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Glycerol steam reforming (GSR) is one of the promising technologies that can realize renewable hydrogen production and efficient utilization of crude glycerol. To illuminate the functions of Ca content (3%, 6%, 9%, and 12 %, by mass) and preparation method for Ni/ATP catalyst structure and its catalytic behaviors, the Ni-xCa/ATP (x=3%, 6%, 9%, and 12%, by mass) catalysts are prepared by co-impregnation (ci) and hydrothermal synthesis (hs) method and then tested in GSR. Characterization results of XRD, N2 adsorption-desorption, H2-TPR, HRTEM, XPS, and NH3/CO2-TPD demonstrate that the combined effect between appropriate Ca additive (6%, by mass) and hs enhance catalyst reducibility, uniform distribution of Ca additive and nickel species over ATP, and adsorption for CO2. This attributes to hs method protects the ATP framework through suppressing the interaction of Ca with ATP and promotes the formation of Ni-CaOx interface sites. Therefore, Ni-6Ca/ATP-hs exhibits the highest conversion (86.77%) of glycerol to gas product and H2 yield (76.17%) and selectivity (58.56%) during GSR. Furthermore, XRD, HRTEM, TG-DTG and Raman analyses confirm that Ni-6Ca/ATP-hs also reveals outstanding anti-sintering and coke resistance. In addition, the structural evolution process of Ni/ATP catalyst with Ca introduction and hs method is presented. Considering the high performance, simple preparation process and low cost, the as-prepared catalyst providing new opportunities for utilization of glycerol derived from biodiesel industry.

In this study, metallic glass is designed tunable for promising functional applications via a facile and stable, one-step process. Creative approach about alloy design and process is based on the unique properties of the Ti-Cu-Ni-Sn metallic glass that are afforded by the varying oxygen affinities of the four constituent elements. This metallic glass exhibits homogeneous nucleation of oxides and uniform formation of the various metal oxides. The alloy design and hydrothermal synthesis to customize the metallic glasses are the most critical factors that determine the characteristics of the metal oxides and the resulting nanostructures and photoelectrode properties. This enables the desired element to be selectively grown via a facile single-step process. These results provide a promising road map for the application of metallic glasses to photoelectrochemical (PEC) solar water splitting, as well as various other new possibilities.

In this work, vanadium and lanthanum co-doped ZnO/CNTs (VL-ZnO/CNTs) composites of large surface area and enhanced light assimilation range were produced for boosted hydrogen evolution from water. The photocatalysts were investigated for their morphological, structural, optical and photocatalytical properties. The photocatalytic activity of the composites was evaluated in pure water and in a mixture of water and methanol under simulated sunlight and visible light illumination. Under simulated sunlight irradiation, the maximum hydrogen generation rate of 925 μmolh−1g−1 from a combination of water and methanol was attained, which is almost 7 times higher than hydrogen generation rate achieved with pure ZnO. The VL-ZnO/CNTs photocatalyst resulted in hydrogen production rate of 267 μmolh−1g−1 from the water-methanol medium when exposed to visible light. This rate was about 3.5 folds lower than that achieved under simulated sunlight illumination. This improvement in hydrogen production rate is attributed to large surface area, high photo-response, better separation/transportation of the charge carriers and synergistic impact of V, La and CNTs in the designed photocatalyst.

The photocatalytic performance of the semiconductor CdS can be improved with carbon materials capable of limiting photocorrosion and the fast recombination of photogenerated charges. For this purpose, carbon derived from biomass exhibit several advantages including low cost, high abundance, and renewability. Here, photocatalytic CdS nanorods modified with carbon derived from the leaves of Japanese raisin trees were synthesized via a single hydrothermal step. Composite CdS nanorods with 5% biomass-derived carbon photocatalyzed H2 evolution 1.8 times faster than unmodified CdS at a rate of 5.71 mmol g−1 h−1. The apparent quantum efficiency of 5%C/CdS nanorods was 14.96%. Furthermore, the addition of biomass-derived carbon to CdS nanorods augmented the stability of the semiconductor under visible light. The characterization of the composite PC indicated that a larger specific surface area, as well as upgraded charge separation caused by biomass-derived carbon, were involved in the acceleration of photocatalytic hydrogen production.

Niobium-based oxides can be used in several applications due to a diverse set of properties. In this work, Na2Nb2O6.H2O sodium niobate nanowires were obtained by hydrothermal synthesis at low temperature. Dehydrated sodium niobate (Na2Nb2O6) and sodium niobate with perovskite structure (NaNbO3) were obtained by submitting Na2Nb2O6.H2O to heat treatment (350 °C and 500 °C, respectively). To obtain protonic niobates, sodium niobates were immersed in nitric acid in order to promote ion exchange reactions. From this procedure, protonic niobates (H3O)2Nb2O6.H2O and (H3O)2Nb2O6 were obtained. The sample NaNbO3 did not undergo any transformation. Cyclic voltammetry tests carried out in a neutral aqueous solution 1 M Na2SO4 showed a wide potential window for both niobates (sodium and protonic). However, the protonic niobate samples (H3O)2Nb2O6.H2O and (H3O)2Nb2O6 presented much higher current density values than the sodium niobates. This result can be related to a structural rearrangement that allowed a significant increase in the intercalation of sodium Na + ions from the electrolyte into the structure of these protonic niobates, when polarized. Therefore, in this work, it was demonstrated that it is possible to obtain protonic niobates from sodium niobates, as well as, it was verified the distinct electrochemical behavior between these materials.

