Externally triggered motion of small objects has potential in applications ranging from micromachines, to drug delivery, and self-assembly superstructures. Here we present a new concept for the controlled propulsion conducting with sizes centimetres hundreds micrometres. It is based on their polarization, induced by an electric field, which triggers spatially separated oxidation reduction reactions involving asymmetric gas bubble formation. This turn leads directional objects. Depending...

Bipolar electrochemistry, a phenomenon which generates an asymmetric reactivity on the surface of conductive objects in wireless manner, is important concept for many purposes, from analysis to materials science as well generation motion. Chemists have known basic long time, but it has recently attracted additional attention, especially context micro- and nanoscience. In this Account, we introduce fundamentals bipolar electrochemistry illustrate its recent applications, with particular focus...

Dihydrogen (H2) constitutes a promising energy carrier for transporting part of the world's demand and concomitantly reducing toxic emissions. Water electrolysis powered by renewable would provide H2 with small carbon footprint. To save global fresh water, seawater has attracted much attention in recent years, since it represents 96.5% Earth's resources is abundant worldwide. However, seawater's composition complex, which poses problems direct splitting. date, splitting usually requires...

Janus particles have different features/chemistry on two opposite sides (see figure). So far, they been obtained mainly by two-dimensional synthetic methods, which are able to break the symmetry but limit amount of produced particles. A true bulk approach, based bipolar electrochemistry, is presented that allows straightforward synthesis such asymmetric micro- and nano-objects.

Dynamic bipolar self-regeneration is a new mechanism that allows controlled motion of metallic microobjects to be induced. This technique based on the concept electrochemistry, in which different redox reactions occur at two extremities substrate under influence an external electric field. To create object, one end has site metal deposition and other dissolution. Propulsion zinc macro- microswimmers speeds up 80 μm s(-1) been achieved.

This review article highlights the most recent advances with respect to preparation of Janus objects by bulk phase processes. Historically concepts developed for generating asymmetric particles have been based on use interfaces or surfaces, which are necessary break symmetry. restricts in many cases amount produced particles, due two-dimensional nature approaches. Therefore synthesis such micro- and nanoobjects is primary importance their production at an industrial scale helps open up field...

Tunable hydrophobic/hydrophilic flexible Teflon nanocone array surfaces were fabricated over large areas (cm(2)) by a simple two-step method involving the oxygen plasma etching of colloidal monolayer polystyrene beads on film. The wettability was controlled dimensions and various additional surface modifications. resultant hydrophobic adhesive (a "gecko" type which water droplet has high contact angle but stays in place) with that correlated aspect ratio/sharpness nanocones. switched to...

Flexible broadband antireflective and light-absorbing nanostructured gold thin films are fabricated by vapor deposition onto Teflon modified with nanocone arrays. The nanostructures created the oxygen plasma etching of polystyrene bead monolayers on surfaces. periodicity height arrays controlled diameter overall time. exhibit a reflectivity less than 1% over wide spectral range (450–900 nm) incident angles (0–70°); this unique optical response is attributed to combination diffractive...

We introduce the photoinduced electrochemiluminescence (P-ECL) of model ECL system involving simultaneous oxidation [Ru(bpy)3]2+ and tri-n-propylamine (TPrA). This classically requires highly anodic potentials greater than +1 V vs SCE for generation. In reported approach, emission is triggered by holes (h+) photogenerated in an n-type semiconductor (SC) electrode, which normally challenging because competing photocorrosion occurring on SC electrodes aqueous electrolytes. employ here Si-based...

Electrochemiluminescence (ECL) is widely employed for medical diagnosis and imaging. Despite its remarkable analytical performances, the technique remains intrinsically limited by essential need an external power supply electrical wires electrode connections. Here, we report electrically autonomous solution leading to a paradigm change designing fully integrated all-optical wireless monolithic photoelectrochemical device based on nanostructured Si photovoltaic junction modified with...

