Hydrothermal Synthesis Research Articles

A one-pot hydrothermal synthesis of morphologically controllable yolk-shell structured CoFe glycerate spheres for oxygen evolution reaction

CoFe-based catalysts are efficient electrocatalysts for the oxygen evolution reaction (OER) in alkaline media. Here, we present a simple one-pot hydrothermal method for synthesizing a series of CoFe glycerates with controllable surface morphologies and investigate their potential as highly efficient catalysts for the OER in alkaline media. These CoFe glycerates exhibit a unique yolk-shell microsphere structure assembled from ultrathin nanosheets. The adjustment of the surface nanosheet size is achieved by varying the CoFe ratio, ensuring a more efficient electrocatalytic system for the OER process. Due to the abundant active sites provided by the yolk-shell structure and interleaved ultrathin nanosheets, Co3Fe1 glycerate (Co3Fe1 gly) demonstrates a low overpotential (283 mV) and a small Tafel slope (44.61 mV dec−1) at 10 mA cm−2. Additionally, Co3Fe1 gly exhibits excellent durability in alkaline electrolytes. Moreover, a series of characterizations demonstrate that the active sites of Co3Fe1 gly are the high-valence Co species generated during the OER process. This study opens a promising avenue for utilizing efficient and low-cost electrocatalysts to enhance OER performance.

(Invited) Research and Development Trends in Sodium-Ion Batteries

Lithium-ion batteries (LIBs) are the most used energy storage technology for electronic devices and electric vehicles. However, the increasing demand for lithium may make it difficult to support the widespread use of LIBs in electric vehicles, utility grids, and other applications. Therefore, developing alternative technologies to LIBs is critical for large-scale energy storage. Studies suggest that using sodium-ion batteries with renewable energies can significantly reduce the cost of electricity. Despite the lower energy density, sodium-ion batteries are appealing for several reasons: (1) sodium is abundant, (2) less critical components are used, and (3) the manufacturing knowledge of LIBs can be used. Herein, we report for the first time a hydrothermal synthesis of a new class of sodium-rich cathode material with the formula Na3+xNixV2-x(PO4)2F2O that could enable the compensation of the irreversible sodium loss in the first charge in a full cell with hard carbon. Trends in sodium-ion batteries will be discussed, considering the new developments in layered oxides, oxy-fluoro-phosphates, and Prussian blue cathodes.

Application of Bifunctional Layered Double Hydroxide Electrocatalysts to Water Splitting

Water splitting is an area of research which is of pressing interest in addressing climate change. Water splitting provides oxygen and hydrogen as products, with hydrogen finding use as a potential high-density fuel to replace fossil fuels. Water splitting manifests as two half-cell reactions, namely the anodic oxygen evolution reaction and the cathodic hydrogen evolution reaction. The purpose of this project is to synthesise a bifunctional electrocatalyst to use in the water splitting reaction, replacing the rare and expensive transition metals catalysts currently in use such as platinum and ruthenium. The ideal material would exhibit strong performance for both the oxygen evolution reaction and the hydrogen evolution reaction.In this project, Layered Double Hydroxides (LDHs) have been synthesised for use in water splitting. LDHs are a group of ionic compounds characterised by their layered structure of positively charged sheets and an interlayer region consisting of the corresponding anions. LDHs typically contain a bivalent and a trivalent metal as part of the generic formula [M2+ 1–xM3+ x(OH)2][An–]x/n·zH2O. In this project the bivalent metal in use is typically cobalt and the trivalent metal is typically iron. The synthesis developed is a simple, one pot hydrothermal synthesis which can be seen in Figure 1. In this synthesis, the process begins with the precursor materials dissolved in solution. These solutions are mixed and stirred until homogenous. The resultant solution is then heated to form an impure product. Following washing steps and centrifugation a purified powder product is obtained. A variety of metallic salts have been tested for their use in these LDHs with the optimum LDHs selected for further study. The metallic salts used to provide the metals for the LDHs are typically hydrated transition metal nitrates.The LDHs have been characterised and their structure confirmed by a variety of analytical techniques including X-Ray Diffraction and Scanning Electron Microscopy. Simple qualitative analysis has been performed with FTIR spectroscopy. These LDHs have been immobilised on a variety of porous, high surface area materials, including nickel foam and copper foam, to enhance the properties seen in the screening study. These materials allow synthesis of high surface area, reactive electrocatalysts. To enhance the stability of the LDHs, carbon materials have been integrated with the LDHs. Examination of a variety of carbon materials involved post-synthesis mixing of the carbon material and the LDH product or inclusion of the carbon material in the LDH synthesis to form a composite. A variety of carbon materials have been analysed including graphene oxide, carbon black and carbon nanotubes. Figure 1

