Carbon quantum dots (CQDs) have recently emerged as promising fluorescent nanothermometers for biological applications, due to their tunable photoluminescence, low cytotoxicity, and chemical versatility. The changes in their fluorescence properties with temperature have opened new ways for precise thermal mapping at the cellular and tissue levels. This review presents a comprehensive overview of the fundamental mechanisms underlying CQD-based thermometry, emphasizing advances in material design, surface passivation, and environmental resilience. Particular attention is given to strategies that improve their stability in complex biological environments, a critical requirement for reliable intracellular sensing. Recent applications, including live-cell and in vivo thermometry, are highlighted to illustrate the expanding scope of CQD-based thermal probes. Future developments, such as near-infrared emissive CQDs, long-term biostability, and integration with machine learning and hybrid nanomaterials to achieve dynamic, high-precision thermal sensing, are outlined. By summarizing both foundational principles and emerging innovations, this review aims to provide a way to advance CQDs as indispensable tools in biomedical diagnostics, therapeutic monitoring, and thermal biology research.

Blood gas analyzers are essential tools for assessing respiratory and metabolic function, especially in patients with respiratory conditions such as COVID-19. The pandemic has underscored the need for affordable, compact, and user-friendly point-of-care testing (POCT) devices for decentralized and home care. These analyzers provide real-time information on oxygenation (pO₂), ventilation (pCO₂), and acid-base balance (pH, pCO₂, and HCO₃⁻) by arterial blood analysis. Modern systems also measure electrolytes (e.g., Na⁺, K⁺, Ca²⁺, and Cl⁻), glucose, and lactate. While widely used in emergency laboratories, ICUs, and operating rooms, their size and complexity hinder their use in ambulances and bedside settings. Overcoming this issue requires the continued development of miniaturized blood gas analyzers compatible with POCT. Carbon-based electrodes have emerged as essential because of their excellent electrical conductivity, chemical stability, biocompatibility, and compatibility with cost-effective production. These properties facilitate the development of compact and environmentally sustainable sensors. In addition, their robustness allows their repeated use, making them highly suitable for both disposable and reusable POCT devices. This review provides an overview of the electrode materials, electrode designs, and sensor technologies used in blood gas analyzers, with a particular focus on miniaturization for POCT applications.

The carbonization of organic crystalline materials, such as metal organic frameworks and covalent organic frameworks, has emerged as a promising approach for producing functional porous carbonaceous materials. However, both the chemically defined long-term ordered structures and the local chemical structures derived from these precursor materials are generally lost, resulting in amorphous carbons. As a result, controlling the molecular-level structure of nanoporous carbons remains a significant challenge. We report a new bottom-up synthesis approach for porous carbons with a molecular-level design, involving the carbonization of well-designed precursor molecules by thermal polymerization. Among the resulting carbons, ordered carbonaceous frameworks, which contain a high-density of regularly aligned single-atomic metal species, have been identified as promising platforms for single-atom catalysts. This approach also enables the synthesis of various three-dimensional porous carbons that reflect the structural features of their precursor molecules. Recent progress in the synthesis and applications of porous carbons derived from molecular precursors is summarized, highlighting their potential for the development of functional materials.

Spent coffee grounds and tea leaves were hydrothermally treated and carbonized to investigate the structure of the resulting carbons and their potential for ethene adsorption. After the hydrothermal treatments, the carbonized yield and the porosity in the carbons were increased. The increases in ultra-micropores and micropore/mesopore volumes which were respectively calculated by CO₂ and N₂ adsorption varied depending on the kind of feedstock. Hydrothermal treatment using ethanol washing to remove crystalline fatty acids, prior to carbonization, considerably increased the BET specific surface area, particularly in coffee grounds. In all carbons studied, ultra-micropores were also developed mainly by the thermal decomposition of cellulose components in the hydrochars. These narrower pores in the carbons were found to be effective for ethene adsorption because of strong correlation between ethene and CO₂ adsorptions.

The effect of the molecular structure of lithium naphthalenide derivatives on the degree of lithium pre-doping was assessed, as part of a simple pre-doping method for natural graphite electrodes. The method involves immersion in a 2-methyltetrahydrofuran (2-MeTHF) solution of lithium naphthalenide derivatives. To increase the reducing ability of lithium naphthalenide, we tested various naphthalene derivatives with electron-donating substituents on the aromatic ring. The results showed that a radical anion solution prepared from 1 mol kg⁻¹ 1,5-dimethylnaphthalene in 2-MeTHF, combined with an excess of lithium metal, achieved a degree of lithium pre-doping of 88 mAh g⁻¹ after 1 h of immersion at room temperature. This method could potentially serve as a pre-doping technique for the negative electrodes in electrochemical energy storage devices.

