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1.
Nat Commun ; 15(1): 9499, 2024 Nov 03.
Artigo em Inglês | MEDLINE | ID: mdl-39489774

RESUMO

The electrocatalytic reduction of nitrate toward ammonia under mild conditions addresses many challenges of the Haber-Bosch reaction, providing a sustainable method for ammonia synthesis, yet it is limited by sluggish reduction kinetics and multiple competing reactions. Here, the titanium hydride electrocatalyst is synthesized by electrochemical hydrogenation reconstruction of titanium fiber paper, which achieves a large ammonia yield rate of 83.64 mg h-1 cm-2 and a high Faradaic efficiency of 99.11% with an ampere-level current density of 1.05 A cm-2 at -0.7 V versus the reversible hydrogen electrode. Electrochemical evaluation and kinetic studies indicate that the lattice hydrogen transfer from titanium hydride promotes the electrocatalytic performance of nitrate reduction reaction and the reversible equilibrium reaction between lattice hydrogen and activate hydrogen not only improves the electrocatalytic activity of nitrate reduction reaction but also demonstrates notable catalytic stability. These finding offers a universal design principle for metal hydrides as catalysts for effectively electrochemical ammonia production, highlighting their potential for sustainable ammonia synthesis.

2.
Spectrochim Acta A Mol Biomol Spectrosc ; 326: 125223, 2024 Sep 27.
Artigo em Inglês | MEDLINE | ID: mdl-39348738

RESUMO

Cysteine, as a vital endogenous small molecule mercaptan, plays a crucial role in various physiological processes. The high sensitivity and selectivity of fluorescent probes provide a method to monitor cysteine, which is helpful to understand the mechanism of cysteine in physiological processes more comprehensively. However, the detection of cysteine can be interfered by other small molecule biothiols. Therefore, the design of fluorescent probe based on the structural characteristics and reactivity of cysteine has become research focus currently. Given the biological compatibilities, biological targets, the metabolic pathway of 3-hydoxythalidomide, and its unique fluorescent properties, herein, we have designed a chemodosimeter, 2-(2,6-dioxopiperidin-3-yl)-1,3-dioxoisoindolin-4-yl acrylate, for the detection of cysteine based on a tandem reaction of thiol-ene click chemistry and aminolysis involving 3-hydroxythalidomide as a parent compound. Experimental data exhibited that the probe showed unique selectivity and sensitivity for cysteine over other amino acid and biothiols. In addition, the fluorescent intensity at 511 nm increased linearly as a function of cysteine concentration in the range of 0-6 × 10-7 M (regression factor, R2 = 0.999), with a limit of detection of 6.1 nM. The sensing mechanism was confirmed through 1H NMR titration and density functional theory calculations. Additionally, the probe was also successfully utilized for the detection of cysteine in sewage and for bioimaging in HeLa cells.

3.
ChemSusChem ; : e202400808, 2024 Aug 20.
Artigo em Inglês | MEDLINE | ID: mdl-39163552

RESUMO

Developing active sites with flexibility and diversity is crucial for single atom catalysts (SACs) towards sustainable nitrogen fixation at ambient conditions. Herein, the effects of doping main group metal elements (MGM) on the stability, catalytic activity, and selectivity of vanadium-based SACs is systematically investigated based on density functional theory calculations. It is found that the catalytic activity of V site can be significantly enhanced by the synergistic effect between MGM and vanadium atoms. More importantly, a volcano curve between the catalytic activity and the adsorption free energy of NNH* can be established, in which V-Pb dimer embedded on N-coordinated graphene (VPb-NG) exhibits optimal NRR activity due to its location at the top of volcano. Further analysis of electronic structures reveals that the unoccupancy ratio (eg/t2g) of V site is dramatically increased by the strong d-p orbital hybridization between V and Pb atoms, subsequently, N2 is activated to a larger extent. These interesting findings may provide a new path for designing active sites in SACs with excellent performance.

