Hydrothermal Research Articles

Photodeposition of highly dispersed MoS2 nanosheets on CdS nanorods with enhanced photocatalytic activity for reduction of p-nitroaniline to p-phenylenediamine

So far, the significant effect of different assembly methods on the microstructures and photocatalytic properties of MoS2/CdS nanocomposite photocatalysts has rarely been reported. In the study, single-crystalline CdS nanorods (NRs) were prepared by a solvothermal method. MoS2 cocatalyst was decorated on the CdS NRs to obtain MoS2/CdS-PD and MoS2/CdS-HT photocatalysts by an in situ photodeposition (PD) technique and a hydrothermal (HT) method, respectively. Under visible light irradiation, the photocatalytic activity of MoS2/CdS-PD and MoS2/CdS-HT for reduction of p-nitroaniline (p-NA) to p-phenylenediamine (p-PDA) was comparatively studied. Results indicate: i) When MoS2 was attached on CdS NRs by the in situ PD, ultrathin MoS2 nanosheets could be uniformly and tightly tethered to CdS NRs to form core-shell MoS2/CdS-PD composite, whereas MoS2 nanosheets were aggregated to form stacked multilayered structure and loosely coupled to CdS NRs to produce non-core-shell MoS2/CdS-HT by the HT method. ii) MoS2/CdS-PD exhibits higher photocatalytic efficiency for p-NA reduction than MoS2/CdS-HT, which can be ascribed to the fact that the interfacial contact between MoS2 and CdS is more intimate and the electron transfer from CdS to MoS2 is more efficient in MoS2/CdS-PD than that in MoS2/CdS-HT.

COMPARATIVE PERFORMANCE ANALYSIS OF SOL–GEL METHOD AND HYDRO THERMAL METHOD FOR ZINC OXIDE NANOPARTICLE SYNTHESIS

Nanomaterials have emerged as an amazing class of materials that consists of a broad spectrum of examples with at least one dimension in the range of 1 to 100 nm. Exceptionally high surface areas can be achieved through the rational design of nanomaterials. Nanomaterials can be produced with outstanding magnetic, electrical, optical, mechanical, and catalytic properties that are substantially different from their bulk counterparts. There has been considerable focus on the synthesis of metal nanoparticles with distinct and exceptional characteristics, making it a highly captivating area of research. Among these nanoparticles, Zinc Oxide NanoParticles (ZnO NPs) have gathered significant attention in the field of bioengineering. Various approaches have been explored for the preparation of ZnO nanoparticles. In this paper we are comparing two synthesis methods as Sol–Gel Method and Hydro Thermal Method for Zinc Oxide Nanoparticles. Sol-gel method based ZnO nanoparticles are compared with Hydrothermal based ZnO nanoparticles in terms of XRD, UV Visible Spectrum and SEM analysis. Sol-gel method based Al-doped Zinc Oxide Nanoparticle (AZnO) is compared with Hydrothermal based Al-doped Zinc Oxide Nanoparticle (AZnO) in terms of XRD, UV Visible Spectrum, SEM analysis and optical properties. At last Sol-gel method based Au-doped ZnO- Sm (NO3)3 is compared with Hydrothermal based Au-doped ZnO nanoparticles in terms of optical properties as transmittance and absorbance, structural properties as XRD analysis. From this paper we can conclude that, Sol-gel method based Au doped ZnO nano particles are efficient than Hydro thermal based ZnO nano particles.

Comparative investigation of the characterization and photoactivity of gold-decorated graphitic carbon nitride: A study aspect of various synthesis approaches

