Facile Template-free Hydrothermal Method Research Articles

Facile synthesis of Ni-doped ZnS nanostructures and their photocatalytic activity to RhB

In this paper, pure ZnS and Ni-doped ZnS nanostructures (Ni–ZnS) were prepared by facile template-free hydrothermal method. The as-prepared Ni–ZnS was characterized by XRD, SEM, EDS, XPS, and UV–Vis DRS. The effects of different Ni doping amounts and hydrothermal reaction temperatures were investigated. The photocatalytic ability was evaluated for the degradation of Rhodamine B (RhB) under visible light irradiation. The results indicated that the doping of Ni effectively enhanced the photocatalytic activity of pure ZnS. Ni–ZnS exhibited significantly enhanced photocatalytic properties, the reaction rate constant (0.01154 min−1) is higher than that of pure ZnS (0.00218 min−1). Carrier separation efficiency and charge transport efficiency were investigated by transient photocurrent response (TPS) and electrochemical impedance spectroscopy (EIS). Scavenger test was used to determine the role of active species, combining the analysis results of UV–Vis DRS, TPS, and EIS, accordingly the photocatalytic mechanism of Ni–ZnS was proposed.

Tailoring the electric, dielectric and optical properties of template-free hydrothermally synthesized CuO nanostructures via Co doping

Facile template-free hydrothermal method was utilized for preparing CuO nanostructures (NSs) doped with Co element (Cu1-xCoxO (x = 0.0, 0.02, 0.04, 0.06 and 0.08)). A single-phase monoclinic crystal with changing in morphology from rod-to sphere-like nanoparticles was observed. The temperature dependency of DC electrical conductivity revealed that the shallow and deep donor levels are responsible for the DC conduction in low and high temperature ranges, respectively. The Ac electrical conductivity, dielectric constant and dielectric loss were also measured as functions in frequency and temperature. The frequency dependence of the AC conductivity was well represented by the Jonscher's universal power law. The AC conduction was governed by the Correlated Barrier Hopping model where the inter-well and intra-well hopping mechanisms contribute to the electrical conduction in the low and high frequency ranges, respectively. The activation energies and the barrier height decreased while the dielectric constant and dielectric loss increased with increasing the Co content. The relaxation and deformational polarizations predominate and the overall behavior of dielectric constant fits well with the Koops' model. The Cole-Cole plots indicated a decrease in the sample resistance with increasing temperatures and Co concentrations. UV–vis absorption spectra exhibited two peaks at wavelengths 252 and 323 nm. The optical energy gap was calculated using Tauc's equation and decrease from 2.24 to 2.1 eV with increasing the Co concentrations. The effect of Co-doping on CuO was explored for oxygen evolution reaction (OER) and found a decrease in the overvoltage (μ) about 50 mV at 0.08 ratios, which declares that the doping of Co element enhances the electrical conductivity and feasibility for further electrocatalytic improvement.

H2S Sensing Characteristics of NiO Nanopetal Film

NiO is one of the most candidate materials for hydrogen sulfide (H2S) sensing due to its catalytic activity for the oxidation reaction of H2S, and high affinity of Ni in the NiO to S for the H2S adsorption. Porous NiO nanopetal film composed of interconnected thin nanosheets was grown by a facile template-free hydrothermal method at the relatively low temperature of 105 °C, and its H2S sensing characteristics was investigated in the temperature range of 25 °C to 400 °C. The NiO nanopetal film based device showed a reliable response to wide range of concentration from 10 ppm to 500 ppm H2S ambient at 400 °C. The sensor started to exhibit the responsivity to 500 ppm H2S gas at 200 °C. The maximum responsivity of the sensor with NiO nanopetals was 400% for 500 ppm H2S exposure at 300 °C. The NiO nanopetal film grown by the simple low-cost hydrothermal synthesis has high potential in applications of chemical, medical, energy, and food industries.

Collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria.

