Low-temperature Hydrothermal Process Research Articles

Phase transfer-assisted indium recovery from spent liquid crystal display panels and its extension in preparing indium-based electrocatalysts for CO2 reduction

Transforming discarded electronic devices into low-cost and high-efficiency catalysts presents a win–win approach to address the scarcity of rare resources and sustainable energy challenges. Herein, we report an effective strategy that combines an ethanol-mediated dodecylamine (DDA) phase transfer with hydrothermal methods for facilitating the facile synthesis of indium (In)-based nanomaterials from the leachates of liquid crystal display panels (LCDPs) toward high-efficiency electrochemical CO2 reduction reaction (eCO2RR). In this strategy, the rapid formation of coordinating compounds between the –NH2 group of DDA and metal ions facilitates the separation of In3+ cations from the acidic LCDPs leach solution by transferring them into an organic phase, which are then converted into InOOH nanoparticles with abundant oxygen vacancies (denoted as In-LCDPs and hereafter) through a low-temperature hydrothermal process. The eCO2RR evaluations confirm the superior electrocatalytic performance of the In-based nanoparticles produced from the LCDPs. In specific, within a broad potential range (−0.77 to −1.17 V vs RHE), the In-LCDPs show a Faradaic efficiency for formate (FEformate) of 85 %, with the highest FEformate of 90.23 % at −0.97 V vs RHE, which is comparable to the FEformate (93.8 % at −0.97 V vs RHE) of In-based catalyst prepared from pure In precursors using the same method. Further investigations reveal that the Sn and Al impurities have minimal impact on the catalytic performance of In-LCDPs, while the presence of Fe3+ impurities significantly enhance the production of hydrogen during the eCO2RR. This work might have provided a scalable pathway to transform LCDPs into value-added electrocatalysts for eCO2RR.

Local polarization redistribution in ZnmIn2S3+m for the enhancing synergetic piezo-photocatalytic overall water splitting

Piezo-photocatalytic water (deuterium oxide) decomposition is a promising strategy for realizing renewable energy, but the manipulation of the polar center remains a big challenge. This study uses a simple low-temperature hydrothermal process to successfully manufacture ZnmIn2Sm+3 (m = 1–3) (ZnIn2S4, Zn2In2S5 and Zn3In2S6). Incorporating both experimental and theoretical analyses, the structural contraction and local polarization of the Zn-S bond in Zn2In2S5 enhance the piezoelectric response and surface charge accumulation, which facilitate charge transfer and reduce the activation energy of water. Remarkably, Zn2In2S5 exhibits excellent piezoelectric photocatalytic total water splitting performance (H2/O2: 4284.72/1967.00 μmol g-1h−1), which is 1.77 times that of photocatalytic performance. Moreover, a significant enhancement in D2O splitting performance can be obtained for the optimized Zn2In2S5. Our work offers valuable insights into the disclosure of local polarization in catalysts for enhancing piezo-photocatalytic overall water splitting.

Fabrication and piezoelectric analysis based on nanogrid architecture composed of ZnO ultrathin nanosheets grown on fiber paper substrates for wearable energy harvesting

In this work, three-dimensional (3D) nanogrid architecture composed of two-dimensional (2D) ZnO ultrathin nanosheets (ZUNSs) is grown on fiber paper substrates by a two-step low-temperature hydrothermal process, and a flexible piezoelectric nanogenerator (PENG) is also developed based on the as-grown ZUNS-paper. Piezoelectric signals were also measured under compressive forces that can harvest energy up to 30 nA and 120 mV. In order to exploit the piezoelectric properties of the unique ZnO nanostructure, a series of simulation experiments based on ZUNSs were conducted systematically through the finite element method (FEM, COMSOL). The size-dependent simulation analysis (including thickness, length, and height) under two different force modes manifests that the ZUNSs possess tremendous merits for optimizing the output performance of piezoelectric nanogenerators, especially in the case of lateral bending. Besides, the anisotropic electricity generation has been investigated and analyzed within the ZUNSs via applying force with various orientations. Our results may provide guidance for the design and performance optimization of wearable self-powered micro/nanoelectric devices.

