One-step Hydrothermal Treatment Research Articles

Mechanism of one-step hydrothermal nitric acid treatment for producing high adsorption capacity porous materials from coal gasification fine slag

The increasing amount of coal gasification fine slag (CGFS) necessitates its resource utilization. CGFS, mainly composed of porous carbonaceous particles and partially fused spherical or agglomerated ash particles, is an inexpensive and high-quality raw material for preparing adsorbent materials. However, the challenge remains in developing a simple, low-cost, and environmentally friendly method to produce high-performance porous materials from CGFS. In this study, a one-step treatment method using 2 mol/L nitric acid under hydrothermal conditions was proposed for CGFS. The adsorbent material (CGFS-2 M) prepared under a solid–liquid ratio of 2:5 and an initial concentration of 200 mg/L methylene blue (MB) exhibited an equilibrium adsorption capacity as high as 210.20 mg/g. The excellent adsorption performance of CGFS-2 M can be attributed to several factors: acid leaching for mineral removal and pore formation, resulting in a specific surface area and total pore volume 2.2 and 1.6 times that of untreated CGFS, respectively, and an optimized mesoporous pore size distribution favorable for MB adsorption; optimal mineral removal and a well-defined carbon microcrystal structure providing more space for MB adsorption; nitric acid treatment increasing the surface oxygen content and hydrophilicity, enhancing its ability to remove MB. The synergistic effect of pore structure improvement and surface modification indicates a feasible research direction for enhancing the performance of CGFS-based adsorbent materials. These results provide theoretical support for the development of efficient CGFS-based adsorbents.

An ionic liquid crystal functionalized nanocellulose lubricant additives

Cellulose, one of nature's most abundant, clean, and sustainable resources, has often shown unsatisfactory results when used as bio-lubricant additives. Herein, nanocellulose (NC) from amorphous waste natural poplar was extracted using deep eutectic solvent encapsulation treatment and chlorine bleaching process. Subsequently, 1-hexadecyl-3-methylimidazolium bromide was integrated onto NC using a one-step hydrothermal treatment (high-temperature and high-pressure environment) to obtain ionic liquid crystal (ILC) functionalized products (named as ILC-NC). After ball-milling process and solid phase separation step, ILC-NC exhibits excellent dispersion stability and lubrication properties in the liquid phase (including water and vegetable oil). Based on the polar and colloidal activity properties of ILC, it can form an ordered molecular layer on NC surface and form a lubricating film-like structure, making NC smoother and sliding well. Compared to ILC/NC aqueous dispersion, ILC-NC reduces the coefficient of friction and wear rate on steel disk surface by 68.75 % and 74.07 %, respectively. The minimum coefficient of friction was further reduced to 0.032 as dispersing ILC-NC in sunflower oil, showing a reduction of 0.134 (77.91 %) compared to pure sunflower oil. Finally, the lubrication theoretical model calculation reveals the lubrication state of ILC-NC on the steel disk surface and proposes the lubrication mechanism.

Fluorescent and colorimetric dual-mode detection of Cu2+ based on carbon dots.

A fluorescent and colorimetric dual-mode strategy based on carbon dots (CDs) was rationally designed for sensitive determination of Cu2+. Green fluorescent CDs with high absolute quantum yield of 72.9% were synthesized by facile one-step hydrothermal treatment of triethylenetetramine and Rose Bengal. Cu2+ could trigger the oxidative and chromogenic reaction of p-phenylenediamine (PPD) to generate chromogenic PPDox, accompanied by the fluorescence quenching of the CDs. The quenching mechanism was identified as the inner filter effect between PPDox and CDs. Therefore, a colorimetric/fluorescent dual-mode detection method for Cu2+ recognition was constructed. The limits of detection for Cu2+ were 4.14μM and 1.28μM for colorimetric and fluorescent mode, respectively. In addition, this method had achieved satisfactory results in the detection of Cu2+ in real serum samples.