MoS2 Modified Aluminum Electrode for Detection of Calcium Oxalate through Electrochemical Oxidation

The disposal of electronic waste (E-waste), encompassing discarded items such as computers, televisions, fridges, cellphones, and associated cabling, presents a significant challenge to both societal welfare and environmental health. Addressing e-waste management is critical to achieving several of the Sustainable Development Goals (SDGs). This study introduces a novel approach to repurposing aluminum from discarded electrical cables for the creation of high-efficiency electrodes that can detect oxalic acid in human urine samples. The process involves stripping 2mm thick cables to yield 7cm long aluminum rods. These rods are then coated with MoS2 nanoparticles via a hydrothermal synthesis technique. X-ray diffraction (XRD) analysis confirms the presence of MoS2 in the 1T phase, while Fourier-transform infrared spectroscopy (FTIR) and Raman spectroscopy provide insights into the vibrational modes and chemical composition. Field emission scanning electron microscopy (FESEM) imaging depicts the MoS2 as having a flower-like nanostructure composed of interwoven nanosheets. The resulting nanocomposite sensor demonstrates an enhanced electrical current response, along with notable selectivity and stability, likely due to the combined effects of the MoS2 materials. The sensor’s amperometric signal is directly correlated with the oxalate ion concentration within a range of 10 to 300 μM and exhibits a detection threshold as low as 2 μM. This sensor technique was evaluated alongside a standard colorimetric assay for measuring oxalic acid levels in urine specimens. Findings indicated a strong correlation (R=0.954) between oxalic acid concentrations assessed using the biosensor and those obtained through the colorimetric approach.Keywords: E-waste, Aluminum Electrodes, MoS2 Nanoparticles, Oxalic Acid Detection, and Electrochemical Sensing, Figure 1

Construction of Ag3PO4/g-C3N4 Z-Scheme Heterojunction Composites with Visible Light Response for Enhanced Photocatalytic Degradation.

Ag3PO4/g-C3N4 photocatalytic composites were synthesized via calcination and hydrothermal synthesis for the degradation of rhodamine B (RhB) in wastewater, and characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and diffuse reflectance spectroscopy (DRS). The degradation of RhB by Ag3PO4/g-C3N4 composites was investigated to evaluate their photocatalytic performance and cyclic degradation stability. The experimental results showed that the composites demonstrated notable photocatalytic activity and stability during degradation. Their high degradation efficiency is attributed to the Z-scheme transfer mechanism, in which the electrons in the Ag3PO4 conduction band and the holes in the g-C3N4 valence band are annihilated by heterojunction recombination, which greatly limits the recombination of photogenerated electrons and holes in the catalyst and enhances the activity of the composite photocatalyst. In addition, measurements of photocurrent (PC) and electrochemical impedance spectroscopy (EIS) confirmed that the efficient charge separation of photo-generated charges stemmed from strong interactions at the close contact interface. Finally, the mechanism for catalytic enhancement in the composite photocatalysts was proposed based on hole and radical trapping experiments, electron paramagnetic resonance (EPR) analysis, and work function evaluation.

