PANI may be used as a polymeric substrate for Ni nanoparticles and rGO.

Graphene family for hydrogen peroxide production in electrochemical system

The development of carbon-based materials to catalyze two-electron (2e^-) pathway of oxygen reduction reaction (ORR) offers great potential for hydrogen peroxide (H₂O₂) production. As a class of novel two-dimensional (2D) carbon materials, graphene and its derivatives have raised increasing attention as excellent noble-metal-free catalysts in 2e ORR due to their unique structure, physical and chemical properties. This review focuses on the synthesis of main graphene family members and graphene based electrodes, as well as their applications for H₂O₂ generation in electrochemical systems. We describe the functions of the graphene family in electrochemical systems, such as accelerating electron transfer and increasing oxygen transfer for cathodes in electrochemical systems, aiming to reveal the enhancement mechanisms of graphene and its derivatives on H₂O₂ production. Furthermore, the challenges and prospects for graphene family used as catalyst for H₂O₂ production in the future are also proposed.

Electrochemical energy storage electrodes from fruit biochar

This review investigates the electrochemical energy storage electrode (EESE) as the most important part of the electrochemical energy storage devices (EES) prepared from fruit-derived carbon. The EES devices include batteries, supercapacitors, and hybrid devices that have various regular and advanced applications. The preparation of EESE from fruit wastes not only reduce the price of the electrode but also lead to enhance the electrochemical properties of the electrode. The astonishing results of fruits biochar at electrochemical analyses guarantee the performance of these electrodes as EESE. Also, using fruit waste as the precursor of the EESE due to protect the environment and reduce environmental pollutions.

Carbon Nanomaterials as Versatile Platforms for Biosensing Applications

A biosensor is defined as a measuring system that includes a biological receptor unit with distinctive specificities toward target analytes. Such analytes include a wide range of biological origins such as DNAs of bacteria or viruses, or proteins generated from an immune system of infected or contaminated living organisms. They further include simple molecules such as glucose, ions, and vitamins. One of the major challenges in biosensor development is achieving efficient signal capture of biological recognition-transduction events. Carbon nanomaterials (CNs) are promising candidates to improve the sensitivity of biosensors while attaining low detection limits owing to their capability of immobilizing large quantities of bioreceptor units at a reduced volume, and they can also act as a transduction element. In addition, CNs can be adapted to functionalization and conjugation with organic compounds or metallic nanoparticles; the creation of surface functional groups offers new properties (e.g., physical, chemical, mechanical, electrical, and optical properties) to the nanomaterials. Because of these intriguing features, CNs have been extensively employed in biosensor applications. In particular, carbon nanotubes (CNTs), nanodiamonds, graphene, and fullerenes serve as scaffolds for the immobilization of biomolecules at their surface and are also used as transducers for the conversion of signals associated with the recognition of biological analytes. Herein, we provide a comprehensive review on the synthesis of CNs and their potential application to biosensors. In addition, we discuss the efforts to improve the mechanical and electrical properties of biosensors by combining different CNs.

3D Graphene Materials: From Understanding to Design and Synthesis Control

Carbon materials, with their diverse allotropes, have played significant roles in our daily life and the development of material science. Following 0D C₆₀ and 1D carbon nanotube, 2D graphene materials, with their distinctively fascinating properties, have been receiving tremendous attention since 2004. To fulfill the efficient utilization of 2D graphene sheets in applications such as energy storage and conversion, electrochemical catalysis, and environmental remediation, 3D structures constructed by graphene sheets have been attempted over the past decade, giving birth to a new generation of graphene materials called 3D graphene materials. This review starts with the definition, classifications, brief history, and basic synthesis chemistries of 3D graphene materials. Then a critical discussion on the design considerations of 3D graphene materials for diverse applications is provided. Subsequently, after emphasizing the importance of normalized property characterization for the 3D structures, approaches for 3D graphene material synthesis from three major types of carbon sources (GO, hydrocarbons and inorganic carbon compounds) based on GO chemistry, hydrocarbon chemistry, and new alkali-metal chemistry, respectively, are comprehensively reviewed with a focus on their synthesis mechanisms, controllable aspects, and scalability. At last, current challenges and future perspectives for the development of 3D graphene materials are addressed.