Tuning morphology and doping additional rare earth (RE) cations are potential techniques to promote the photocatalytic performance of ceria (CeO2), evaluating the collaborative effects of morphology and RE dopants is significant for producing high active ceria-based catalysts. So in this work, cubic, polyhedral and rod-like nanoceria doped with 10mol % La (lanthanum), Y (yttrium), or Sm (samarium) were synthesized by a facile template-free hydrothermal method. Phases, morphologies, oxygen vacancies (OVs) concentration, energy band structure, photo-carriers separation/recombination, and photodegradation ratio toward methylene blue (MB) dye of as prepared ceria were studied. Results show that doped CeO2 maintains a similar morphology structure with un-doped sample and the band gap narrows slightly. Y-doped nanoceria, with an improved separation and a reduced recombination of photo-excited electrons (e-) and holes (h+), owns a higher MB photodegradation ratio than that of samples doping with La or Sm, which is measured as 79.04, 84.43, and 85.59% for Y-doped cubic, polyhedral, and rod-like CeO2. The collaborative influence of morphology tuning and RE (La, Y, and Sm) doping on photocatalytic performance of nanoceria includes the effects of doped elements and the formation of OVs. The elevation of OVs concentration as well as the separation efficiency of photo-generated e-/h+ are suggested to further enhance the photocatalytic performance of ceria.

Design of ultrasensitive gas sensor based on self-assembled Pd-SnO2/rGO porous ternary nanocomposites for ppb-level hydrogen

With the accelerating development of the hydrogen economy, more requirements are put forward for the detection capability of portable hydrogen sensors. Though the fast and accurate detection of hydrogen has been indispensable, there are still some challenges in the detection of extremely low concentrations of hydrogen. In this work, Pd-SnO2/rGO ternary nanocomposites with porous structures were synthesized by a facile template-free hydrothermal method. The effects of each element and its contents on the sensitivity and selectivity to hydrogen were systematically studied. The best hydrogen sensing property was produced by the synergistic effect of the 5.0 Pd-SnO2/rGO ternary nanocomposite, which showed a response of 32.38 toward 200 ppm hydrogen at 360 ℃. Especially, the response of 5.0 Pd-SnO2/rGO to 0.5 ppm (500 ppb) hydrogen reached 2.4, indicating the great potential in the detection of extremely low concentrations of hydrogen. The mechanism of high hydrogen sensitivity and selectivity was elaborated in combination with the analysis of band structure. All the as-prepared sensors exhibit quantitative concentration-response function relationships, favorable reversibility, and long-term stability. This work may provide a feasible strategy for the design of novel H2 sensors with high sensitivity to extremely low concentrations of hydrogen.

Template-free hierarchical trimetallic oxide photocatalyst derived from organically modified ZnCuCo layered double hydroxide

High-performance photocatalysts have considerable potential to address energy and environmental issues. In this study, dodecylbenzenesulfonate (DBS) modified ZnCuCo layered double hydroxide (DBS-ZnCuCo LDH) microspheres were synthesized through the facile template-free hydrothermal method. Subsequently, ZnCuCo mixed-metal oxides (MMOs) with morphological features of the DBS modified LDH, enhanced surface area, increased light absorption and effective charge separation were prepared by the calcination of the as-synthesized LDH at 650 °C. Structural, morphological, and photoelectrochemical properties of ZnCuCo and DBS-ZnCuCo LDHs and the corresponding MMOs (ZnCuCo MMO1 and ZnCuCo MMO2) were investigated. SEM and TEM images revealed that DBS-ZnCuCo LDH and ZnCuCo MMO2 possess 3D flower-like hierarchical morphologies with interlaced petal-like nanosheets. Although ZnCuCo LDH was inactive for photocatalytic H2 production under visible light irradiation, ZnCuCo MMO2 exhibited a high H2 production rate (3700 μmol g−1 h−1), benefiting from the synergy of the ZnO, CuO, and Co3O4. Furthermore, 95% sulfamethazine (SMZ) degradation was obtained after 60 min of photocatalysis, which is considerably higher than the degradation efficiency of ZnCuCo LDH (24%) and ZnCuCo MMO1 (58%). Based on the photoelectrochemical tests, Z-scheme and double charge transfer mechanisms were proposed to explain the enhanced photocatalytic H2 production and degradation of SMZ. Scavenging tests revealed that O2•− radicals were the main reactive species in the photodegradation of SMZ. A possible degradation pathway was proposed based on the detection of intermediate products.

