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Water pollution caused by organic pollutants has aroused great concern to earth sustainability in the last several decades. Herein, a facile one-pot solvothermal approach was ...developed to construct bimetallic platinum-rhodium alloyed nano-multipods (PtRh ANMPs) in oleylamine (OAm) by adopting creatinine and cetyltrimethylammonium chloride (CTAC) as the co-structure-directing agents. The as-fabricated nanocatalyst exhibited extraordinary catalytic behaviors towards 4-nitrophenol (4-NP) and rhodamine B (RhB) reduction by sodium borohydride (NaBH4). Impressively, the resultant catalyst showed highly facilitated rate constant (k: 0.209/0.354 min−1) and turnover frequency (TOF: 1.0 × 10−3/0.44 × 10−3 mol g−1 min−1) towards 4-NP and RhB reduction in comparison with commercial Pt black under the same conditions. This research offers some valuable insights for facile preparation of advanced nanostructures as efficient and recyclable catalyst in environmental remediation field.
The sluggish oxygen reaction kinetics concomitant with the high overpotentials and parasitic reactions from cathodes and solvents is the major challenge in aprotic lithium‐oxygen (Li–O2) batteries. ...Herein, PtIr multipods with a low Lewis acidity of the Pt atoms are reported as an advanced cathode for improving overpotentials and stabilities. DFT calculations disclose that electrons have a strong disposition to transfer from Ir to Pt, since Pt has a higher electronegativity than Ir, resulting in a lower Lewis acidity of the Pt atoms than that on the pure Pt surface. The low Lewis acidity of Pt atoms on the PtIr surface entails a high electron density and a down‐shifting of the d‐band center, thereby weakening the binding energy towards intermediates (LiO2), which is the key in achieving low oxygen‐reduction‐reaction (ORR) and oxygen‐evolution‐reaction (OER) overpotentials. The Li–O2 cell based on PtIr electrodes exhibits a very low overall discharge/charge overpotential (0.44 V) and an excellent cycle life (180 cycles), outperforming the bulk of reported noble‐metal‐based cathodes.
PtIr multipods with low Lewis acidity of the Pt atoms are reported as an advanced cathode for high‐performance Li–O2 batteries. The low Lewis acidity of the Pt atoms on the PtIr surface entails a down‐shifting of the d‐band center, which brings low oxygen‐reduction‐reaction and oxygen‐evolution‐reaction overpotentials.
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Alkaline hydrogen evolution reaction (HER) electrocatalysts with high catalytic activity and long-term durability are of significance for sustainable energy applications. Herein, we ...prepared trimetallic PtNiCo hollow alloyed 3D multipods (HAMPs) with rough surfaces by an effective one-pot solvothermal strategy coupled with acid etching, as evidenced by a series of characterizations. By virtue of the trimetals and unique structures, the PtNiCo HAMPs exhibited excellent HER performance in 1.0 M KOH electrolyte with a low overpotential (η, 20 mV) and small Tafel slope (46.3 mV dec−1), superior to homemade PtNi HAMPs, PtCo nanocrystals (NCs) and commercial Pt/C catalysts. This study provides some constructive guidelines for synthesis of advanced hollow multimetallic catalysts in energy systems.
Economical production of highly active and robust Pt catalysts on a large scale is vital to the broad commercialization of polymer electrolyte membrane fuel cells. Here, we report a low-cost, one-pot ...process for large-scale synthesis of single-crystal Pt multipods with abundant high-index facets, in an aqueous solution without any template or surfactant. A composite consisting of the Pt multipods (40 wt %) and carbon displays a specific activity of 0.242 mA/cm2 and a mass activity of 0.109 A/mg at 0.9 V (versus a reversible hydrogen electrode) for oxygen reduction reaction, corresponding to ∼124% and ∼100% enhancement compared with those of the state-of-the-art commercial Pt/C catalyst (0.108 mA/cm2 and 0.054 A/mg). The single-crystal Pt multipods also show excellent stability when tested for 4500 cycles in a potential range of 0.6–1.1 V and another 2000 cycles in 0–1.2 V. More importantly, the superior performance of the Pt multipods/C catalyst is also demonstrated in a membrane electrode assembly (MEA), achieving a power density of 774 mW/cm2 (1.29 A/cm2) at 0.6 V and a peak power density of ∼1 W/cm2, representing 34% and 20% enhancement compared with those of a MEA based on the state-of-the-art commercial Pt/C catalyst (576 and 834 mW/cm2).