Cobalt-free CuO catalyst for hydrolytic dehydrogenation of sodium borohydride and ammonia borane

The environmental and economic impact of Co-based catalysts necessitates the use of a more environmentally friendly and less expensive catalyst, such as CuO. A cobalt-free CuO catalyst was developed via a simple low-temperature hydrothermal process. The efficiency of the catalyst was analysed for the dehydrogenation of NaBH4 as well as NH3BH3. Compared with the commercial particulate CuO, hydrothermally prepared CuO nanoplate (CuO HT) exhibits a good hydrogen evolution rate, the rate of hydrogen evolution for CuO_Commercial and CuO HT was experimentally measured to be 240 ml H2/min/g and 470.5 ml H2/min/g respectively for 0.2 g catalyst for the dehydrogenation of NaBH4. At a 10 times lower concentration of NaBH4 with 0.2 g of CuO HT catalyst, the rate of HER recorded was 1086 ml H2/min/g. The high catalytic activity of CuO HT could be related to the surface oxygen vacancies or defects generated due to the participation of high molar concentrations of NaOH during the reaction. The stability of both catalysts was investigated, and the rate of hydrogen evolution reaction after three cycles was determined to be 492 ml H2/min/g for CuO_Commercial and 925.1 ml H2/min/g for CuO HT. Despite the fact that the rate of hydrogen evolution was observed to be increased for the third cycle, the volume of water displaced was decreased when compared to the first cycle, which could be due to the presence of a less active Cu2O phase retained after temperature treatment. Similarly, with the best catalyst concentration of CuO HT (0.2 g), the hydrogen evolution rate of NH3BH3 was also measured to be 1175 ml H2/min/gm. The result evokes a new insight into the evolution of sustainable and eco-friendly catalysts for a better hydrogen economy.

Enhanced Structural and Electrochemical Properties of Zn-Doped NiCo2O4 Synthesized by Low-Temperature Microwave Hydrothermal Process

The specific capacitance (Cp) is an important parameter influencing the energy storage capacity of materials. In this study, a series of NiZn x Co2-x O4 (x = 0.0–0.10) nanoparticles were prepared using the microwave-hydrothermal (M-H) method. The samples were characterized by using X-ray diffraction (XRD), Scanning electron microscopy (SEM), Fourier transform Infrared (FTIR), X-ray photoelectron spectroscopy (XPS) and electrochemical studies. It is observed from X-ray diffraction that all the samples are cubic in nature with space group Fd-3m. The average lattice constant is varied in between 7.63 (x = 0.0) to 8.34 (x = 0.10). The linear increase in lattice constant is due to the difference in the ionic radii. The average grain size is in the range of 80 (x = 0.0) − 124 nm (x = 0.10) for all the samples, and grains are found to be spherical in nature. The characteristic metal oxygen vibration bands were observed at 578 cm−1 and 661 cm−1. The valence states of Ni2+/Ni3+, Co2+/Co3+ and Zn2+ were confirmed by X-ray photoelectron spectroscopy. The electrochemical studies were performed on all the samples. The high value of specific capacitance (Cp) 871.91 Fg−1 is observed for sample x = 0.06. Therefore, Zn doped NiCo2O4 shows good impedance and electrochemical properties which is promising material for supercapacitor applications.

Life cycle assessment of bio-oil prepared from low-temperature hydrothermal oxide-catalyzed cotton stalk

The technological development of preparing bio-oil from low-temperature hydrothermal conversion of agricultural and forestry waste has positive significance for alleviating the shortage of oil energy supply and reducing environmental pollution. This paper selects typical oxides (Al2O3, CeO2, MgO, SiO2, TiO2, and ZnO) as catalysts to set up a low-temperature (220 °C) hydrothermal conversion process of cotton stalk containing pretreatment processes including chopping. For moderate amplification estimation, lab-scale experimental data is used as a benchmark for calculation, and the functional unit for this study is set to be a 1 kg bio-oil product. The results suggest that the cerium dioxide-involved process with the highest bio-oil yield and highest synthetic consumption, and the silica-involved process with the lowest bio-oil yield, caused the highest environmental impact, resulting in greenhouse gas (GHG) emissions of 67.729 kg CO2e/kg and 60.001 kg CO2e/kg, respectively. It indicates that catalysts need to consider the balance between synthetic consumption and catalytic performance. Magnifying lab-scale data to an industrial scale using scale-up frameworks introduces a low model uncertainty, as the practical value had little effect on the overall evaluation results. However, existing equipment data should be used to reduce the uncertainty of the model itself. The environmental sustainability of bio-oil production by low-temperature hydrothermal liquefaction still needs to be improved, especially by catalyst recovery and bio-oil yield improvement.