Unraveling the structure and electrochemical supercapacitive performance of novel tungsten bronze synthesized by facile template-free hydrothermal method

In this study, we report a facile hydrothermal method for preparing novel tungsten oxide bronze (HxWO3) and nanostructured tungsten oxide (WO3) using different structure-directing agents. The effects of phase and morphology of the hydrothermally fabricated nanostructured WO3 on the charging/discharging performance of electrochemical pseudocapacitors are thoroughly investigated. Most of the as-prepared samples exhibit WO3•0•33H2O orthorhombic structure, whereas post annealing at 350 °C promotes phase transformation to a phase-pure hexagonal structure (h-WO3). Scanning electron microscope (SEM) images show a variation of the prepared samples’ morphology between one-, two-, and three dimensions. The difference in structure between the developed bronze and the known WO3 phases is confirmed by Raman spectroscopic investigations. The optical bandgap estimated from diffuse reflectance is the highest for novel HxWO3 (2.84 eV) and h-WO3 (2.73– 2.80 eV), whereas it is lowest for the monoclinic phase (2.66 eV). X-ray photoelectron spectroscopy (XPS) analysis confirms the formation of higher amount of oxygen vacancies in h-WO3 than HxWO3. An exceptional capacitance of 1280 F/g at 1 A/g is obtained for h-WO3 when tested in 0.5-M H2SO4 aqueous electrolyte, which is superior to HxWO3. The symmetrical supercapacitor device of HxWO3 exhibits an energy density of 8 W h/kg with high stability and good capacitive retention. The number and size of the various crystallographic tunnels in the fabricated h-WO3 are found to be the primary driving forces for improving the capacitive performance and stability.

Hydrogen sensing properties of Pd/SnO2 nano-spherical composites under UV enhancement

The rapid and efficient detection of hydrogen plays an important role in the development of hydrogen energy. The response and selectivity of typical metal oxide semiconductor (MOS) sensors to low concentration hydrogen detection still need to be improved to meet the application of hydrogen. In this work, Pure SnO2 hollow spheres and different molar ratio of Pd decorated SnO2 spherical composites were synthesized by a facile template-free hydrothermal method. High response of 14.5 and fast response/recovery time of 2.2/22.4 s to 200 ppm hydrogen were achieved by 5.0 mol% Pd/SnO2 at 330 °C. The response to 200 ppm hydrogen was enhanced to 18.1 and the recovery time was also improved to 17.4 s with 10 mW/cm2 UV irradiation. Especially, the response to interfering gases was inhibited with UV irradiation, which improved the selectivity of as-prepared sensors to hydrogen molecules. Linear dependence of the responses of as-prepared sensors on the hydrogen concentration was observed, indicating the great potential for quantitative detection of H2 at ppm level. This work provides a facile route to synthesize porous spherical Pd/SnO2 for hydrogen detection and a reference for the future design of hydrogen detectors with UV irradiation.