Limitations and Opportunities of Self-Supported Co-Based Anodes for Pure Water-Fed Anion Exchange Membrane Water Electrolyzers

Hydrogen has been regarded as an energy source with a potential to be used in various sectors, including transportation, power generation and industrial processes1-3. Producing hydrogen via water electrolysis using green electricity will be necessary for a sustainable future. Proton exchange membrane water electrolysis (PEMWE) is one of mature and leading electrolysis technologies, while anion exchange membrane water electrolysis (AEMWE) is regarded as a new, emerging technology4. However, PEMWE system suffers from their expensive cost and scarcity of iridium-based oxygen evolution reaction (OER) catalysts, having no alternative OER catalysts. Compared to PEMWE, AEMWE can be pursued with non-platinum group metal (non-PGM) thanks to its alkaline environment4,5.Here, non-PGM Co-based catalyst coated anodes were prepared using a simple hydrothermal reaction followed by heat treatment. Different phases and crystallinity of cobalt-based anodes were prepared and tested in pure water-fed AEMWE devices. To investigate the catalyst-ionomer/membrane interfaces at the anodes, the loadings of Co3O4 catalyst and ionomer topcoats were controlled. The cell performance in polarization curves was correlated with electrochemical impedance spectroscopy (EIS) and cyclic voltammetry (CV) measurements. The comparison of anodes operated with pure water feed and with supporting electrolyte was made to highlight the importance of catalyst-ionomer interface in pure water-fed AEMWE. Lastly, our self-supported Co3O4 anode outperformed a commercial Co3O4 NP ink-based anode, projecting a potential of direct growth of catalyst materials on PTLs in pure water-fed AEMWE.Reference(1) Agyekum, E. B.; Nutakor, C.; Agwa, A. M.; Kamel, S. A Critical Review of Renewable Hydrogen Production Methods: Factors Affecting Their Scale-Up and Its Role in Future Energy Generation. Membranes 2022, 12 (2).(2) Qusay, H.; Sameer, A.; Aws Zuhair, S.; Hayder, M. S.; Marek, J. Green hydrogen: A pathway to a sustainable energy future. Int. J. Hydrogen Energy 2024, 50, 310-333.(3) Joonsik, H.; Krisha, M.; HeeJin, C. A review of hydrogen utilization in power generation and transportation sectors: Achievements and future challenges. Int. J. Hydrogen Energy 2023, 48 (74), 28629-28648.(4) Lee, S. A.; Kim, J.; Kwon, K. C.; Park, S. H.; Jang, H. W. Anion exchange membrane water electrolysis for sustainable large-scale hydrogen production. Carbon Neutralization 2022, 1 (1), 26-48.(5) Juchan, Y.; Myeong Je, J.; Xiaojun, Z.; Yoo Sei, P.; Jooyoung, L.; Sung Mook, C.; Yadong, Y. Non-precious electrocatalysts for oxygen evolution reaction in anion exchange membrane water electrolysis: A mini review. Electrochem. Commun. 2021, 131, 107118.

The synthesis and characterization of novel boron-containing B/Al-ZSM-12 zeolite

In this study, new type of boron-substituted Al-ZSM-12 was developed using hydrothermal synthesis technique and methyltriethylammonium chloride as a template; physical and chemical characteristics of B/Al-ZSM-12 were studied in detail. The presence of tetrahedral boron in the isomorphically substituted zeolite was confirmed by FTIR, Raman, DRS UV–Vis, DRIFTS, 29Si and 11B NMR, and ICP–MS methods. Due to the incorporation of boron into Al-ZSM-12 zeolite, the resulting crystallites of B/Al-ZSM-12 have a shorter b-axis length compared to unsubstituted Al-ZSM-12. Moreover, boron atoms do not affect the change in the structure of Al-ZSM-12 zeolite, while being embedded in the framework, affect acidic properties, increasing total acidity and a providing high concentration of Brønsted acid sites compared to Al-ZSM-12. Meanwhile, the surface area increases from 320 m2 g−1 for Al-ZSM-12 to 350 m2 g−1 for B/Al-ZSM-12.

