Real-time monitoring of dopamine (DA) levels, a critical neurotransmitter involved in motor function and blood pressure regulation, requires more sensitive and selective sensors over a dynamic ...concentration range. The immense need to build highly efficient catalysts has always been at the forefront of electrochemical detection research toward DA. Herein, we design and synthesis an iron carbides-based heterostructure composite (Fe/Fe3C@CNT) by the introduction of microwave-assisted method and multiwalled carbon nanotubes (CNTs). Remarkably, it took only about 1.5 min to completely the preparation process including the pyrolysis of ferrocene (iron sources) and the formation of Fe/Fe3C nanoparticles uniformly distributed on the CNTs. Due to the unique heterostructure, enhanced electrical conductivity and adequate dispersion of active sites, the fabricated sensors exhibit favorable selectivity and great sensing property, yielding a distinguishable and selective response to DA down to 15 nM with a good linearity scope of 0.050–40 μM. The developed Fe/Fe3C@CNT electrode was then successfully applied to monitor the DA level from the real samples, which holds considerable promise for electrochemical detection and biosensing applications.
•The Fe/Fe3C nanoparticles uniformly attached on the CNTs by a fast microwave-assisted method.•The particular heterostructure can provide rich active sites and achieve efficient catalytic performance.•The Fe/Fe3C@CNT/GCE exhibits great electrochemical sensing toward dopamine because of effective exposure of active sites.•The novel electrochemical sensor has the potential to detect dopamine in real biological serum samples.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
An organic-inorganic hybrid is a promising electrode material for aqueous batteries due to its larger potential in improving electrochemical performance. Herein, we designed and prepared a ...naphthoquinone@FeO
x
(OH)/iron foam (NQ@FeO
x
(OH)/IF) hybrid electrode as a highly-efficient anode in Ni/Fe batteries
via
combining electro-deposition of FeO
x
(OH) and
in situ
hydrothermal growth of naphthoquinone. The as-prepared hybrid electrode materials present a 2D nanosheet morphology of FeO
x
(OH) and a branch/band-like structure of NQ, with the formation of NQ-FeO
x
(OH) interfaces. Such an interface structure is revealed to have more electron active sites, with increased electron delocalization caused by the aromatic ring structure, thereby enhancing the transport of the electrons in the electrode materials. Thus, a superior electrochemical performance of the NQ@FeO
x
(OH)/IF electrode was received, with a large areal capacity of ∼2.23 mA h cm
−2
and a favorable rate capability of 1.09 mA h cm
−2
at 40 mA cm
−2
. Besides, the NQ@FeO
x
(OH)/IF anode was coupled with the NiCo
2
O
4
cathode to assemble a Ni/Fe battery, as a result, an admirable energy density of 235.2 W h kg
−1
and a maximum power density of 5.4 kW kg
−1
were obtained. The study on high-performance NQ@FeO
x
(OH)/IF electrode materials paves the way to design and synthesize better iron-based materials for Ni/Fe batteries.
An organic-inorganic hybrid is a promising electrode material for aqueous batteries due to its larger potential in improving electrochemical performance.
An organic–inorganic hybrid is a promising electrode material for aqueous batteries due to its larger potential in improving electrochemical performance. Herein, we designed and prepared a ...naphthoquinone@FeO x (OH)/iron foam (NQ@FeO x (OH)/IF) hybrid electrode as a highly-efficient anode in Ni/Fe batteries via combining electro-deposition of FeO x (OH) and in situ hydrothermal growth of naphthoquinone. The as-prepared hybrid electrode materials present a 2D nanosheet morphology of FeO x (OH) and a branch/band-like structure of NQ, with the formation of NQ–FeO x (OH) interfaces. Such an interface structure is revealed to have more electron active sites, with increased electron delocalization caused by the aromatic ring structure, thereby enhancing the transport of the electrons in the electrode materials. Thus, a superior electrochemical performance of the NQ@FeO x (OH)/IF electrode was received, with a large areal capacity of ∼2.23 mA h cm −2 and a favorable rate capability of 1.09 mA h cm −2 at 40 mA cm −2 . Besides, the NQ@FeO x (OH)/IF anode was coupled with the NiCo 2 O 4 cathode to assemble a Ni/Fe battery, as a result, an admirable energy density of 235.2 W h kg −1 and a maximum power density of 5.4 kW kg −1 were obtained. The study on high-performance NQ@FeO x (OH)/IF electrode materials paves the way to design and synthesize better iron-based materials for Ni/Fe batteries.