Development of Modified Mesoporous Carbon from Palm oil Biomass for Energy Storage Supercapacitor Application

Energy storage system research including battery and supercapacitor devices has been studied to increase efficiency, lower their cost and improve environmental friendliness. Supercapacitor (SC) device offers high transient response and power density which suitable for many applications. The electrodes in supercapacitor device usually produced from highly porous carbon materials. In this study, the modified mesoporous carbon was produced from Palm empty fruit bunch (EFB) biomass. The production of mesoporous carbon was done using a low-temperature hydrothermal carbonization process. The mesoporous carbon from EFB biomass has shown good properties in terms of high surface area and porosity. To improve the electrical conductivity of the carbon the modification by nitrogen doping with ammonium chloride and urea was studied. The effect of different nitrogen sources on surface area and pore properties were reported. The modified mesopore carbon was tested in a symmetrical swagelok supercapacitor cell to evaluate the specific capacitance and efficiency using galvanostatic charge-discharge method. The modified mesoporous carbon with urea doped exhibits the highest specific capacitance of 121 F g-1 at current loading of 0.1 A g-1 in an aqueous 1M H2SO4 electrolyte. The modified mesoporous carbon with urea doped has lower internal resistance due to nitrogen from urea enhance the electronic conductivity of the electrodes and thus increase the supercapacitor performance.

Catalytic mechanism of the Schikorr reaction promoted by the copper oxide nanosheet during a low-temperature hydrothermal process

The Schikorr reaction 3Fe(OH)2 → Fe3O4 + H2 + 2H2O, has been proposed for nearly 100 years. Although it has shown great potential application value in steel corrosion, recovery of ferrous waste liquid, and other fields, the reaction catalyst itself is still unclear. We confirmed that Cu(II) ions were essentially converted into the oriented CuO nanosheets as a catalyst during a low-temperature hydrothermal process. Moreover, this catalytic reaction required the participation of hydroxide ions without relationship to sulfate ions and trace dissolved oxygen molecules in the solution. The growth process tracing experiment found that green rust was the reaction intermediate, and the reaction stage from green rust to Fe3O4 was the reaction rate control stage. Finally, the reaction rate was clearly defined by using the FWHM of the XRD diffraction peak of the (3,1,1) crystal plane of Fe3O4, and the activation energy was calculated as 79.46 ± 5.05 kJ mol−1.

Synthesis of Ag and Mn/ZnO nanoparticles using a hydrothermal method - A brief study and their role in the electrocatalytic oxidation of glucose in alkaline media

Ag and Mn/ZnO were synthesized via a low-temperature hydrothermal process and applied as glucose oxidation reaction (GOR) catalysts. The sample characterization was performed by scanning electron microscopy (SEM) and energy dispersive X-ray analysis (EDX), which revealed homogenous clustered nanoparticles for synthesized materials. The various amounts of Ag and Mn were loaded in ZnO nanostructure and their electrocatalytic effect on GOR was investigated by electrochemical techniques such as cyclic voltammetry (CV) and electrochemical impedance spectroscopy in an alkaline solution containing 3 mM glucose and 0.1 M NaOH. The Ag/ZnO and Mn/ZnO with 50% and 60% loading, respectively, were identified as the best electrocatalysts. The experimental data showed that the larger effective surface area of Ag/ZnO-50 (6.9 cm2) and Mn/ZnO-60 (9.25 cm2) accompanied by faster glucose diffusion coefficient due to the effective impact of Ag and Mn loading on the ZnO nanostructure improved the GOR for Ag/ZnO-50 and Mn/ZnO-60 compared to the ZnO.

