Carbon quantum dots (CQDs) were synthesized via ultrasound-assisted treatment of four carbon precursors - graphite, carbon black, graphene, and graphene oxide - without the use of toxic reagents or extreme conditions. A key finding of this work is the identification of a UV-Vis absorption band in the 650-680 nm range, attributed to the Q band of metal-free phthalocyanine (pi-pi* transition), whose intensity is precursor-dependent and represents a novel optical feature of significant current interest, given the ongoing scientific discussion surrounding red-fluorescent CQDs. All obtained CQDs present nanometric sizes (average diameters between 3.2 and 4.5 nm) and negative zeta potentials ranging from -18.7 to -29.6 mV. The novel absorption feature at 650-680 nm is a key finding. Photoluminescence emission maxima were observed in the 430-512 nm region, with graphene- and graphene oxide-derived dots displaying higher emission intensities compared to those from graphite and carbon black. The effective optical band gap, estimated using the Tauc method for indirect transitions, ranges from 0.79 to 4.26 eV depending on precursor and surface state distribution. Characterization was performed by FTIR, UV-Vis, and photoluminescence (PL) spectroscopy, transmission electron microscopy (TEM), and zeta potential analysis. The crystalline structure and degree of graphitization of the precursor play a determining role in the final optical and colloidal properties of the nanomaterial. These results position the obtained CQDs as promising candidates for biosensing, bioimaging, and optoelectronic applications.

The hydroxyapatite (HA), Ca10(PO4)6(OH)2, is chemically similar to the minerals in natural body construction parts (teeth and bone) and bioactive, having excellent biocompatibility. At the same time, pristine HA possesses a certain surface reactivity and mechanical properties, insufficient for modern medical applications. This problem is being resolved by several strategies of engineering and surface functionalization to tailor properties of HA and other CaP materials. Herein, in this review we discuss most important classic and recent techniques and approaches of HA surface modification, including doping and substitution with metal and non-metal ions, coating methods, biomolecule immobilization, polymer grafting, silanization, plasma treatment, among other approaches. Several process mechanisms, chemical and structural changes in resulting compounds, leading to enhanced antibacterial activity, osteointegration, cell adhesion, drug and impurities loading and remediation, and corresponding biomedical and other applications are discussed. Key HA properties are integration with metallic or polymeric matrices, drug loading capacity, antibacterial activity (preventing colonization of bacteria), osteoconductivity, and biocompatibility of implants. Resulting surface-engineering HA-based hybrid and composite materials possess more applications in regenerative medicine, controlled drug delivery, implant technologies, and bone tissue regeneration, as well as in the non-medical areas. Several challenges remain yet non-resolved, related to the scalability of surface functionalization processes and stability of modified (functionalized) HA phases in the conditions of human body under physiological conditions, needing further investigations and strong efforts. Functionalization and surface engineering of HA are routes toward novel biomaterials for the development of implants, bone regeneration, and drug delivery. This article is a part of a multi-part review on HA functionalization and surface engineering.

The constant research for sustainable alternatives to address the global energy and environmental crisis has led to a renewed focus on solar energy as a clean and renewable energy source. Due to their unique optical and electronic properties, mixed halide perovskites offer a promising platform for CO2 conversion. Therefore, this work proposed the synthesis of mixed halide perovskites based on M3Bi2I6Br3 (M = Cs, K) for visible-light-driven CO2 and H2O conversion. The mixed perovskites were immobilized in floated (porous) substrates for easier application and easy recovery of the materials. The mixed perovskites exhibited better crystallinity, higher light absorption, and lower recombination of the photogenerated charges than the reference materials (M3Bi2I9). These properties promoted higher CO2 and H2O conversion efficiencies to generate HCOOH (3,170 mu mol) and H2 (160 mu mol), respectively. Although the efficiency of Cs3Bi2I6Br3 was higher than that of K3Bi2I6Br3, it was possible to reach the efficiency for CO2 reduction of Cs3Bi2I9. Finally, the formation of a passive layer of BiOX (X = I, Br) on the K3Bi2I6Br3 surface was demonstrated, which eventually reduced the efficiency of the CO2 reduction.