In recent decades, photocatalysis has been broadly considered one of the potential approaches for different environmental and medicinal applications. Different synthesis methods possess different benefits and drawbacks, requiring thorough comparison to optimize the usage of precursors, equipment, and photocatalysis activity of the materials. In this study, the gold-decorated graphitic carbon nitride nanocomposites (AuCN) were successfully fabricated via different methods, including hydrothermal (HT), radiation under visible light (Ir), and chemical reduction (VC). The characterization of the prepared materials was investigated, which showed an efficient exfoliation of graphitic carbon nitride (g-C3N4 − CN) sheets and uniform embedment of gold nanoparticles (AuNPs). The AuCN sample synthesized from the chemical approach (AuCN-VC) showed the strongest signals of the AuNPs content, while the material prepared from the hydrothermal method (AuCN-HT) indicated a better CN crystalline structure. Furthermore, the photoactivity of the fabricated materials was also compared with pristine CN via the analysis of band structure, elucidating an improvement in the band gap energy to 2.25, 2.59, and 2.68 eV for the hydrothermal, irradiation, and chemical approaches, respectively. According to the photocatalysis results, AuCN-VC possessed the highest photo behavior under visible illumination with the hydrogen peroxide yield production at 271.5 mM/g.h. Meanwhile, the observation in the antibacterial activity exhibited the greatest performance regarding AuCN-HT with the recorded inhibition zone diameters of 9.3 and 8.6 mm against P. aeruginosa and S. aureus, respectively, under photo-excitation. According to the aforementioned results, the synthesized AuCN composites suggest great potential in a wide range of applications in environmental remediation and renewable production.

Enhanced hydrogen evolution performance of MoSe2 photocatalysts synthesized by hydrothermal and ultrasonic methods

Molybdenum diselenide (MoSe2) catalyst for efficient hydrogen (H2) evolution was synthesized using hydrothermal (HM) and ultrasonic (UM) methods. Several analytical techniques were employed to investigate how the synthesis method of MoSe2 influences physicochemical properties of MoSe2. The results revealed that during visible light irradiation, the photocatalytic H2 evolution rate of MoSe2 synthesized with the HM technique was 421.27 µmol g−1 h−1 which was higher than that of MoSe2 prepared using the UM method (336.15 µmol g−1 h−1). The observed results could be attributed to the enhanced characteristics of hydrothermally produced MoSe2, including better crystalline size, narrow band gap, and increased surface areas. The surface area of MoSe2 could be enhanced through the use of HM, leading to improved light absorption, increased availability of active sites, and effective separation and inhibition of charge carrier recombination.

Photocatalytic Degradation of Emerging Contaminants with N-Doped TiO2 Using Simulated Sunlight in Real Water Matrices

In the present work, the photodegradation performances of N-doped TiO2 photocatalysts with enhanced absorption of visible light were exploited for the abatement of some representative contaminants of emerging concern (CECs). Pristine TiO2 and N-TiO2 were synthesized using hydrothermal (HT) and sol–gel (SG) routes, they were characterized using XRD and UV-Vis spectroscopy, and their band gaps were determined via analysis in diffuse reflectance. Their photodegradation efficiency was tested on a mixture of recalcitrant organic pollutants, namely, benzotriazole, diclofenac, sulfamethoxazole, and bisphenol A, using a solar simulator lamp with two different cut-off filters (λ > 340 nm and λ > 400 nm). The evaluation of the photocatalytic performances was initially carried out in spiked ultrapure water and subsequently in aqueous matrices of increasing complexity such as Po River water and water coming from an aquaculture plant. The exclusive utilization of visible light (λ > 400 nm) highlighted the advantage of introducing the dopant into the TiO2 photocatalyst since this modification allows for the material to be responsive to visible light, which is not sufficient in the case of pristine TiO2 and the higher efficiency of materials obtained via the sol–gel route. Thanks to the doping, improved performance was obtained in both ultrapure water and real water matrices, indicating the potential of the doped material for future applications in the field.

Improvement of hydrochar/biochar pellets prepared from cotton stalk by hydrothermal pretreatment process