Graphite intercalation compounds (GICs) have been extensively studied, however, their visual appearance has not been systematically documented, and this plays a crucial role in understanding their physical properties and evaluating their potential applications. Alkali metal GICs (Li-, Na-, K-, Rb-, and Cs-GICs), which are known for their vivid gold and blue colors, were synthesized using a common host graphite under standardized conditions. Photographs were taken under controlled settings to capture their visual appearance, and reflectance spectra were measured to provide optical data, thereby contributing to a standardized color sample compilation. In addition, their structures and electrical conductivities, as well as the relationship between the crystallinity of the host graphite and the perceived appearance of the GICs, were investigated. This study provides a comprehensive reference dataset on GIC appearance, which will support future research on intercalation compounds.

Changes in the total carbon (TC), total organic carbon (TOC), total inorganic carbon (TIC), residual oxidizable carbon (ROC), and dissolved organic carbon (DOC) in soil permanently planted with white clover (Trifolium repens) and tall fescue (Festuca arundinacea) as the result of fertilization were quantified. Two nitrogen fertilisers, ammonium sulfate (AS) and urea (U), were separately applied with rice husk biochar carbonized at 700 °C (B) at 5 t ha^–1 (B5) and 10 t ha^–1 (B10). Adding the biochar to the AS or U resulted in an increase of the TOC, TIC, and ROC of both plants, with the exception of the TIC in ASB5 (white clover) and UB5 and ASB10 (tall fescue). In white clover, TC increased more when the biochar was added, particularly ASB10 and UB10, which also showed the smallest TOC reductions and largest ROC increases. In white clover, UB5 and UB10 resulted in greater DOC losses than when using U alone, likely due to increased microbial activity and mineralization of DOC. Meanwhile, in tall fescue, ASB5 and ASB10 reduced the DOC losses more than AS, likely due to the biochar’s DOC sorptive potential and reduced microbial decomposition. U fertilizer alone resulted in greater percentage changes in TC, TOC, ROC, TIC, and DOC than AS fertilizer in both plants. TC correlated positively with TIC, TOC, ROC, DOC, soil nitrogen, exchangeable calcium, and soil pH. Overall, U applied with 10 t ha^–1 biochar improved carbon stabilization in white clover, while AS with biochar reduced DOC losses in tall fescue. The study demonstrates the potential of integrating biochar with nitrogen fertilizers to increase soil carbon retention in two different pasture families.

Inks were prepared that were aqueous dispersions of single-wall carbon nanotubes (SWCNTs) for screen printing. Poly(3,4-ethylenedioxythiophene)/poly(4-styrenesulfonate) (PEDOT:PSS) was used to improve the dispersion of the SWCNTs and dimethyl sulfoxide (DMSO) was added to adjust the viscosity for screen printing as well as to increase the conductivity of films produced from it by its secondary doping effect on PEDOT:PSS. By changing the DMSO-to-PEDOT:PSS volume ratio, ink viscosity suitable for screen printing was obtained. Films screen-printed on water-resistant paper substrates using the SWCNT/PEDOT:PSS/DMSO ink at a PEDOT:PSS-to-DMSO volume ratio of 100 : 75 had a low sheet resistance of 4.0±0.4 Ω/sq without any post-treatment, such as by acid treatment or high-temperature heating. Aqueous inks suitable for the screen printing of low-resistance films will be beneficial for various applications, including circuit boards and radio frequency identification, which require low-resistance and flexible conductive films supported on fragile substrates, such as paper.

The densities (ρ) of ultrathin graphite films with thicknesses of 41–300 nm were experimentally determined by the sink–float method using acetone and diiodomethane as solvents. The films were prepared using the heat treatment of spin-coated benzimidazobenzophenanthroline ladder polymer films. The measured ρ of the films decreased with decreasing film thickness, with the thinnest film (thickness=41 nm) having the lowest ρ of 1.76±0.01 g/cm³. X-ray absorption near-edge structure measurements of the films in the C K-edge region confirmed their graphitic structure and that the thinner films had a higher degree of orientational disorder. Therefore, for the ultrathin graphitic films prepared from this precursor in the present study, those with thicknesses in the range of several tens to hundreds of nanometers were found to have lower ρ values, which may be attributed to the highly disordered local graphitic structures.

Non-graphitizable carbon has received considerable attention owing to its larger alkali metal ion capacity than that of graphite. However, the behavior of alkali metal ions at the non-graphitizable carbon/electrolyte interface remains unclear. The effects of electrolyte and solid electrolyte interphase (SEI) on alkali metal ion transfer resistance in non-graphitizable carbon were here investigated separately. In lithium-ion transfer reactions, the resistance was quite small and independent of the electrolyte or SEI. In contrast, the resistance in sodium-ion transfer reactions showed a much greater dependence on the SEI than on the electrolyte, with the SEI derived from fluoroethylene carbonate (FEC) having a larger resistance than the SEI derived from ethylene carbonate. Analysis of the SEI by X-ray photoelectron spectroscopy revealed that this FEC-based SEI contained a large amount of NaF. There were no other significant differences between EC-derived SEI and FEC-derived SEI. This finding underscores the importance of designing an optimal SEI to reduce the sodium-ion transfer resistance in non-graphitizable carbon.