4.
Small ; : e2312004, 2024 Aug 29.
Artigo em Inglês | MEDLINE | ID: mdl-39206612

RESUMO

Thermochromic vanadium dioxide (VO2) can intelligently modulate the transmittance of indoor solar radiation to reduce the energy consumption of air conditioning in buildings. Nevertheless, it remains a great challenge to simultaneously improve the luminous transmittance (Tlum) and solar modulation ability (ΔTsol) of VO2. In this study, a novel approach is employed utilizing a coordination compound to finely tune the growth of a VO2 based composite film, yielding a hierarchical film comprising Zn2V2O7 nanoflakes and VO2@Zn2V2O7 core-shell nanoparticles. Remarkably, the resulting composite films showcase exceptional optical performance, achieving a Tlum of up to 73.0% and ΔTsol of 15.7%. These outcomes are attributed to the antireflection properties inherent in the nanoflake structure and the localized surface plasmon resonance of well-dispersed VO2 nanoparticles. In addition, the Zn2V2O7-VO2 film demonstrates remarkable environmental durability, retaining 90% of its initial ΔTsol even after undergoing aging at 100 °C under 50% relative humidity for a substantial period of 30 days - a durability equivalent to ≈20 years under ambient conditions. This work not only achieves a harmonious balance between Tlum and ΔTsol but also introduces a promising avenue for the design of distinctive composite nanostructures.

5.
Nat Commun ; 15(1): 2076, 2024 Mar 07.
Artigo em Inglês | MEDLINE | ID: mdl-38453928

RESUMO

Attaining high hydrogenation performance under mild conditions, especially at ambient pressure, remains a considerable challenge due to the difficulty in achieving efficient mass transfer at the gas-liquid-solid three-phase interface. Here, we present a zeolite nanoreactor with joint gas-solid-liquid interfaces for boosting H2 gas and substrates to involve reactions. Specifically, the Pt active sites are encapsulated within zeolite crystals, followed by modifying the external zeolite surface with organosilanes. The silane sheath with aerophilic/hydrophobic properties can promote the diffusion of H2 and the mass transfer of reactant/product molecules. In aqueous solutions, the gaseous H2 molecules can rapidly diffuse into the zeolite channels, thereby augmenting H2 concentration surround Pt sites. Simultaneously, the silane sheath with lipophilicity nature promotes the enrichment of the aldehydes/ketones on the catalyst and facilitates the hydrophilia products of alcohol rediffusion back to the aqueous phase. By modifying the wettability of the catalyst, the hydrogenation of aldehydes/ketones can be operated in water at ambient H2 pressure, resulting in a noteworthy turnover frequency up to 92.3 h-1 and a 4.3-fold increase in reaction rate compared to the unmodified catalyst.

6.
Int J Biol Macromol ; 253(Pt 7): 127110, 2023 Dec 31.
Artigo em Inglês | MEDLINE | ID: mdl-37783249

RESUMO

Current cellulose-based adsorbents suffer from the drawbacks of low adsorption capacity or slow adsorption rate for heavy metal ions. It is imperative to prepare new cellulose-based materials to improve the adsorption ability. In this work, we aim to introduce phosphonate groups to improve the adsorption ability of cellulose and select polyethyleneimine (PEI) for synergistic adsorption. A novel cellulose phosphonate/polyethyleneimine composite (MCCP-PEI) is prepared via the Mannich reaction. The structure and composition of MCCP-PEI are characterized by various advanced microscopy and spectroscopy techniques, and the results show that MCCP-PEI possesses abundant nano-porous structure, strong chelating sites, and excellent hydrophilicity. Besides, the adsorption behavior of MCCP-PEI for heavy metals has been systematically investigated. The results show that the adsorbent can quickly remove toxic Cu(II) and Pb(II) from water within 15 min and 20 min, respectively. The saturated adsorption capacity for Cu(II) and Pb(II) is 250.0 and 534.7 mg·g-1, respectively. X-ray photoelectron spectroscopy analysis combined with Density Functional Theory calculations reveal that the adsorption mechanism is chemical complexation and electrostatic attraction, and the phosphonate group plays a key role in the adsorption process.