In this paper, we exploited a unique reaction of silver ions to create and design urchin-like gold microstructures (UL-AuMSs) with controllable length of nanothorns. The UL-AuMSs were synthesized via ...a simple one-pot synthetic protocol without using any surface capping agents or polymeric stabilizers. The reactants consisted of tetrachloroauric (III) acid, silver nitrate, and hydrogen peroxide (H2O2). H2O2 functioned as the sole reducing agent while trace silver ions played an important role as the shape controlling agent. Without trace silver ions, quasi-sphere gold microstructures (QS-AuMSs) were obtained. The time-dependent SEM investigations corroborated that UL-AuMSs and QS-AuMSs grew from flower-like gold microstructures (FL-AuMSs). The added trace silver ions reacted with physically adsorbed chloride ions on gold surfaces and formed into solid silver chloride capable of altering the dendritic growth of QS-AuMSs to the dominated trunk-growth of UL-AuMSs. The cleaned UL-AuMSs with average thorn lengths of 166 and 187nm expressed high SERS activity as 0.1nM of Rhodamine 6G could be detected with a short 15-min incubation. The easily visualized UL-AuMSs under a microscope assisting the SERS detection at selected spots was demonstrated.
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•A higher concentration of trace Ag+ shortens the length of nanothorns.•The surface of UL-AuMSs can be easily modified since stabilizer was not employed.•UL-AuMSs with high SERS activity could detect a low concentration of 0.1nM R6G.•The microstructure can be easily visualized under microscope for SERS detection.
The presented work is dedicated to the study and comparison of scintillating properties of zinc oxide samples prepared in different morphologies: whiskers, nanowalls, multipods, and ceramics. It was ...shown that total transmittance, photo- and radioluminescence spectra, and radioluminescence kinetics can vary significantly depending on sample structure and preparation conditions. The highest total transmittance was registered for ZnO ceramics (>50% at 0.5 mm thickness). Differences in the transmittance of whiskers, nanowalls, and multipods can be attributed to their shape and thickness which affects the amount of light refraction and scattering. The study of radioluminescence demonstrated that all samples, except undoped ceramics and air annealed whiskers, have predominantly fast luminescence with a decay time <1 ns. High transmittance of ceramics opens the way for their use in the registration of high energy X-ray and gamma radiation, where a large volume of scintillators is required. In cases, where large scintillator thickness is not a necessity, one may prefer to use other ZnO structures, such as ensembles of whiskers and nanowalls. Studies of near-band-edge luminescence components at low temperatures showed that the structure is quite similar in all samples except Ga doped ceramics.
The sluggish oxygen reaction kinetics concomitant with the high overpotentials and parasitic reactions from cathodes and solvents is the major challenge in aprotic lithium‐oxygen (Li–O2) batteries. ...Herein, PtIr multipods with a low Lewis acidity of the Pt atoms are reported as an advanced cathode for improving overpotentials and stabilities. DFT calculations disclose that electrons have a strong disposition to transfer from Ir to Pt, since Pt has a higher electronegativity than Ir, resulting in a lower Lewis acidity of the Pt atoms than that on the pure Pt surface. The low Lewis acidity of Pt atoms on the PtIr surface entails a high electron density and a down‐shifting of the d‐band center, thereby weakening the binding energy towards intermediates (LiO2), which is the key in achieving low oxygen‐reduction‐reaction (ORR) and oxygen‐evolution‐reaction (OER) overpotentials. The Li–O2 cell based on PtIr electrodes exhibits a very low overall discharge/charge overpotential (0.44 V) and an excellent cycle life (180 cycles), outperforming the bulk of reported noble‐metal‐based cathodes.