Hydrothermal (HT) pretreatment can change the internal components of biomass to efficiently improve the comprehensive utilization value of the resource. In this paper, cotton stalk (CS) was hydrothermally pretreated firstly at 180–280 °C and densified into hydrochar pellet and then pyrolyzed at 400 °C to prepare biochar pellet. A variety of the characterization analyses (SEM, XRD, etc.) were conducted to investigate the effect of the evolution behavior of the main components (cellulose, hemicellulose and lignin) in CS during HT process on the physicochemical property of the resulted biofuel pellets. The results show that HT process improves significantly the quality of the resulted biomass. As HT temperature increasing from 180 °C to 280 °C, the carbon content of the hydrochar increases from 46.91% to 67.26%, while the oxygen content decreases from 46.61% to 26.0%. Meanwhile, the alkali metal content of CS decreases significantly during HT process. HT process promotes the significant decompositions of the hemicellulose below the process temperature of 230 °C and cellulose below 280 °C and the aromatization growth of the resulted CS. Crystalline cellulose is the major contributor to the mechanical properties of the hydrochar and biochar pellets. Compared with the hydrochar pellet, the biochar pellet has the much lower properties due to the decomposition of the crystalline cellulose during the pyrolysis process. The combustion characteristic of the hydrochar decreases significantly due to the decreasing cellulose content with HT intensity, while the correlation between them is severely weakened by the pyrolysis process. HT process significantly improves HHV of the resulted hydrochar pellet and the lignin is responsible for the increasing HHV. However, HHV of the resulted biochar pellet shows a slowly downward trend with the increasing HT temperature. The hydrochar and biochar pellets with the maximum energy density both were prepared from CS pretreated at 230 °C and HT process improves the energy density of the resulted hydrochar pellet and biochar pellet to different certain. The apparent density has a crucial effect on the quality of the biofuel pellet. Thus, the quality of the biochar pellet can be improved greatly by HT process.

Relative assessment of the microstructure, properties and bioactivity of 3D-printed and rolled Ti6Al4V with micro-arc oxidation (MAO) and hydrothermal (HT) treatment

The surface modification of 3D printed Ti6Al4V (3D-Ti64) and rolled Ti6Al4V (RO-Ti64) was carried out using optimized micro-arc oxidation (MAO) and hydrothermal (HT) treatment processes. The results showed that the 3D-Ti64 coating had a typical porous structure that was identical to the phase composition of the RO-Ti64 coating, and both exhibited super hydrophilic properties (contact angle of 0°). It was found that the 3D-Ti64 coating (1.40 × 10−7A/cm2, 39.38 MPa) had greater corrosion current density and adhesion strength compared to the RO-Ti64 coating (0.76 × 10−7A/cm2, 33.69 MPa). In addition, the HAP crystals formed by 3D-Ti64 and RO-Ti64 coatings after being cultured in SBF were not significantly different, indicating that both coatings had comparable in vitro bioactivity. However, the 3D-printed porous Ti64 coating formed a porous structure only around the edges, while the central region had a flocculent structure with unfinished electrolytic oxidation. Moreover, it was found that more HAP crystals were formed in the edge region after HT treatment. In short, the MAO and HT treatment parameters optimized on rolled Ti alloys can be inherited for continued use on 3D-printed Ti alloy solids. However, more considerations may need to be made for the 3D printing of porous Ti alloys.

Alcohol production from fatty acids via Ni3Fe/Rutile: Revealing the role of oxygen vacancy and metal-support electronic density characteristics

Ni3Fe clusters anchored on rutile (R-TiO2) were synthesized by hydrothermal (HT), coprecipitation (CP) and impregnation (IM) methods, and the catalytic performance of different NiFe/R-TiO2 catalysts were investigated for hydrogenation of fatty acid into alcohol. Notably, HT-NiFe/R-TiO2 catalyst, with the highest specific surface area and Ni3Fe nanoparticles dispersion, exhibited the best hydrogenation activity towards alcohol production, with complete conversion and yield reach of 92.5 % at 4 MPa H2, 210 ℃ and 6 h. The structure–reactivity relationship was investigated by a series of catalysts characterization, DFT calculation and corroborated through hydrogenation performance evaluations. Anchoring Ni3Fe clusters onto highly dispersed basic site surfaces with different Ov concentrations can change the electron distribution and strength of the metal-support interaction, causing more stable adsorption of the H and acids molecular toward fatty alcohol production. This work provides further insight into the structure–activity of NiFe/TiO2 catalysts synthesized through different methods.

Tracking Lattice Distortion Induced by Defects and Framework Tin in Beta Zeotypes.

