One-step Hydrothermal Synthesis Research Articles

Synthesis and Properties of Nickel Copper Phosphorus (NixCuyPz) Catalyst

Nowadays, scientists around the world are paying more attention to renewable hydrogen fuels. There is a growing need for precious metal catalysts to calculate the cost of obtaining renewable energy, an efficient method of producing H2 by electrolysis of water, as well as to facilitate the decomposition of water into its elemental parts. Today, due to the increase in the problem of the shortage of energy resources and the growing of CO2 emissions into the atmosphere, attention is being paid to hydrogen energy. However, the production of H2 requires low-cost, efficient catalysts that facilitate hydrogen/oxygen separation reactions in the water splitting. For this purpose, intermediate metal phosphides (Fe, Co, Ni, Cu, Mo, W) were used as effective electrocatalysts for water decomposition. The catalytic activity of intermediate metal phosphides to form hydrogen is largely dependent on the phosphorus content, but the P atoms play an important role in increasing efficiency. The production of hydrogen by electrolysis of water on the basis of bifunctional catalysts has good prospects for use in the energy industry. In the article, the one-step hydrothermal synthesis method and physico-chemical (electronic structure and conductivity, structure morphology) of double metal phosphide with NixCuyPz composition were studied.

Nb(V)-containing saponite: A versatile clay for the catalytic degradation of the hazardous organophosphorus pesticide paraoxon under very mild conditions

A synthetic saponite clay containing structural Nb(V) metal centres (NbSAP) was investigated in the abatement of paraoxon-ethyl, an anti-cholinergic organophosphorus pesticide, under mild conditions (neutral pH, room temperature and ambient pressure) in heterogenous phase, without additional basic additives. The material was selected according to its high surface acidity and ease of preparation through a one-step hydrothermal synthesis. The presence of Nb(V) ions played a crucial role in efficiently catalysing the degradation of aggressive chemical substrates. A niobium(V) oxide with very low surface acidity was also tested as a reference material. The study employed a multi-technique approach to monitor the pesticide degradation pathway and by-products formed during abatement experiments in polar non-protic and aqueous solvents. Notably, in water, the concentration of paraoxon-ethyl significantly decreased by 82 % within the first hour of contact with the clay. Additionally, NbSAP demonstrated a good performance after three repeated catalytic cycles and subsequent reactivation.

Biomass Carbon Dots as Fluorescent Probes for Fast and Highly Selective Detection of Fe3 + in Water Media.

In this study, a novel fluorescent probe for the rapid and highly selective detection of Fe3 + based on biomass carbon dots (b-CDs) was developed. The b-CDs were obtained via one-step hydrothermal synthesis by utilizing laurel fallen leaves. And the as-synthesized b-CDs were applied for sensing Fe3+ based on fluorescence (FL) quenching effect both in water and phosphate buffer solution (PBS) with a wide linear range from 1 µM to 300 µM, the detection limits (LODs) respectively to be 0.34 µM in water and 0.48 µM in PBS solution. The FL intensity of b-CDs was quenched fleetly within 1min after adding Fe3+. The sensing mechanism of the b-CDs + Fe3+ system can be attributed to the internal filtration effect (IFE) mechanism and the electron transfer (ET) between b-CDs and Fe3+ in water, and only the IFE mechanism in PBS solution based on multiple experimental evidences. Moreover, the as-proposed probe was successfully adopted for monitoring Fe3+ in lake water and tap water samples. This research shows some merits of economic, simplicity, green, high selectivity, and quick response for Fe3+ determination, and provides an approach for the water quality monitoring of Fe3+ and the effective utilization of waste biological materials.

Green Synthesis of Luminescent Carbon Dots from Ficus benghalensis Aerial Roots for Bioimaging.