Influence of typical pretreatment on cotton stalk conversion activity and bio-oil property during low temperature (180–220 ℃) hydrothermal process

• Pretreatment could enhance cotton stalk (CS) hydrothermal conversion activity. • CS surface microstructure changed by pretreatments benefits hydrothermal bio generation. • The best bio-oil properties and CS conversion activity was realize by NaOH/EtOH pretreatment. • Pretreatment could be used as an important way to regulate the composition of bio-oil. Conversion of agricultural and forestry waste biomass into high value-added bio-oil by mild hydrothermal method is of great significance to reduce the diesel consumption and alleviate the shortage of high-quality fuel oil supply. Most of the current research focuses on the parameter adjustment in the hydrothermal process, including temperature, time, catalyst and cosolvent, but the influence of the structure of raw materials on the hydrothermal conversion activity and the properties of hydrothermal oil is less. In this study, several typical pretreatment methods (including ball milling, alkali + ball milling, urea/NaOH and NaOH + ethanol) were used to change the structural characteristics of agricultural waste cotton stalks (CS), and the treated CS were used for hydrothermal conversion at low temperature (180–220 ℃). Taking the yield of hydrothermal bio-oil as index, the results show that various pretreatment can effectively improve the hydrothermal conversion activity of CS, improve the combustion performance of hydrothermal bio-oil and adjust the composition of hydrothermal oil. The hydrothermal bio-oil obtained by NaOH + EtOH pretreatment has the best properties, the yield is 7.41 % (wt, 220 ℃, 2 h), the calorific value is 24.16 MJ/kg, and the energy recovery is 10.98 %, which is higher than untreated CS bio-oil (with yield of 3.90 wt% at 220 ℃ and 2 h, calorific value is 23.32 MJ/kg and energy recovery of 10.98 %). The research will strengthen the role of lignocellulosic raw material structure in the hydrothermal process, which will play an important role in promoting the industrialization process of hydrothermal technology in the field of biomass, especially considering the optimization of operating parameters of various raw materials in the future industrialization.

The influence of sodium on the catalytic properties, low-temperature hydrothermal stability, and sulfur resistance of Cu-SAPO-34 for NOx reduction by NH3-SCR

In the actual diesel vehicle after-treatment systems, Cu-SAPO-34 selective catalytic reduction (SCR) of NOx catalyst simultaneously experiences the failure of sodium (Na) poisoning, low-temperature hydrothermal (LTH) deactivation and SO2 poisoning. This work investigated that the Na-loaded Cu-SAPO-34 catalysts were severally subjected to LTH treatment and sulfur poisoning for the first time. Our characterizations revealed that Na played entirely different roles in above two scenarios. In the LTH process, Na readily exchanges the protons of Si-OH-Al moieties on the zeolite framework, which inhibits the hydrolysis of the framework and further restrains the formation of SCR-inactive species. However, for SO2 poisoning, the presence of Na accelerates the deactivation of Cu-SAPO-34 because more stable sulfate species are formed on the catalyst, which severely block the pores and reduce the active sites. It is expected that these results could assist the design of SCR catalysts to meet ultra-low NOx emission.

Enhancing UV resistance of TiO2 reinforced Kevlar 29 fiber using Sol-Gel & Low-temperature Hydrothermal Processes

ABSTRACT Mechanical properties of Kevlar fibers are significantly affected by their chemical structure when they are subjected to ultraviolet (UV) environment owing to photo degradation effect. In this work, Kevlar fibers are modified by means of impregnating with the titanium dioxide (TiO2) using low temperature hydrothermal process and dip coating methods. Ultraviolet–visible absorption spectrum confirms that hydrothermal treated Kevlar fibers exhibited outstanding UV resistance among others. The UV durability of the TiO2 modified Kevlar fiber is carried out using accelerated photoageing method up to 180 hours. Results of the tensile test showed that the best tensile strength was demonstrated by the modified fiber.