Extraction of Graphene Nanostructures from Colocasia esculenta and Nelumbo nucifera Leaves and Surface Functionalization with Tin Oxide: Evaluation of Their Antibacterial Properties

Expeditious evolution of antimicrobial resistance in recent years has been identified as a growing concern by various health organizations around the world. Herein, facile and environmentally benign production of highly antibacterial carbonaceous nanomaterials from Colocasia esculenta and Nelumbo nucifera leaves is reported. After carbonization and oxidative treatment, smaller graphene domains are formed in Colocasia esculenta derivatives, whereas larger sheetlike structures are observed in the case of Nelumbo nucifera. Smaller particle size makes quantum confinement effects more prominent, as is evident in fine-tuning of the photoluminescence emission after each stage of treatment. The influence of precursor materials on the antibacterial properties of the nanosystems is also demonstrated. When microbiocidal activity was tested against model bacteria Pseudomonas aeruginosa, the nanocomposite derived from Colocasia esculenta leaves showed higher activity than the antibiotic drug clarithromycin (control) with a measured zone of inhibition of 40±0.5 mm. This is one of the highest values reported in comparison with plant-based carbon-silver nanosystems. Quantitative analysis revealed that the nanocomposite obtained from Colocasia esculenta leaves has antimicrobial efficacy equivalent to those of commercial antibiotic drugs and is able to eradicate bacteria at much lower concentrations than that obtained from Nelumbo nucifera leaves.

Graphene-Modified Composites and Electrodes and Their Potential Applications in the Electro-Fenton Process

In recent years, graphene-based materials have been identified as an emerging and promising new material in electro-Fenton, with the potential to form highly efficient metal-free catalysts that can be employed in the removal of contaminants from water, conserving precious water resources. In this review, the recent applications of graphene-based materials in electro-Fenton are described and discussed. Initially, homogenous and heterogenous electro-Fenton methods are briefly introduced, highlighting the importance of the generation of H2O2 from the two-electron reduction of dissolved oxygen and its catalysed decomposition to produce reactive and oxidising hydroxy radicals. Next, the promising applications of graphene-based electrodes in promoting this two-electron oxygen reduction reaction are considered and this is followed by an account of the various graphene-based materials that have been used successfully to give highly efficient graphene-based cathodes in electro-Fenton. In particular, graphene-based composites that have been combined with other carbonaceous materials, doped with nitrogen, formed as highly porous aerogels, three-dimensional materials and porous gas diffusion electrodes, used as supports for iron oxides and functionalised with ferrocene and employed in the more effective heterogeneous electro-Fenton, are all reviewed. It is perfectly clear that graphene-based materials have the potential to degrade and mineralise dyes, pharmaceutical compounds, antibiotics, phenolic compounds and show tremendous potential in electro-Fenton and other advanced oxidation processes.

Overview of biochar production from preservative-treated wood with detailed analysis of biochar characteristics, heavy metals behaviors, and their ecotoxicity

Concerns over the disposal of preservative-treated wood waste and its related environmental problems are the main driving forces of research into the recycling of preservative-treated wood. Preservative-treated wood waste composed of cellulose, hemicellulose, and lignin with several types of heavy metals can be recycled in various ways, such as wood-based composites, heavy metal extraction, energy recovery, etc. In particular, thermochemical conversion has attracted considerable attention recently because energy can be recovered from biomass as liquid fuel and bio-oil, as well as produce bio-char with a high carbon content, which can be applied to valuable products, such as soil amendment, adsorbents, solid fuels, and catalyst supports. On the other hand, environmental issues, such as heavy metal volatilization and heavy metal leaching, are still a challenge. This review reports the state-of-the-art knowledge of biochar production from preservative-treated wood with the main focus on the feedstock, process technology, biochar characteristics, application, and environmental issues. This review provides important information for future studies into the recycling of preservative-treated woods into biochar.

Simultaneous determination of dihydroxybenzene isomers using a three-dimensional over-oxidized polypyrrole–reduced graphene oxide composite film electrode prepared by an electrochemical method

A 3D-over-oxidized polypyrrole–reduced graphene oxide composite film was prepared by an electrochemical procedure, which showed high electrochemical activity and good selectivity for simultaneous determination of dihydroxybenzene isomers.