Assuntos
Metais Pesados , Poluentes Químicos da Água , Água , Polietilenoimina/química , Chumbo , Celulose , Metais Pesados/química , Poluentes Químicos da Água/química , Adsorção , Cinética
7.
Nanomaterials (Basel) ; 13(11)2023 May 23.
Artigo em Inglês | MEDLINE | ID: mdl-37299618

RESUMO

The advent of greenhouses greatly promoted the development of modern agriculture, which freed plants from regional and seasonal constraints. In plant growth, light plays a key role in plant photosynthesis. The photosynthesis of plants can selectively absorb light, and different light wavelengths result in different plant growth reactions. Currently, light-conversion films and plant-growth LEDs have become two effective ways to improve the efficiency of plant photosynthesis, among which phosphors are the most critical materials. This review begins with a brief introduction of the effects of light on plant growth and the various techniques for promoting plant growth. Next, we review the up-to-date development of phosphors for plant growth and discussed the luminescence centers commonly used in blue, red and far-red phosphors, as well as their photophysical properties. Then, we summarize the advantages of red and blue composite phosphors and their designing strategies. Finally, we describe several strategies for regulating the spectral position of phosphors, broadening the emission spectrum, and improving quantum efficiency and thermal stability. This review may offer a good reference for researchers improving phosphors to become more suitable for plant growth.

8.
Inorg Chem ; 62(8): 3692-3702, 2023 Feb 27.
Artigo em Inglês | MEDLINE | ID: mdl-36764007

RESUMO

Direct oxidative coupling of alcohols with amines over cheap but efficient catalysts is a promising choice for imine formation. In this study, porous CeO2-MnO2 binary oxides were prepared via an interfacial reaction between Ce2(SO4)3 and KMnO4 at room temperature without any additives. The as-prepared porous CeO2-MnO2 catalyst has a higher fraction of Ce3+, Mn3+, and Mn4+ and contains larger surface area and more oxygen vacancies. During the oxidative coupling reaction of alcohol with amine to imine, the as-obtained CeO2-MnO2 catalyst is motivated by the above encouraging characteristics and exhibits superior catalytic activity (98% conversion and 97% selectivity) and can also work effectively under a wide scope of temperatures and substrates. The in-depth in situ DRIFTS and density functional theory (DFT) results demonstrate that there is a strong interaction between CeO2 and MnO2 in the CeO2-MnO2 catalyst, exhibiting especially a positive synergistic effect in the direct coupling of alcohol and amine reaction.

9.
Nanoscale ; 14(35): 12713-12721, 2022 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-35996893

RESUMO

Controllable synthesis of MOFs with desired structures is of great significance to deepen the understanding of the crystal nucleation-growth mechanism and deliver unique structural features to their derived metal oxides with target catalytic applications. In this study, NH2-Ce-BDC with morphology similar to a second-order magic cube (mc) is facile synthesized via H+ mediation in nucleation and growth stages. The pertinent variables that can greatly influence the formation of magic cube-like structures (MCS) were investigated, in which the concentric diffusion field was found to be one of the key factors. Upon calcination, the derived CeO2 inherits unique gullies and grooves located on the pristine MOFs surface, which is quite useful for atomic layer deposition (ALD) of platinum (Pt) nanoparticles because of strong interaction with MOF-derived CeO2 (mc-CeO2). XPS, H2-TPR, Raman, and in situ DRIFTS characterization results show that there is a stronger interaction between Pt and mc-CeO2 in mc-Pt/CeO2 compared with c-Pt/CeO2 that is derived from the well-developed cubic Ce-MOFs. Furthermore, Pt2+ ions, hydroxyl oxygen, and oxygen defects in mc-Pt/CeO2 account highly for exemplary catalytic activity toward HCHO oxidation.