(Digital Presentation) Mn-VOH Micro Flakes Interconnected with CNT As Cathodes for Aqueous Zinc-Ion Batteries

With increasing energy consumption and environmental awareness, the demand for next-generation energy storage systems has grown. Aqueous zinc-ion batteries (AZIBs) have received considerable attention among various types of energy storage devices due to their high safety standards and low cost. Herein, we present a sustainable synthesis approach for synthesizing MnVOH@CNT composite material and its application as the cathode material for aqueous Zinc-ion batteries (AZIBs) by using a low-temperature (120 °C) hydrothermal process. Moreover, with a continuous network structure and expanded interlayer spacing, such a configuration can provide rapid electron transfer kinetics (DZn 2+: 10 ̶ 11−10−12 cm2 s−1) while ensuring close interaction between MnVOH and CNT during cycling. The materials have excellent electrochemical properties as cathodes in the AZIBs. The resultant batteries exhibit a high intercalation storage capacity of c.a. 380 mAh g−1 at acurrent density of 0.1 A g−1, minimized polarization, and excellent capacity retention of c.a. 90% after 300 cycles. Furthermore, operando synchrotron X-ray absorption, near-edge spectroscopy was used for the first time to confirm the Zn2+ charge-storage mechanism. Operando synchrotron X-ray diffraction, studies were also done to better understand the structural changes of the MnVOH@CNT nanocomposite during the discharge/charge processes. Meanwhile, the ZIBs using MnVOH@CNT as cathode can maintain an energy density of c.a. 190 Wh kg−1 at a high power density of 3.2 kW kg−1, demonstrating that MnVOH@CNT is a promising cathode material for high-performance cathode material for low-cost and environment-friendly AZIB applications. KEYWORDS: AZIB, MnVOH@CNT, operando XANES, operando XRD, cathode material

Van der Waals Epitaxial Growth of ZnO Films on Mica Substrates in Low-Temperature Aqueous Solution

In this article, we demonstrate the van der Waals (vdW) epitaxial growth of ZnO layers on mica substrates through a low-temperature hydrothermal process. The thermal pretreatment of mica substrates prior to the hydrothermal growth of ZnO is essential for growing ZnO crystals in epitaxy with the mica substrates. The addition of sodium citrate into the growth solution significantly promotes the growth of ZnO crystallites in a lateral direction to achieve fully coalesced, continuous ZnO epitaxial layers. As confirmed through transmission electron microscopy, the epitaxial paradigm of the ZnO layer on the mica substrate was regarded as an incommensurate van der Waals epitaxy. Furthermore, through the association of the Mist-CVD process, the high-density and uniform distribution of ZnO seeds preferentially occurred on mica substrates, leading to greatly improving the epitaxial qualities of the hydrothermally grown ZnO layers and obtaining flat surface morphologies. The electrical and optoelectrical properties of the vdW epitaxial ZnO layer grown on mica substrates were comparable with those grown on sapphire substrates through conventional solution-based epitaxy techniques.

W-Doped LiNi1/3Co1/3Mn1/3O2 with Excellent High-Rate Performance Synthesized via Hydrothermal Lithiation

High energy consumption and excess lithium are required for the preparation of transition metal layered oxide cathodes through high-temperature solid-phase sintering. Exploring new low-cost preparation methods can raise the cost competitiveness of commercial lithium-ion batteries. Herein, nanoscale LiNi1/3Co1/3Mn1/3O2(NCM111) was prepared via a hydrothermal lithiation process from transition metal sulfates. The dissolution-recrystallization mechanism during the low-temperature hydrothermal process enables the formation of nanoparticles. The nanoscale particle size shortens the diffusion channel of lithium ions, which can significantly boost the rate-performance of NCM111. The high concentration of Li+ in the solution hinders Ni2+ from occupying the 3a site of Li+ during the formation of the layered structure, inhibiting the cation mixing, and the unreacted lithium in the solution can be easily recycled. The conductivity of the material is improved by introducing the high valence ion W6+, while the strong W–O bond stabilizes the layered structure and further restrains cation mixing. The results show that the W-doped NCM111 has a specific capacity of 131.9 mAh g−1 at an ultra-high discharge rate of 20 C (3200 mA g−1).