Effect of SrF2:Pr3+-Yb3+ Nanophosphor on Downconversion of High Energy Photons for Efficient Dye-Sensitized Solar Cells

An emerging important class of photovoltaics for the next generation, the dye sensitized solar cells (DSSCs) has attracted great attention due to its low-cost, simple fabrication process and good performance. Though, one of the major loss mechanisms leads to lowering the power energy conversion efficiency is thermalization of charge carriers generated by the absorption of high energy photons. One promising novel strategy to decrease such thermalization loss is the use of downconversion (DC) luminescent materials as spectral converters. The rare-earth doped downshifting materials can converts higher energy photons into lower energy photons based on energy transfer from lanthanide ions to Yb3+ ions. In addition, the downconversion nanoparticles (DCNPs) are also act as scattering centers which can facilitates the light capture in photo-absorbing layer. With this aim, the rare earth doped downconversion SrF2: Pr3+-Yb3+ nanoparticles were synthesized by facile template free hydrothermal method. X-ray diffraction analysis confirms the formation cubic SrF2 phase. The prepared SrF2: Pr3+-Yb3+ down-shifting nanophosphor shows strong absorption in UV region and broad luminescence band emission in visible region evidenced from absorption and photoluminescence studies respectively. The enhancement in power conversion efficiency (PCE) was achieved by employing the synthesized downconverting nanomaterial as bottom layer in DSSC photoanode (Fig.1). The photovoltaic performance of the device was studied using standard solar simulator at 1 Sun intensity (AM 1.5 G) and DSSC with SrF2: Pr3+-Yb3+ shows improved efficiency of 9.066% than bare TiO2 based device (8.395%). The down-shifting nanophosphor material enhanced the efficiency of DSSC by 7.4% with 7.5% increment in photocurrent density compared to bare TiO2 based device. Figure 1

Porous α-Fe2O3/SnO2 nanoflower with enhanced sulfur selectivity and stability for H2S selective oxidation

Being abundant and active, Fe2O3 is suitable for selective oxidation of H2S. However, its practical application is limited due to the poor sulfur selectivity and rapid deactivation. Herein, we report a facile template-free hydrothermal method to fabricate porous α-Fe2O3/SnO2 composites with hierarchical nanoflower that can obviously improve the catalytic performance of Fe2O3. It was disclosed that the synergistic effect between α-Fe2O3 and SnO2 promotes the physico-chemical properties of α-Fe2O3/SnO2 composites. Specifically, the electron transfer between the Fe2+/Fe3+ and Sn2+/Sn4+ redox couples enhances the reducibility of α-Fe2O3/SnO2 composites. The number of oxygen vacancies is improved when the Fe cations incorporate into SnO2 structure, which facilitates the adsorption and activation of oxygen species. Additionally, the porous structure improves the accessibility of H2S to active sites. Among the composites, Fe1Sn1 exhibits complete H2S conversion with 100% sulfur selectivity at 220 °C, better than those of pure α-Fe2O3 and SnO2. Moreover, Fe1Sn1 catalyst shows high stability and water resistance.

Hierarchically porous LiMn0.1Fe0.9PO4@C microspherical cathode materials prepared by a facile template-free hydrothermal method for high-performance lithium-ion batteries

A simple and scalable method has been developed to fabricate hierarchically porous LiMn0.1Fe0.9PO4@C microspheres via a template-free hydrothermal route, which involves the formation and self-assembly of nanoparticles, followed by the dissolution-precipitation process during the hydrothermal reaction. After a simple carbon coating, the obtained porous LiMn0.1Fe0.9PO4@C microspheres simultaneously integrate hierarchical porous microspherical structures, nano-sized LiMn0.1Fe0.9PO4 primary particles with high crystallinity, and uniform carbon coating in the thorough interior. Their unique structures can ensure high ionic and electronic conductivity during the electrochemical reaction of the LiMn0.1Fe0.9PO4 cathode materials. Therefore, very high discharge capacities of 147.8, 144.2, 138.6 and 134.9 mAh g−1 at the current rate of 0.2 C at 100th, 200th, 300th and 500th cycle could be achieved for the porous LiMn0.1Fe0.9PO4@C microspheres. These encouraging results suggest that the hierarchically porous LiMn0.1Fe0.9PO4@C microsphere prepared by the facile and efficient template-free hydrothermal method should be a promising candidate cathode material for the advanced lithium-ion battery.