10.
PLoS One ; 17(6): e0269086, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-35653411

RESUMO

Four types of flowerlike manganese dioxide in nano scale was synthesized via a liquid phase method in KMnO4-H2SO4 solution and Cu particles, wherein the effect of Cu particles was investigated in detail. The obtained manganese dioxide powder was characterized by XRD, SEM and TEM, and the supercapacity properties of MnO2 electrode materials were measured. The results showed that doping carbon black can benefit to better dispersion of copper particles, resulting in generated smaller size of Cu particles, and the morphology of MnO2 nanoparticles was dominated by that of Cu particles. The study of MnO2 synthesis by different sources of Cu particles showed that the size of MnO2 particles decreased significantly with freshly prepared fine copper powder compared with using commercial Cu powder, and the size of MnO2 particles can be further reduced to 120 nm by prepared Cu particles with smaller size. Therefore, it was suggested that the copper particles served as not only the reductant and but also the nuclei centre for the growth of MnO2 particles in synthesis process MnO2, and that is the reason how copper particles worked on the growth of flower-like MnO2 and electrochemical property. In the part of investigation for electrochemical property, the calculated results of b values indicated that the electrode materials have pseudo capacitance property, and the highest specific capacitance of 197.2 F g-1 at 2 mV s-1 and 148 F/g at 1 A/g were obtained for MCE electrode materials (MnO2 was synthesized with freshly prepared copper particles, where carbon black was used and dispersed in ethanol before preparation of Cu particles). The values of charge transfer resistance in all types of MnO2 materials electrodes were smaller than 0.08 Ω. The cycling retention of MCE material electrode is still kept as 93.8% after 1000 cycles.


Assuntos
Compostos de Manganês , Nanoestruturas , Cobre , Compostos de Manganês/química , Óxidos/química , Pós , Fuligem
11.
Colloids Surf B Biointerfaces ; 215: 112496, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35427845

RESUMO

The multifunction antibacterial hemostatic materials can reduce blood loss, infection and wound complications, which probably decrease morbidity and health care costs. However, the contradictory relationship between antibacterial ability and biocompatibility, and the unnecessary blood loss restricts the practical application of hydrophilic cationic antibacterial hemostatic materials. Herein, a multifunctional temperature-triggered antibacterial hemostatic fluorocopolymer aggregate coating was developed. After self-assembly and quaternization process, the quaternized poly(N,N-dimethylaminoethylmethacrylate)-b-poly(1H,1H,2H,2H-heptadecafluorodecyl acrylate) block copolymers (PDMA-b-PFOEMA) aggregate coating consisting of fluoropolymer and quaternary ammonium salt were built. The synergistic effect on fluorinated block with low surface energy and quaternary ammonium salt block with bactericide activity severs the way of initial bacterial attachment and proliferation, while the migration of fluorinated block greatly promotes the biocompatibility and anti-adhesion performance in response to the switch from room temperature to physiological temperature. Furthermore, the fluorocopolymer aggregate coating with hydrophobic properties possessed the property of rapid coagulation, low blood loss, minor secondary bleeding and least bacteria infiltration. The multifunctional temperature-triggered fluorocopolymer aggregate coating with antifouling, antibacterial and hemostatic properties may have a great potential in the biomedical application.


Assuntos
Incrustação Biológica , Hemostáticos , Antibacterianos/química , Antibacterianos/farmacologia , Bactérias , Incrustação Biológica/prevenção & controle , Hemostasia , Interações Hidrofóbicas e Hidrofílicas , Compostos de Amônio Quaternário/química , Propriedades de Superfície , Temperatura
12.
ACS Appl Mater Interfaces ; 14(14): 16611-16620, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35349256