Novel Damsissa carbon quantum dots (DCQDs) to improve the protection efficiency of permanganate phosphate conversion coats (PPC) on steel

Carbon quantum dots (CQDs) are spherical zero dimensional nanoparticles, generally below 10 nm in size, which received increasing attention in diverse application fields owing to their important characteristics and advantages as good water solubility, potential of environmental protection and preparation from abundant and sustainable raw materials. In this work, Damsissa carbon quantum dots (DCQDs) were generated via hydrothermal reaction microwaves irradiation. The DCQDs material was characterized by FTIR, TEM, EDX, XRD, and XPS to confirm the morphological and functionality aspects as well as particle size distribution, elemental composition, crystallite structure, and elemental identification in terms of chemical state. The FTIR analysis referred to associated assignments of C-H, C=O, C=C, C-N, besides other groups. The TEM study confirmed a ranged homogenous particle distribution at 3-6 nm. The EDX and XPS results verified carbon, nitrogen and oxygen as the main elements in DCQDs. The protection efficiency performance of permanganate phosphate conversion coat (PPC) was investigated and monitored by using different concentrations of DCQDs in the coating bath utilizing the potentiodynamic polarization technique, besides electrochemical impedance spectroscopy. The results referred to 97.4% maximum protection efficiency for the coat in presence of 400 mg/L DCQDs. The impedance results showed that as the concentration of DCQDs increase, the capacity of the double layer (Cdl) decreases due to the adsorption ofDamsissa carbon dots on the steel surface. However, the potentiodynamic polarization results indicated that the presence of DCQDs in HCl solution could lead to the polarization of the cathodic and anodic curves to denote that these retard the cathodic and anodic reactions at the steel surface inhibiting the corrosion process. The coats synthesized in absence and in presence of diverse amounts of DCQDs were examined by the TEM, EDX, XPS, and XRD studies to elucidate the role of DCQDs in the improvement of the corrosion protection of the coat. The results indicated that the DCQDs molecules ofDamsissa were adsorbed at the steel surface to efficiently retard the dissolution of iron and decrease the Fe2+ ions concentration in the coating solution causing higher nucleation rate over the crystal growth and thus leading to the formation of a uniform protective film.

Synthesis of Ag Doped ZnO Nanowire by Hydrothermal Method and its Characterization

This research is mainly focused over synthesizing zinc oxide (ZnO) nanowire (NW) and silver doped zinc oxide nanowires (Ag/ZnO) using two step hydrothermal method which comprises of seed layer deposition and hydrothermal nanowire growth step. Hydrothermally grown nanowires are of great significance. The synthesized nanowires were characterized by UV-Vis Spectroscopy (UV-Vis), X- ray Diffraction Spectroscopy (XRD), Energy Dispersive Spectroscopy (EDS), Field Emission Scanning Electron Microscopy (FE-SEM) and High-Resolution Transmission Electron Spectroscopy (HR-TEM). XRD pattern revealed as-synthesized materials are of crystalline nature having crystallite size of 166.27 nm and 42.32 nm for ZnO nanowire and Ag doped nanowire, respectively. Further confirmation was done by EDS, SEM and TEM. The microscopic images of SEM and TEM evidenced for successful fabrication of nanowires.

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.

Nanosize Controllable Two‐Dimensional (Cu–S)n Metal–Organic Framework Hybrid With Reduced Graphene Oxide by In Situ Microwave and Hydrothermal Synthesis for Electrochemical Neurotransmitter Detection

ABSTRACTWe present a groundbreaking technique for controllably synthesizing nanosized semiconductive two‐dimensional (2D) (Cu–S)n metal–organic framework (MOF)/graphene nanocomposites for electrochemical sensing of neurotransmitter 2‐phenethylamine (PEA). The (Cu–S)n MOF size is controlled by graphene oxide proportions, enhancing electrocatalytic activity. The modified electrode exhibits a surface area increase from 0.0639 to 0.1906 cm2 and impressive limit of detection (0.0156 and 0.004 μM) within linear ranges of 15–200 μM and 1–10 μM, offering exceptional selectivity, reproducibility, and repeatability for biosensing.

Platinum-Ruthenium Bimetallic Nanoparticle Catalysts Synthesized Via Direct Joule Heating for Methanol Fuel Cells.