Luminescent carbon quantum dots (CQDs) were synthesized via a simple and eco-friendly approach using unfunctionalized multi-walled carbon nanotubes (MWCNTs) and hydroxyl-functionalized MWCNTs (MWCNT-COOH) as precursors. The synthesis involved a 1:1:1 mixture of MWCNTs, Theraphthal (TP), and ascorbic acid in water, followed by centrifugation and filtration. Transmission electron microscopy (TEM) confirmed the spherical morphology of the CQDs, with average sizes of 3.26 ± 0.57 nm for CQD-A and 3.46 ± 0.57 nm for CQD-B. Fourier-transform infrared (FTIR) spectroscopy and UV-Vis analysis revealed variations in surface functionalization and optical properties. The green fluorescence observed under UV irradiation highlights the potential of these CQDs for applications in bioimaging and optoelectronics.

Fluorescent nanodiamonds (FNDs) have emerged as promising tools for cell imaging, drug delivery, and other technologies. In this study, the surface of functionalized NDs was modified with an extract of the medicinal plant Cissus incisa to enhance their luminescence. NDs (3–6 nm) were dispersed in distilled water with addition of one or several components: 30

Nowadays, the continuous search of new cost-effective carbon-based materials has attracted interest due to the growing energy demand. Among these carbon-based materials, MOF-derived materials stand out due to their multiple applications. In this work, carbon-based materials, MnMO@C (M = Cu, Co, Ni), were prepared through pyrolysis of their MOF structures synthesized by solvothermal method with trimesic acid. The formed products were characterized using XRD, SEM, and XPS. Photocatalytic activity of these materials for hydrogen evolution an aqueous media was revealed, showing results of up to 296 μmol g−1 h−1 under visible-light irradiation.

Commonly used methods for MOF synthesis, such as solvothermal, mechanochemical, and electrochemical syntheses each, have their own disadvantages, such as long reaction times and the need for specialized equipment. The direct mixing method is a simple, fast, and cheap alternative that allows for MOF production at room temperature in times as short as 15 min. The room-temperature synthesis via a direct mixing method of Ni and Mg MOFs based on trimesic acid (BTC) and terephthalic acid (BDC) was studied by evaluating the effect on the product of the synthesis parameters: pH, base, stirring time, and metal–ligand molar ratio. It was found that the base used to adjust the pH was a critical factor to ensure the formation and purity of each MOF, where Na+ from NaOH could alter the crystal structure of Mg MOFs by incorporating into it due to its size similarity with Mg2+, while the ability of K+ from KOH to enter the crystal structure was much lesser due to its larger size and allowed for the proper development of the Mg MOFs crystal structure Similarly, a higher molar ratio of the ligand to the metal resulted in the incorporation of the base’s metal into the MOF as an impurity due to an excess of ligand without enough metal to coordinate with. Pure Ni-BTC and Ni-BDC MOFs could be obtained in 15 min, while the Mg-BTC MOF always contained the base-forming metal as an impurity. All the products had irregular morphologies which resulted in lower surface areas and pore volumes when compared to MOFs obtained by other methods. The improvement of these properties is crucial to make the direct mixing method a viable alternative as higher surface areas and pore volumes are beneficial for many of the applications of MOFs, and it was identified that the choice of metal salt precursor plays an important role over these properties. As such, experimentation with different precursors is an important avenue of future research for the improvement of this method.

Quantum dots (QDs) have a high light conversion coefficient, and the light they re-emit tends to have a very narrow spectrum. Graphene is considered one of the leading candidates for its application as a future element in nanoelectronics. Pure graphene is of interest as a highly durable membrane or a highly efficient sensor, while graphene quantum dots (GQDs) with a modified surface can be used in semiconductor electronics as a basis for organic diodes, light emitters, biosensors, and chemical sensors. The methods for producing graphene quantum dots involve the use of toxic compounds such as acids (HNO3, H2SO4), KMnO4, sodium borohydride, hydrazine hydrate, and dimethylhydrazine. The aim of this research is to carry out the "greener" synthesis of graphene quantum dots (GQDs). Ultrasound was applied for 12 h to black carbon and graphite precursors with reducing agents. The obtained nanoparticles were characterized by FTIR spectroscopy and UV–Vis spectroscopy.