RESUMO

Stimuli-responsive organic materials with controllable luminescence are of enormous importance because of their potential applications in sensing, data security, and display devices. In this study, a multistimuli-responsive squaraine dyad (SQ-d) composed of two rigid squaraine moieties and a flexible ethylene linker was rationally designed and synthesized. SQ-d exhibits polymorphic luminescence, which can be reversibly switched by various external stimuli, including solvent vapor exposure, heat, and shear force. Unexpectedly, the weakly luminescent phase (O1) of SQ-d exhibits concentration-controlled vapochromic behavior. Film O1 can convert to a highly green-emissive phase (G1) under a low concentration of CHCl3 vapor and convert to a highly yellow-emissive phase (Y) under a high concentration of CHCl3 vapor; these originate from two distinct crystallization-induced emission enhancement processes. To the best of our knowledge, this is the first investigation of the effect of vapor concentration on the phase transitions of organic vapochromic luminophores. By analyzing the single-crystal structures and photophysical properties of SQ-d, we concluded that the green and yellow emissions probably originated from a zigzag stacking mode and an H-type π-π stacking mode, respectively. Finally, two prototypes based on SQ-d for applications in information encryption and vapor sensing were successfully demonstrated.

13.
ACS Appl Mater Interfaces ; 14(11): 13836-13847, 2022 Mar 23.
Artigo em Inglês | MEDLINE | ID: mdl-35286068

RESUMO

Both 3-hydroxy-2-butanone and triethylamine are highly toxic and harmful to human health, and their chronic inhalation can cause respiratory diseases, eye lesions, dermatitis, headache, dizziness, drowsiness, and even fatality. Developing sensors for detecting such toxic gases with low power consumption, high response with superselectivity, and stability is crucial for healthcare and environmental monitoring. This study presents a typical gas sensor fabricated based on AuPdO modified Cu-doped K2W4O13 nanowires, which can selectively detect 3-hydroxy-2-butanone and triethylamine at 120 and 200 °C, respectively. The sensor displays excellent sensing performance at reduced operating temperature, high selectivity, fast response/recovery, and stability, which can be attributed to a synergistic effect of Cu dopants and AuPdO nanoparticles on the K2W4O13 host. The enhanced sensing response and selectivity could be attributed to the oxygen vacancies/defects, bandgap excitation, the electronic sensitization, the reversible redox reaction of PdO and Cu, the cocatalytic activity of AuPdO, and Schottky barrier contacts at the interface of tungsten oxide and Au. The significant variations in the activation capacities of Cu-doped K2W4O13, Pd/PdO, and Au nanoparticles toward 3H-2B and TEA, and the diffusion depth of the two gases in the coated sensing layer may cause dual selectivity. The designed gas sensor materials can serve as a sensitive target for detecting toxic biomarkers and hold broad application prospects in food and environmental safety inspection.

14.
Chemosphere ; 282: 131032, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34098306

RESUMO

The direct removal of heavy metal ions from acidic wastewater is a hard problem. In this study, a novel superabsorbent, polyvinyl alcohol phosphate ester (PVAP), was designed and prepared to remove Pb(II) from acidic wastewater (pH = 3). The PVAP can absorb water and swell to reach equilibrium within 30 s, which provides the conditions for ultrafast kinetic adsorption. For 100 mg/L Pb(II) solution, the adsorption reaches equilibrium within 5 min, and the removal ratio is more than 99.9% over a wide pH range of 3-6. Adsorption kinetics and isotherm data are consistent with pseudo-second-order and Langmuir model, respectively. The calculated maximum adsorption capacity for Pb(II) is 558.66 mg/g. Thermodynamic results show that the adsorption is spontaneous and exothermic process. The removal ratio for Pb(II) of PVAP still maintains above 99% after ten recycles. The PVAP can also simultaneously remove more than 97% of other heavy metal ions (Cu(II), Cd(II), Zn(II), Co(II), and Ni(II)) from an acidic solution. Moreover, the PVAP can efficiently purify simulated acid mine heavy metal wastewater, and the results meet EPA drinking water standards. The studies of X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared (FT-IR) spectroscopy prove that the adsorption mechanism involves surface complexation. This new superabsorbent is a promising candidate for acidic heavy metal sewage disposal.


