Several physico-chemical effects and properties in the solid state involve nanoscale interactions between adjacent materials and morphologies. Arrays of binary nanostructures can generate intimate interactions between different sub-components, but fabricating binary nanostructures is challenging. Here, we propose a concept to achieve diverse binary nanostructure arrays with high degrees of controllability for each of the sub-components, including material, dimension and morphology. This binary nanostructuring concept originates with a distinctive binary-pore anodized aluminium oxide template that includes two dissimilar sets of pores in one matrix, where the openings of the two sets of pores are towards opposite sides of the template. Using the same growth mechanism, the binary-pore template can be extended to multi-pore templates with more geometrical options. We also present photoelectrodes, transistors and plasmonic devices made with our binary nanostructure arrays using different combination of materials and morphologies, and demonstrate superior performances compared to their single-component counterparts.

No abstract

Utilizing plasmonic nanostructures for efficient and flexible conversion of solar energy into electricity or fuel presents a new paradigm in photovoltaics and photoelectrochemistry research. In a conventional photoelectrochemical cell, consisting of a plasmonic structure in contact with a semiconductor, the type of photoelectrochemical reaction is determined by the band bending at the semiconductor/electrolyte interface. The nature of the reaction is thus hard to tune. Here instead of using a semiconductor, we employed a ferroelectric material, Pb(Zr,Ti)O3 (PZT). By depositing gold nanoparticle arrays and PZT films on ITO substrates, and studying the photocurrent as well as the femtosecond transient absorbance in different configurations, we demonstrate an effective charge transfer between the nanoparticle array and PZT. Most importantly, we show that the photocurrent can be tuned by nearly an order of magnitude when changing the ferroelectric polarization in PZT, demonstrating a versatile and tunable system for energy harvesting.

Instead of conventional semiconductor photoelectrodes, herein, we focus on BiFeO3 ferroelectric photoelectrodes to break the limits imposed by common semiconductors. As a result of their prominent ferroelectric properties, the photoelectrodes are able to tune the transfer of photo-excited charges generated either in BiFeO3 or the surface modifiers by manipulating the poling conditions of the ferroelectric domains. At 0 V vs Ag/AgCl, the photocurrent could be switched from 0 μA cm(-2) to 10 μA cm(-2) and the open-circuit potential changes from 33 mV to 440 mV, when the poling bias of pretreatment is manipulated from -8 V to +8 V. Additionally, the pronounced photocurrent from charge injection of the excited surface modifiers could be quenched by switching the poling bias from +8 V to -8 V.

An easily accessible photocathodic material was fabricated to realize high-efficiency water splitting. After optimizing the PEC system, the photocurrent was further amplified to −1.2 mA cm−2.

spectrum of solar radiations, a key point for PEC water splitting is to explore photoelectrode materials with a high-effi cient solar light utilization. Since the pioneering work demonstrated by Fujishima and Honda in 1972, TiO 2 has been extensively investigated as a photoanode material, attributing to its advantages of high photochemical stability, cost effectiveness, and nontoxicity. [ 2 ] However, in view of the large band gap (3.2 eV for anatase and 3.0 eV for rutile), low electron mobility (1 cm 2 V −1 s −1 ) and short minority carrier (hole) diffusion length (10-100 nm) of TiO 2 , its practical application for PEC is restricted. [ 3 ] Thus, many efforts have been devoted to address this issue. [ 4 ] In particular, owning to the signifi cant capability of decoupling light absorption and charge carrier collection, and shortening minority carrier diffusion distance compared to bulk structures, 1D nanostructures (e.g., nanorod, [ 5 ] nanowire, [ 6 ] and nanotube [ 7 ] of TiO 2 have been intensively studied. Additionally, rational construction of complex hierarchical TiO 2 nanostructures, such as branched nanowire array [ 8 ] and nanotube photonic crystal, [ 9 ] can further increase the light absorption effi ciency and contact surface areas, thus enhance the PEC performance accordingly. Although the TiO 2 nanostructuring could effi ciently transfer the holes at the TiO 2 /electrolyte interface via diffusing across the axial direction of the nanostructures, the low mobility of electrons in TiO 2 is still an obstacle because they must transport along the radial direction to reach to the current collector. [ 8a ] As previously demonstrated, core/ shell nanostructures, in which the core acts as a conductive path, could be an excellent candidate to facilitate the electrons separation and transportation simultaneously in the axial direction. [ 10 ] Furthermore, in order to promote the solar light utilization of the TiO 2 -based core/shell nanostructures, introducing surface plasmon resonance (SPR) of Au nanoparticles (NPs) is a promising approach, ascribing to the advantages of its visible light absorption and good stability. [ 11 ] However, most of the existing TiO 2 -based core/shell nanostructures require complex multistep fabrication processes and the structure could only be roughly adjusted, which make it diffi cult to quantitatively optimize the charge carrier collection. [ 12 ] Meanwhile, although the Constructing core/shell nanostructures with optimal structure and composition could maximize the solar light utilization. Here, using an Al nanocone array as a substrate, a well-defi ned regular array of AZO/TiO 2 core/shell nanocones with uniformly dispersed Au nanoparticles (AZO/TiO 2 /Au NCA) is successfully realized through three sequential steps of atomic layer deposition, physical vapor deposition, and annealing processes. By tuning the structural and compositional parameters, the advantages of light trapping and short carrier diffusion from the core/shell nanocone array, as well as the surface plasmo...

In order to fulfill the multiple requirements for energy production, storage, and utilization in the future, the conventional planar configuration of current energy conversion/storage devices has to be reformed, since technological evolution has promoted the efficiency of the corresponding devices to be close to the theoretical values. One promising strategy is to construct multifunctional 1D nanostructure arrays to replace their planar counterparts for device fabrication, ascribing to the significant superiorities of such 1D nanostructure arrays. In the last three decades, technologies based on anodic aluminium oxide (AAO) templates have turned out to be valuable meaning for the realization of 1D nanostructures and have attracted tremendous interest. In this review, recent progress in energy-related devices equipped with heterogeneous 1D nanostructure arrays that fabricated through the assistance of AAO templates is highlighted. Particular emphasis is given on how to develop efficient devices via optimizing the componential and morphological parameters of the 1D nanostructure arrays. Finally, aspects relevant to the further improvement of device performance are discussed.

Perfectly ordered nanoparticle arrays are fabricated on large-area substrates (>cm(2)) via a cost-effective nonlithographic route. Different surface plasmon resonance (SPR) modes focus consequently on their own positions due to the identical shape and uniform size and distance of these plasmonic metallic nanoparticles (Ag and Au). On the basis of this and FDTD (finite-difference time-domain) simulation, this work reveals the variation of all SPR parameters (position, intensity, width, and mode) with nanoparticle heights, which demonstrates that the effect of heights are different in various stages. On increasing the heights, the major dipole SPR mode precisely blue-shifts from the near-infrared to the visible region with intensity strengthening, a peak narrowing effect, and multipole modes excitation in the UV-vis range. The intensity of multipole modes can be manipulated to be equal to or even greater than the major dipole SPR mode. After coating conformal TiO2 shells on these nanoparticle arrays by atomic layer deposition, the strengthening of the SPR modes with increasing the heights results in the multiplying of the photocurrent (from ∼2.5 to a maximum 90 μA cm(-2)) in this plasmonic-metal-semiconductor-incorporated system. This simple but effective adjustment for all SPR parameters provides guidance for the future design of plasmonic metallic nanostructures, which is significant for SPR applications.