Achieving nano-patterned features by micro-EDM process using vertically aligned ZnO nanorods grown on microprobe tip: A scaling approach

Fabricating the nanopatterned features through a cost-effective nanomachining technique is one of the great challenges in NEMS industries. The micro-electrical-discharge machining process is one of the promising machining technologies which is capable to write the micro-scale features on any electrically conductive materials. However, its potential has not been tested yet for replicating the nanoscale features through the scaling approach. Hence, this article addresses a scaling approach for fabricating the nanopatterned features on super finished titanium alloy (Ti-6Al-4 V) using vertically aligned ZnO nanorods grown on the apex of the microtip. For achieving this, first of all, cylindrical micro-tools of diameter (ø) 90–95 μm (tungsten) were fabricated through a micro-electrochemical turning process under KOH (2.5 M) electrolyte medium. On the apex of the micro tools, the ZnO nanorods were grown by the low-temperature hydrothermal process by dipping the apex of the tip in seed and growth solution followed by essential heat treatment at 90 °C. It was found that the grown nanorods were well defined in shape and size and further utilized as nanotools during short-duration discharge (5 ms) μ-EDM experiments. It was expected that by downsizing the tooltip, the discharge energy per unit pulse may be reduced due to the localization effect. Moreover, it is well-known fact that the discharge happens only in the nearest established gap in the μ-EDM process. The experimental results of this study confirmed the same. The FESEM micrographs were utilized for the morphological characterization of formed nanopatterned cavities, microtools, and nanorods while the chemical characterization of the same is carried out by EDX spectroscopy. Additionally, the stability of the machining process was tested first for multiple discharge energy pulses then after a short duration discharge energy pulse has been characterized by voltage-current (V-I) waveforms during nanocavity fabrication. Finally, the supporting results of this experimental investigation show the feasibility of the approach towards nano-EDM with extensive potentials/applications in micro/nanofabrication devices.

Introduction of a Zn-based metal\u2013organic framework @ biomass porous activated carbon as a high-sensitive coating for a stainless steel SPME fiber: application to the simultaneous analysis of nonsteroidal anti-inflammatory drugs

The present study introduces a high-efficiency nanocomposite material featuring a zinc-based metal–organic framework and a novel porous activated carbon derived from bread waste. The prepared nanocomposite, namely Zn-MOF-5@BHPAC, has been synthesized by a low-temperature hydrothermal process and coated onto the surface of a stainless steel wire with epoxy glue. The fabricated fiber has been employed as an SPME fiber applied in the extraction and pre-concentration of some nonsteroidal anti-inflammatory drugs (NSAIDs) before their high-performance liquid chromatography-ultraviolet (HPLC-UV) studies. The characterization studies were performed utilizing field emission scanning electron microscopy, elemental mapping, energy-dispersive X-ray spectroscopy, elemental analyzer, Fourier-transform infrared spectroscopy, and Brunauer–Emmett–Teller surface area analysis. Under the optimal conditions, the method demonstrated low detection limits (LODs, 0.06–0.15 µg L–1), wide linear ranges (LRs, 0.20–380 µg L–1) with good linearity (R2 > 0.991), good precisions (RSDs < 6.95%), and acceptable relative recoveries (RR > 85%). Using the green and affordable biomass of bread as a novel carbon-rich source is an innovative idea provided in this study. In addition, the hybridization of the obtained carbon-based material with the MOF compound to create a new high-capacity sorbent is another strength of the proposed method. Long service lifetime, economic efficiency, environmental friendliness, and high extraction capability were some of the other advantages of the suggested procedure. Therefore, the method can utilize successfully for the simultaneous determination of NSAIDs (as model analytes) in different matrixes.

Activated Carbon Preparation from Sugarcane Leaf via a Low Temperature Hydrothermal Process for Aquaponic Treatment.