Assuntos
Álcool de Polivinil , Poluentes Químicos da Água , Adsorção , Concentração de Íons de Hidrogênio , Cinética , Chumbo , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Água , Poluentes Químicos da Água/análise
15.
Nanoscale ; 13(1): 117-123, 2021 Jan 08.
Artigo em Inglês | MEDLINE | ID: mdl-33140814

RESUMO

Simultaneously maximizing the dispersion of noble metals and demonstrating optimal activity are of significant importance for designing stable metal catalysts. In this study, highly dispersed ultrafine platinum (Pt) particles with a size of <1.5 nm anchored onto a mesoporous CeO2 structure have been synthesized by coordinating Pt ions with amino groups in NH2-Ce-MOFs, followed by high-temperature calcination. It was found that the presence of -NH2 groups in Ce-MOFs played a crucial role in anchoring Pt species with high dispersion on the MOF framework. Interestingly, the anchored Pt species were beneficial for the formation of Ce-Pt sites during the conversion from Ce-BDC to CeO2. As a result, the as-prepared catalysts held dense surface peroxo species, responsible for boosting CO oxidation at low temperatures.

16.
Nanoscale Res Lett ; 15(1): 17, 2020 Jan 21.
Artigo em Inglês | MEDLINE | ID: mdl-31965343

RESUMO

This study demonstrates a simple hydrothermal method while can be generalized for controllable synthesis of noble metallic carbonaceous nanostructures (e.g., Au@C, Ag@C) under mild conditions (180-200 °C), which also provides a unique approach for fabricating hollow carbonaceous structures by removal of cores (e.g., silver) via a redox etching process. The microstructure and composition of the as-achieved nanoparticles have been characterized using various microscopic and spectroscopic techniques. Cetyltrimethylammonium bromide (CTAB), serving as a surfactant in the reaction system, plays a key role in the formation of Ag@C, Au@C nanocables, and their corresponding hollow carbonaceous nanotubes in this work. The dynamic growth and formation mechanism of carbonaceous nanostructures was discussed in detail. And finally, laser-induced photothermal property of Au@C nanocomposites was examined. The results may be useful for designing and constructing carbonaceous metal(s) or metal oxide(s) nanostructures with potential applications in the areas of electrochemical catalysis, energy storage, adsorbents, and biomedicine. This study demonstrate a facile hydrothermal synthesis of noble metal carbonaceous nanocomposites (e.g., Au@C) with simple procedures under mild conditions, which can be25expanded as a general method for preparing diverse carbonaceous core-shell nanoparticles. The Au@C carbonaceous nanostructures exhibit interesting UV-Vis properties dependent upon shell thickness.

17.
J Nanosci Nanotechnol ; 20(3): 1651-1659, 2020 Mar 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492327

RESUMO

Density function theory (DFT) method was developed and applied for fundamentally understanding the doping effect of various metals (Al, Ti and Cr) on vanadium dioxide (VO2). The substitution doping of Al, Ti and Cr in VO2 could lead to significant changes in electronic structure, band gap and optical property. Different from physical experiments, the DFT method could be utilized for fundamental understandings at an atomic scale. It was found via DFT calculations that: (i) Al doping caused a slightly distorted octahedron in monoclinic VO2(M), and narrowed the band gap of VO2(M) due to the upward shift of the valence band (VB), while Cr doping narrowed the band gap because of the downward shift of the conduction band (CB); (ii) Ti doping slightly widened the band gap of VO2(M); and (iii) the optical reflectivity of VO2(M) decreased after substitution doping low-valent metals (e.g., Al). This study will be beneficial for designing and controlling elemental doping to obtain metal oxide nanocomposites with unique band gap and electronic structure for thermochromic energy saving applications.