We have developed an efficient strategy to synthesize an active and durable electrocatalyst of Pd hydride nanocubes (NCs). Instead of the traditional chemical method, the PdH0.43 NCs are firstly prepared via a hydrogen diffusion procedure, followed by hydrothermal synthesis of an amorphous CuO layer encapsulating the PdH0.43 NCs to prevent the hydrogen atoms from escaping. Obvious lattice expansion is demonstrated playing a pivotal role in the enhancement of their oxygen reduction reaction (ORR) activity and durability. The obtained PdH0.43@CuO NCs catalysts exhibit an ORR mass activity of 0.18 A mg−1 at 0.90 V versus reversible hydrogen electrode in an alkaline medium, which is about five times higher than that of commercial Pt/C. Accelerated durability tests show that there is only a 32 mV decay in half-wave potential even after 10,000 potential cycles, indicating the excellent stability of PdH0.43@CuO NCs. Density functional theory (DFT) calculations also indicate that, compared to Pd, PdH0.43 has a lower limiting barrier to form OH− during the ORR process. The present study illustrates the importance of lattice expansion caused by hydrogen and offers an available strategy to design highly efficient and durable Pd-based electrocatalysts for alkaline fuel cells.

Propane dehydrogenation (PDH), employing Pt- or Cr-based catalysts, represents an emerging industrial route for propylene production. Due to the scarcity of platinum and the toxicity of chromium, alternative PDH catalysts are being pursued. Herein, we report the construction of Zn-containing zeolite catalysts, namely Zn@S-1, for PDH reaction. Well-isolated zinc cations are successfully trapped and stabilized by the Si-OH groups in S-1 zeolites via in-situ hydrothermal synthesis. The as-prepared Zn@S-1 catalysts exhibit good dehydrogenation activity, high propylene selectivity, and regeneration capability in PDH reaction under employed conditions. The in-situ partial reduction of zinc species is observed and the partially reduced zinc cations are definitely identified as the active sites for PDH reaction.

Deep-ultraviolet (deep-UV) nonlinear optical (NLO) crystals are key materials in creating tunable deep-UV lasers for frequency conversion technology. However, practical application of the sole usable crystal, KBe2 BO3 F2 , has been hindered by the high toxicity of beryllium and its layering tendency in crystal growth. Herein, we report a beryllium-free deep-UV NLO material NaSr3 (OH)(B9 O16 )[B(OH)4 ] (NSBOH), synthesized by a covalent bond modification strategy under hydrothermal conditions. Moisture-stable NSBOH exhibits strong second-harmonic generation (SHG) at 1064 nm (3.3 × KH2 PO4 ) and 532 nm (0.55 × β-BaB2 O4 ), both amongst the largest powder SHG responses for a deep-UV borate, with good phase-matchability and a short wavelength cutoff edge (below 190 nm). NSBOH possesses a 3D covalent anionic [B9 O19 ]∞ honeycomb-like framework with no layering. The Sr2+ and Na+ ions, residing in the cavities of the anionic framework, act as templates for the assembly and favorable alignment of NLO-active groups, resulting in an optimal balance between strong SHG activities and wide UV transparency. These merits indicate NSBOH is a very attractive candidate for deep-UV NLO applications.

Bismuth antimony telluride (Bi0.5Sb1.5Te3) is a ternary compound with good thermoelectric properties at near room temperature. In this research, Bi0.5Sb1.5Te3 powders were hydrothermally synthesized at different temperatures (100, 150, 190, and 230°C) for 24 h. The deposition procedure of Bi0.5Sb1.5Te3 thin films was done by using thermal evaporation. The phases and microstructures of powders and thin films were investigated by x-ray diffraction and field emission scanning electron microscopy. Moreover, the size distribution of powders was investigated using a particle size analyzer. The phase and microstructural results of the different synthesized powders confirmed that the Bi0.5Sb1.5Te3 thin film prepared by powder synthesis at 150°C for 24 h is the best choice for manufacturing with good thermoelectric properties because of its nano-sized grains and high purity. The results showed that the Bi0.5Sb1.5Te3 thin film fabricated by powders synthesized at 150°C has a single rhombohedral phase with a good semiconductor performance. The results of thermoelectric tests confirmed that the Bi0.5Sb1.5Te3 thin film fabricated using a hydrothermal method and thermal evaporation deposition approach shows a high Seebeck coefficient (183.5 μV/K) and low electronic thermal conductivity (1.32 × 10−4 W/m k−1) at 298 K. Besides, the power factor values of 0.7, 2.59 and 2.9 μW/cm K−2 were obtained at 298, 373 K and 473 K, respectively.

Designing of complex nanostructure with a high specific surface area using transition metal selenide seems to be a necessity in response to the challenges of the hydrogen release process for renewable energy. Herein, we synthesized the electrocatalyst nickel foam-supported with nanostructured nickel–cobalt selenide using the hydrothermal process at 150 and 180 °C and has been investigated in hydrogen evolution reaction. Synthesis of nickel–cobalt selenide nanostructure on nickel foam carried out with different Ni+2:Co+2 mol ratios of 0:10, 2:8, 6:4, 4:6, 8:2, and 10:0 in the structure of electrodes. The XRD results indicate the formation of the nickel–cobalt selenide phase in different ratios. The FESEM and TEM results show the formation of mesoporous three-dimensional nano-lactic with petal thickness in the range of 20–30 nm. Also, to evaluate the properties and electrocatalytic efficiency, electrochemical tests of Tafel slope, cyclic voltammetry, linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) were used. The Tafel result test shows a cathodic slope of −61.3 mV and an exchange current density of 0.86 mA cm−2 in the Ni8Co2Se-150 (Ni+2:Co+2 = 8:2) sample, which LSV shows −185 mV at a current density of −10 mA cm−2. EIS test shows a polarization resistance value of 2744 Ω for mentioned sample and was selected as the best sample with the highest catalytic activity.