The effects of hydrothermal treatment, 0–5% KMnO4 content, and 300–400 °C pyrolysis temperature, were studied for activated carbon preparation from sugar cane leaves in comparison with non-hydrothermal treatment. The percent yield of activated carbon prepared by the hydrothermal method (20.33–36.23%) was higher than that prepared by the non-hydrothermal method (16.40–36.50%) and was higher with conditions employing the same content of KMnO4 (22.08–42.14%). The hydrothermal and pyrolysis temperatures have the effect of increasing the carbon content and aromatic nature of the synthesized activated carbons. In addition, KMnO4 utilization increased the O/C ratio and the content of C-O, Mn-OH, O-Mn-O, and Mn-O surface functional groups. KMnO4 also decreases zeta potential values throughout the pH range of 3 to 11 and the surface area and porosity of the pre-hydrothermal activated carbons. The use of the pre-hydrothermal activated carbon prepared with 3% KMnO4 and pyrolyzed at 350 °C as a filter in an aquaponic system could improve the quality of water with pH of 7.2–7.4, DO of 9.6–13.3 mg/L, and the turbidity of 2.35–2.90 NTU. It could also reduce the content of ammonia, nitrite, and phosphate with relative removal rates of 86.84%, 73.17%, and 53.33%, respectively. These results promoted a good growth of catfish and red oak lettuce.

A High-Performing Nanostructured Ir Doped-TiO2 for Efficient Photocatalytic Degradation of Gaseous Toluene

TiO2-based photocatalysts still have some limitations such as large bandgap and low surface area, leading to low efficiency in the photocatalytic degradation of VOCs and limiting it to use in sunlight. Here we report that the nanostructured Ir-doped TiO2 as an efficient photocatalyst generates an excellent risk-reduction material of gaseous toluene. We have succeeded in developing a nanostructured Ir-doped TiO2 and initially found that excellent efficient photocatalytic VOC decomposition can be achieved in our materials The nanostructured Ir-doped TiO2 was synthesized by a one pot, low temperature hydrothermal process with different ratios of Ir doped into the TiO2. It exhibited a high surface area, uniformly spherical morphology of 10–15 nm. Its activity for the photocatalytic degradation of gaseous toluene exhibited up to 97.5% under UV light. This enhancement could be explained by iridium doping which created a high concentration oxygen vacancy and changed the recombination rate of the photogenerated charge carriers. More generally, our study indicates a strategic way to develop the novel nanostructured material for numerous applications.

Fluorescent carbon dots crosslinked cellulose Nanofibril/Chitosan interpenetrating hydrogel system for sensitive detection and efficient adsorption of Cu (II) and Cr (VI)

• One-pot synthesis of carbon dots cross-linked cellulose nanofibril hydrogel. • The introduction of chitosan by solvent displacement forms IPN hydrogel. • Carbon dots provide visual detection during Cu (II) and Cr (VI) adsorption. • Amphoteric biomass and carbon dots provide adsorption sites for Cu (II) and Cr (VI). • The mechanism of Cu (II) and Cr (VI) sorption and sensing was determined. To address the pollution of heavy metal ions in water resources, a novel self-assembled nitrogen-doped carbon dots (NCDs) crosslinked, cellulose nanofibril (CNF) and chitosan (CS) based interpenetrating polymer network (IPN) hydrogel (NCDs-CNF/CSgel) was prepared for simultaneous fluorescent detection and adsorption of Cu (II) cation and Cr (VI) anion. The NCDs cross-linked CNF hydrogel network was synthesized by an environmentally friendly low-temperature hydrothermal process and subsequently, solvent replacement was used to form the second layer of CS network. The morphology, chemical structure, fluorescent properties, and adsorption behaviors of NCDs-CNF/CSgel were analyzed. The results showed that NCDs-CNF/CSgel exhibited a wide linear range of fluorescence response for Cu (II) (50–1000 mg/L, detection limit of 40.3398 mg/L) and superior sensitivity and selectivity of fluorescence response for Cr (VI) (linear range of 1–50 mg/L, detection limit of 0.7093 mg/L). NCDs-CNF/CSgel showed high adsorption capacities of 148.30 mg/g and 294.46 mg/g for Cu (II) and Cr (VI), respectively, and fitted well to the pseudo-second-order model and the Langmuir model. The detection of Cu (II) and Cr (VI) and their adsorption mechanisms onto NCDs-CNF/CSgel were further determined. Hence, this work provides a green and sustainable approach for the synthesis of a functional material which can be applied for the detection and adsorption of heavy metal ions.