In this work, carbon quantum dots (CQDs) were prepared using a one-step hydrothermal green synthesis method from a low-cost and eco-friendly renewable biomass, specifically the Ficus benghalensis aerial roots (FB-AR). For the past two decades, CQDs have been noted for their tunable emission spectrum, quantum yield, biocompatibility, photostability, and unique optoelectronic properties such as photoluminescence (PL), and fluorescence. The synthesized Ficus benghalensis carbon quantum dots (FB-CQDs) were characterized for their physical, structural, and chemical properties using XRD, Raman, HRTEM, XPS, FTIR, TG-DTG, UV-visible, and photoluminance analysis. XPS analysis confirmed the presence of phytoconstituent functionalities and the composition of components. The FB-CQDs, which exhibit long-range emissions, have potential applications in various biological and therapeutic fields. Their bioimaging capability is tested in Escherichia coli bacteria. However, despite their promising characteristics, the FB-CQDs showed no antibacterial inhibition against Escherichia coli and Staphylococcus aureus, likely due to its carbonization temperature.

Heterostructure VO2@VS2 tailored by one-step hydrothermal synthesis for stable and highly efficient Zn-ion storage

Abstract The increasing demand for advanced energy storage solutions has driven extensive research into Zn-ion batteries due to their safety, cost-effectiveness, and environmental compatibility. This study presents a synthesis and evaluation of VO2@VS2 hollow nanospheres as a novel cathode material for Zn-ion batteries. The VO2@VS2 composite, synthesized via a one-step hydrothermal method, demonstrates a significant improvement in electrochemical performance. The material exhibits a reversible capacity of 468 mAh g−1 at 0.1 A g−1 and maintains a high capacity of 237 mAh g−1 at 1.0 A g−1 over 1000 cycles with a retention rate of 85%. Electrochemical analyses reveal enhanced charge transfer and Zn-ion storage, attributed to the synergistic effect and built-in electric field of the VO2 and VS2 heterostructure. Additionally, the composite shows superior electrochemical kinetics, facilitating rapid ion transport and charge transfer. In-situ Raman analysis confirms the reversible Zn-ion storage mechanism, further validating the composite’s structural stability during cycling. Density functional theory calculations further support these findings, indicating the composite’s potential for high-rate capability and long-term cycling stability. This research highlights the promise of VO2@VS2 hollow nanospheres in advancing the performance of aqueous Zn-ion batteries.

One-step hydrothermal synthesis of F,N,S-doped photoluminescent carbon dots with yellowish-orange emission for sensitive Cu2+ ion detection: Environmental and biomedical applications

Herein, fluorine-, nitrogen-, and sulfur-doped carbon dots (FNS-CDs) were prepared via a one-step hydrothermal synthesis using flufenamic acid and thiourea as precursors, which showed yellowish-orange fluorescence both in aqueous solution and in the solid state. The as-prepared FNS-CDs were monodisperse and had an average diameter of 4 nm, good water solubility, a fluorescence quantum yield of 18.63 %, and excellent pH and ionic strength stability. The optimal excitation/emission wavelengths of the FNS-CDs were 406/570 nm, with an excitation-dependent wavelength range of 365–435 nm. The surface states, morphologies, and elemental compositions of the FNS-CDs were characterized using FTIR, XRD, TEM, and XPS. In addition, the FNS-CDs without any further modification exhibited high selectivity and sensitivity as nanosensors for Cu2+ over other metal ions. The PL quenching phenomenon can be used to detect Cu2+ ions within a linear range of 1–25 μM with a detection limit of 83.10 nM and an association constant of 1.29 × 104 M−1. The PL of the FNS-CDs was significantly quenched by Cu2+ ions through static quenching and was restored upon the subsequent addition of EDTA. The practical application was demonstrated through the detection of Cu2+ ions in real water samples, yielding recovery rates ranging from 97.8 % to 103.9 % with an RSD below 2.5 %. The FNS-CDs/Cu2+ complex exhibits potent antibacterial activity against S. aureus (85.27 %±2.1 %) and E. coli (91.31 %±1.6 %), whereas the FNS-CDs/Cu2+ has a higher inhibitory effect on the growth of E. coli. Furthermore, the FNS-CDs (100 μg/mL) were used for cell imaging, showing low toxicity to HCT-116 cells exhibited yellowish-orange fluorescence under a confocal microscope.