Structural unsteadiness and limited electrochemical kinetics upon cycling seriously impede further applications of birnessite cathodes for rechargeable aqueous zinc‑ion batteries (ZIBs), even though they have high voltage platforms and distinctively layered structures for preferable (de)intercalation of zinc ions. Herein, yolk-shell structured K-birnessite (K0.48Mn2O4·0.49H2O)@mesoporous carbon nanospheres (KMOH@C) with rich oxygen vacancies are synthesized for the first time with a two-step diffusion-driven strategy of hydrothermal synthesis followed by etching with KOH. The transport of reaction ions is regulated by surface charge and pore structure of the carbon shells, thus K-birnessite is preciously transferred into the hollow mesoporous carbon (HMC) nanospheres. Furthermore, the etching effect of KOH and the confinement effect of HMC nanospheres generate intercalated K+ and abundant oxygen vacancies into KMOH, leading to an excellent electrochemical kinetics. Meanwhile, HMC nanospheres also endow rapid electron/ion transport and stabilize the crystal structure of K-birnessite. Therefore, KMOH@C exhibits superior electrochemical performances with high reversible capacities of 412.7 and 122.2 mA h g‒1 at 0.5 and 10.0 A g‒1 than reported cathodes, respectively. Moreover, an exceptional cyclability of 129.6 mA h g‒1 even after 6000 cycles at 3.0 A g‒1 is achieved, making the KMOH@C cathode highly competitive for eco-friendly aqueous ZIBs.

TiO2 nanobelts were prepared by hydrothermal synthesis and acid treatment, then calcination at different temperatures. And subsequently Pt nanoparticles were deposited on the TiO2 nanobelts. Pt/TiO2 catalytic properties were investigated in the oxidation of formaldehyde. These catalysts were characterized by various techniques and the characterization results showed that the applied thermal treatment temperature greatly influenced the phase composition and surface structure of TiO2 nanobelts, as well as the number of oxygen vacancies and hydroxyl groups on the surface. The Pt/TiO2 nanobelts thermally treated at 600°C had more oxygen vacancies, which were conducive to the activation of adsorbed oxygen, formed more Ti-(OH)x-Pt species, and showed higher catalytic activity. At 25°C and relative humidity of 55%, the conversion of formaldehyde reached 91.6%.

In this work, manganese iron oxide nanoparticles (MnFe2O4NPs) were synthesized by hydrothermal method using sodium dodecyl sulfate, sodium hydroxide, iron chloride, and manganese chloride. Four morphologies (observed by electron microscopy) were selected to be studied: flakes, rough-octahedrons, regular-octahedrons, and icosahedrons. The four samples were functionalized with the myricetin flavonoid (Myr). Hence, tetraethyl orthosilicate was employed to coat a SiO2 layer on the nanoparticles, and then, Myr was added for obtaining the so-call MnFe2O4NPs/Myr. The fast Fourier transform infrared spectroscopy (FTIR) confirmed the SiO2 coating formation and the Myr-functionalization. In addition, both Raman spectroscopy, and X-ray photoelectron spectroscopy (XPS), demonstrated the high density of oxygen vacancies in the flakes and rough-octahedrons MnFe2O4NPs. This amount was higher than that observed in the regular-octahedrons and icosahedrons MnFe2O4NPs. Among the synthesized samples, the icosahedrons MnFe2O4NPs exhibited the maximum efficiency for Myr-functionalization due to 0.53 MnFe2O4NPs/SiO2 mass rate for coupling 1 mg of Myr. This efficiency was attributed to the low oxygen vacancies concentration on the surface of the nanoparticles. The Myr-functionalization promoted a size stability enhancement (about twice) in all the samples, with no significant changes in size across 112 days (stored at RT).

In this work, a novel honey/bayberry (HSHB) microsphere was prepared via a simple and green hydrothermal method to investigate the UO22+ adsorption behavior in simulated nuclear effluent. The results showed that spherical HSHB (about 40 nm) had the maximum adsorption capacity of 271.00 mg/g at 328.15 K and displayed a desirable selectivity for the UO22+. Furthermore, combined with the characterization analysis and adsorption experimental results, the phenolic hydroxyl group of HSHB could be combined with UO22+ through chelation. Therefore, these facts indicate that HSHB could be used as a low-cost and environmentally friendly adsorbent for UO22+ removal from nuclear effluent.

Metal sulfides, such as NiCo-sulfides, have attracted tremendous attention from the view of high conductivities and electrochemical activities. However, their structure degradation during the redox process causes cycling instability, which results in the limitation of the application of metal sulfides. Herein, we study the combination of metal sulfides with carbonaceous materials. The NHCS/Ni2CoS4 composite is synthesized via a facile two-step method that entails first the fabrication of the N-doped hollow carbon spheres (NHCS) followed by the loading of Ni2CoS4 nanocubes into the NHCS via hydrothermal synthesis. The as-obtained NHCS/Ni2CoS4 composite electrode shows a super electrochemical performance (1465 F g−1 at 0.5 A g−1) and has a satisfactory cycling stability (87.4% capacitance retention). These results indicate that NHCS/Ni2CoS4 is a promising electrode material for high-performance supercapacitors.

In this study, a superficial and highly efficient hydrothermal synthesis method was developed for the in situ growth of amine-functionalized iron containing metal–organic frameworks (H2N–Fe-MIL-101 MOFs) on porous nickel foam (NicF) skeletons (H2N–Fe-MIL-101/NicF). The uniform decoration of the H2N–Fe-MIL-101 nanosheets thus generated on NicF was immobilized with follicle-stimulating hormone (FSH) antibody (Ab-FSH) to detect FSH antigen. In the present work, the Ab-FSH tagged H2N–Fe-MIL-101/NicF electrode was first applied as an immunosensor for the recognition of FSH, electrochemically. With all of the special characteristics, this material demonstrated superior specific recognition and sensitivity for FSH with an estimated detection limit (LOD) of 11.6 and 11.5 fg/mL for buffered and serum solutions, respectively. The availability of specific functional groups on MOFs makes them an interesting choice for exploring molecular sensing applications utilizing Ab-FSH tagged biomolecules.