Properties of multifunctional composite materials based on nanomaterials: a review

Composite materials are being used for high-end applications such as aviation technology, space ships, and heavy equipment manufacturing. The use of composite materials has been observed in recent advancements in the field of multifunctional composite materials (MFCMs). There is continuous progress related to improvements, innovations, and replacement of metals inspite of rigorous destructive and non-destructive testing, proving the toughness and lifelong durability of such materials. The present study aims to review the topics relevant to modern multifunctional composite materials. The reviewed articles mostly cover the field of MFCMs based on nanomaterials. The structural functions emphasize on the mechanical properties such as fracture toughness, strength, thermal stability, damping, stiffness, and tensile strength. The non-structural properties include biodegradability, thermal conductivity, electrical conductivity, and electromagnetic interference (EMI) shielding. The study has concluded that the applications of multifunctional nanoparticle-based composite materials and structures include durable but light-weight aircraft wings, components and structures of electric self-driving vehicles, and biomedical composite materials for drug delivery.

Composite materials are being used for high-end applications such as aviation technology, space ships, and heavy equipment manufacturing.

The performance of UiO-66-NH2/graphene oxide (GO) composite membrane for removal of differently charged mixed dyes

The dye wastewater treatment by membrane separation technology has obtained extensive attention in recent years. Nevertheless, it was rare for research on the removal of differently charged mixed dyes. In this study, several UiO-66-NH₂ composite membranes were prepared and optimization experiments were conducted. The performance of composite membranes were evaluated by the removal of cationic (Methylene blue, MB), neutral (Rhodamine B, RB), and anionic (Congo red, CR) dyes. The optimization results demonstrated that the UiO-66-NH₂/graphene oxide (UNG) composite membrane (PUF/PDA/UNG) which was loaded on polyurethane foam modified with polydopamine (PUF/PDA) had the best properties. In filtration experiments, the solution pH exhibited greater effect on the removal efficiency of MB and CR than RB. When NaCl, KCl, CaCl₂ and Na₂SO₄ coexisted in the dye solution, the removal efficiency of MB by PUF/PDA/UNG membrane were 96.62%, 98.17%, 86.39% and 99.34% respectively. The presence of humic acid showed slight inhibitory effect on the removal of MB by PUF/PDA/UNG membrane (71.93%). The experimental results for mixed dyes filtration showed that PUF/PDA/UNG membrane could effectively remove MB, RB and CR in binary (i.e., MB/RB and RB/CR) and ternary (i.e., MB/RB/CR) systems through secondary filtration. And PUF/PDA/UNG membrane could remove MB and CR simultaneously through one-time filtration in MB/CR binary system. The removal mechanism was mainly attributed to the aggregation of mixed dyes, electrostatic interaction between dye molecules and the membrane surface, and hydrogen bonding. All results suggested that the as-prepared PUF/PDA/UNG membrane have great potential in practical treatment of dye wastewater.

Bioelectronic tongue: Current status and perspectives

In the course of evolution, nature has endowed humans with systems for the recognition of a wide range of tastes with a sensitivity and selectivity which are indispensable for the evaluation of edibility and flavour attributes. Inspiration by a biological sense of taste has become a basis for the design of instruments, operation principles and parameters enabling to mimic the unique properties of their biological precursors. In response to the demand for fast, sensitive and selective techniques of flavouring analysis, devices belonging to the group of bioelectronic tongues (B-ETs) have been designed. They combine achievements of chemometric analysis employed for many years in electronic tongues (ETs), with unique properties of bio-inspired materials, such as natural taste receptors (TRs) regarding receptor/ligand affinity. Investigations of the efficiency of the prototype devices create new application possibilities and suggest successful implementation in real applications. With advances in the field of biotechnology, microfluidics and nanotechnologies, many exciting developments have been made in the design of B-ETs in the last five years or so. The presented characteristics of the recent design solutions, application possibilities, critical evaluation of potentialities and limitations as well as the outline of further development prospects related to B-ETs should contribute to the systematisation and expansion of our knowledge.