Investigation into the adsorption mechanism of Fe(III) by biomass carbon derived from tea residue and its high-value conversion into bismuth ferrite for enhanced activation of peroxymonosulfate towards antibiotics degradation

Water pollution caused by heavy metals and antibiotics adversely affects human health. However, the harmful solid waste generated via traditional pollution removal processes significantly increases the recovery cost. Herein, we study the adsorption mechanism of hydrothermal activated carbon (AHTC) from tea residue on heavy metals, with AHTC having a good adsorption capacity of 699.0 mg/g for Fe(III). We then use one-step hydrothermal synthesis to produce an AHTC/bismuth ferrite composite (BFOC) material using solid waste to perform activation peroxymonosulfate to degrade antibiotics. The experimental results reveal that the BFOC exhibits good photocatalytic performance, with 94.60 % of the oxytetracycline (20 mg/L) sample degraded within 40 min. BFOC also shows catalytic activity against other antibiotics. The reaction mechanism of the catalyst and intermediate of the OTC reaction are also studied. This study offers a new strategy for the adsorption of heavy metals and the degradation of organic pollutants.

Construction of ultra-thin NiMo3S4 nanosheet sphere electrode for high-performance hybrid supercapacitor

The construction of electrode materials with rational morphology and structure based on bimetallic sulfides is crucial to improve the performance of supercapacitors. Ultra-thin three-dimensional nickel molybdenum sulfide nanosheet spheres (NiMo3S4 NSSs) are grown on nickel foam (NF) using a one-step hydrothermal synthesis. NiMo3S4 NSSs have a diameter of ∼ 5 μm and nanosheet thickness of 200 nm. The effects of increasing the hydrothermal synthesis time and molar concentration ratios of Ni2+ to MoO42- on the morphologies of the NiMo3S4 are investigated. Due to the synergistic effect of NiMo3S4 NSSs and bimetallic ions which can provide a larger solution contact areas and improve the redox activity, the electrode exhibits good electrochemical properties. The specific capacity of NiMo3S4 NSSs/NF electrode can reach 1002.4 C/g (1 A/g). After being assembled into a hybrid supercapacitor (HSC) with activated carbon (AC), the energy density can reach 72.1 Wh/kg at the power density of 749.9 W/kg. In addition, the HSC shows an excellent stability of 89 % after 10, 000 charge-discharge cycles (10 A/g).

Adsorption characteristics and mechanisms of bisphenol A on novel nitrogen-modified biochar derived from waste masks and biomass.

Resource utilization of waste masks has become an urgent scientific issue. In this work, with sustainably, waste masks and biomass were co-pyrolysis with oxygen limitation to prepare mask-based biochar (MB). Then, urea was introduced to prepare novel nitrogen modified mask-based biochar (NMB) via a one-step hydrothermal synthesis method. The adsorption characteristics of NMB on the emerging environmental pollutant, bisphenol A (BPA), were evaluated via batch adsorption tests. Moreover, the physicochemical properties of the materials were characterized with various advanced techniques. Also, the roles of waste masks and nitrogen modification were explored. The adsorption mechanisms of NMB on BPA were revealed as well as the performance differences between different adsorbents. The results showed that waste masks participated in thermochemical reactions, shaped the microsphere structure of biochar, and increased the types of surface functional groups. The nitrogen modification enriched the surface elemental composition and activated the specific surface area via the mesopore. These would enhance the adsorption performance. The maximum adsorption of BPA by NMB was 62.63mg·g-1, which was approximately 2.35-5.58 times higher than that of the control materials. Temkin model and pseudo-second-order model optimally simulate the isothermal and kinetic adsorption, respectively. The adsorption mechanisms are jointly by physical and chemical adsorption, which mainly includes π-π interaction, hydrogen bonding, intraparticle diffusion, surface adsorption, and ion exchange. After discussion and evaluation, NMB has lower preparation process cost (7.21 USD·kg-1) and safety, with potential for environmental applications. This study aims to expand new ideas for the comprehensive utilization of waste masks and the preparation of eco-friendly materials. Moreover, it provides a theoretical basis for the removal of BPA.