One-pot hydrothermal synthesis of silicon, nitrogen co-doped carbon dots for enhancing enzyme activity of acid phosphatase (ACP) to dopamine and for cell imaging

Developing water-soluble nanomaterials with high photoluminescence emission and high yield for biological analysis and imaging is urgently needed. Herein, water-soluble blue emitting silicon and nitrogen co-doped carbon dots (abbreviated as Si-CDs) of a high photoluminescence quantum yield of 80 % were effectively prepared with high yield rate (59.1 %) via one-step hydrothermal treatment of N-[3-(trimethoxysilyl)propyl]ethylenediamine (DAMO) and trans-aconitic acid. Furthermore, the Si-CDs demonstrate environmental robustness, photo-stability and biocompatibility. Given the importance of the potentially abnormal levels of acid phosphatase (ACP) in cancer diagnosis, developing a reliable and sensitive ACP measurement method is of significance for clinical research. The Si-CDs unexpectedly promote the catalytic oxidation of ACP on dopamine (DA) to polydopamine under acidic conditions through the produced reactive oxygen species (ROS). Correspondingly, a fluorescence response strategy using Si-CDs as the dual functions of probes and promoting enzyme activity of ACP on catalyzing DA was constructed to sensitively determine ACP. The quantitative analysis of ACP displayed a linear range of 0.1–60 U/L with a detection limit of 0.056 U/L. The accurate detection of ACP was successfully achieved in human serum through recovery tests. As a satisfactory fluorescent probe, Si-CDs were successfully applied to fluorescent imaging of A549 cells in cytoplasmic with long-term and safe staining. The Si-CDs have the dual properties of outstanding fluorescent probes and auxiliary oxidase activity, indicating their great potential in multifunctional applications.

Yeast-Derived Carbon Dot/Cuprous Oxide Composite Electrochemical Sensor for Paracetamol

A novel yeast-derived carbon dot/cuprous oxide nanocomposite (Y-CDs/Cu2O) electrochemical sensor was developed for paracetamol. The Y-CDs were prepared by a one-step hydrothermal treatment and composited with Cu2O nanoparticles via ultrasonication assembly. Transmission electron microscopy, X-ray diffraction, Fourier-transform infrared spectroscopy, and X-ray photoelectron spectroscopy were conducted to characterize the morphology and structure of the synthesized nanomaterials systematically. After modification onto a glassy carbon electrode, the resulting sensor displayed excellent electrochemical performances toward paracetamol with a wide linear range (0.5–100 μM), low limit of detection (LOD, 90 nM), good repeatability, and stability (retaining 94% of initial response after 4 weeks). Remarkably, the electrochemical sensor presented good selectivity against potentially coexisting species. Satisfactory results were obtained for the analysis of commercial pharmaceutical tablets and human serum. The attractive sensitivity could be ascribed to the ultra-small size and surface-abundant functional groups of Y-CDs as well as the superior electroconductivity of Cu2O. Thus, the synergistic effect illustrates the Y-CD-Cu2O hybrid structure is promising for constructing high-performance electrochemical sensors.

Mesoporous Nitrogen-Doped Holey Reduced Graphene Oxide: Preparation, Purification, and Application for Metal-Free Electrochemical Sensing of Dopamine.

Holey graphenic nanomaterials with porosity within the basal plane attract significant interest. It is observed that the perforation of graphene can enhance the specific surface area of the nanosheet, ensuring effective wetting and penetration of electrolytes to the electrode surface, facilitating rapid charge transfer, and boosting the electrocatalytic efficacy of the transducers. This study reports the first example of nitrogen-doped holey reduced graphene oxide with a mesoporous morphology of the graphene basal plane (N-MHG). It is shown that N-MHG can be synthesized through a one-step hydrothermal treatment of GO using NH3 and H2O2. A straightforward procedure for the purification of N-MHG has also been developed. AFM, TEM, and Raman analyses have revealed that N-MHG possesses a highly mesoporous network structure with a pore size ranging from 10 to 50 nm. X-ray photoelectron spectroscopy data have indicated a partial reduction of the graphene oxide sheets during the etching process but also show a 3-5 times higher content of C═O and O-C═O fragments compared to rGO. This could account for the remarkable stability of the N-MHG aqueous suspension. An electrochemical sensor for dopamine analysis is assembled on a glassy carbon electrode with N-MHG/Nafion membrane and characterized by cyclic voltammetry and electrochemical impedance spectroscopy.