PtIr multipods with low Lewis acidity at the Pt atoms are reported as an advanced cathode for high‐performance Li–O2 batteries. The low Lewis acidity of the Pt atoms on the PtIr surface entails a down‐shifting of the d‐band center, which brings low oxygen‐reduction‐reaction and oxygen‐evolution‐reaction overpotentials.
Zinc oxide and gold–zinc oxide (Au–ZnO) nanostructures with multiple rods (multipods) morphology were successfully prepared. Au–ZnO nanostructures were synthesized via a simple precipitation route ...method in the presence of oligoaniline-coated gold nanoparticles. The Au–ZnO catalyst obtained was applied for the degradation of methyl orange in an aqueous solution under UV irradiation. Effects of the operational parameters such as the solution pH, amount of photocatalyst, and dye concentration on the photocatalytic degradation and decolorization of methyl orange were studied. Detailed studies including kinetic study and regeneration of catalyst were carried out on the optimal conditions for the photodegradation of methyl orange by Au–ZnO multipods in aqueous solution. Effect of foreign species on the photodegradation of methyl orange was also studied. An enhancement of the photocatalytic activities for photodegradation of methyl orange was observed when the gold nanoparticles were loaded on the zinc oxide multipods. The proposed catalyst was applied for the degradation of methyl orange in synthetic wastewater samples with satisfactory results.
Well-crystalline Cd-doped ZnO multipods were synthesized by simple and facile hydrothermal process by using zinc chloride, cadmium chloride, hexamethylenetetramine and ammonium hydroxide at ...low-temperature. The synthesized materials were characterized in terms of their morphological, structural, compositional and optical properties. The morphological investigations done by field emission scanning electron microscopy (FESEM) reveal that the synthesized products are multipods shaped and grown in high density. The structural and compositional properties, observed by X-ray diffraction (XRD), energy dispersive spectroscopy (EDS) attached with FESEM and Fourier transform infrared (FTIR) spectroscopy exhibit that the synthesized multipods are well-crystalline and possessing wurtzite hexagonal phase pure Cd-doped ZnO. The as-synthesized Cd-doped ZnO multipods exhibited good optical properties as was confirmed by UV-vis. spectroscopy. Finally, the as-synthesized Cd-doped ZnO multipods were used environmental remediation application. For this, the synthesized multipods were used as an effective photocatalyst for the photocatalytic degradation of acridine orange (AO) which exhibit -92.4% degradation within 90 min. This work demonstrates that doped ZnO materials could be used as efficient photocatalyst for the photocatalytic degradation of various organic dyes and chemicals.
Novel multipods-branched Cd-Se-S micro-/nanostructures (MNSs) were successfully prepared in a tube furnace by thermal evaporation under atmospheric pressure through using high-purity CdS and CdSe ...mixture powder with a molar ratio of 1:1 as evaporation source, high-purity Ar gas as carrier and protective gas, and mica wafer as substrate. Under the optimum condition, the evaporation temperature was 1100 °C, Ar gas flow rate was 200 sccm, and the distance between the evaporation source and substrate was 22 cm. The microstructure examination revealed that the length of the obtained branches was up to tens of microns and the diameter of the branches was of a few microns. The composition and crystal structure analyses indicated that, the chemical composition of the multipods-branched Cd-Se-S MNSs was CdSe0.86S0.14, which had a hexagonal structure and good crystallinity. The photoluminescence spectrum at room temperature displays an intrinsic emission peak around 620 nm. In addition, their growth might be controlled by a vapor-solid mechanism.
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