Investigating the synergistic effect of RuO2 nanoparticle-decorated V2O5 nanoflakes for sensitive detection of 2,4-dinitrophenol and 2,4-dinitrotoluene

The dinitroaromatic compounds 2,4-Dinitrophenol (2,4-DNP) and 2,4-Dinitrotoluene (2,4-DNT) are prevalent contaminants in various water sources due to their extensive use in explosive synthesis and other industrial applications. The highly toxic and carcinogenic nature of these compounds poses significant risks to human health and environment, making the development of facile, rapid, cost-effective, and selective detection methods crucial. This research presents the one-step hydrothermal synthesis of RuO2 nanoparticle-decorated V2O5 nanoflakes to fabricate an electrochemical sensor for the detection of 2,4-DNP and 2,4-DNT. The synthesized materials were characterized using XRD, Raman spectroscopy, FESEM, HRTEM, and XPS techniques. The electrochemical behavior of 2,4-DNP and 2,4-DNT was investigated using cyclic voltammetry, square wave voltammetry and chronoamperometry. Under optimized conditions, 2,4-DNP and 2,4-DNT exhibited two reduction peaks corresponding to the nitro-functional groups on the aromatic ring. Notably, the 7 wt% RuO2 in V2O5 nanocomposite-modified glassy carbon electrode (RV7/GCE) demonstrated the lowest detection limits of 1.07 nM and 1.01 nM within the linear dynamic range (LDR) of 5.0 nM–35.0 µM for 2,4-DNP, and 2,4-DNT, respectively. Furthermore, the sensor exhibited excellent reusability and reproducibility, delivering consistent results for both laboratory-controlled and real-world samples. This advancement offers efficient detection and monitoring of these hazardous compounds in environmental and industrial settings.

One-step hydrothermal synthesis of iron phosphate dihydrate with ferric salt dephosphorized sludge

This study presents a novel approach for one-step hydrothermal synthesis of iron phosphate dihydrate (FePO4·2 H2O) using ferric salt dephosphorization sludge (FePs) from liquor wastewater. The gradual dissolution of FePs, facilitated by increasing temperatures and concentrations of phosphoric acid, releases Fe3+ and PO43- ions during hydrothermal reactions. These ions recrystallize into iron phosphate dihydrate and iron hydroxy-phosphate (Fe5(PO4)4(OH)3·2 H2O) depending on the conditions. Through a single-factor experiment, the effects of total organic carbon (TOC) in FePs and hydrothermal reaction conditions on the phase and morphology of the products were investigated, then the recrystallization process of iron phosphate dihydrate was also simulated by molecular dynamics. The first charge/discharge capacities of lithium iron phosphate (LFP) batteries synthesized from the optimal products were 153.1 and 149.4 mAh·g−1 at 0.1 C rate, respectively, and the cycling performance could be maintained under different rates, which has a good application prospect. The reaction fully utilized the iron and phosphorus resources in FePs, and the filtrate could be recycled to avoid the waste of resources, which provided a new idea for the resource utilization of FePs.