– The current study aims to prepare an Nb,Ta-containing ordered mesoporous catalyst MCM-41, using hydrated mixed oxide of niobium and tantalum, extracted from the columbite ore processing, as an alternative source of these metals. Direct hydrothermal synthesis was employed to incorporate the metals into the molecular sieve structure using the TEOS + sodium silicate mixture as silica source and varying Nb and Ta content in terms of Si/Me (Me = Nb and Ta) molar ratios of 60, 30 and 15 to evaluate the influence of the charge of these metals on both structural formation and properties of the material. The material was characterized by XRD, SEM, TEM, N2 adsorption, UV–Vis-DRS, and FTIR investigations to the incorporation of the metal into the MCM-41 framework. The techniques employed proved the successful replacement of Si atoms by metallic cations of Nb and Ta. The catalyst showed good structural order preservation and surface area (>600 m2 g-1) with mesoporous behavior with capillary condensation even at a higher metal load. This research signifies a successful procedure of a novel bimetallic mesoporous material with promising properties for several applications using an abundant ore as a metal source.

Herein, we report a facile hydrothermal synthesis of MnO2 nanoparticles anchored multi walled carbon nanotubes (MnO2@MWCNTs) as potential anode materials for lithium-ion (Li-ion) batteries. The prepared MnO2@MWCNTs were characterized by several techniques which confirmed the formation of MnO2 nanoparticles anchored MWCNTs. The X-ray diffraction and Raman-scattering analyses of the prepared material further revealed the effective synthesis of MnO2@MWCNTs. The fabricated Li-ion battery based on MnO2@MWCNTs exhibited a reversible capacity of ~823 mAhg−1 at a current density of 100 mAg−1 for the first cycle, and delivered a capacity of ~421 mAhg−1 for the 60 cycles. The coulombic efficiency was found to be ~100% which showed excellent reversible charge–discharge behavior. The outstanding performance of the MnO2@MWCNTs anode for the Li-ion battery can be attributed to the distinctive morphology of the MnO2 nanoparticles anchored MWCNTs that facilitated the fast transport of lithium ions and electrons and accommodated a broad volume change during the cycles of charge/discharge.

Herein, we report the single-step synthesis of ZnO nanostructures by a simple urea hydrolysis method. Pure phase ZnO and hydrozincite (Zn5(CO3)2 (OH)6) nanostructures are easily obtained separately at the optimized hydrothermal conditions, which involve controlling the urea concentration and reaction parameters such as temperature and time. Outside of these conditions, hydrozincite (Zn5(CO3)2 (OH)6) with a small admixture of basic zinc carbonate Zn4CO3 (OH)6⋅H2O are obtained as by products. X-ray diffraction and electron microscopy reveal that the obtained ZnO sample is comprised of spherical nanoparticles and have a hexagonal wurtzite crystalline structure. Further, a single-step synthesis approach was developed that produces micron sized rod-shaped ZnO structures.

Efficient removal of radioactive cesium from complex wastewater is a challenge. Unlike traditional precipitation and hydrothermal synthesis, a novel vast specific surface area adsorbent of copper hexacyanoferrates named EA-CuHCF was synthesized using a one-pot solvothermal method under the moderate ethanol media characterized by XRD, SEM, EDS, BET, and FTIR. It was found that the maximum adsorption capacity towards Cs+ was 452.5 mg/g, which is far higher than most of the reported Prussian blue analogues so far. Moreover, EA-CuHCF could effectively adsorb Cs+ at a wide pH range and low concentration of Cs+ in geothermal water within 30 minutes, and the removal rate of Cs+ was 92.1%. Finally, the separation factors between Cs+ and other competitive ions were higher than 553, and the distribution coefficient of Cs+ reached up to 2.343 × 104 mL/g. These properties suggest that EA-CuHCF synthesized by the solvothermal method has high capacity and selectivity and can be used as a candidate for Cs+ removal from wastewater.

High electroactivity and good mechanical robustness of electrode materials are essential to deliver excellent electrochemical energy storage performance. Herein, metal–organic frameworks (MOF) derived mixed metal oxides (MMO, ZnO@NiO and Co3O4@NiO) are prepared by a two-step annealing process in air. Zinc-based MOF (ZIF-8) and cobalt-based MOF (ZIF-67) were employed, respectively, as hard templates for the chemical encapsulation of Ni(OH)2 nanostructures by hydrothermal synthesis. The as-prepared ZIF-8@Ni(OH)2 and ZIF-67@Ni(OH)2 were then converted to corresponding MMO through annealing in air. Meanwhile, MOF-derived carbon was preserved in the as-fabricated MMO structure, thus improving the electronic conductivity as well as the mechanical stability of the materials. In virtue of these features, high specific capacitance of 1017 and 744 F·g−1 can be delivered at a current density of 1 A·g−1 for the Co3O4@NiO and ZnO@NiO samples, respectively. In addition, both of the samples have shown excellent cycling performance, which exhibited excellent capacitance retentions of 90.1% and 93.0% after 10,000 cycles for the Co3O4@NiO and ZnO@NiO samples, respectively, demonstrating their very promising use in next-generation pseudocapacitors.

Transition metal selenides have significant advantages in improving the capacity and cycling performance of lithium-ion batteries. The NiSe2 nanofoams doped with C and Ni are first synthesized by simple hydrothermal synthesis methods, and their performance as electrode materials for lithium-ion batteries (LIBs) was evaluated. The obtained material can keep the capacity of the 575.9 mA h g–1 at 2 A g–1 cycle with a reversible capacity retention of 73.4% after 600 cycles. When the current density comes back to 0.2 A g‒1, capacity can still return to 938.5 mA h g–1, which shows that the electrode has good structural stability, which indicates it is of great value as anode material for LIBs.