Fluorescent nanodiamonds (FNDs) emit light through a specific type of photoluminescence in which light emission is very rapid and is quenched almost immediately upon removal of the light source. To enhance the fluorescent properties of FNDs, a sustainable synthesis and functionalization strategy was developed by combined physicochemical treatments. The primary nanodiamonds (NDs) were obtained using a hydrothermal method and subsequently functionalized using ascorbic acid (AA), theraphthal (TP), urea (UR), and 30 % hydrogen peroxide (H2O2). The surface activation was enhanced by applying direct ultrasound treatment for 15 and 20 h, along with ozone (O3) exposure for 0.75 and 1.5 h, followed by ultrasound for 5 h. Prior to the final functionalization step, the NDs suspensions were subjected to a cleaning process by centrifugation and filtration with 200 nm membranes. After functionalization, the samples were duly characterized by FT-IR, UV-Vis, and photoluminescence (PL) spectroscopy, ζ-potential analysis and electron microscopy, i.e., HR-TEM and SEM. From the detailed analyses, incorporation of oxidative and nitrogen-containing functional groups on the NDs was confirmed. Which was further corroborated by the appearance of a faint blue to lime-green photoluminescence (∼500–520 nm), which is attributed to nitrogen-related defects near the surface (with N–V–N as the most consistent interpretation under our conditions). It is deduced that, the combined treatment with O3 and ultrasound effectively favored the formation of the emissive centers and significantly reduced the duration of the experimental process. FNDs developed by this method have been shown to be extremely stable and resistant to photo-bleaching, making them highly useful for long-term bioimaging applications, diagnostics and drug release systems.

Due to the chemical similarities with calcified tissues of mammals, calcium orthophosphate (abbreviated as CaPO4) bioceramics have a broad range of promising biomedical applications. To further extend their use, CaPO4 bioceramics are modified with various additives and dopants. Since luminescence is an effective minimally invasive tool for in situ studies of tissue engineering, drug delivery and restoration phenomena, a utilization of CaPO4 bioceramics doped with luminescent compounds seems to be very promising. This approach has been developed as the result of the studies of natural CaPO4, which were found to possess luminescent properties mainly due to the presence of rare-earth (RE) dopants. In comparison to other luminescent substances, the use of luminescent CaPO4 bioceramics is an exceptional area of biomedical applications due to its biodegradability, bioactivity, biocompatibility, osteoconductivity, non-toxicity and non-inflammatory nature. Such biomaterials possess intrinsic features that can be adjusted through various ways, such as changing the available dopants and their amounts, synthesizing temperature, reaction time and production techniques. Therefore, luminescent CaPO4 bioceramics are used in a variety of biomedical applications, including imaging probes, drug delivery, bone tissue engineering and antibacterial studies. This review analyses the synthetic methods, luminous properties and biomedical applications of luminescent CaPO4 bioceramics. Future directions are also outlined.

Hydroxyapatite, a bioceramic material, possesses sufficient stability in aqueous and organic medium and it is mainly known for its role in tooth and bone structure. However, it is less-known that, in certain conditions, the HA can be used as a catalyst in its free, metal-doped and composite forms. HA as a catalyst is generally prepared by impregnation or co-precipitation methods, sometimes from natural P-containing wastes. HA can be doped with mono- or polymetallic ions or nanoparticles and can contain other admixtures or supports (i.e., carbon). Different Ca/P ratios (ideal 1.67; the ranges are 1.5-1.7 in synthetic and 1.5-1.8 in biologic forms) can be revealed for the HA. Nanosized HA forms are frequent in several applications. A variety of distinct processes can be HA-catalyzed, such as oxidation of alcohols, dehydrogenation, hydrogenation and hydrogenolysis, C-C bond formation, among other important existing low- and large-scale organic processes. The HA can be also used for catalytic environmental remediation, CO2 fixation, and N2O decomposition. In this review, we emphasize most recent advances (mainly last decade) on the catalytic HA applications, except for biomedical ones.