An organic–inorganic hybrid is a promising electrode material for aqueous batteries due to its larger potential in improving electrochemical performance. Herein, we designed and prepared a ...naphthoquinone@FeOx(OH)/iron foam (NQ@FeOx(OH)/IF) hybrid electrode as a highly-efficient anode in Ni/Fe batteries via combining electro-deposition of FeOx(OH) and in situ hydrothermal growth of naphthoquinone. The as-prepared hybrid electrode materials present a 2D nanosheet morphology of FeOx(OH) and a branch/band-like structure of NQ, with the formation of NQ–FeOx(OH) interfaces. Such an interface structure is revealed to have more electron active sites, with increased electron delocalization caused by the aromatic ring structure, thereby enhancing the transport of the electrons in the electrode materials. Thus, a superior electrochemical performance of the NQ@FeOx(OH)/IF electrode was received, with a large areal capacity of ∼2.23 mA h cm−2 and a favorable rate capability of 1.09 mA h cm−2 at 40 mA cm−2. Besides, the NQ@FeOx(OH)/IF anode was coupled with the NiCo2O4 cathode to assemble a Ni/Fe battery, as a result, an admirable energy density of 235.2 W h kg−1 and a maximum power density of 5.4 kW kg−1 were obtained. The study on high-performance NQ@FeOx(OH)/IF electrode materials paves the way to design and synthesize better iron-based materials for Ni/Fe batteries.
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•Hierarchical micro- and nanostructures can be fabricated by ns lasers on Cu.•Microstructures arise from the accumulation of laser-induced resolidified materials.•Surface ...nanostructures originate from the redeposition of laser-induced plasmas.•Enhanced laser-induced evaporation and melting result in complex surface structures.
Hierarchical surface micro- and nanostructures have attracted much attention in recent years due to their important roles in many applications. Among numerous techniques, ultrafast laser surface texturing technology has gained great success in recent years due to its flexibility and controllability in preparing large-area hierarchical micro- and nanostructures on a wide range of metal surfaces. However, recent studies have demonstrated that low-cost nanosecond (ns) lasers are also reliable tools to induce hierarchical micro- and nanostructures formation on metals, but the underlying formation mechanism is not yet understood. In this study, by observing the morphology evolution of surface structures, we proposed that the formation of surface hierarchical micro- and nanostructures originates from the accumulation of laser-induced resolidified materials and the redeposition of laser-induced plume. On one hand, our proposed mechanism explains the effect of laser pulse width on the morphology of surface structures, and, on the other hand, it explains some phenomena observed in other studies, which can benefit potential applications of this technology in different areas.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
Facial attributes are fundamental for studying deep structured information. Single-task face analysis reaches great performance, while analysis of multiple attributes meets challenges, including the ...network design and cross-dataset learning. In this paper, we propose cross-dataset face analysis based on multi-task learning (CFA-Net), which accomplishes landmark, head pose, age, gender, facial expression, and Action Unit (AU) analysis. Firstly, we balance between the shared and the task-specific structure to design an efficient and accurate network. To guarantee the excellent performance of each task, we utilize classification-based, regression-based, ranking-based, or deep label distribution learning-based methods to extract specific features for diverse tasks. Then, face analysis trained on a single dataset has strict requirements for this dataset. Even if this dataset currently meets the demand, the scalability is poor when tasks increase. Therefore, our training set is a mixture of multiple datasets, and each dataset covers one or several task related labels. Each sample possesses one or several tasks’ labels, and we adopt a sample-dependent loss strategy, which only penalizes available ground truth. The proposed CFA-Net only occupies 1.58G GPU memory and costs 0.021s to address one image. In summary, the proposed CFA-Net behaves fast, occupies less memory, and performs well in every subtask, even better than those under single-task training.
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CEKLJ, EMUNI, FIS, FZAB, GEOZS, GIS, IJS, IMTLJ, KILJ, KISLJ, MFDPS, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, SBMB, SBNM, UKNU, UL, UM, UPUK, VKSCE, ZAGLJ
•Proposed an effective hydrothermal phosphatization method with a new phosphorus source.•Prepared NiCoP/NF electrodes with enhanced area capacitance.•Synthesized FexPOy/IF electrode as a potentially ...candidate for anode.•Assembled a battery-supercapacitor hybrid device.
It is a challenge to build a hybrid energy storage system by combining the power of supercapacitors with the energy of batteries. In this work, an effective and promising phosphatized method using aluminium phosphide as phosphorus source was proposed to prepare metal phosphides. The introduction of water vapor in phosphatized process not only participates in the reaction, but also accelerates the etching and phosphatization of electrode, which promotes the formation of characteristic architecture. Then, NiCo and Fe-based electrodes were synthesized through hydrothermal phosphatization. The NiCoP/nickel foam (NiCoP/NF) electrodes which have favorable electrochemical performance at high current densities achieved a high areal capacity (19.90 F cm−2 at 50 mA cm−2) and favorable cycling stability (capacity retention of 92% at a high current density of 50 mA cm−2 after 2000 cycles). Furthermore, we successfully built NiCoP/NF//FexPOy/IF battery-supercapacitor hybrid system with advanced electrochemical performance. The device possesses a high areal capacity of 6.28 F cm−2, a maximum volumetric energy density of 56.11 mW h cm−3 and power density of 0.642 W cm−3. These results confirm that the phosphatized method is promising for the preparation of metal compounds, and the battery-supercapacitor hybrid system effectively combine the merits of supercapacitors and batteries, indicating the Fe-based electrode as a potentially candidate for next generation anode for hybrid systems.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
Increasing reaction temperature triggered the reactivity of more Cu species on Cu-zeolites and thereby improved the methanol yield in continuous methane-water conversion.