Solar photocatalytic degradation of dye using zinc oxide (ZnO) is a sustainable and efficient wastewater treatment method which could mineralize the dye to carbon dioxide and water without creating secondary waste or sludge. Sunlight is a natural source of light that extends over both ultraviolet and visible range which could irradiate ZnO to initiate the photocatalytic reaction for degradation of dye. The dried Luffa cylindrica (LC), the sponge gourd is suitable to be applied as a biotemplate in synthesis as it is fibrous and porous that will lead to high surface area of the synthesized material. In this study, a biomimetic zinc oxide was synthesized by using LC as biotemplate via simple hydrothermal synthesis method. Both synthesized ZnO samples were characterized by using X-ray diffraction (XRD) and scanning electron microscope (SEM) to confirm their crystalline phase and morphology, respectively. Compared with the non-templated ZnO, the biotemplated ZnO possessed relatively high crystallinity with higher diffraction peaks that assigned to the hexagonal wurtzite structure. Significant difference could be observed between the morphology of the ZnO synthesized without biotemplate and the ZnO synthesized with LC. It was found that the Luffa-templated ZnO inherited the structure of LC which the spherical nanoparticles connected continuously to each other in a dendritic-like morphology, while relatively large micron-sized particles were obtained in the ZnO synthesized without biotemplate. Photocatalytic activity of the synthesized ZnO was evaluated by degradation of Reactive Green 19 (RG19) under natural solar light irradiation. Results showed that enhanced photocatalytic degradation of RG19 at 65.8% was achieved in Luffa-templated ZnO compared with that of the non-templated ZnO which was only 40.8%. This indicated that the Luffa-templated ZnO possessed improved physical properties which could enhance its photocatalytic activity.

We report the hydrothermal syntheses of three uranyl oxide hydroxy-hydrate (UOH) materials containing Sm(III) ions (UOH-Sm) by controlling the solution pH and a new way to make Sm-doped porous uranium oxides with different U-to-Sm atomic ratios via their thermal decompositions. While layer-structured UOH-Sm phases with U-to-Sm atomic ratios of 1 (UOH-Sm1) and 4 (UOH-Sm2) were obtained from the reaction of schoepite and samarium nitrate with final solution pH values of over 4, similar reactions without pH adjustment with final solution pH values of less than 4 led to the formation of a uranyl oxide framework (UOF-Sm) with a U-to-Sm atomic ratio of 5.5. The crystal structure of compound UOF-Sm was revealed with synchrotron single-crystal X-ray diffraction and confirmed with transmission electron microscopy. The two-dimensional uranyl oxide hydroxide layers, similar to that for β-U3O8, are linked by double pentagonal uranyl polyhedra to form a three-dimensional framework with Sm(III) ions in the channels. Scanning electron microscopy characterization revealed nanoplate crystal morphologies for the two UOH-Sm phases, in contrast to the needle morphology for UOF-Sm. Subsequent thermal treatments led to the formation of Sm-doped uranium oxides, maintaining the original crystal shapes and U-to-Sm ratios but with nanopores. This work demonstrated that the hydrothermal synthesis conditions, especially fine-tuning of the solution pH, have a significant impact on the uranium hydrolysis, thus leading to well-defined products. This will facilitate the targeted syntheses of UOH phases with lanthanide (Ln) ions and explore the subsequent applications of these materials and Ln-doped porous uranium oxides as potential nuclear or functional materials.

The thermal insulators with extraordinarily ultra-low dielectric constants (k

The aim of this work was to develop a novel method for the preparation of structured Co-Mn mixed oxide catalysts: deposition on stainless steel meshes by hydrothermal synthesis. The use of meshes enabled the deposition of a thin layer of the active phase, which significantly suppressed the influence of internal diffusion. Consequently, the prepared catalysts exhibited from 48 to 114 times higher catalytic activity in ethanol oxidation than the commercial pelleted Co-Mn-Al catalyst. Moreover, we have shown that their catalytic activity correlated with the amount of surface oxygen vacancies determined by XPS. Finally, the outstanding activity of the catalyst with Co:Mn ratio of 0.5 was ascribed to the mutual effect of high number of oxygen vacancies and exceptional redox properties.

Exploring high-performance cathode materials for aqueous zinc ion batteries (ZIBs) is still one of the critical issues. Copper vanadate compound has become a potential cathode material for ZIBs with a novel displacement reaction mechanism of reversible reduction/oxidation of Cu2+/Cu0. Herein, we reported Cu0.95V2O5 nanoflowers prepared using a hydrothermal synthesis method as a capable cathode material for ZIBs. The Cu0.95V2O5 nanoflowers exhibit high specific capacity of 405 mAh·g−1 at the current density of 100 mA·g−1, benefiting from the displacement reaction mechanism and phase transformation mechanism from Cu0.95V2O5 to the open and stable architecture Cu0.4V2O5 and Zn3(OH)2V2O7·2H2O phase. The cathode exhibits excellent rate performance with a high capacity of ~ 200 mAh·g−1 at 5 A·g−1 and outstanding cycle stability with a capacity retention of 92% after 1000 cycles. It is anticipated that the novel Cu0.95V2O5 nanoflowers are promising cathode material in the application for zinc ion batteries.

Here we report a facile one-step hydrothermal synthesis of cobalt sulfide-modified multi-walled carbon nanotubes (CoS2/MWCNTs) nanohybrids as electrode materials for application in supercapacitor. Benefiting from the stable network structure constructed by the synergistic effect of MWCNTs and cobalt sulfide materials, the volume change caused by ion intercalation/de-intercalation during the charging/discharging process is buffered, thus reducing the influence on the electrochemical performance, which greatly enhances the rate capability and cycling stability of the nanohybrids electrode. Through the synergistic enhancement effect of cobalt sulfide and MWCNT electrode materials, the electrochemical energy storage performance of the nanohybrids is greatly improved. The optimal CoS2/MWCNT-30 electrode exhibits a high specific capacitance of 632.5 F g−1, excellent rate capability of 81.5% (0.3–10 A g−1), and outstanding cycling stability with about 95.3% retention after 5000 cycles. These results indicate that the CoS2/MWCNT-30 nanohybrid electrode synthesized by a facile and cost-effective synthesis pathway has excellent electrochemical energy storage performance and has a great prospect as an electrode material for the application of high-performance supercapacitors.