Tris-assisted one-step fabrication of functional carbon dots for specific folate receptor positive-expressed cancer cell imaging

Specific staining of cancer cells is momentous for cancer research. Nanoprobe with multivalent recognition is emerging as powerful tools for bioimaging, but the nonspecific cell uptake and complex functional modification procedures are still obstacles for specific detection and convenient synthesis. Carbon dots (CDs) with an intrinsic targeting ability, excellent optical properties and biocompatibility acquired from an efficient one-step fabrication procedure were urgently desired in specific cancer cells visualization. Herein, inspired by the interrelationships between interface and biomolecular mechanisms, we suggested that it was possible to construct CDs with the desired characteristics for folate receptor (FR) positive-expressed cancer cell imaging via rich hydroxyl groups Tris-assisted one-step hydrothermal treatment of folate acid (FA) and l-Arginine (L-Arg) precursors. The prepared small-sized F-CDs were equipped with abundant hydroxyl, pterin and negative charge surface, and possessed environmental friendliness, outstanding photostability and biocompatibility. Moreover, F-CDs had an intrinsic FR positive-expressed cancer cell targeting ability without any post-modification of the ligands. Rich hydroxyl groups play a vital role in endowing the optical properties and biological effects of F-CDs. F-CDs could be used as a promising candidate for FR-expressed cancer cell labeling and tracking. In addition, the caveolae-mediated endocytosis pathway of F-CDs was ascertained. More importantly, experimental results confirmed that the combination of physicochemical properties may provide an efficient strategy to overcome non-specific cell uptake interactions for cell labeling. Our strategy put forward a promising alternative to design fluorescent CDs for extensive chemical and biomedical applications.

Phase engineering of high-purity 1T-MoS2 synthesis with organic chemical groups for enhanced supercapacitors

The preparation of metallic molybdenum disulfide (1T-MoS2) through the phase engineering strategy could bring exceptional electrochemical performance with high conductivity and significant interlayer spacing. However, synthesizing high-purity 1T-MoS2 using a simple method remains a challenge. In this work, high-purity 1T-MoS2 was successfully produced through a one-step hydrothermal treatment facilitated by the presence of organic chemical groups. The resulting MoS2 exhibited a high capacitance of 180 F g−1 at 1.0 A g−1 as a supercapacitor electrode and demonstrated an impressive cycling stability of 84.6% after 10000 cycles. Moreover, an asymmetric supercapacitor (ASC) device constructed using the prepared CA-MoS2 and activated carbon on carbon cloths exhibited good supercapacitor performance. These findings demonstrate that organic chemical groups can be utilized to assist the phase engineering of transition metal dichalcogenides in energy storage and conversion.

Surface modification of TiNb alloys by hydrothermal-precalcification treatment and its excellent in vitro osteogenic bioactivity

The superb comprehensive mechanical properties of titanium and its alloys make them ideal materials for artificial bone repair. However, the osseointegration between normal tissue and implant is lengthy due to the relatively poor surface osteogenic bioactivity of titanium-based materials. For the sake of accelerating the bone healing process, surface modification for the titanium- based implant is therefore of great necessity. In this paper, the novel [Formula: see text]-typed TiNb alloy with good biocompatibility was modified by a simple hydrothermal-precalcification method. The experimental results demonstrate that these hydrothermally prepared TiNb alloys were coated by a superhydrophilic Nb-doped TiO2 film with a hierarchical micro-nanostructure. After subsequent pre-calcification treatment, calcium and phosphorus species with low content were successfully introduced into the film without morphological change. The simulated body fluid (SBF) soaking experiments show that the TiNb alloy with the two-step surface treatment represented excellent in vitro bioactivity. After incubating in SBF for only 1 day, the TiNb alloy surface was thoroughly coated with a layer of newly formed spherical hydroxyapatite clusters. Comparatively, no obvious hydroxyapatite was deposited on the TiNb alloy surface with the one-step hydrothermal treatment even after five days of incubation in SBF. As a result, the hydrothermal–precalcification treatment is an ideal method to improve the osteogenic bioactivity of TiNb alloy, which can be further extended to surface modification of other titanium-based implant materials.