Enhanced non-enzymatic multicomponent detection via one-step hydrothermal synthesis of widely dispersed Zn-SnO2 nanoparticles on nitrogen-doped reduced graphene oxide

ABSTRACT Herein, we report a new type of non-enzymatic nanostructured biosensor designed for the concurrent determination of dopamine, cholesterol, and glucose in human blood samples. The prepared biosensor using low-temperature one-pot hydrothermal processing is a Zn-doped SnO2-dispersed nitrogen-doped reduced graphene oxide (N-rGO)/Zn-SnO2 nanocomposite. This modified electrode allows direct electron transfer and thus offers electrochemical techniques to detect target molecules in analytes without the use of enzymes. The biosensor displayed good voltammetric responses within the human reference range: 20–70 nM for dopamine, 1–8 mM for cholesterol, and 1–10 mM for glucose. It also showed excellent reusability and can be restored by washing with ethanol. Due to the use of Zn-doped SnO2 nanoparticles for enhanced catalytic activity and N-rGO for high conductivity and active sites, sensitive and selective detection can be achieved. This hybrid composite demonstrates excellent catalytic activity, repeatability, stability, and clinical comparability for real-time measurement of dopamine, cholesterol, and glucose simultaneously.

Nitrogen–silicon Co-doped carbon dots synthesized based on lemon peel for copper (II) detection via a dynamic quenching mechanism

As a metal, copper plays an important role in biological systems. However, excessive intake can lead to toxicity and disease. Therefore, there is a need to establish accurate and sensitive methods to detect and monitor copper levels in food and the environment. Herein, nitrogen-silicon co-doped carbon dots (N,Si-CDs) were synthesized using lemon peel as the biomass precursor by one-step hydrothermal synthesis with the addition of citric acid solution and 3-aminopropyl triethoxysilane (APTES). The prepared N,Si-CDs showed excellent photobleaching resistance, brilliant fluorescence performance and good selectivity. The experiments showed that the fluorescence of N,Si-CDs decreased after the interaction of N,Si-CDs with copper ions. Further studies showed that the decrease in fluorescence intensity of the fluorescent probe due to Cu2+ was dynamic quenching. In addition, the fluorescence intensity of N,Si-CDs showed a good linear relationship with the concentration of copper ions. The linear range was 0.5 μM–250 μM, the R2 was 0.995, and the limit of detection was 0.43 μM. Finally, the method has been successfully applied to the detection of copper ions in the water environment and food, and the recoveries of 99.4%–102.1 % were obtained, which indicated that the method had a promising future.

A single-component sensor array to detect multiple antibiotics via dual-emission chlorophyll carbon dots

In this study, dual-emission carbon dots (DE-CDs) were fabricated using a straightforward one-step hydrothermal synthesis with natural chlorophyll as the carbon precursor. These DE-CDs not only preserve the porphyrin structure of chlorophyll, exhibiting notable fluorescence at 682 nm, but they also display the characteristic fluorescence emission of conventional CDs at 450 nm. Leveraging the unique dual-emission properties of DE-CDs, we have engineered a single-component fluorescent sensor array for the high-throughput detection of antibiotics, which are emerging contaminants in water. The fluorescence responses (F450, F682, and the F450/F682 ratio) of the DE-CDs toward various antibiotics were analyzed using principal component analysis (PCA), enabling the facile differentiation of multiple antibiotics with good reproducibility achieved in real water samples. This innovative DE-CDs approach eliminates the need for multiple sensing probes and offers a practical concept for the creation of single-component sensing platforms.

Remarkable photodegradation breakdown cost, antimicrobial activity, photocatalytic efficiency, and recycling of SnO2 quantum dots throughout industrial hazardous pollutants treatment

