Precise control of the filling stages in branched nanopores

Sousa, C. T.; Apolinário, Arlete; Leitao, Diana C.; Pereira, A. M.; Ventura, J.; Araújo, João P.

doi:10.1039/c2jm14828e

Cited by 27 publications

(22 citation statements)

References 26 publications

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“…Small imperfections in the alumina barrier and pore structure along the PAA template lead to different local current densities and a heterogeneous material deposition [42]. Therefore, the faster growing pores eventually reach the top of the template and block their neighbors by growing over the adjacent pores in a mushroom-like structure [23], leading to fP values as low as 25%. The heterogeneous j distribution can be verified by XRD measurements where high temperatures produce smaller grain sizes, associated with higher j [ figure 2(b) …”

Section: Temperaturementioning

confidence: 99%

“…Recent results demonstrated [8,10,[21][22][23] that pulsed electrodeposition (PED), is an excellent alternative to the two previous methods. In PED, the reduction of the PAA barrier layer is not performed by chemical etching, which isotropically attacks the alumina, hence reducing the wall and barrier layer thickness alike, usually leading to low PAA homogeneity.…”

Section: Introductionmentioning

confidence: 99%

“…In PED, the reduction of the PAA barrier layer is not performed by chemical etching, which isotropically attacks the alumina, hence reducing the wall and barrier layer thickness alike, usually leading to low PAA homogeneity. A different approach relies on the linear dependence between the anodization voltage and pore diameter, inter pore distance and δb [20,[23][24][25] , respectively, for the used pH, temperature and electrolyte) [26]. This method allows reducing the barrier layer thickness without changing the diameter of the main pore [8,10].…”

Section: Introductionmentioning

confidence: 99%

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Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

Azevedo¹,

Sousa²,

Ventura³

et al. 2014

Mater. Res. Express

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With the increasing demand for high quality methods for the fast fabrication of extremely high aspect ratio nanoparticles, the research for efficient, low-cost and simple techniques has become fundamental. A promising approach on the synthesis of these materials is here addressed. Pulsed electrodeposition in porous anodic alumina templates was improved enabling, for the first time, a simple and cost effective fabrication method for vertically aligned nanomaterials with aspect ratios never reported with this method. Iron nanowires were electrodeposited and the effect of electrolyte molar concentration, temperature and stirring, pulse shape and barrier layer thickness on the deposition quality was investigated to potentially increase the template filling and the nanowires length. The electro-deposition temperature and current density were also found to be determinant parameters affecting NWs crystallography. A methodology of surface response design of experiment was conducted to retrieve the optimum values for the deposition parameters. With the determined optimized process, we were able to obtain filling ratios up to 93% and aspect ratios over 10 times higher than previous reports for an alternating current method. The high deposition homogeneity combined with the simplicity of the pulsed deposition method, can open new opportunities for the nanofabrication of nanowires.

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Section: Temperaturementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

Azevedo¹,

Sousa²,

Ventura³

et al. 2014

Mater. Res. Express

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“…This may arise because of the breakdown of barrier layer at the relatively high j ed . In fact, due to the non-steady state voltage in the electrodeposition process, a non-uniform filling of PAO template is expected to occur [23]. On the other hand, by performing Cu pre-plating, the corresponding voltage-time curves in Figs.…”

Section: Resultsmentioning

confidence: 98%

“…This kind of barrier layer is a dielectric [22] so that the stability of the electrodeposition is obtained by avoiding dielectric breakdown [4]. Additionally, there is a facility in the pulsed electrodeposition that applies different durations of off-time between pulses in order to limit the hydrogen and heat evolutions at the deposition interface so as to stabilize the process [23]. Using a pulsed ac electrodeposition also improves the pore-filling of PAO templates, uniformity and crystallinity of the arrays of Fe, Co and Ni NWs due to the improvement in the homogeneity of the electrodeposition [13,24,25].…”

Section: Introductionmentioning

confidence: 99%

Electrodeposition efficiency of Ni in the fabrication of highly ordered nanowire arrays: The roles of Cu pre-plating and barrier layer temperature

Ahmadzadeh

Almasi-Kashi

Ramazani

et al. 2015

Applied Surface Science

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Hydrogen Optical Metamaterial Sensor Based on Pd Dendritic Nanostructures

Rocha-Rodrigues¹,

Hierro-Rodríguez²,

Guerreiro

et al. 2016

ChemistrySelect

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In this manuscript we present a new type of hydrogen optical metamaterial sensor based on the fabrication of Pd dendritic nanostructures. The fabrication of the sensor relies on a cheap self-assembly process based on the pulsed electrodeposition method in nanoporous alumina templates. By performing optical transmission measurements, we demonstrate how this sensor can monitor hydrogen gas concentrations at room temperature either by evaluating the rate of signal decay during the Pd hydrogen absorption (transient regime) or by measuring the total variation in signal once the system achieves the equilibrium state (stationary regime). We take into account the effects of the Pd-hydrogen phase transition and its size dependency to explain the kinetics of the hydrogen absorption and desorption in the studied samples. By using the transient detection method, the sensor is able to detect in approximately 50 s the explosive H 2 (g) concentration threshold of 4 % v/v at atmospheric pressure and room temperature.[a] MSc.

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Precise control of the filling stages in branched nanopores

Cited by 27 publications

References 26 publications

Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

Ultra-long Fe nanowires by pulsed electrodeposition with full filling of alumina templates

Electrodeposition efficiency of Ni in the fabrication of highly ordered nanowire arrays: The roles of Cu pre-plating and barrier layer temperature

Hydrogen Optical Metamaterial Sensor Based on Pd Dendritic Nanostructures

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