ConspectusThe electrochemical conversion of sunlight by photoelectrochemical cells (PECs) is based on semiconductor electrodes that are interfaced with a liquid electrolyte. This approach highly promising, first, because it can be employed for the generation chemical fuel (e.g., H2) to store solar energy used on-demand generate electricity when sun not available. Second, seen as concept reminiscent photosynthesis, where CO2 converted into valuable feedstock energy. Thus, sometimes referred...

Transition metal-based catalyst layers for hydrogen evolution (HER) and urea oxidation (UOR) are coupled to a Perovskite/Silicon (PK/Si) tandem photovoltaic (PV) cell tested H2 production from urea-rich alkaline...

Swimmer in the dark: Propulsion of a conducting object is intrinsically coupled with light emission using bipolar electrochemistry. Asymmetric redox activity on surface swimmer (black bead; see picture) causes production gas bubbles to propel glass tube simultaneous electrochemiluminescence (ECL) monitor progress swimmer.

Based on the principles of bipolar electrochemistry, localized pH gradients are generated at surface conducting particles in solution. This allows toposelective deposition inorganic and organic polymer layers via a pH-triggered precipitation mechanism. Due to intrinsic symmetry breaking process, concept can be used generate straightforward way Janus particles, with one section consisting deposits obtained from non-electroactive precursors. These indirect electrodeposits, such as SiO(2),...

Ni electrodeposited on n-type Si from aqueous solutions in the form of isolated or coalescent nanoparticles (NPs) protects underlying and partially exposed photocorrosion-induced electrical passivation. Such photoanodes, fabricated without need for additional protecting layers, a buried junction, high-vacuum techniques, show high photovoltage ∼500 mV oxygen evolution reaction (OER), state-of-the-art photocurrents, faradaic efficiencies > 90% under AM 1.5G illumination conditions at pH 14....

The controlled electrodeposition of functional polydopamine (PDA) thin films from aqueous dopamine solutions is demonstrated with a combination electrochemistry, atomic force microscopy (AFM), and surface plasmon resonance (SPR) measurements. PDA micropatterns are then fabricated by on micrometer length scale gold electrodes used for attaching amino-modified single-stranded DNA (ssDNA). After hybridization fluorescently labeled ssDNA, the fluorescence characterization reveals that: (i) can...

Abstract Apart from being key structures of modern microelectronics, metal-insulator-semiconductor (MIS) junctions are highly promising electrodes for artificial leaves, i.e. photoelectrochemical cells that can convert sunlight into energy-rich fuels. Here, we demonstrate homogeneous Si/SiO x /Ni MIS junctions, employed as photoanodes, be functionalized with a redox-active species and simultaneously converted high-photovoltage inhomogeneous by electrochemical dissolution. We also report on...

In spite of the notorious instability Si in alkaline solutions, partially covered with hemispherical Ni particles show striking performances for sunlight-assisted water oxidation.

A bulk procedure based on bipolar electrochemistry is proposed for the generation of Janus-type carbon tubes. The concept illustrated with tubes that are selectively modified at their ends various metals and conducting polymers. No surface or interface required to break symmetry therefore this approach could be used mass production Janus micro- nano-objects. We show evidence technique very versatile, allowing choice kind material deposited whether end product mono- bifunctionalized.

We report for the first time vertical propulsion of conducting beads in liquid filled capillaries by bipolar electrochemistry. The beads, when exposed to an external electric field, act as electrodes showing hydroquinone oxidation on one side and proton reduction other side. related asymmetric bubble generation occurring at bottom part drives their motion. characteristic features can be tuned changing parameters such applied field or capillary shape. Using a conical capillary, we show that...

Miniaturized structures that can move in a controlled way solution and integrate various functionalities are attracting considerable attention due to the potential applications fields ranging from autonomous micromotors roving sensors. Here we introduce concept which allows, depending on their specific design, directional motion of objects water, combined with electronic such as emission light, sensing, signal conversion, treatment transmission. The approach is based electric field-induced...