Hydrothermal synthesis of novel two-dimensional α-quartz nanoplates and their applications in energy-saving, high-efficiency, microalgal biorefineries

A facile template-free hydrothermal method was successfully developed for the controlled synthesis of ultrathin α-quartz nanoplates (NPLs) for the first time. Analyses of the α-quartz NPLs revealed the characteristic anisotropic nanostructures of highly crystalline α-quartz with an average lateral size and thickness of 1.14 ± 0.32 μm and 7.7 ± 0.6 nm, respectively. Importantly, efficient extraction of highly valuable chemicals such as astaxanthin (ATX) from the microalgal cells of Haematococcus pluvialis (H. pluvialis) was accomplished by lacerating the cell walls using the ultrathin α-quartz NPLs under mild ultrasonication. The incorporation of α-quartz NPLs enhanced the ATX extraction efficiency significantly (99%, 18.0 ± 0.6 mg ATX/g cell) when coupled with 5 min of ultrasonication. The dosage of α-quartz NPLs (800.0 mg/L) for maximum ATX extraction was reduced substantially to only 8% of the nanomaterial dose used in the extraction controls. The enhanced extraction efficiency and dosage were explained by the role of the structural anisotropy of α-quartz NPLs in multiple phase separation-extraction processes. This work provides a novel, facile, and economical route for the synthesis of uniform ultrathin nanoplates, offering a new material for the highly efficient harvesting of chemical products from various microalgal biorefinery processes.

Boosting the performance of half/full lithium-ion batteries by designing smart architecture anode of SnS2 nanosheet coating on NiCo2S4 hollow spheres

An innovative and controlled strategy has been proposed to design tin disulfide (SnS2) nanosheet coating on nanostructure hollow sphere of ternary spinel sulfide (NiCo2S4) composites smart architecture as anodes (NiCo2S4/SnS2) for lithium-ion batteries (LIBs) by a facile template-free hydrothermal method. The NiCo2S4/SnS2 electrode showed good electrochemical performances, for instance, high reversible capacity (1260 mA h g−1@0.1 A g−1), favorable rate capability and good cycles stability (627 mA h g−1 @0.5 A g−1 after 300 cycles), which is ascribed to smart architecture hollow structure, good electrical conductivity and contribution of synergistic effect. The mechanism of lithiation and delithiation process in NiCo2S4/SnS2 composite electrodes was further shed light upon. Moreover, the advanced full batteries have been assembled by combing NiCo2S4/SnS2 anodes with commercial NMC111 cathodes, which presented good cycle stability and potential promising application. Our work provides novel way to design multifunction metal sulfides with desirable architecture and superior property in energy storage area.

Multi-shelled hollow cube CaTiO3 decorated with Bi12O17Cl2 towards enhancing photocatalytic performance under the visible light

It is highly desirable to combine the microstructure management and heterostructure construction technique to remold inherent wide band gap semiconductor CaTiO3 with the purpose of enhancing its visible light absorption capacity and photocatalytic performance. Herein, a novel multi-shelled hollow cube Bi12O17Cl2/CaTiO3 heterostructure has been successfully synthesized by a facile template-free method for photocatalytic hydrogen production and degradation pollutants in water under the visible light. The investigations of microstructure, physicochemical property and photoelectric behaviors indicate that the multi-shelled hollow cube architecture and synergetic effect of 2D-3D structural coupling are dominant reasons to enhance phototcatalytic performance, which can significantly improve the absorption and utilization of visible light, multiply abundant active radical generation and boost the separation and migration efficiency of photoproduced electron-hole pairs. Moreover, the probable photocatalytic reaction mechanisms, the feasible migration behaviors of photo-produced charges, the influence factors of enhancing photocatalytic activities are proposed in depth. It is intended that further innovative works on the multi-shelled hollow cube architecture design of high-performance photocatalyst by facile template-free hydrothermal method can be inspired.