The use of powder X-ray diffraction (PXRD) coupled with lattice parameter refinement is used to investigate the crystal structure of Sn-Beta materials. A newly developed semiempirical PXRD model with a reduced tetragonal unit cell is applied to obtain the characteristic crystallographic features. There is a robust correlation between lattice parameters and the concentration of tin and defects for materials prepared via hydrothermal (HT) and postsynthetic (PT) methods. With tin incorporation, PT Sn-Beta samples, which possess a more defective structure, exhibit an extended interlayer distance in the stacking sequence and expansion of the translation symmetry within the layers, leading to larger unit cell dimensions. In contrast, HT Sn-Beta samples, having fewer defects, show a minimal effect of tin site density on the unit cell volume, whereas lattice distortion is directly correlated to the framework tin density. Furthermore, density functional theory (DFT) studies support an identical trend of lattice distortion following the monoisomorphous substitution of T sites from silicon to tin. These findings highlight that PXRD can serve as a rapid and straightforward characterization method to evaluate both framework defects and heteroatom density, offering a novel approach to monitor structural changes and the possibility to evaluate the catalytic properties of heteroatom-incorporated zeotypes.

Effects of cellulose and lignin on xylooligosaccharides production from xylan: The superiority of acetic acid/sodium acetate hydrolysis

Xylooligosaccharides (XOS) are high-value products derived from xylan in lignocellulose and have a variety of prebiotic applications. The intertwining of xylan, cellulose, and lignin in lignocelluloses may affect XOS production. In order to investigate those impacts, the comparative analysis of XOS production was conducted using corncob, poplar and xylan as substrates through the hydrolysis using acetic acid/sodium acetate (AC/SA), acetic acid (AC), and pure water. The results revealed that the hydrolysis of different feedstocks using AC/SA generated the highest XOS yield and the least by-products compared to AC hydrolysis and hydrothermal (HT) treatment. The presence of cellulose led to the reductions of XOS production from xylan by AC/SA hydrolysis, AC hydrolysis, and HT treatment by 6.6%, 6.3%, and 4.3%, respectively. The presence of cellulose and lignin largely decreased XOS yields by 22.2%, 22.0%, and 88.5%, respectively. Obviously, the cellulose slightly inhibited xylan hydrolysis, while lignin had a strong negative effect on xylan hydrolysis. Besides, the adverse effect of lignin on xylan hydrolysis was the greatest in HT treatment. Despite the presence of cellulose and lignin, AC/SA hydrolysis exhibited the superior ability in XOS production and reduced the formation of by-products compared to AC hydrolysis and HT treatment.

Comparative Study of MgO Nanopowders Prepared by Different Chemical Methods.

Magnesium oxide (MgO) was synthesized by three different methods: the sol-gel (SG), microwave-assisted sol-gel (MW), and hydrothermal (HT) methods for comparing the influence of the preparation conditions on the properties of the products. The powders were annealed at 450 °C. The samples were characterized by X-ray diffraction, scanning electron microscopy (SEM), transmission electron microscopy (TEM/HRTEM), selected area electron diffraction (SAED), energy-dispersive X-ray spectroscopy (EDX), BET specific surface area and porosity, photoluminescence, and UV-Vis spectroscopy. The samples consisted mainly of periclase as a crystalline phase, and the MW and HT preparation methods generated particles with higher specific surface areas. The powders had less-defined morphologies and high levels of aggregation. The optical band gaps of the samples were determined from UV DRS, and the photocatalytic activities of the magnesium oxides obtained by the three methods towards the degradation of methyl orange (MO) under UV light irradiation was evaluated.