In this work, we have synthesised a mixture consisting of sodium calcium silicate and calcium silicate nanostructures in the presence and absence of the hydrothermal method. The synthesised products were identified utilising many techniques such as XRD, EDS, FT-IR, HR-TEM, and FE-SEM. The XRD demonstrated that the mean crystallite size of the product, which was synthesised in the absence of the hydrothermal method, is 72.71 nm. The average crystallite size of the products, which were synthesised using the hydrothermal method at 160℃ for 4, 8, and 16 h, are 44.85, 34.89, and 37.38 nm, respectively. HR-TEM confirmed that all the products consist of irregular and rod shapes. The product, which was synthesised after 8 h of hydrothermal treatment, was operated as an adsorbent for the efficient removal of toxic ions (Cd(II) and Hg(II)) from aqueous media. The maximum adsorption capacity of the adsorbent towards Hg(II) and Cd(II) ions are 177.94 and 199.20 mg/g, respectively. The removal process of the studied ions was fitted well with the pseudo-second-order kinetic model and Langmuir equilibrium isotherm. Thermodynamic parameters confirmed that the removal process of the studied ions was spontaneous, chemical, and endothermic.

In order to compare the effect of preparation method on the catalytic performance over Ni/3D-SBA-15 catalyst for CO2 methanation, one-pot and two-pot synthesis strategies were used in this work. 3D-SBA-15-derived Ni-phyllosilicate catalyst could be obtained via a two-pot hydrothermal synthesis using 3D-SBA-15 and nickel nitrate as precursors at 180 °C. This Ni-phyllosilicate catalyst with a monolithic macromorphology and a microcosmic appearance of 3D-networked framework covered by nanosheets, was also achieved via a one-pot hydrothermal method with elimination of the preparation and pretreatment of 3D-SBA-15. The one-pot-synthesized Ni/S–O catalyst not only showed high catalytic activity due to the small-sized Ni particles, but also exhibited excellent anti-sintering property owing to the strong metal-support interaction derived from Ni-phyllosilicate. Compared with the two-pot synthesis, many advantages were observed for one-pot synthesis including monolithic appearance, high convenience, large Ni-phyllosilicate amount and low cost.

This work aims to investigate the influence of aluminium and fluoride ions on the mechanism of wollastonite formation during a two-step synthesis. For the synthesis, three mixtures with different chemical compositions were prepared. The first step of the synthesis was carried out under hydrothermal conditions (stirring – 50 rpm; 200 °C, 4–48 h); the second step was carried out in a furnace with a temperature range of 900–1100 °C for 1 h. The chemical composition of the primary mixture has been determined to exert a significant influence on the mineralogical composition of the hydrothermal synthesis products, since tobermorite and xonotlite dominated in the pure system, while tobermorite and cuspidine dominated in the mixture with aluminium and fluoride ions. After calcination of the precursors, pure wollastonite was obtained using a mixture of amorphous silica and calcium oxide, while in the other two mixtures, it was identified together with wollastonite cuspidine and fluormayenite or gehlenite. Dilatometric and BET analyses of the products showed that Al3+ and F− ions caused densification and loss of porosity during the formation of wollastonite. The synthesised products were characterised by STA, XRD, DIL and BET analyses.

The syntheses and crystal structures of two bimetallic molecular compounds, namely, bis[bis(6,6′-dimethyl-2,2′-bipyridine)copper(I)] hexafluoridozirconate(IV) 1.134-hydrate, [Cu(dmbpy)2]2[ZrF6]·1.134H2O (dmbpy = 6,6′-dimethyl-2,2′-bipyridyl, C12H12N2), (I), and bis[bis(6,6′-dimethyl-2,2′-bipyridine)copper(I)] hexafluoridohafnate(IV) 0.671-hydrate, [Cu(dmbpy)2]2[HfF6]·0.671H2O, (II), are reported. Apart from a slight site occupany difference for the water molecule of crystallization, compounds (I) and (II) are isostructural, featuring isolated tetrahedral cations of copper(I) ions coordinated by two dmbpy ligands and centrosymmetric, octahedral anions of fluorinated early transition metals. The tetrahedral environments of the copper complexes are distorted owing to the steric effects of the dmbpy ligands. The extended structures are built up through Coulombic interactions between cations and anions and π–π stacking interactions between heterochiral Δ- and Λ-[Cu(dmbpy)2]+ complexes. A comparison between the title compounds and other [Cu(dmbpy)2]+ compounds with monovalent and bivalent anions reveals a significant influence of the cation-to-anion ratio on the resulting crystal packing architectures, providing insights for future crystal design of distorted tetrahedral copper compounds.

The manganese based lithium ion sieve H1.6Mn1.6O4 is regarded as a promising adsorbent for recovering lithium from salt-lake brines. However, the poor recycle stability caused by the dissolution of manganese hinders its industrial application. In this work, the Co-doped H1.6CoxMn1.6-xO4 ion sieve with enhanced cycling performance for Li + adsorption was prepared through hydrothermal synthesis. The results of XRD and SEM indicated that Co-doping did not affect the spinel crystal structure of Li1.6Mn1.6O4 and a micro array structure was obtained. The cooperative effect of Co-doping and the micro array structure morphology on the Li + adsorption performance was investigated. Compared with H1.6Mn1.6O4(23.53 mg/g), the adsorption capacity of H1.6Co0.16Mn1.44O4 reached 29.95 mg/g. Also, H1.6Co0.16Mn1.44O4 showed excellent cycling performance that the Li + adsorption capacity maintained over 88% and the dissolution rate of manganese was below 2% after five cycles. The Co-doped H1.6CoxMn1.6-xO4 ion sieves show the prospects to be employed for the Li + extraction from aqueous lithium resources.

Searching for novel anode materials to address the issues of poor cycle stability in the aqueous lithium-ion battery system is highly desirable. In this work, ammonium vanadium bronze (NH4 )2 V7 O16 with brick-like morphology has been investigated as an anode material for aqueous lithium-ion batteries and Li+ /Na+ hybrid ion batteries. The two novel full cell systems (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 and (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 both demonstrate good rate capability and excellent cycling performance. A capacity retention of 78.61 % after 500 cycles at 300 mA g-1 was demonstrated in the (NH4 )2 V7 O16 ||Li2 SO4 ||LiMn2 O4 system, whereas no capacity attenuation is observed in the (NH4 )2 V7 O16 ||Na2 SO4 ||LiMn2 O4 system. The reaction mechanisms of the (NH4 )2 V7 O16 electrode and impedance variation of the two full cells were also researched. The excellent cycling stability suggests that layered (NH4 )2 V7 O16 can be a promising anode material for aqueous rechargeable lithium-ion batteries.