In the conducted research, a one-step hydrothermal synthesis of pure and titanium-doped tin dioxide quantum dots is elaborated upon, with a thorough analysis of their structural, optical, morphological, and photocatalytic properties undertaken using advanced analytical techniques. Through X-ray Diffraction XRD, the crystalline nature and phase purity of the tetragonal structures of SnDs were confirmed, with the crystallite sizes measured at 3.0 nm for SnD1 and 7.66 nm for SnD2, following treatments at 240 °C and 300 °C, respectively. The structural integrity of SnO2 was maintained despite titanium doping. FTIR spectroscopy verified the existence of specific vibrational modes indicative of surface hydroxyl groups. HRTEM images revealed the spherical morphology of particles, with diameters of 3.5 nm for SnD1 and 9.1 nm for SnD2. Optical band gaps, determined through UV-DRS, ranged from 3.33 eV in SnD1 to 3.47 eV in SnDTi2. The photocatalytic degradation of Congo Red dye under xenon lamp irradiation was quantitatively assessed; notably, SnD1 exhibited a 23 % higher rate constant compared to SnD2, attributed to its smaller particle size and a 31 % greater surface area. Doping with 4 % Ti in Sn0.96Ti0.04O2 more than doubled the degradation rate compared to a 6 % Ti doping in Sn0.94Ti0.06O2. Furthermore, the generation of hydroxyl radicals was significantly enhanced, showing an increase of approximately 220 % for SnD1 and 80 % for SnD2. The capability of these nanomaterials to reduce the chemical oxygen demand of industrial organic pollutants to within regulatory limits under solar irradiation was documented, with SnD1 maintaining its photocatalytic efficiency over seven cycles of reuse. In the photocatalytic degradation rate of Congo Red dye, which was 23 % higher for SnD1 compared to SnD2, and the threefold increase in the degradation rate for SnDTi1 compared to SnDTi2. An economic assessment, based on electricity tariffs in Saudi Arabia, highlighted the cost-effectiveness of SnD1, which ranged from 26.93 to 30.36 USD per breakdown cost of the photodegradation process, showing it to be less costly than SnD2. Conversely, SnDTi1 was found to be more economical than SnDTi2, with costs ranging from 26.67 to 33.09 USD. Collectively, the results emphasize the outstanding photocatalytic performance and cost-efficiency of SnDs, reinforcing their potential as sustainable solutions for the treatment of industrial wastewater. Additionally, the antibacterial efficacy of these materials against a range of bacteria, yeast, and fungi was investigated and substantiated.

High-performance humidity sensors based on reduced graphene oxide sheets decorated with cobalt and iron doped ZnO nanorods

Humidity sensors based on doped zinc oxide (ZnO) / reduced graphene oxide (rGO) composites have shown potential since the doped ZnO/rGO material is sensitive to changes in humidity. Here, the present work report of one-step hydrothermal synthesis of ZnO/rGO and doped ZnO/rGO nanocomposites where ZnO has been doped with cobalt and iron at concentrations of 2 %. X-ray diffraction validates the substitution of transition metal cations in the ZnO lattice. Scanning electron microscopy depicts a graphene-layered structure with intact ZnO rods. Humidity sensors based on Fe doped ZnO/rGO composite showed response and recovery periods of 27 s and 24 s, respectively, in the range of 11–97 % relative humidity. The composite has the sensitivity of 2.2 kΩ at 100 Hz which is the highest as compared to ZnO/rGO and Co doped ZnO/rGO. Because of the greatest sensitivity and quick reaction and recovery timer, Fe doped ZnO/rGO composites appear to be ideal for use as humidity sensors.

One-step hydrothermal synthesis of CeVO4/bentonite nanocomposite as a dual-functional photocatalytic adsorbent for the removal of methylene blue from aqueous solutions

Cerium vanadate/modified bentonite (CeVO4/mbt) nanocomposite with different composition percentages was synthesized through a simple one-step hydrothermal method at 180 ℃, and then its photocatalytic activity was evaluated by decolorizing methylene blue (MB) in an aqueous solution under light exposure. In order to increase the surface area as an important parameter in photocatalytic processes, bentonite was modified by ball mill method. The structural and optical properties of the synthesized composites were determined by XRD, FT-IR, DRS, FESEM, EDS, and BET measurements. XRD and EDS results confirmed the successful synthesis of pure CeVO4. FESEM images and EDS mapping showed a proper distribution of rice-like CeVO4 nanoparticles on bentonite. The removal efficiency of MB with only 0.1 g of CeVO4/mbt nanocomposite in 15 min was about 99%, which is significant compared to neat bentonite and pure CeVO4 with efficiency of 30% and 57%. The mentioned nanocomposite followed the first-order kinetics, had a reaction rate constant equal to 0.1483 min–1, and showed acceptable stability in five consecutive cycles.

