Electrochemical Synthesis of One‐Dimensional Mesoporous Pt Nanorods Using the Assembly of Surfactant Micelles in Confined Space

Abstract

One-dimensional metallic nanostructures, particularly those composed of noble metals, have sparked great scientific interest for practical applications, owing to their uniquely anisotropic structure. [1] Recent advances in energy conversion materials have shown that 1D materials are particularly effective as electrocatalysts for the methanol oxidation reaction (MOR) and oxygen reduction reaction (ORR) at low costs. [2] The facile synthesis of 1D Pt nanocatalysts (e.g., nanorods, [3] nanowires, [4] nanotubes, [5] and others [6] ) with noteworthy enhanced electrocatalytic activity and durability is becoming increasingly important.On the other hand, the formation of well-defined nano/ mesoporous structures [7] of metals affords electrocatalysts showing a superior performance because of their high porosity, large area per unit volume, and excellent activitystructure relationship. Therefore, the successful synthesis of 1D mesoporous Pt motifs can be expected to be a new direction in the fabrication of superior electrocatalysts. The traditional hard-templating method, which is widely used to synthesize mesoporous carbon materials, [8] metal oxides, [9] and metals, [10] cannot easily be used for the synthesis of 1D mesoporous metal motifs, because this method involves several steps: the formation of an original template followed by deposition of metals within the mesopores and subsequent removal of the template. Lyotropic liquid crystals (LLCs) made of highly concentrated surfactants have also been used as soft templates. [11] However, due to the high viscosity of the LLCs, it is not so easy to deposit selectively metals in the target area. The method using LLCs cannot be applied as a general electrochemical method for shape-controlled synthesis of mesoporous metals. As another way, the alloydealloying approach, in which a less noble metal is selectively dissolved from a bimetallic alloy, is an attractive and much used strategy to synthesize porous metals. [12] However, it is hard to control the sizes of the mesopores and to construct robust mesopore walls.Herein, we report a general "all-wet electrochemical approach" to synthesize novel self-supported 1D Pt nanorods (NRs) with a high density of mesopores (which are denoted as "mesoporous Pt nanorods, MPNRs") by using the assembly of micelles [13] in the confined space of a polycarbonate (PC) membrane. The MPNRs with various aspect ratios can be synthesized by simply controlling the electrodeposition times. The fabrication procedure of 1D MPNRs is schematically illustrated in Figure 1. A Pt thin film serving as conductive layer was deposited on one side of the PC membrane with a pore size of 50 nm (see Figure S1 in the Supporting Information). The electrolyte solution containing K 2 PtCl 4 and 1.0 wt % Brij 58 (C 16 H 33 (OCH 2 CH 2 ) 20 OH) was used to prepare 1D MPNRs at a constant potential of À0.2 V vs. Ag/ AgCl at room temperature. After the electrodeposition, the PC membranes were soaked in NaOH and ethanol solutions to dissolve the PC membranes and the surfa...

Controlled Synthesis of Highly Crystallized Mesoporous Mn2O3 and Mn3O4 by Using Anionic Surfactants

“…The improved activity of the mesoporous samples is probablyd ue to their accessible porous framework which provides abundant actives ites and efficient electron/ mass transport across the system. [54][55][56] The higherO RR activity of meso-Mn 2 O 3 compared to meso-Mn 3 O 4 is most likely be due to the presence of ah igherv alence Mn III state. [57] With increasing the oxidation number of the central Mn, the ORR activity of the Mn oxidest ends to increase.…”

Bimetallic core–shell Ag@Pt nanoparticle-decorated MWNT electrodes for amperometric H2 sensors and direct methanol fuel cells

“…The high cost of rare Pt, however, is a significant hurdle, and many efforts have focused on the development of novel Pt-based nanomaterials with a core-shell and/or nanoporous structures in order to achieve a maximized surface area using a minimum amount of Pt [14][15][16][17]. Silver atoms are a suitable choice for the sacrificial template in the synthesis of Pt-based core-shell NPs via GRR, because conductive Ag has the same face-centered cubic (fcc) crystal structure as Pt, as well as a similar lattice constant spacing that facilitates effective Pt growth on the core [18].…”

Photothermal exposure of polydopamine-coated branched Au–Ag nanoparticles induces cell cycle arrest, apoptosis, and autophagy in human bladder cancer cells

“…For example, Au@Pt with nanostructured dendritic Pt shells has been successfully synthesized. [18][19][20][21][22] Recently, Li et al 23 proposed that branched Au-Ag NPs coated with polydopamine (PDA) would exhibit excellent structural stability, biocompatibility, and photothermal properties. The photothermal property of branched Au NPs is enhanced by the Au-Ag nanostructures, while the PDA coating strongly improves the structural stability and biocompatibility.…”