Bubble dynamic templated deposition of three-dimensional palladium nanostructure catalysts: Approach to oxygen reduction using macro-, micro-, and nano-architectures on electrode surfaces

Growth mechanism of three-dimensional porous tin foam based on the coupled effects of reduction reaction competition and interface regulation

This paper systematically conducted a study on the microstructural evolution of tin foam prepared by the hydrogen bubble dynamic template (HBDT) under key deposition parameters, and established a growth model for three-dimensional (3D) porous tin foam based on the coupled effects of competitive reduction reactions and interface regulation. By exploring the competitive relationship between hydrogen evolution and metal deposition, a novel mechanism was proposed for the hydrogen bubble template, revealing the dual role of hydrogen bubbles in metal deposition under the coupling of tin ion concentration and deposition potential. It was also elucidated that the competitive equilibrium between hydrogen evolution and tin ion reduction was crucial for sustaining the dynamic stability of the bubble template, ultimately inducing the formation of 3D porous structures. In addition, the correlation between pore structures (pore size and density) and bubble behavior was deeply discussed to gain a comprehensive perspective. Therefore, this study holds significant importance for guiding the research on customizing the 3D porous tin foam structures in controlled crystallization reactions.

A feasible electrochemical biosensor for determination of glucose based on Prussian blue - Enzyme aggregates cascade catalytic system

The coral-like gold micro/nanostructures were formed onto carbon cloth followed by a Prussian blue (PB) electrochemical deposition to construct a highly sensitive H₂O₂ biosensor. The SEM image of PB/Au/CC showed the coral-like gold morphology, and EDS and XPS tests also further confirmed the successful loading of Au and PB. The electrochemical tests of PB/Au/CC displayed the electrode possessed excellent performance in sensing H₂O₂, which was quantified in the linear range from 0.002 to 13.97 mM at an applied potential of -0.05 V, with a sensitivity of 454.97 μA mM^-1 cm^-2 and a detection limit of 0.5 μM (S/N = 3). And then a convenient sensing platform was established via the cross-linking enzyme aggregates method, using PB as the mediator to realize the construction of glucose BIOSENSOR GOx_EA@PB/Au/CC. The biosensor responded to glucose in the sensitivity of 70.76 μA mM^-1 cm^-2 within the linear range from 0.05 to 3.15 mM with a detection limit of 10 μM. The sensitivity was much higher than the electrode constructed by the cross-linking enzyme method (GOx@PB/Au/CC), and it was also highly selective, reproducible, and stable. Besides, the proposed biosensor was successfully applied to the glucose determination in real human serum samples, which proved its practicability.

Hierarchical Nanoporous Sn/SnOx Systems Obtained by Anodic Oxidation of Electrochemically Deposited Sn Nanofoams

A simple two-step electrochemical method for the fabrication of a new type of hierarchical Sn/SnO_x micro/nanostructures is proposed for the very first time. Firstly, porous metallic Sn foams are grown on Sn foil via hydrogen bubble-assisted electrodeposition from an acidulated tin chloride electrolyte. As-obtained metallic foams consist of randomly distributed dendrites grown uniformly on the entire metal surface. The estimated value of pore diameter near the surface is ~35 µm, while voids with a diameter of ~15 µm appear in a deeper part of the deposit. Secondly, a layer of amorphous nanoporous tin oxide (with a pore diameter of ~60 nm) is generated on the metal surface by its anodic oxidation in an alkaline electrolyte (1 M NaOH) at the potential of 4 V for various durations. It is confirmed that if only optimal conditions are applied, the dendritic morphology of the metal foam does not change significantly, and an open-porous structure is still preserved after anodization. Such kinds of hierarchical nanoporous Sn/SnO_x systems are superhydrophilic, contrary to those obtained by thermal oxidation of metal foams which are hydrophobic. Finally, the photoelectrochemical activity of the nanostructured metal/metal oxide electrodes is also presented.

Formation of hierarchically-ordered nanoporous silver foam and its electrocatalytic properties in reductive dehalogenation of organic compounds

Nanostructuring of silver notably improved its electrocatalytic activity in reductive dehalogenation of a variety of aryl and alkyl bromides.

Building with bubbles: the formation of high surface area honeycomb-like films via hydrogen bubble templated electrodeposition

While the evolution of hydrogen gas is often a troublesome process accompanying electrodeposition, this feature can be exploited to template the growth of highly porous surfaces. This process, known as the dynamic hydrogen bubble template (DHBT) method, can be utilised to create a wide range of macroporous films with nanostructured pore walls. This feature article presents an overview of the status of the DHBT technique, highlighting preparation techniques and emerging applications.

Formation of nanostructured porous Cu-Au surfaces: the influence of cationic sites on (electro)-catalysis

The fabrication of nanostructured bimetallic materials through electrochemical routes offers the ability to control the composition and shape of the final material that can then be effectively applied as (electro)-catalysts. In this work a clean and transitory hydrogen bubble templating method is employed to generate porous Cu-Au materials with a highly anisotropic nanostructured interior. Significantly, the co-electrodeposition of copper and gold promotes the formation of a mixed bimetallic oxide surface which does not occur at the individually electrodeposited materials. Interestingly, the surface is dominated by Au(I) oxide species incorporated within a Cu(2)O matrix which is extremely effective for the industrially important (electro)-catalytic reduction of 4-nitrophenol. It is proposed that an aurophilic type of interaction takes place between both oxidized gold and copper species which stabilizes the surface against further oxidation and facilitates the binding of 4-nitrophenol to the surface and increases the rate of reaction. An added benefit is that very low gold loadings are required typically less than 2 wt% for a significant enhancement in performance to be observed. Therefore the ability to create a partially oxidized Cu-Au surface through a facile electrochemical route that uses a clean template consisting of only hydrogen bubbles should be of benefit for many more important reactions.

The new age of carbon nanotubes: an updated review of functionalized carbon nanotubes in electrochemical sensors

Since the discovery of carbon nanotubes (CNTs), they have drawn considerable research attention and have shown great potential application in many fields due to their unique structural, mechanical, and electronic properties. However, their native insolubility severely holds back the process of application. In order to overcome this disadvantage and broaden the scope of their application, chemical functionalization of CNTs has attracted great interest over the past several decades and produced various novel hybrid materials with specific applications. Notably, the rapid development of functionalized CNTs used as electrochemical sensors has been successfully witnessed. In this featured article, the recent progress of electrochemical sensors based on functionalized CNTs is discussed and classified according to modifiers covering organic (oxygen functional groups, small organic molecules, polymers, DNA, protein, etc.), inorganic (metal nanoparticles, metal oxide, etc.) and organic-inorganic hybrids. By employing some representative examples, it will be demonstrated that functionalized CNTs as templates, carriers, immobilizers and transducers are promising for the construction of electrochemical sensors.