The worst scenario for the humanity due to climate change and limiting global temperature seems now real and can be avoided, applying the ideas, approaches and solutions of the “carbon negative footprint” in decrease of greenhouse gas emissions and reaching their net zero. Herein, we describe main definitions and terms of the carbon neutrality and negativity, current and near-future trends in achieving their goals, and corresponding techniques and materials. Global strategies to reach carbon neutrality/negativity are discussed, including green chemistry routes, efficient materials processing, correct materials selection and substitution, use of naturally renewable and recyclable materials, among other definite or synergistic carbon-capture ideas. Carbon negative materials include biochar, several carbon negative concretes and cements, biomass, bamboo-, wood- and grass-derived construction materials, recycled polymers and biopolymers, MOFs and MOF-derived nanocarbons, as well as other nanomaterials and nanocomposites on their basis, including nano-enabled membranes and filters. Carbon capture and storing methods include the DAC (direct air capture), carbon mineralization (in particular, with use of nanomaterials), concrete process optimization, oxy-fuel combustion technology, using high-capacity industrial residues and effluents, liquid and solid sorbents or chemical-looping CO2 capture, among other alternative capture and regeneration methods. Thus captured carbon can be stored or released in the form of materials “made from air” pollution, including, in particular, carbon-negative construction materials, plastics, coatings, paints and inks. In addition to carbon footprint from construction industries, the future carbon negative technologies, life cycle assessments and circular economy principles, policies and market mechanisms, public-private collaborations, costs, scalability, and environmental impacts of carbon negative materials are discussed.

At present, the development of materials that have great gas adsorption capacities and a good cost–benefit ratio has been of great interest for the generation of new technologies that could solve a large number of environmental and energy production problems, among the most studied materials for this application are metal-organic frameworks (MOFs) due to their surface properties and the great variety of ways in which they can be synthesized. However, a large part of these metal–organic compounds cannot be carried to real applications, due to stability issues or that its adsorption capacity does not justify its manufacturing cost, for which numerous literary reports have proposed improving the performance of MOFs through postsynthetic modifications (PSM). In this review, a compilation of the methods of PSMs in the MOFs that are applicable in the gas adsorption technologies critically analyzing their feasibility to be carried on a large scale and placing special emphasis on their adsorption capabilities, selectivity, reuse, and pore size.

The effectiveness of the combined action of ultrasound and g-radiation on Lactobacillus casei is studied. A superadditive death effect is shown, whose magnitude depends on dose levels, sequence of effects, and the presence of theraphthal (sodium salt of cobalt 4,5-octacarboxyphthalocyanine) as a sonosensitizer.

This study presents the sono-photocatalytic hydrogen generation (HER), using ZnO and theraphthal, a watersoluble sodium salt of cobalt 4,5-carboxyphthalocyanine (TP). HER efficiency was optimized by a multivariable design of experiments modifying 5 factors (additives): (i) ascorbic acid, (ii) zinc oxide load, (iii) ultrasound power, (iv) ethanol, and (v) theraphthal under UV irradiation. Differences in hydrogen production according to the variable employed factors were observed in the reactions, resulting in higher yields when larger amounts of ethanol were used. Hydrogen evolution reached a maximum concentration near to 67 mu mol (669 mu mol g-1) in the HER process, when zinc oxide, theraphthal, and ascorbic acid in water/ethanol mixture were combined. Statistical analysis suggests that the H2 production was influenced mainly by the presence of alcohol in the reaction medium.