Platinum-Ruthenium (PtRu) bimetallic nanoparticles are promising catalysts for methanol oxidation reaction (MOR) required by direct methanol fuel cells. However, existing catalyst synthesis methods have difficulty controlling their composition and structures. Here, a direct Joule heating method to yield highly active and stable PtRu catalysts for MOR is shown. The optimized Joule heating condition at 1000°C over 50 microseconds produces uniform PtRu nanoparticles (6.32wt.% Pt and 2.97 wt% Ru) with an average size of 2.0 ± 0.5 nanometers supported on carbon black substrates. They have a large electrochemically active surface area (ECSA) of 239 m2 g-1 and a high ECSA normalized specific activity of 0.295mA cm-2. They demonstrate a peak mass activity of 705.9mA mgPt -1 for MOR, 2.8 times that of commercial 20 wt.% platinum/carbon catalysts, and much superior to PtRu catalysts obtained by standard hydrothermal synthesis. Theoretical calculation results indicate that the superior catalytic activity can be attributed to modified Pt sites in PtRu nanoparticles, enabling strong methanol adsorption and weak carbon monoxide binding. Further, the PtRu catalyst demonstrates excellent stability in two-electrode methanol fuel cell tests with 85.3% current density retention and minimum Pt surface oxidation after 24 h.

Structural characterization of an unprecedented mixture of H4Nb2O7 and TT-Nb2O5 phases obtained by hydrothermal synthesis

Several crystal structures of niobium-based materials are currently being studied. In this work, for the first-time a mixture of H4Nb2O7 and Nb2O5 materials was obtained from ammonium niobate oxalate using the urea hydrolysis reaction in a hydrothermal synthesis. The techniques used for characterization, such as X-ray diffraction (XRD), Rietveld refinement, Scanning Electron Microscopy (SEM), Scanning Transmission Electron Microscopy (STEM), and High-Resolution Transmission Electron Microscopy (HRTEM), confirmed a combination of pyrochlore-type H4Nb2O7 and pseudohexagonal TT-Nb2O5 phases, with distinct nanostructures and anisotropic growth in the TT- Nb2O5 phase, in addition to controlling phase fractions by synthesis time. These discoveries suggest potential applications in various environmental applications due to the material’s adsorptive capacity.

Comparative microstructural analysis of V2O5 nanoparticles via x-ray diffraction (XRD) technique

Vanadium pentoxide (V2O5) nanoparticles exhibit diverse properties and have been studied for a wide range of applications, including energy storage, catalysis, environmental remediation, and material enhancement. In this work, we have reported the synthesis of vanadium pentaoxide (V2O5) nanoparticles using hydrothermal method. Ammonium metavanadate (NH4VO3) was used as a source of vanadium. These syntheses were carried out at four different concentrations of vanadium source. The hydrothermal reaction was conducted at a temperature of 180 °C for a duration of 24 hours, followed by an additional 24 hours period of natural cooling. Four samples were annealed in air using a muffle furnace at 500 °C for five hours. The x-ray diffraction technique was used to study the structural aspects. A comparative analysis of the microstructure was conducted utilizing the Scherrer method, the Williamson–Hall method and its various models, size-strain analysis, and the Halder–Wagner method. The crystallite size and microstrain were determined using these distinct methods, revealing a systematic correlation between the crystallite size and microstrain obtained through the different techniques.

Facile synthesis of NH2-MIL-53(Al)@BiOBr@CQDs ternary heterostructure photocatalyst for degradation of ciprofloxacin in water

The construction of ternary heterojunction photocatalysts can achieve multi-gradient transfer of charges and accurate control the position of photogenerated electrons which has received increasing attention. In this paper, NH2-MIL-53(Al)@BiOBr@CQDs-10 % (ABCQDs-10 %) was prepared via a facile hydrothermal and chemical synthesis processes. Three-dimensional serration of NH2-MIL-53(Al) as a platform for irregular BiOBr nanosheets, CQDs promote interfacial contact and act as electron transport channels between BiOBr and NH2-MIL-53(Al) and constitute Z-type heterojunctions with high redox properties. ABCQDs-10 % shows the best photocatalytic removal efficiency (94.24 %) of CIP, the reaction rate constants (0.045 min−1) were 1.2 and 64 times higher than BiOBr and NH2-MIL-53(Al), respectively. The excellent degradation performance is attributed to the construction of Z-type heterojunction of NH2-MIL-53(Al)@BiOBr@CQDs which improve electron-hole separation and transfer efficiency. The main active species was •O2-. The photocatalytic activity of ABCQDs-10 % had not obvious loss after cycle experiments and the crystal structure had no significant changes, means high stable photocatalytic activity.