Ultrasensitive electrochemical detection of ochratoxin A based on signal amplification by one-pot synthesized flower-like PEDOT-AuNFs supported on a graphene oxide sponge

To enhance the sensitivity of an aptasensor, a novel strategy was designed to develop an electrochemical aptasensor based on poly(3,4-ethylenedioxy thiophene)-gold nanoflower (PEDOT-AuNF) composites supported on a three-dimensional graphene oxide sponge (GOS). GOS with a three-dimensional sponge-like porous structure, exhibiting excellent electrical conductivity and a large surface area, provided the first amplification of the electrochemical signal for ochratoxin A (OTA) detection. PEDOT-AuNFs, synthesized by an ionic liquid-assisted one-pot method, presented a peculiar hierarchical flower-like structure, a high electroactive surface area, and more binding sites for immobilizing the aptamer molecules by the Au-S bonds. When PEDOT-AuNFs were supported on the surface of GOS by the interaction of the π-π packing between PEDOT and graphene oxide, a synergistic effect was produced to provide the second amplification for the aptasensor. PEDOT-AuNFs/GOS provided an ultrasensitive detection technique by multiple signal amplification for the electrochemical sensing of OTA. Consequently, this strategy not only endowed the aptasensor with high sensitivity but also needed no complicated signal amplification. The electrochemical sensor was fabricated successfully on a glassy carbon electrode to detect OTA with a linear response in the range of 0.01-20 ng L^-1 and a limit of detection of 4.9 pg L^-1. Moreover, it displayed good specificity, reproducibility and stability. The utilization of the proposed aptasensor for the quantitative determination of OTA in wine indicates that it can find promising applications in detecting OTA and even other mycotoxins in foodstuffs.

Emerging Trends in the Syntheses of Heterocycles Using Graphene-based Carbocatalysts: An Update

Graphene-based carbocatalysts owing to numerous amazing properties such as large specific surface area, high intrinsic mobility, excellent thermal and electrical conductivities, chemical stability, ease of functionalization, simple method of preparation, effortless recovery and recyclability have gained a superior position amongst the conventional homogeneous and heterogeneous catalysts. In this review, an endeavor has been made to highlight the syntheses of diverse heterocyclic compounds catalyzed by graphene-based catalysts. Further, the study also reveals that all the catalysts could be reused several times without significant loss in their catalytic activity. Additionally, most of the reactions catalyzed by graphene-based carbocatalysts were carried out at ambient temperature and under solvent-free conditions. Thus, the graphene-based catalysts do not merely act as efficient catalysts but also serve as sustainable, green catalysts. This review is divided into various sub-sections, each of which comprehensively describes the preparation of a particular heterocyclic scaffold catalyzed by graphene-derived carbocatalyst in addition to synthesis of graphene oxide and reduced graphene oxide, functionalization, and structural features governing their catalytic properties. Synthesis of heterocycles catalyzed by graphene-based carbocatalysts.

Applications of three-dimensional graphenes for preconcentration, extraction, and sorption of chemical species: a review

This review (with 115 refs) summarizes applications of 3-dimensional graphene (3DGs) and its derivatives in the fields of preconcentration, extraction, and sorption. Following an introduction into the field (including a definition of the materials treated here), the properties and synthetic strategies for 3DGs are described. The next section covers applications of 3DG-based adsorbents in solid phase extraction of organic species including drugs, phthalate esters, chlorophenols, aflatoxins, insecticides, and pesticides. Another section treats applications of 3DGs in solid phase microextraction of species such as polycyclic aromatic hydrocarbons, alcohols, and pesticides. We also describe how the efficiency of assays may be improved by using these materials as a sorbent. A final section covers conclusions and perspectives. Graphical abstract Graphical abstract contains poor quality and small text inside the artwork. Please do not re-use the file that we have rejected or attempt to increase its resolution and re-save. It is originally poor, therefore, increasing the resolution will not solve the quality problem. We suggest that you provide us the original format. We prefer replacement figures containing vector/editable objects rather than embedded images. Preferred file formats are eps, ai, tiff and pdf.Tiff file of graphical abstract was attached. Schematic presentation of synthesis of three-dimensional graphene (3DG) from two-dimensional graphene (2DG) with self-assembly, template-assisted and direct deposition methods. Application of 3DG-based nanoadsorbents in direct immersion-solid phase microextraction (DI-SPME), headspace-SPME (HS-SPME), magnetic-solid phase extraction (Magnetic-SPE), dispersive-SPE, and magnetic sheet-SPE.