Understanding the supercapacitive properties and charge storage dynamics of MnCo2S4 bimetallic sulfide electrodes synthesized via a single-step hydrothermal process

A recent study delves into the enhancement of supercapacitors to increase their energy density while maintaining fast charge-discharge capabilities and longevity. This is achieved by developing electrode materials with improved conductivity and carefully designed nanostructures to overcome the limitations of pseudocapacitors. The study highlights MnCo2S4 for its impressive specific capacitance and cost-effectiveness. It elucidates the synergistic interactions and charge transfer dynamics between manganese (Mn) and cobalt (Co), which significantly enhance electrochemical performance. A new one-step hydrothermal synthesis method is presented for producing MnCo2S4 nanogranules directly on a nickel foam substrate, eliminating the need for binders and achieving an optimized morphology that boosts electrochemical activity. Through a thorough analysis involving X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), field-emission scanning electron microscopy (FE-SEM) along with cyclic voltammetry (CV), galvanostatic charge-discharge (GCD), and electrochemical impedance spectroscopy (EIS), the study comprehensively characterizes the structural, morphological, and electrochemical properties of MnCo2S4. The synthesized MnCo2S4 electrode exhibited an outstanding capacitance of 6375 mF/cm2 at a current density of 25 mA/cm2. This exceptional performance is mainly attributed to its well-designed 3-D nanogranular structure, which not only enhances the accessibility of electrolyte ions to active sites, thus improving electrochemical reactivity and capacitive utilization, but also utilizes the synergistic interaction between manganese and cobalt. This synergy promotes enhanced redox reactions and stability, resulting in a higher specific capacitance and energy density. These results highlight the crucial role of advanced electrode material development and creative synthesis methods in advancing supercapacitors as a viable energy storage solution, demonstrating the groundbreaking potential of MnCo2S4 in electrochemical energy storage progress.

N-rich carbon nanosphere as fluorescent nanoprobe for intracellular iron

Nitrogen rich carbon nanoparticles are known to provide higher fluorescence stokes shift, and thereby are potential candidates for fluorescent sensors. Herein, a facile one-step hydrothermal synthesis is reported for N-rich carbon nanospheres (G-CNS) from caffeine and o-phenylenediamine as precursors. The as-synthesized G-CNS showed high fluorescence with λem at 509 nm, with a highly selective fluorescence turn-off response towards Fe2+/Fe3+, rendering these carbon nanospheres as potential candidates to detect intracellular labile iron pool in live cells. The intracellular labile iron pool in iron-overloaded cells was sensed using the synthesized G-CNS. Mechanistically, the fluorescence quenching via dynamic pathway involves the formation of an excited state charge transfer process, which undergoes non-radiative decay.

Nitrogen assisted one-step hydrothermal synthesis of commercial TiO2 for methylene blue degradation under visible light irradiation

Strategies to make more efficient use of sunlight have been developed. Different synthesis parameters have been studied for the production of multiphase photocatalysts. In this work, for the first time, the performance of a one-step nitrogen-assisted hydrothermal synthesis of TiO2 using TiO2–P25 as a Ti precursor was investigated for the degradation of methylene blue under visible light irradiation. Urea and ethylenediamine (EDA) were evaluated as nitrogen sources. The produced photocatalysts had a rod-like nanostructure with the formation of mesopores. The resulting phase was a heterojunction of anatase, TiO2(B), and rutile, which enhanced charge separation. The presence of nitrogen during the hydrothermal reaction altered the morphology of TiO2, impacting the crystallite size. The U photocatalyst (urea source) achieved the best result for visible light with prior adsorption, degrading around 11 % of methylene blue in 5 h. This shows that it is possible to obtain a photocatalyst with superior performance to TiO2–P25 under both ultraviolet and visible light. This study presents an efficient strategy for improving the optical response of TiO2 by using nitrogen during a hydrothermal reaction, which has potential for industrial applications.