ZnO/Ag2ZrO3 nanocomposites: A tailored nanostructure for enhanced supercapacitor, photocatalytic & antimicrobial applications

The present study reported the synthesis of a novel ZnO/Ag2ZrO3 nanocomposite by a two-step method, involving hydrothermal synthesis followed by a co-precipitation method. As synthesized ZnO/Ag2ZrO3 nanocomposite was further used for the supercapacitor study, photocatalytic dye degradation, and antimicrobial applications. It was fairly challenging to enhance the supercapacitor performances of ZnO. Therefore, it was imperative to develop a novel approach utilizing a binary nanostructure composed of ZnO and Ag2ZrO3. This strategy aims to synergistically enhance the energy storage and conversion capabilities of inorganic materials, while simultaneously augmenting the photocatalytic and antimicrobial activity in the synthesized ZnO/Ag2ZrO3 nanocomposites. Among ZnO, Ag2ZrO3, and ZnO/Ag2ZrO3 nanocomposites with a varying weight percentage of Ag2ZrO3 (10 %, 20 %, 30 %, & 40 %), the ZnO/Ag2ZrO3 (20 %) electrode exhibited the highest specific capacitance (463.3 Fg–1) and energy density (10.2 Whkg–1) at current density 1 mAcm–2. Furthermore, we examined the photocatalytic activity, in the presence of persulfate ion (PS), the ZnO/Ag2ZrO3 (20 %) nanocomposite demonstrated superior degradation efficiency for Rhodamine B (RhB), Methyl Orange (MO), and Methylene Blue (MB). Almost 100 % degradation of RhB was observed in just 120 min of visible light irradiation, whereas only 27.6 %, 62.4 %, and 42.7 % of RhB degradation was observed on the pristine ZnO, ZnO/PS, and ZnO/Ag2ZrO3 (20 %) materials, respectively. This enhanced photocatalytic activity was attributed to the synergetic effect of photoinduced electron activating PS ions to form sulfate radicals (˙SO4̄), higher visible light harvesting by ZnO/Ag2ZrO3 nanocomposite, and better charge separation. Five cycles of reusability test with no significant loss in dye degradation efficiency, confirms the stability test of ZnO/Ag2ZrO3 (20 %) nanocomposite. Moreover, the synthesized ZnO/Ag2ZrO3 (20 %) nanocomposite possesses improved antimicrobial potential against both gram +ve and gram -ve bacteria.

Investigation of alite hydration in the presence of low- and high-silica zeolites

Synthetic zeolites that are obtained from the hydrothermal reaction of NaOH with fly ash have a well-defined pore structure and pozzolanic properties. This work examines the effect of the low-silica (Na-A) and high-silica (ZSM-5) zeolite structure on the kinetics of alite hydration and mineralogical characteristics of the reaction products. The addition of the Na-A and ZSM-5 zeolites reduced the rate of heat release during the hydration reaction, which is typical for commonly used pozzolanic additives. The ZSM-5 zeolite had a much higher Si/Al ratio relative to the Na-A zeolite, which translated into a higher pozzolanic activity and resulted in greater stability of the hydration reaction kinetics. The addition of zeolites caused the heat of hydration to decrease compared to the reference pastes (the alite reference paste—206 J/g): Na-A 15%—148.9 J/g; ZSM-5 15%—149.9 J/g. The concentration of calcium ions in the alite solution and the content of active silica were identified as the most important parameters affecting the kinetic, morphological, and structural characteristics of the C–S–H phase. The addition of zeolites increased the amount of C–S–H gel phases formed. At the same time, the proportion of portlandite in the hydration products of the alite–zeolite systems decreased. Pozzolans reduced the ratio of CaO/SiO2 in the C–S–H phase, which for pastes with the addition of the Na-A ranged from 1.61 to 1.37, and for the ZSM-5 from 1.91 to 0.47. This ratio decreased with the dosage and the age of alite paste. In summary, this research has shown that synthetic zeolites are a viable pozzolanic additives.