Synthesis of 3D flower-like Fe3S4 microspheres and quasi-sphere Fe3S4-RGO hybrid-architectures with enhanced electromagnetic wave absorption

3D flower-like Fe3S4 microspheres and quasi-sphere Fe3S4-RGO hybrid-architectures were successfully fabricated by a facile template-free hydrothermal method. The results of morphology revealed that the single Fe3S4 was composed of many nanoflakes and the Fe3S4-RGO composites mainly distributed together into a ball up and down the RGO sheet. The electromagnetic parameters of the single Fe3S4 and Fe3S4-RGO composites could be controlled by adjusting different filler loading and the addition of different GO to achieve impedance matching. Both the single Fe3S4 and Fe3S4-RGO composites exhibited an excellent EM absorption ability. The minimum reflection loss (RL) of the single Fe3S4 with 50% filler loading could achieve −66.87 dB at 10.57 GHz for the thickness of 2.2 mm, and the absorption bandwidth (RL < −10 dB) could reach 3.49 GHz. For the Fe3S4-RGO composites, the minimum RL of FSR-1 could be −40.25 dB at 9.67 GHz with the thickness of 2.0 mm. In addition, the effective absorption bandwidth of FSR-2 could reach 3.85 GHz at only 1.45 mm and the minimum RL was −29.25 dB at 14.24 GHz. Consequently, the single Fe3S4 and Fe3S4-RGO composites are promising materials as a high performance and adjustable EM wave absorber.

Cytotoxicity of versatile nano-micro-particles based on hierarchical flower-like ZnO

ZnO (nano)structures remain of great interest in biomedical applications due to their unique properties and possible morphologies. Biocompatibility of typically fabricated ZnO structures remains questionable and they still lack desired biological functions, whence their functionalization is of high interest. In this work, we fabricated micro-sized ZnO hierarchical flower-like structures using facile template-free hydrothermal method to act as carriers for the delivery of gold nanoparticles (Au) and/or Biotin (Vitamin B) to cells. Au nanoparticles (~24 nm), as well as Biotin molecules were successfully deposited on the ZnO surface due to non-covalent physical interactions. We have then cultured two cells lines: SH-SY5Y (human malignant neural) and HEK-293 (human non-malignant) and observed that ZnO hierarchical particles exhibited cell line-dependent cytotoxicity. It appeared that further functionalization of ZnO with Au nanoparticles and subsequently with Biotin led to lower discrepancy between the two cell lines response indicating that cytotoxic pathways of pure ZnO were masked by the available surface adsorbed particles (Au/Biotin). Two-photon immunocytochemistry microscopy further confirmed that Biotin decorated particles affected neuroblastoma cells cytoskeleton. These findings contribute to the understanding of cytotoxic pathways of surface-decorated nano-micro-structures made from ZnO with two molecules typically used in anticancer and regenerative medicine therapies.

Facile template-free synthesis of Ni-SiO2 catalyst with excellent sintering- and coking-resistance for dry reforming of methane

Ni-SiO2 catalysts were synthesized by facile template-free hydrothermal method with ammonia-assisted via using low-cost silica sol as precursor and successfully employed to dry reforming of methane reaction. It was found that ultra-small Ni nanoparticles around 3.2 nm rationally obtained with high dispersion. The strong metal-support interaction generated from the in-situ ammonia-assisted process further stabilized the Ni species during the DRM reaction. Furthermore, the high activity, stability and H2/CO ratio of Ni-SiO2 remained initial value even continued reacting at 700 °C for 30 h. Almost no visualization of metal growth and carbon deposition were observed on the spent catalyst.