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•High ...methanol yield in continuous methane-water conversion was achieved on Cu-SSZ-13.•Increasing reaction temperature results in the increase of Cu active sites.•Cu-OH and isolated Cu2+ show higher methane activation temperatures than Cu2O2+.•Isotope labeling reveals the reaction mechanism for methane-water to methanol.
Methane-selective continuous conversion to methanol is highly challenged by the high CH dissociation energy and the facile over-oxidation of methane. In this work, we reported continuous methane conversion to methanol over Cu-zeolites using water as the oxidant at different reaction temperatures (200–450 °C) and found that the space–time yield (STY) of methanol depended on the reaction temperature, with a high methanol STY of 189.9 μmol/gcat./h (578.7 mmol/molCu/h) at the selectivity of 91 % on Cu-SSZ-13 being achieved at the optimal temperature of 350 °C. Increasing the reaction temperature from 200 to 350 °C resulted in the increase of the kinetic orders of methane and water for catalytic oxidation of methane. An important reason was indicated that higher reaction temperatures not only enhanced a high methane conversion rate but also triggered the reactivity of more Cu species on Cu-zeolites based on the quantification analysis of the available active sites and in-situ spectroscopic study. It was revealed that the CuxOy clusters (e.g., Cu2(μ-O)2+) as the active sites exhibited the reactivity at 200 °C, while the Cu(II)–OH species on 8-membered rings and the isolated Cu2+ ions on 6-membered rings presented the reactivity at higher temperatures (≥300 °C). This could be attributed to higher activation energies of Cu(II)–OH species and isolated Cu(II) sites. Besides, isotope labeling experiments indicated that the combination of methyl and hydrogen dissociated from water and methanol reforming resulted in a low methanol yield at high temperatures (≥350 °C).
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
NO adsorption/desorption on MnOx-CeO2 catalyst promotes the generation of active oxygen and thereby improves soot oxidation activity.
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•NO adsorption changes chemical states of surface ...Ce and Mn ions in MnOx-CeO2 mixed oxides.•The formation of surface NO-adsorbed species increases the oxygen vacancies.•The main products during nitrates decomposition are NO and O2 rather than NO2.•NO adsorption/desorption improves the soot oxidation rate.
The role of NO adsorption/desorption on soot oxidation activity of MnOx-CeO2 mixed oxides was investigated in this work. NO adsorption/desorption on MnOx-CeO2 results in a visible promotion of the low-temperature reactivity. Physico-chemical characterization reveals that the formation of NO adsorbed species, mainly nitrates, leads to changes in the surface Ce/Mn states and in an increase of oxygen vacancies. Moreover, TPD-MS indicates that the decomposition of surface nitrates accelerates the desorption of oxygen in the catalyst. Soot-TPR-MS confirms that the oxygen species desorbed from nitrates decomposition play an important role during soot oxidation. The isothermal experiments evidence that NO adsorption/desorption enhances soot oxidation rate, with active oxygen playing a key role in a cooperative C + NO2 + O2 reaction with the catalyst.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UL, UM, UPCLJ, UPUK, ZRSKP
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•Methane-to-methanol reactions depend on zeolite crystal structure and Brønsted acid sites.•Different active Cu sites for methane-to-methanol and NH3-SCR were found.•CuII(OH)+ and ...CuxOy cluster species are important active sites for methane-to-methanol.•Apparent differences of hydrothermal stability in methane-to-methanol and SCR reactions were revealed.
This study investigated and compared the reactivities of NH3-SCR and methane-to-methanol reactions over the monolithic Cu/SSZ-13 catalysts with different zeolite crystal sizes before and after hydrothermal aging. It was found that the methanol yield decreases with the increase in crystal size in methane-to-methanol, and a severe deactivation was detected after aging. However, the NH3-SCR performance presents a higher thermal stability and even an enhanced low-temperature reactivity after aging. The fresh and aged catalysts were comprehensively characterized by XRD, SEM, N2 physisorption, NH3-TPD, H2-TPR, XPS, UV–vis-NIR and in-situ DRIFTS measurements. The results indicate that the isolated Cu2+ species, including those that interacted with two Al in 6MR and CuII(OH)+ motifs, and acid sites are main active centers for NH3-SCR. While CuxOy clusters, CuII(OH)+ motifs and Brønsted acid sites in the Cu-CHA frameworks could be important active sites for methane-to-methanol. Besides, the stable SCR performance is ascribed to the stable textural property, higher crystallinity of zeolite, increased NH3 storage capacity and isolated Cu2+ active sites. The loss of the catalytic activity in methane-to-methanol is mainly attributed to the decrease of Brønsted acid sites and CuxOy concentration and the break of zeolite crystal structure. This work concludes the differences in active sites and hydrothermal stability between NH3-SCR and methane-to-methanol reactions, it is very helpful to understand the two reactions.
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GEOZS, IJS, IMTLJ, KILJ, KISLJ, NLZOH, NUK, OILJ, PNG, SAZU, SBCE, SBJE, UILJ, UL, UM, UPCLJ, UPUK, ZAGLJ, ZRSKP