A rapid response room temperature hydrogen sensor based on a three-dimensional Pd–In2O3/rGO aerogel

A three-dimensional (3D) Pd–In2O3/rGO aerogel was fabricated via a one-step hydrothermal treatment and freeze-drying.

One-step regeneration and upgrading of spent LiFePO4 cathodes with phytic acid.

The regeneration and upgrading of spent LiFePO4 cathodes (S-LFP) were achieved via a one-step hydrothermal treatment. The reducing effect of phytic acid could restore the degraded structure associated with an aqueous Li source. Meanwhile, Li ions are easily chelated by phytic acid groups, and a Li3PO4 coating layer could be formed to reconstruct the surface of the LFP. The regenerated LFP exhibits faster reaction kinetics, larger high-rate charge/discharge capacity, and better cycling performance than commercial LFPs, suggesting that our proposed strategy is a promising technology for the recovery of spent cathode materials.

Recycling of hazardous jarosite residues based on hydrothermal crystal transformation

Jarosite [MeFe3(SO4)2(OH)6] is a typical non-ferrous smelting slag produced in the process of iron removal from hydrometallurgical solution, which contains a large number of valuable and toxic metal elements. Treating the complex and hazardous jarosite residue in an economically and environmentally sound way has always been an urgent problem. A novel one-step hydrothermal treatment method was proposed in this paper for recycling of jarosite residues. It can be seen from the XRD and TEM results that jarosite residues could be completely transformed into hematite crystal particles under hydrothermal conditions at temperature above 220℃. Meanwhile, other valuable metal components (such as nickel sulfate hexahydrate) entrained in the residue will be dissolved in the aqueous solution, which can be reused in the hydrometallurgical process. Through phase composition analysis of the hydrothermal process, it is concluded that jarosite was firstly pyrolyzed to generate Fe3+. The obtained Fe3+ was then hydrolyzed to Fe (OH)3, which was transformed into Fe2O3 through dehydration condensation and directional arrangement. Further roasting the hematite particles, the obtained product contained 62.57 % of Fe, but only 0.21 % of S and 0.04 % of As, which meets the requirements of raw materials for iron making. In addition, compared with the current international standard ISO 1248:2006 (E), the obtained hematite particles with nanometer size and single crystal structure can be used as iron oxide red pigment. Overall, the one-step hydrothermal treatment of jarosite residues followed by reduction roasting not only realizes the economic recycling of the metal resources, but also solves the stacking problem of those hazardous residues.

In-situ growth and mechanism of MgAl-NO3-LDHs film on Ti6Al4V via one-step hydrothermal treatment with a high concentration of alkaline growth solution

The stable TiO2 passive film on titanium alloys has made it very difficult the in-situ growth of layered double hydroxides (LDHs) on their surface. In this paper, the in-situ growth of MgAl-NO3-LDHs on TC4 titanium alloy (Ti6Al4V) was successfully realized by one-step hydrothermal treatment with a high concentration of alkaline growth solution. The in-situ growth process of MgAl-NO3-LDHs on Ti6Al4V under different concentrations of growth solution was investigated by characterizing the morphology, structure and composition of the LDHs at different growth time. It was found that the key to the in-situ growth of MgAl-NO3-LDHs on Ti6Al4V was the conversion of the surface TiO2 and Al2O3 passive film to TiOH62− and AlOH4− which acted as active sites for the immobilization of LDHs crystal nuclei on Ti6Al4V, under a much higher concentration of alkaline growth solution than that for the low corrosion resistant alloys. The conversion degree of TiO2 and Al2O3 passive film to active sites increased with increasing growth solution concentration, and thereby increased the MgAl-NO3-LDHs content and reduced their lamellas size. The growth process of MgAl-NO3-LDHs on Ti6Al4V is composed of three stages: active sites formation, dense growth and sparse growth of the LDHs.