Insight into efficient pollutant degradation from paramorphic SnO2 hierarchical superstructures

Three-dimensional (3D) hierarchical architectures are currently attracting extensive interests owing to their fascinating morphology-dependent properties and potential applications. In this work, we have developed a facile template-free hydrothermal method to synthesize various 3D SnO2 hierarchical superstructures. It is found that the amount of urea, pH value and the pre-oxidation process play a crucial role in the micro/nanostructural evolutions of building blocks and final products. Oriented attachment and self-assembling dual-controlled mechanisms are then proposed to illustrate the formation of 3D hierarchical superstructures. The application in photocatalysis for the degradation of methylene blue (MB) demonstrates that the as-synthesized SnO2 hierarchical superstructures have highly efficient photocatalytic activity for the degradation of organic pollutants. Particularly, the SnO2 hierarchical superstructure constructed by ultrathin nanosheets can degrade 93% of MB within 150 min, which is much higher than that of commercial SnO2 powders. The enhanced photocatalytic performances can be attributed to the high surface-to-volume ratio, the abundant active sites and the efficient separation of photogenerated electrons and holes induced by the unique 3D loose and microporous superstructures. These new insights obtained in this study will be beneficial for the practical applications of oxide semiconductor materials for photocatalytic degradation of organic pollutants.

1D-Co3O4, 2D-Co3O4, 3D-Co3O4 for catalytic oxidation of toluene

A facile template-free hydrothermal method was applied to successfully synthesize a series of bulk cobalt oxides with different morphologies (1D-Co3O4 nanoneedle, 2D-Co3O4 nanoplate, and 3D-Co3O4 nanoflower). The catalytic activity for the toluene combustion over various types of catalysts was investigated. The 3D-Co3O4 nanoflower performed the excellent activity and the temperature required for achieving a toluene conversion of 90 % (T90%) at approximately 238 °C with the activity energy (Ea) of 71.6 KJ mol−1, which was 19 ℃ lower than that of 1D-Co3O4 nanoneedle with Ea of 97.1 KJ mol−1 at a space velocity (WHSV = 48, 000 mL g−1 h−1). The effect of shape on the physicochemical properties of the Co3O4 catalysts were characterized by various analytical techniques. It has been found that large specific surface area, low temperature reducibility, highly defective structure with abundant surface active oxygen species and rich Co3+ cationic species were responsible for the excellent catalytic performance of 3D-Co3O4 nanoflower. In addition, complete conversion of toluene had remained the same after 3D-Co3O4 nanoflower was observed for 120 h, suggesting it exhibited the long-term stability for toluene combustion. Therefore, 3D-Co3O4 nanoflower might be a potential non-noble catalyst in practical application.

One-step facile hydrothermal synthesis of flowerlike Ce/Fe bimetallic oxides for efficient As(V) and Cr(VI) remediation: Performance and mechanism

Toxic heavy metals As(V) and Cr(VI) removal from water environment has becoming more and more urgent due to their adverse health effect. In this study, the flowerlike Ce/Fe bimetallic oxides (CFBO), which combined the superiority of three-dimensionally (3D) hierarchical architectures and bimetallic synergistic effect, were innovatively designed and synthesized via one-step facile template-free hydrothermal method. Compared with pure iron oxides (PIO), the obtained CFBO exhibited excellent performance for As(V) and Cr(VI) removal, and the maximum adsorption capacities toward As(V) and Cr(VI) increased from 49.09 mg/g to 164.94 mg/g and 38.07 mg/g to 127.42 mg/g, respectively. Both As(V) and Cr(VI) removal efficiency decreased with an increasing solution pH due to the pHzpc of CFBO, but exhibited slightly change with coexisting anions except for SiO32− and PO43− ions. Combined results of FT-IR and XPS, it was concluded that the abundant hydroxyl groups existed on the surface of CFBO played a key role in the high uptake of As(V) and Cr(VI), and subsequently formed inner-sphere surface complexes. Attractively, the remarkable removal efficiency of As(V)/Cr(VI) in column experiments revealed that the CFBO had great potential for practical application.