Enhancing photocatalytic water splitting: Comparative study of TiO2 decorated nanocrystals (Pt and Cu) using different synthesis methods

The use of light radiation to cause the dissociation of water into hydrogen (H2) gas has tremendous promise as a green method of hydrogen production. Herein, we reported a comparative study for the photocatalytic activity of TiO2 nanocomposite with two co-catalysts e.g., Pt or Cu nanocrystals (3–4 nm) using different synthesis procedures; incipient wet impregnation (Imp), hydrothermal (HT), or photo-deposition (PD) methods. The effect of catalyst mass loading percentages (0.1–1 wt.%) was investigated. The mass loading of 0.3 wt% for both co-catalysts exhibited the highest value of the generated hydrogen. Even without a precious metal such as Pt, Cu/TiO2 synthesized using the PD method provided an initial rate of 24 mmol h-1g−1, which is 3.5 and 1.4 times higher than the composite synthesized using HT and Imp methods. On the other hand, the highest rate for Pt co-catalyst was observed for the Imp method with a rate of 58 mmol h-1g−1 which was higher by 1.6 and 1.1 times than the composite synthesized using PD and HT methods, respectively. This study offers new perspectives on the significant influence of the co-catalyst deposition technique on the efficiency of photocatalysis for producing hydrogen through water splitting.

Synergistic effect of complementary cleaner energy sources on controllable emission from hybrid power systems in optimal power flow framework

The increased penetration of renewable energy resources into the power system may make the system operation extremely vulnerable due to their inherent volatility and variability. Thus, optimum utilization of cleaner power generation into the power system without affecting the operational economy, voltage security and stability becomes a challenging issue. To minimize this adverse impact of intermittent renewable resources, hydro power sources may be considered as an effective option. Inclusion of hydro power may contribute towards optimal utilization of the abundant clean energy and enhance the capability to mitigate the volatile renewable power sources while forming a stable hybrid power system (HPS). In this context, an intelligent generation scheduling (IGS) mechanism is proposed to effectively mitigate these complex challenges. To further analyze these issues, multiple case studies under different operating conditions are carried out to portray the significance of incorporating the complementary behaviour of hydro-solar generation with thermal power generation facilities in environmental optimal power flow (EOPF) framework. Widely accepted IEEE 30 bus benchmark system is considered for the validation of results. Optimal operational paradigm (OOP) for the three different HPS configurations i.e. (1) Solar-Thermal (ST); (2) Hydro-Thermal (HT); and (3) Solar-Hydro-Thermal (SHT) is evaluated using Jaya algorithm (JA) while meeting the real time constraints. With the OOP, a comparative performance evaluation is carried out among different hybrid configurations in fulfilling the multiple objectives. Results show the supremacy of SHT configuration in minimizing the operating cost by 1.324×105 US$/y to 2.445×105 US$/y and emission up to 15.768 Tons/y compared to other configurations.

Effect of the Elaboration Method on Structural and Optical Properties of Zn1.33Ga1.335Sn0.33O4:0.5%Cr3+ Persistent Luminescent Nanomaterials.

Near-infrared (NIR) persistent luminescence (PersL) materials have demonstrated promising developments for applications in many advanced fields due to their unique optical properties. Both high-temperature solid-state (SS) or hydrothermal (HT) methods can successfully be used to prepare PersL materials. In this work, Zn1.33Ga1.34Sn0.33O4:0.5%Cr3+ (ZGSO:0.5%Cr3+), a newly proposed nanomaterial for bioimaging, was prepared using SS and HT methods. The results show the crystal structure, morphology and optical properties of the samples that were prepared using both methods. Briefly, the crystallite size of the ZGSO:0.5%Cr3+ prepared using the SS method is ~3 µm, and as expected, is larger than materials prepared using the HT method. However, the growth process used in the hydrothermal environment promotes the formation of ZGSO:0.5%Cr3+ with more uniform shapes and smaller sizes (less than 500 nm). Different diameter ranges of nanoparticles were obtained using HT and ball milling (BM) methods (ranging from 25-50 nm) and by using SS and BM methods (25-200 nm) as well. In addition, the SS-prepared microstructure material has stronger PersL than HT-prepared particles before they go through ball milling to create nanomaterials. On the contrary, after BM treatment, ZGSO:0.5%Cr3+ HT and BM NPs present higher PersL and photoluminescence (PL) properties than ZGSO:0.5%Cr3+ SS and BM NPs, even though both kinds of NPs present worse PersL and PL compared to the original particles before BM. To summarize: preparation methods, whether by SS or HT, with additional grinding as a second step, can have a significant impact on the morphological and luminescent features of ZGSO:0.5%Cr3+ PersL materials.