In this paper, a hydrothermal synthesis method synthesized a foamed nickel (NF)-supported Ag-doped Ag2S@MoS2 hydrogen evolution catalyst. Silver doping can improve the conductivity of MoS2, thereby improving the hydrogen evolution activity of MoS2. Compared with a single MoS2, the Ag2S@MoS2 electrode has a larger specific surface area and has many highly catalytic S edges. In 1 M KOH, the overpotential of Ag2S@Ag0.33MoS2/NF electrode at 10 mA cm−2 is approximately 188 mV. Comparing with the overpotential of NF (391 mV) and MoS2/NF (290 mV), it is much lower. Further changing the amount of silver added, the overpotential of Ag2S@Ag0.5MoS 2/NF is further reduced to 165 mV at a current density of 10 mA cm−2. When the voltage is 0.35 V, the current densities of Ag2S@Ag0.33MoS2/NF (42.45 mA cm−2) and Ag2S@Ag0.5MoS2/NF (55.5 mA cm−2) are higher than those of NF (4.91 mA cm−2) and MoS2/NF (20.51 mA cm−2).

Phototherapy exhibits significant potential as a novel tumor treatment method, and the development of highly active photosensitizers and photothermal agents has drawn considerable attention. In this work, S and N atom co-doped carbon dots (S,N-CDs) with an absorption redshift effect were prepared by hydrothermal synthesis with lysine, o-phenylenediamine, and sulfuric acid as raw materials. The near-infrared (NIR) absorption features of the S,N-CDs resulted in two-photon (TP) emission, which has been used in TP fluorescence imaging of lysosomes and tumor tissue pH and real-time monitoring of apoptosis during tumor phototherapy, respectively. The obtained heteroatom co-doped CDs can be used not only as an NIR imaging probe but also as an effective photodynamic therapy/photothermal therapy (PDT/PTT) therapeutic agent. The efficiencies of different heteroatom-doped CDs in tumor treatment were compared. It was found that the S,N-CDs showed higher therapeutic efficiency than N-doped CDs, the efficiency of producing 1O2 was 27%, and the photothermal conversion efficiency reached 34.4%. The study provides new insight into the synthesis of carbon-based nanodrugs for synergistic phototherapy and accurate diagnosis of tumors.

A tetraimidazole-decorating tetraphenylpyrazine has been designed and utilized for the fabrication of a novel metal-organic framework (MOF), denoted as {Mn(Tipp)(A)2}n·2H2O (TippMn, where Tipp = 2,3,5,6-tetrakis[4-[(1H-imidazol-1-yl)methyl]phenyl]pyrazine and A = deprotonation of 1,4-naphthalenedicarboxylic acid), through hydrothermal synthesis. Structural analysis reveals that TippMn possesses a 2-fold-interpenetrated 4,8-connected three-dimensional (3D) network with an unprecedented {416·612}{44·62} topology. Fluorescent spectral investigations indicate that TippMn shows discriminative fluorescence when treated by Cr3+ and Cu2+, giving an INHIBIT logical gate performance. Meanwhile, TippMn can be further used as a sensor for MnO4- and 2,4,6-trinitrophenol (TNP) by fluorescence quenching. Notably, the sensing processes toward Cu2+, Cr3+, MnO4-, and TNP are labeled with high selectivity and sensitivity, quick response, and good recyclability. It is anticipated that this MOF-based versatile sensor could shed light on the exploration of MOFs for fluorescent sensors, optical switches, etc.

Iron removal is an important step in zinc hydrometallurgy, and hematite process not only can effectively remove iron, but also is environmentally friendly and has certain economic benefits, so it has great application potential in zinc hydrometallurgy. The oxidative hydrolysis of Fe(Ⅱ) was studied by the change of ions in solution with different initial ferrous ion concentration. Meanwhile, the oxidation rates of Fe(Ⅱ) at different initial Zn(Ⅱ) concentrations were also studied. The results show that temperature has an important influence on the oxidative hydrolysis of Fe(Ⅱ). Increasing the temperature can inhibit the formation of complex and make more Fe(Ⅱ) precipitate directly in the form of hematite, which is not limited by the hydrolysis rate of Fe(Ⅲ). The oxidation reaction of Fe(Ⅱ) approximately conforms to the second order reaction rate. Zinc sulfate can promote the oxidation of Fe(Ⅱ). When the initial Zn(Ⅱ) concentration was 20, 40, 60 and 80 g/L, the oxidation kinetic constants of Fe(Ⅱ) were 2.433, 4.492, 10.106 and 14.857 L·mol−1·min−1, respectively.

The rapid deactivation caused by coke deposits is the major obstacle to the ethane aromatization of Zn-based catalysts. We have successfully synthesized a Zn-embedded inside HZSM-5 crystal catalyst (Zn@HZSM-5) by hydrothermal synthesis using preformed Zn/SiO2 as the only silicone source. Based on various characterization results, including in situ etching XPS, operando DRIFTS, as well as NMR, it is found that Zn(OH)+ and [Zn–O–Zn]2+ species are active sites for ethane aromatization for zinc-based catalysts, and their dynamic transformation significantly changes reaction performance of ethane dehydrogenation. For the Zn/HZSM-5 catalyst, the existence of a large number of [Zn–O–Zn]2+ species causes higher initial ethane conversion and higher selectivity of aromatics, resulting in a large amount of coke deposits. Moreover, [Zn–O–Zn]2+ species on the Zn/HZSM-5 catalyst fast transit to Zn(OH)+ species and subsequently form the sintered ZnO species, leading to rapid deactivation. For the Zn@HZSM-5 catalyst, the embedded structure contributes to forming more Zn(OH)+ species and delays the transformation of the Zn(OH)+ species to [Zn–O–Zn]2+ species, resulting in slowly increased selectivity of aromatics during the reaction. Therefore, the Zn@HZSM-5 catalyst realizes stable ethane conversion with dynamic selectivity.