Rational hydrothermal-assisted green synthesis of blueish emitting carbon dots as an optical sensing platform for antibiotic detection in the milk sample

Carbon dots (CDs) derived from biological entities significantly play a major part in environmental and biomedical applications, comprising electrocatalytic oxidations, antibiotics detection, biosensing, and bioimaging. In the present work, facile green synthesis of blue-emitting CDs has been done using one-step hydrothermal treatment of pulp extract of Ziziphus mauritiana, acting as a natural source of carbon for optical determination of ciprofloxacin (CIP) antibiotics. The process is easy, safe for the environment, and doesn't require any specialized equipment or chemicals. The structural and optical characteristics of the synthesized CDs are done using XRD, FTIR, UV–visible spectroscopies, SEM-EDX, PL, and TEM. CDs were found to have a quasi-spherical shape with an average size of 2.54 nm. Nitrogen (1.2 wt.%), oxygen (41.8 wt.%), and carbon (40.7 wt.%) are the main component found in CDs, as observed by EDX. These CDs showed blue emission under UV light, excitation-dependent emission, and wide excitation-emission spectra. These prepared CDs were used to selectively detect CIP and exhibit a high quantum yield of 30% at the excitation wavelength of 340 nm. After the optimal parameters, the sensor gave the linear detection range from 10 to 100 µM along with a detection limit of 0.56 µM. Moreover, the practical applicability of the developed sensor was confirmed in real milk samples to test the consistency and accuracy of the sensor. In conclusion, the proposed method is a green, rapid, highly sensitive, and selective method for the detection of CIP in real milk samples, demonstrating the potential application of CDs in food detection.

UV-light enhanced gas sensor based on Ga doped ZnO for ultra-high sensitive and selective n-butanol detection

N-butanol gas is a common volatile organic compound (VOC) that can pose a threat to human health and pollute the atmospheric environment. However, the n-butanol gas sensors suffer from low response and selectivity. Herein, we synthesized the Ga-doped ZnO (ZOG) sensors by one-step hydrothermal treatment and subsequent calcination. The oxygen vacancies content of 1-ZOG has increased by 46 % compared to pure ZnO. Rich oxygen vacancies can increase the response signal of 1-ZOG to 174.78 in darkness for 100 ppm n-butanol, which is 2.4 times that of ZnO. Furthermore, the gas sensing performance of 1-ZOG is improved by light excitation. Under UV irradiation, the response of 1-ZOG sensor to 100 ppm n-butanol is 3.6 times that of pure ZnO, up to 636.81. Meanwhile, the response signal of 1-ZOG to n-butanol is at least 6.32 times that of other gases under UV light, showing ultra-high selectivity. This study proved that both Ga doped and photo-excited are effective strategies for improving the sensitivity and selectivity of ZnO based gas sensors.

In-situ reconstruction of self-supported amorphous Ni-Mo electrode for stable hydrogen evolution at large and intermittent current density

Solar power drived water splitting for hydrogen production is pivotal for sustainable energy conversion. Yet, it is challenging to develop earth abundant, high active, and durable electrodes to catalyzing hydrogen evolution reaction (HER) under fluctuating solar electricity. Herein we report self-supprted NiMo phosphate (NiMo-Pi) electrodes, where amorphous NiMo-Pi with nanosheets-like structure grow directly on conductive Ni foam by a facile one-step hydrothermal treatment. The electronic structures of Ni and Mo are tuned by O and P in NiMo-Pi electrodes, resulting the down-shift of their d-band centers. NiMo-Pi electrodes offer high activity and stability for HER, delivering -100 and -500 mA cm−2 mgcat−1 with overpotentials of 343 and 461 mV, repectively. They also sustain long-term electrolysis at a constant industrial-level current density of 500 mA cm−2 and at dynamic current densities ranging from -10 to -1 000 mA cm−2. Their HER activity become higher after stability tests, benefitting from in-situ surface reconstruction. This reconstruction makes the surface rich in active higher-lying d-band centers. This work suggests that tuning the electronic structure of electrodes is an efficient way to design efficient and stable electrodes for HER under harsh conditions.

Phosphorus-doped molybdenum disulfide as counter electrode catalyst for efficient bifacial dye-sensitized solar cells

MoS2 is a promising counter electrode material for dye-sensitized solar cell owing to its optical and electrical properties and two-dimensional layered structure. However, it still suffers from minimal conductivity, poor charge transport and less active sites. The present study offers a promising method for enhancing catalytic and fast charge transfer in MoS2 through heteroatom doping of phosphorus. A facile one-step hydrothermal treatment was acquired to do the phosphorus doping. The spin-coated P-doped MoS2 (MSP2) counter electrode (CE) shows a superior power conversion efficiency of 7.93% for front illumination and 5.34% for rear illumination, outperforming Pt-based (7.41% and 5.75%) CE. Thus, phosphorous incorporation increases the number of active sites and improves the catalytic property of the material. The P-doped MoS2 (MSP2) CE film also shows high transmittance, making it a suitable choice for bifacial type of solar cell.