Facile and controllable preparation of mesoporous silica nanoparticles with ultra-large mesopores enabled by an ammonium chloride–assisted hydrothermal process

This work reports the facile preparation of monodispersed ultra-large mesopore mesoporous silica nanoparticles (ULP-MSNs) with controllable mesopore sizes and particle sizes. The key design to such preparation lies in the application of ammonium chloride (NH4Cl) assisted-hydrothermal (AAH) process to as-prepared conventional MSNs, whose small mesopore sizes of about 2 nm can be effectively enlarged to over 16 nm. Based on the systematic study of the synthetic parameters, it was recognized that the initial ethanol added in the synthesis mixture (1st ethanol), NH4Cl, and the ethanol added in the mixture (2nd ethanol) during the hydrothermal (HT) process and HT conditions play synergistic roles in enlarging mesopores by AAH process. The mechanism of mesopore enlargement was also studied. By this method, ULP-MSNs with variable mesopore sizes in a range of 14 nm–26 nm, large synthesis domain, and controllable particle sizes ranging from 106 nm to 267 nm can be produced in a facile manner. This work, we believe, represents a new strategy for the preparation of ULP-MSNs and will promote their various applications.

The effect of pretreatment choice on cellulosic ethanol production from sugarcane straw: An insight into environmental impact profile and GHG emissions mitigation potential in Brazil

The exploration of residual lignocellulosic biomass for biofuel production is crucial to achieve significant greenhouse gas (GHG) emissions mitigation within the following decades, translating to diminished agricultural environmental impact and land-use change dynamics. On the other hand, cellulosic ethanol production pathways are typically resource-intensive, in energy and chemical terms, which directly influence its carbon intensity. Pretreatment choice, to this end, is key, since it dictates the overall process performance and yield, and may include crucial flows, under the life-cycle perspective, such as solvents and other chemicals. This work, then, aims to evaluate the effect of pretreatment choice, namely hydrothermal (HT), steam explosion (SE), and alkaline (AK), in the technical and environmental performance of cellulosic ethanol production from sugarcane straw (SCS), extending this analysis to the final GHG emissions mitigation potential for gasoline and fossil-generated electricity substitution, under the Brazilian context in São Paulo. Results show that, while AK provided the highest ethanol yield, this pretreatment option gave the lowest electricity generation surplus, and its sodium hydroxide usage was identified as an important environmental hotspot in most impact categories, which narrowed down its GHG emission mitigation gap for gasoline substitution. HT and SE presented similar ethanol and electricity yields, with SE being the most balanced option in terms of productivity and environmental impact profile. By selecting the SE route, all of the available SCS in São Paulo could be converted into 10% of the Brazilian annual ethanol production, and mitigate 5.4 MtCO2e of gasoline emissions, 15% of the Brazilian Biofuel Policy (RenovaBio) target for 2022.

Hydrothermal treatment of rice straw for carbohydrate production

This study focused on the effect of hydrothermal (HT) treatment at 180 – 210 °C for holding 0 - 15 min on the solubilization of rice straw and the changes of HT residue. The optimum treatment conditions for the highest solubilization and solid reduction of rice straw was 210 °C for holding 0 min. Under this condition, the extraction yield and total organic carbon (TOC) concentration of the HT liquid part were the highest, about 44% and 7850 mg/L, respectively. The dry residue showed that the HT conditions above 200 °C for holding a short time were more efficient, which was confirmed by FT-IR and the changes of surface morphology under microscope. The reactor headspace could be an important factor because HT treatment with a lower headspace (HTp210-0(15)) yielded more soluble carbohydrate under the test conditions. Also, energy input calculated based on the 1 ton removed hemicellulose (extraction yield) in the headspace experiments proved this finding.

