Two approaches have been utilized to optimize the energy storage characteristics of doped carbon materials derived from Lignosol, a biomass product, to address the rising energy demand issues. Herein, phosphorus and nitrogen co-doped carbon (PNDC) materials with varying doping agent volumes were synthesized by utilizing microwave irradiation. Chemical activation and physical activation were employed to enhance these materials' characteristics. Chemical activation was performed in a one-pot, single-step process, rather than a traditional multi-step protocol, using small amounts of potassium hydroxide. Furthermore, the physical activation method required multiple steps: doped carbon was prepared via microwave, exposed to water, filtered, frozen and then dried. With this, the expansion properties of water at freezing temperatures were exploited to alter the materials' surface characteristics. All materials were characterized and compared for their physicochemical properties. All defect ratios supported the presence of doping. Additional results revealed that both chemical and physical activation approaches effectively modify the topographical features as well as the electrochemical activity (charge storage) of the doped carbon materials. The chemically activated doped carbon exhibited the highest resulting surface area of 1352 m2 g-1 and a specific capacitance value of 347 F g-1 with excellent cycling stability as compared to other similarly synthesized materials.

Plastics are in high demand for various uses worldwide because of their low cost, versatility, lightweight, low density, flexibility, high strength, and durability. An increase in single-use plastics and ineffective solid waste disposal and recycling strategies have resulted in a global microplastic (MP) pollution epidemic, with negative implications for the ecosystem and public health safety. Analytical methods, including thermogravimetry and chromatography, have been developed to detect MPs. Nevertheless, molecular spectroscopy methods such as Near Infrared (NIR), Fourier Transform Infrared (FTIR), Raman, and fluorescence spectroscopy for MP analysis have gained attention in recent years due to their rapidity, low cost, accuracy, and portability of spectrometers. This review article provides in-depth coverage of the survey of current literature on the challenges, toxicity, sample pretreatment, and spectroscopic (Fluorescence, Raman, FTIR) and real-time (satellite imagery, unmanned aerial vehicles, and aquatic drone technology) microplastic detection methods. Machine learning, micro-hyperspectral imaging, and chemometrics approach to microplastic detections are discussed. The challenges, future directions, and prospects for decreasing global MP pollution and their analysis are discussed.

Fuel cells are a promising alternative to non-renewable energy production industries such as petroleum and natural gas. The cathodic oxygen reduction reaction (ORR), which makes fuel cell technology possible, is sluggish under normal conditions. Thus, catalysts must be used to allow fuel cells to operate efficiently. Traditionally, platinum (Pt) catalysts are often utilized as they exhibit a highly efficient ORR with low overpotential values. However, Pt is an expensive and precious metal, posing economic problems for commercialization. Herein, advances in carbon-based catalysts are reviewed for their application in ORRs due to their abundance and low-cost syntheses. Various synthetic methods from different renewable sources are presented, and their catalytic properties are compared. Likewise, the effects of heteroatom and non-precious metal doping, surface area, and porosity on their performance are investigated. Carbon-based support materials are discussed in relation to their physical properties and the subsequent effect on Pt ORR performance. Lastly, advances in fuel cell electrolytes for various fuel cell types are presented. This review aims to provide valuable insight into current challenges in fuel cell performance and how they can be overcome using carbon-based materials and next generation electrolytes.

In this study, we have evaluated the effect of potassium hydroxide (KOH) on the energy storage performance of metal-free carbon-based materials prepared from molasses. Molasses are a renewable-resource biomass and economical by-product of sugar refinement, used here as a carbon precursor. Two co-doped carbon materials using molasses were synthesized via a time and cost-efficient microwave carbonization process, with ammonium polyphosphate as a phosphorus and nitrogen doping agent. The phosphorus and nitrogen co-doped carbon (PNDC) samples were prepared in the presence and absence of a chemical activating agent (KOH), to study the role of chemical activation on PNDCs. Physical characterizations were performed to gain insight into the composition, pore size and topographical data of each material. Electrochemical characterization via cyclic voltammetry in 1 M sulfuric acid (H2SO4) as well as in 6 M KOH as electrolytes, revealed high current density and specific capacitance for the chemically activated material (PNDC2) compared to one without chemical activation (PNDC1). The capacitance value of 244 F/g in KOH electrolyte was obtained with PNDC2. It is concluded that addition of KOH prior to carbonization increases the surface functionality, which significantly enhances the electrochemical properties of the PNDC material such as current density, stability, and specific capacitance.

Renewable resources and their byproducts are becoming of growing interest for alternative energy. Here, we have demonstrated the use of Arkansas’ most important crop, soy, as a carbon precursor for the synthesis of carbonized activated materials for supercapacitor applications. Different soy products (soymeal, defatted soymeal, soy flour and soy protein isolate) were converted into carbonized carbon and co-doped with phosphorus and nitrogen simultaneously, using a facile and time-effective microwave synthesis method. Ammonium polyphosphate was used as a doping agent which also absorbs microwave radiation. The surface morphology of the resulting carbonized materials was characterized in detail using scanning electron microscopy. X-ray photoelectron spectroscopy was also performed, which revealed the presence of a heteroelemental composition, along with different functional groups at the surface of the carbonized materials. Raman spectroscopy results depicted the presence of both a graphitic and defect carbon peak, with defect ratios of over one. The electrochemical performance of the materials was recorded using cyclic voltammetry in various electrolytes including acids, bases and salts. Among all the other materials, soymeal exhibited the highest specific capacitance value of 127 F/g in acidic electrolytes. These economic materials can be further tuned by changing the doping elements and their mole ratios to attain exceptional surface characteristics with improved specific capacitance values, in order to boost the economy of Arkansas, USA.

High operational costs of modern medical devices and the required specialized, skilled personnel with certifications to operate most medical instrumentation remains a challenge and an impediment to rapid medical diagnosis and clinical analysis. The simplicity, portability, and ease of operation makes Raman spectrometers appealing for rapid medical diagnosis and clinical analysis at an affordable cost. Besides, the combined use of Raman spectroscopy and multivariate analyses has further facilitated effective pattern recognition providing accurate classification, and/or differentiation of biological and clinical samples. This review article highlights recent advances in Raman spectroscopy in medical diagnosis and clinical analysis between January 2018 and December 2020. Recent innovations in the use of Raman spectroscopy for chemical analysis in human specimens are discussed. Applications of Raman spectroscopy in cancer immunotherapy, cancer imaging, and detecting disease biomarkers in clinical samples are further highlighted. The review article highlights recent innovations in the use of Raman spectroscopy for the detection of various pathogens in human specimens. Moreover, recent innovations of combined uses of Raman spectroscopy and multivariate regression analyses for pattern recognition, and/or classification of clinical samples are discussed. Furthermore, insights into the projection in the use of Raman spectroscopy in medical diagnosis and clinical sample analysis are discussed.