Seed strategy synthesis of porous NASICON structured NaTi2(PO4)3/carbon aerogel nanocomposites for high-performance hybrid capacitive deionization

The limited capacity of conventional carbon electrode materials hinders the practical application of capacitive deionization (CDI). Hence, it is imperative to develop electrode materials with high sodium ion adsorption and reliable stability to facilitate the construction of hybrid CDI (HCDI) systems. Notably, NaTi2(PO4)3 (NTP) has received significant attention due to its high capacity and rapid transportation ability of sodium ions. However, the poor electrical conductivity and limited electrolyte contact area of NTP have prevented further improvement in its deionization capacity. Herein, we report a seed strategy to synthesize NTP/carbon aerogel (CA). P25 was used as a seed crystal to prepare TiO2/CA via the sol–gel method and supercritical CO2 drying. NTP/CA was then obtained from TiO2/CA by hydrothermal synthesis and calcination. This strategy preserved the rational network skeleton of CA and endowed NTP/CA with a high specific surface area of 420 m2/g. The enhanced electrical conductivity provided by CA yielded a remarkable salt adsorption capacity of 43.3 mg/g in a 500 mg/L NaCl solution and a stable cycle desalination capability. This work provides a new perspective for constructing three-dimensional, highly efficient and stable HCDI electrode materials.

Controllable preparation of carbon coating Ge nanospheres with a cubic hollow structure for high-performance lithium ion batteries

Germanium based nanomaterials are very promising as the anodes for the lithium ion batteries since their large specific capacity, excellent lithium diffusivity and high conductivity. However, their controllable preparation is still very difficult to achieve. Herein, we facilely prepare a unique carbon coating Ge nanospheres with a cubic hollow structure (Ge@C) via a hydrothermal synthesis and subsequent pyrolysis using low-cost GeO2 as precursors. The hollow Ge@C nanostructure not only provides abundant interior space to alleviate the huge volumetric expansion of Ge upon lithiation, but also facilitates the transmission of lithium ions and electrons. Moreover, experiment analyses and density functional theory (DFT) calculations unveil the excellent lithium adsorption ability, high exchange current density, low activation energy for lithium diffusion of the hollow Ge@C electrode, thus exhibiting significant lithium storage advantages with a large charge capacity (1483 mAh/g under 200 mA g−1), distinguished rate ability (710 mAh/g under 8000 mA g−1) as well as long-term cycling stability (1130 mAh/g after 900 cycles under 1000 mA g−1). Therefore, this work offers new paths for controllable synthesis and fabrication of high-performance Ge based lithium storage nanomaterials.

Intra-lanthanide separation performance of DOTP: Solid-phase extraction and selective precipitation studies

The applicability of 1,4,7,10-Tetraazacyclododecane-1,4,7,10-tetra(methylene phosphonic acid) (DOTP) for intra-lanthanide (Ln) separation was investigated through two approaches: the synthesis of inorganic–organic hybrid sorbents and selective precipitation in an aqueous solution. Hybrid sorbents combining zirconium oxide and DOTP were fabricated through post-synthetic grafting and hydrothermal synthesis. The successful syntheses were verified by FTIR and 31P magic-angle spinning (MAS) NMR spectroscopies. All the hybrid sorbents showed a lanthanide uptake of approximately 10–20 μmol/g at pH 3 and displayed only moderate selectivity, with the highest separation factor (SF) of about 10 for Lu3+ over La3+. In contrast, the selective precipitation of lanthanides by DOTP in an aqueous solution was successful in the presence of Cu2+. When a Cu-DOTP complex was introduced into a La/Lu equimolar solution, lanthanide ions were selectively precipitated with an SF of approximately 30–190. When the initial stoichiometry was set to Ln:Cu-DOTP = 8:1, roughly 95 % of the lanthanides in the precipitate were Lu3+, regardless of the pH ranging from 3 to 5. This precipitation process demonstrated selectivity even for adjacent lanthanide pairs. The selectivity is assumed to be a result of structural variations in the precipitates of Ln-Cu-DOTP, which is supported by the characterization results obtained from X-ray diffraction (XRD), thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), and UV–Vis spectroscopy. The findings presented in this study indicate that DOTP has the potential for use in the selective extraction of lanthanides, which may offer promising advancements in intra-lanthanide separation.