Bright yellow fluorescent nitrogen and boron doped-CNPs based turn “off–on” probe for highly sensitive and selective detection of glyphosate and hypochlorite

In the present work, water-soluble fluorescent nitrogen/boron-doped carbon nano particles (N/B-CNPs) were prepared using o-phenylenediamine and boric acid precursors by a simple one step hydrothermal (HT) method. High Resolution Transmission Electron Microscope (HR-TEM) analysis showed that the N/B-CNPs are spherical in shape with an average size of ∼ 15 nm. The functional and structural composition of N/B-CNPs were confirmed by Fourier Transform Infrared (FTIR), Raman and Nuclear Magnetic Resonance (NMR) spectral studies. N/B-CNPs exhibited excellent photophysical property and photostability at different physiological conditions. N/B-CNPs showed bright yellow fluorescence at 566 nm upon excitation at 400 nm. N/B-CNPs were utilized as a fluorometric probe towards the simultaneous detection of glyphosate and hypochlorite. The fluorescence intensity of N/B-CNPs was selectively quenched in the presence of glyphosate (turn-off) and quenched emission intensity was restored in the presence of hypochlorite (turn-on). The fluorescence quenching mechanism was further ascertained using Stern-Volmer and time resolved fluorescence analysis. The detection probe showed a linear response for glyphosate over the concentrations range of 5.00 to 85.00 µM, with a limit of detection value of 0.088 µM. While in the case of hypochlorite the turn-on assay exhibited good linearity over the range of 5.00 to 50.00 µM with limit of detection as low as 0.12 nM. The N/B-CNPs turn-off/turn-on fluorometric assay exhibited excellent sensitivity and selectivity towards glyphosate and hypochlorite, even in the presence of other interference ions. The practical applicability of the proposed assay was demonstrated by fabricating a paper strip-based sensor and fluorescent thin film. Furthermore, the in vivo toxicity of the N/B-CNPs was evaluated in plant by performing dosage dependent assay.

Effect of synthesis route on the photoluminescence properties of SrTiO3:Pr,Al phosphor: Nanoparticles and microcubes

Sr0.998Pr0.002Ti0.998Al0.002O3 phosphors were prepared by hydrothermal (HT) and polymeric precursor (PP) methods. PP sample exhibits broadening of X-ray diffraction peaks due to the higher surface region of nanoparticles compared to HT sample. X-ray absorption spectroscopy results depicted defects associated with the formation of TiO5 octahedra for HT sample, which is ascribed to the rapid crystallization process in HT synthesis of the mesocrystals with cube-like shape. A quenching of 4f → 4f emissions in Pr3+ ions and a broad spectrum are observed for HT sample, which are attributed to structural disorder in the forming and modifying lattice due to charge compensation between Sr-O11 and Sr-O12 (or TiO5 and TiO6) clusters and intermediate levels in band gap states.

Promotion effects of FeCu co-doping on Co3O4-based catalysts for linear α-olefins to alcohols

For the preparation of alcohols from linear α-olefins, Cu or/and Fe doped Co3O4 catalysts were synthesized using two processes and their structural and catalytic properties were studied. Using microwave-assisted and hydrothermal (HT) crystallization processes, doped Co3O4 with the rod-like morphology and the lamellar morphology were obtained, respectively, and the two morphology both showed the dominantly exposed Co3O4 (111) and (220) planes which were related to the successive hydroformylation and hydrogenation steps of olefins. With microwave-assisted process, Cu doped Co3O4 dramatically improved the hydroformylation reactivity of 1-octene. FeCu or NiCu co-doped Co3O4 raised nonanol selectivity and the promotion of FeCu co-doping was better. At 150 °C and 7 MPa for 4 h reaction, 2Fe2Cu-Co3O4(nFe:nCu:nCo = 2:2:100) exhibited 1-octene conversion of 99.82% and nonanol selectivity of 50.80%. With HT crystallization process, 2Fe2Cu-Co3O4-HT displayed 1-octene conversion of 99.69% and nonanol selectivity of 67.87% under 150 °C, 7 MPa for 5 h reaction. The effects of reaction temperature, pressure, time and catalyst dosage on the activity were discussed. At the set reaction conditions, 2Fe2Cu-Co3O4-HT exhibited high activity for C6 ∼ C12 olefins converting to C7 ∼ C13 alcohols. The roles of Cu or/and Fe doping and the effects of the exposed crystal planes of Co3O4 were revealed by characterizations.