18.
J Nanosci Nanotechnol ; 20(3): 1946-1954, 2020 03 01.
Artigo em Inglês | MEDLINE | ID: mdl-31492366

RESUMO

This study represents a facile but efficient glycothermal method for synthesis of vanadium dioxide, VO2(B) nanoparticles with various geometries from spheres to rods, flakes or their agglomeration structures, by controlling reaction conditions (e.g., vanadium resources, reducing agents and surfactants). The as-prepared VO2(B) nanoparticles were characterized in microstructure and composition, and also examined in terms of gas sensing performance. It was found that the VO2(B) nanoparticles exhibit a good sensitivity towards alcohols (ethanol, isopropanol, and butanol) and acetone at the optimised operating temperature of 300 °C. The gas sensing performance was further compared with other vanadium oxides investigated previously, such as V2O5, Na1.08V3O8. The plausible gas sensing mechanism of the as-prepared nanoparticles was discussed in detail. This study would expand the family of vanadium oxides that can be made as potential sensors for applications in detecting environmental safety and human health.

19.
ChemSusChem ; 13(6): 1645-1655, 2020 Mar 20.
Artigo em Inglês | MEDLINE | ID: mdl-31270940

RESUMO

Layered double hydroxides (LDHs) containing first-row transition metals such as Fe, Co, and Ni have attracted significant interest for electrocatalysis owing to their abundance and excellent performance for the oxygen evolution reaction (OER) in alkaline media. Herein, the assembly of holey iron-doped nickel-cobalt layered double hydroxide (NiCo-LDH) nanosheets ('holey nanosheets') is demonstrated by employing uniform Ni-Co glycerate spheres as self-templates. Iron doping was found to increase the rate of hydrolysis of Ni-Co glycerate spheres and induce the formation of a holey interconnected sheet-like structure with small pores (1-10 nm) and a high specific surface area (279 m2 g-1 ). The optimum Fe-doped NiCo-LDH OER catalyst showed a low overpotential of 285 mV at a current density of 10 mA cm-2 and a low Tafel slope of 62 mV dec-1 . The enhanced OER activity was attributed to (i) the high specific surface area of the holey nanosheets, which increases the number of active sites, and (ii) the improved kinetics and enhanced ion transport arising from the iron doping and synergistic effects.

20.
J Colloid Interface Sci ; 554: 91-102, 2019 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-31284151

RESUMO

In this work, carbon and nitrogen co-doped yolk-shell ZnFe2O4 nanostructures (CN-ZnFe2O4) were successfully synthesized through a facile self-templated method with in situ doping strategy. A series of characterizations were processed to present a comprehensive properties of the as-prepared photocatalyst samples. Doping amount could be moderated by the addition mass of dopamine, which was regarded as both the carbon and nitrogen source. And the void space between yolk and shell could be adjusted by heating rates in the calcination process of precursors. With an excellent separation efficiency of photogenerated electron-hole pairs and transfer efficiency of photogenerated electrons, the obtained CN-ZnFe2O4 sample exhibited an enhanced visible light response than ZnFe2O4. And their photocatalytic performances towards gaseous 1, 2-dichlorobenzene (o-DCB) was also systematically studied. The results demonstrated that the CN-ZnFe2O4 sample with 100 mg dopamine addition and 20 °C/min calcination heating rate exhibited the best o-DCB degradation efficiency. In situ Fourier Transform infrared (FTIR) spectroscopy was also recorded to give a detailed information of intermediate products and reveal the mechanism of photocatalytic degradation towards o-DCB. Particularly, density functional theory (DFT) calculation was used to further study the electronic structure of prepared samples to support the experimental results and especially explain the mechanism of enhanced photocatalytic activity through a proposed lattice junction. Additionally, electron paramagnetic resonance (EPR) technique was carried out to prove the reactive oxygen species involved in the photodegradation process. This work not only presents a promising strategy in photocatalyst fabrication but also provides a new sight of enhanced photocatalysis mechanism.

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