Five kinds of BZSM-5 molecular sieve with different Si/B ratio and a SiZSM-5 molecular sieve were prepared by hydrothermal synthesis method followed by acid exchange and pelletization. The samples were characterized by XRD, SEM, FT-IR, ICP, low temperature N2 physical adsorption and desorption, NH3-TPD and Py-IR. The catalytic performance in the reaction of methanol to hydrocarbons was evaluated in the fixed bed reactor. Compared with SiZSM-5, the amount and strength of Bronsted (B) acid were enhanced by introducing skeleton boron and the activity of the catalyst was greatly improved. The characterization and evaluation results indicated that the BZSM-5 catalyst synthesized from the gel of SiO2/B2O3 20 with Si/B ratio 74.48 had modest acidity strength, acid amount of 0.18 mmol NH3·g−1 and large mesopore volume of 0.23 cm3·g−1. The B acid ratio was higher and the acid strength of BZSM-5 was weaker than that of AlZSM-5, which could inhibit the deep coke formation and increase the activity stability. B-2 had the best lifetime which could reach 672 h under the same evaluation reaction conditions, due to the best matching of moderate acidity and good diffusion properties.

The high capacitive, cost-effective, non-toxic nickel–cobalt layered double hydroxide nanofoam pseudocapacitive electrode materials doped with aluminium (NiCoAl-LDH) have been hydrothermally synthesized on the electrochemically modified graphite (G) substrate with zinc and copper (Zn/G and Cu/Zn/G). The Al3+ diffusion in the LDH during the hydrothermal synthesis resulted in an ultrathin nanofoam morphological structure well adapted to the entire surface of Zn/G and Cu/Zn/G. The high areal capacitance of the best efficient NiCoAl-LDH/Cu/Zn/G electrode of 2.17 F cm−2 at 5 mA cm−2 decreases to 1.83 mF cm−2 at 75 mA cm−2 showing an excellent rate capability of 84%. An asymmetric supercapacitor (ASC) designed with graphite as negative electrode exhibits an energy density of 29.3 Wh kg−1 at a power density of 575 W kg−1. It still remains at 5.6 Wh kg−1 at a higher power density of 3477 W kg−1 at a discharge time of 5.8 s indicating ultra-fast energy storage ability of the G//NiCoAl-LDH/Cu/Zn/G device. Its cyclic tests were also made by constructing a coin-cell-type device for industrial applications. The capacitance of the coin-cell operating within 1.6 V was protected around 100% even after over 10,000 charge–discharge cycles at the current densities up to 1.8 mA cm−2.

Two new compounds, Cs2[Cu2Re6S8(CN)6]⋅3H2O (I) and (H3O)2[Cu{Cu2(µ-CN)}Re6Se8(CN)6]·6.5H2O (II), were synthesized under hydrothermal conditions from a mixture of CuCN and Cs2.67K1.33[Re6S8(CN)2(OH)4]·4H2O or Cs2.75K1.25[Re6Se8(CN)4(OH)2]·H2O, respectively. The reaction involves replacement of OH– by CN– and the formation of interpenetrating anionic framework through –CN–Cu–CN– bridges. The framework cavities accommodate counterions and water molecules. The obtained compounds were characterized by single crystal X-ray diffraction (CIF files CSD nos. 2048821 (I), 2048822 (II)), IR spectroscopy, and elemental analysis.

Niobium pentoxide (Nb2O5) was synthesized by the microwave-assisted hydrothermal method using two different niobium precursors: niobium ammoniacal oxalate (P1) and niobium chloride (P2). The XRD result confirms the presence of Nb2O5 with low crystallinity for both precursor samples. The SEM images show differences between the material morphologies but with the same aggregation particle characteristics. Photocatalytic degradation of the rhodamine B (RhB) dye was performed using both samples of Nb2O5 as a photocatalyst under UVC illumination using a 24 factorial design experimental method. The studied variables were the type of precursor (P1 and P2), the RhB concentration (1 × 10−5 and 3 × 10−5 M), the Nb2O5 photocatalyst dosage (25 and 50 mg), and the time of the photocatalysis analysis (30 and 60 min), verifying the influence on the RhB dye removal efficiency. The factorial design showed that all variables had a significant effect on the process, but the variables with the most influence were RhB concentration and photocatalysis time. For both precursors, the samples that showed greater removal efficiency were those under conditions 1 × 10−5 M, 50 mg, and 60 min, obtaining 92.87% and 98.99%, respectively. The high rate of RhB removal suggests that the Nb2O5 obtained by microwave-assisted hydrothermal synthesis has the potential to be used in photocatalytic processes to remove organic pollutants from effluents.

To improve the adsorption performance and simplify uranium separation from aqueous media in post-treatment processes, a magnetic CoFe2O4@rGO composite was synthesized by microwave-hydrothermal method. The results of XRD, Raman, TEM/HRTEM, FTIR, BET and VSM characterization show that spinel-type cobalt ferrite CoFe2O4 nanoparticles ca. 13.4 nm in size are dispersedly anchored on the graphene sheet, and the saturation magnetization of the nanocomposite is 46.7 mA/(m2·g). The effects of different pH, initial concentration and other conditions on uranium adsorption capacity were investigated, and adsorption kinetics equations were fitted to determine the adsorption behaviour of uranium on CoFe2O4@rGO in simulated uranium-containing seawater. It was observed that the uranium adsorption capacity of CoFe2O4@rGO composite at pH=5 is 127.6 mg/g, which is 1.31 and 2.43 times that of rGO and pure CoFe2O4. The adsorption process conforms to Langmuir and quasi-second-order kinetic model. The excellent adsorption performance of CoFe2O4@rGO makes it potentially useful in the treatment of uranium-polluted water.