Optimized ZnSn(OH)6 porous hollow microspheres via doping Ag for detecting formaldehyde

Pure and 4 wt% Ag-doped ZnSn(OH)6 were fabricated via one-step hydrothermal treatment, respectively, and the two samples were characterized by XRD, XPS, SEM and TEM technologies. Test results reveal that the Ag-doped ZnSn(OH)6 is a hollow microspheres with porous structure. What’s more, the Ag-doped ZnSn(OH)6 based on sensor exhibited a relatively high sensing response (49.12) and fast response/recovery capability (16/10 s) to 100 ppm formaldehyde than those to pure ZnSn(OH)6 (24.78) at 200 °C. The reason for enhancement was contributed to hollow spherical structure, which provided higher specific surface area, more active sites. In addition, the Ag doping was conducive to gas molecules dissociation, which stimulated the reactions happening between the sensing material and gas molecules. Thus, the Ag-doped ZnSn(OH)6 is more suitable and promising candidate material to prepare gas sensor for detecting formaldehyde.

Poria cocos-derived carbon dots for cellular imaging, free radical scavenging and pH sensing

Green, economical preparation of carbon dots (CDs) from traditional Chinese herbal medicine Poria cocos via a one-step hydrothermal treatment was reported. The CDs exhibited excellent aqueous dispersibility, superior photoluminescence (PL) property and low cytotoxicity. Taking advantage of these properties, CDs were demonstrated as excellent multicolor bioimaging agents for the cellular imaging of MDA-MB-435S cells, with main distributions in the cell membranes and cytoplasm. Moreover, the CDs also exhibited good radical scavenging activity against 1,1-diphenyl-2-picrylhydrazyl (DPPH) thanks to their inheritance of characteristic functionalities from Poria cocos. Lastly, our study also shown that the PL of CDs was reversibly sensitive to pH in the range of 4.0 and 9.0, and a highly sensitive pH-sensing assay was developed exploiting this phenomenon. In summary, the study opened up new development paths for the modernization and vitalization of traditional Chinese medicine in biomedical research.

A ratiometric fluorescent probe for simultaneous detection of L-ascorbic acid and alkaline phosphatase activity based on red carbon dots/polydopamine nanocomposite

Herein, efficient red carbon dots (R-CDs) were synthesized by one-step hydrothermal treatment of N-(4-amino phenyl) acetamide and (2,3-difluoro phenyl) boronic acid. The optimal emission peak of R-CDs was at 602 nm (under 520 nm excitation) and the absolute fluorescence quantum yield of R-CDs was 12.9%. Polydopamine, which was formed by the self-polymerization and cyclization of dopamine in alkaline condition, emitted characteristic fluorescence with peak position of 517 nm (under 420 nm excitation) and affected the fluorescence intensity of R-CDs through inner filter effect. L-Ascorbic acid (AA), which was the hydrolysis product of L-ascorbic acid-2-phosphate trisodium salt under the catalytic reaction of alkaline phosphatase (ALP), effectively prevented the polymerization of dopamine. Combined with the ALP-mediated AA production and the AA-mediated polydopamine generation, the ratiometric fluorescence signal of polydopamine with R-CDs was correlated closely with the concentration of both AA and ALP. Under optimal conditions, the detection limits of AA and ALP were 0.28 μM during linear range of 0.5–30 μM and 0.044 U/L with linear range of 0.05–8 U/L, respectively. This ratiometric fluorescence detection platform can efficiently shield the background interference of sophisticated samples by introducing a self-calibration as reference signal in a multi-excitation mode, which can detect AA and ALP in human serum samples with satisfactory results. Such R-CDs/polydopamine nanocomposite provides a steadfast quantitative information and makes R-CDs be excellent candidate for biosensors via combining target recognition strategy.