Biochemical synthesis of calcium phosphates (CaP) with use of enzymes is a novel trend in the synthesis of hydroxyapatite (HA) and other biocompatible calcium salts and composites. These compounds are biocompatible, possess good mechanical properties, and are suitable for a variety of purposes in bone tissue engineering. In this review, we discuss the biosynthesis (or enzymatic synthesis) of calcium phosphates and its comparison with conventional chemical methods. Main attention is paid to properties of CaP compounds for biochemical applications, classification and role of various enzymes in the biomineralization processes, role of bacteria and fungi, mechanisms of mineralization in several steps and possible real-time monitoring. A large number of morphologies of biochemically obtained CaP is shown, in particular for nanoscale range. Enzymes in natural biomineralization processes with participation of common bacteria, possessing a periplasmic alkaline phosphatase, are discussed in the point of view of their contribution in formation of fossils and rocks. CaP composites with natural biopolymers (chitosan, polysaccharides, cellulose) and synthetic polymers are described, as well as CaP compounds, functionalized with a series of biomolecules. The use of biowaste (animal, plant and aquatic origin, such as bone waste, eggshells, naturally derived biomolecules and biomembranes, marine organisms, etc.), used as raw materials for the preparation of CaP, is also shown.

This research investigates the concentrations, sources, and health risks of polycyclic aromatic hydrocarbons (PAHs) and nitrated PAHs (NPAHs) in particulate matter with an aerodynamic diameter of 10 μm or less (PM[Formula: see text]) from critical urban centers in northern Mexico: Metropolitan Monterrey Area (MMA), Chihuahua (CHI), and Ciudad Juárez (CDJ). Advanced gas chromatography-mass spectrometry (GC-MS and GC-NCI-MS) revealed significant PAHs concentrations, with levels in MMA reaching 108.89 ± 99.90 ng/m[Formula: see text], CHI at 100.69 ± 122.60 ng/m[Formula: see text] and CDJ at 73.26 ± 90.85 ng/m[Formula: see text]. Significantly, 3-nitrofluoranthene (3N-FLA) and 1-nitropyrene (1N-PYR), known for their potent toxicity, were among the most prominent NPAHs, with total concentrations in MMA, CHI, and CDJ at 470.32 pg/m[Formula: see text], 247.26 pg/m[Formula: see text], and 193.20 pg/m[Formula: see text], respectively. Source apportionment using diagnostic ratios (DRs) and principal component analysis (PCA) indicated that biomass burning, vehicular emissions, and industrial activities were the primary sources of MMA. At the same time, CHI and CDJ were influenced more by industrial and diesel emissions. Health risk assessments based on benzo[a]pyrene equivalent (BaPeq) concentrations and excess cancer risk (ECR) demonstrated moderate to significant cancer risks, with CDJ exhibiting the highest NPAHs-related risk. This study makes several significant contributions: it presents the first analysis of PAHs and NPAHs levels in these urban areas, identifies key emission sources, and quantifies associated health risks, providing essential data for developing targeted public health policies and environmental regulations.

Bimetallic and trimetallic metal-organic frameworks (MOF), as well as their MOF-derived metal-containing nanocarbons, are reviewed in respect of their applications in water splitting processes for hydrogen evolution reactions and oxygen evolution reactions. MOFs for these purposes are generally prepared via solvothermal processes and then subjected to pyrolysis yielding respective metalated nanocarbons. Trimetallic MOF compounds and their respective nanocarbons are shown to have better electrocatalytic activity in comparison with bimetallic ones and able to withstand a higher current density. The use of metallic or base substrates, such as metal foams, graphene, and doping in metal-organic structures, helps the electrocatalyst to get a better response. Several nanocarbon catalysts derived from trimetallic MOFs possess high potential values similar to those of the commercial Pt/C catalyst in oxygen reduction reaction. Relative characteristics of bi- and trimetallic MOFs and metalated nanocarbons (synthesis methods, properties, peculiarities, stability in aqueous/nonaqueous media) are briefly discussed.

The use of biofuels dates back to the nineteenth century and has yet to be well explored as a conventional energy source. But the rising demand for petrochemical goods and the resulting environmental hazards prompted us to look again at a prospective candidate, such as biofuels. This chapter briefly overviews biofuels' role in the current environment, various types of biofuels, and their natural resources focusing more on biobutanol with their extended synthetic procedures and, ultimately, how we might achieve energy security by making good use of these highly compatible resources with the aid of more technological advancements.