A gold nanoparticle-coated and surface-textured TiO2 inverse opal (Au/st-TIO) structure that provides a dramatic improvement of photoelectrochemical hydrogen generation has been fabricated by nano-patterning of TiO2 precursors on TiO2 inverse opal (TIO) and subsequent deposition of gold NPs. The surface-textured TiO2 inverse opal (st-TIO) maximizes the photon trapping effects triggered by the large dimensions of the structure while maintaining the adequate surface area achieved by the small dimensions of the structure. Au NPs are incorporated to further improve photoconversion efficiency in the visible region via surface plasmon resonance. st-TIO and Au/st-TIO exhibit a maximum photocurrent density of ∼0.58 mA cm(-2) and ∼0.8 mA cm(-2), which is 2.07 and 2.86 times higher than that of bare TIO, respectively, at an applied bias of +0.5 V versus an Ag/AgCl electrode under AM 1.5 G simulated sunlight illumination via a photocatalytic hydrogen generation reaction. The excellent performance of the surface plasmon-enhanced mesoporous st-TIO structure suggests that tailoring the nanostructure to proper dimensions, and thereby obtaining excellent light absorption, can maximize the efficiency of a variety of photoconversion devices.

A hierarchically patterned metal/semiconductor (gold nanoparticles/ZnO nanowires) nanostructure with maximized photon trapping effects is fabricated via interference lithography (IL) for plasmon enhanced photo-electrochemical water splitting in the visible region of light. Compared with unpatterned (plain) gold nanoparticles-coated ZnO NWs (Au NPs/ZnO NWs), the hierarchically patterned Au NPs/ZnO NWs hybrid structures demonstrate higher and wider absorption bands of light leading to increased surface enhanced Raman scattering due to the light trapping effects achieved by the combination of two different nanostructure dimensions; furthermore, pronounced plasmonic enhancement of water splitting is verified in the hierarchically patterned Au NPs/ZnO NWs structures in the visible region. The excellent performance of the hierarchically patterned Au NPs/ZnO NWs indicates that the combination of pre-determined two different dimensions has great potential for application in solar energy conversion, light emitting diodes, as well as SERS substrates and photoelectrodes for water splitting.

Dual-scale diamond-shaped gold nanostructures (d-DGNs) with larger scale diamond-shaped gold nanoposts (DGNs) coupled to smaller scale gold nanoparticles have been fabricated via interference lithography as a highly reliable and efficient substrate for surface enhanced Raman scattering (SERS). The inter- and intra-particle plasmonic fields of d-DGNs are varied by changing the periodicity of the DGNs and the density of gold nanoparticles. Because of the two different length scales in the nanostructures, d-DGNs show multipole plasmonic peaks as well as dipolar plasmonic peaks, leading to a SERS enhancement factor of greater than 10(9). Simulations are carried out by finite-difference time-domain (FDTD) methods to evaluate the dependence of the inter- and intra-particle plasmonic field and the results are in good agreement with the experimentally obtained data. Our studies reveal that the combination of two different length scales is a straightforward approach for achieving reproducible and great SERS enhancement by light trapping in the diamond-shaped larger scale structures as well as efficient collective plasmon oscillation in the small size particles.

In this letter, we report a facile approach to improve the capacitor properties of nickel hydroxide (Ni(OH)2) by simply coating gold nanoparticles (Au NPs) on the surface of Ni(OH)2. Au NP-deposited Ni(OH)2 (Au/Ni(OH)2) has been prepared by application of a conventional colloidal coating of Au NPs on the surface of 3D-Ni(OH)2 synthesized via a hydrothermal method. Compared with pristine Ni(OH)2, Au/Ni(OH)2 shows a 41% enhanced capacitance value, excellent rate capacitance behavior at high current density conditions, and greatly improved cycling stability for supercapacitor applications. The specific capacitance of Au/Ni(OH)2 reached 1927 F g(-1) at 1 A g(-1), which is close to the theoretical capacitance and retained 66% and 80% of the maximum value at a high current density of 20 A g(-1) and 5000 cycles while that of pristine Ni(OH)2 was 1363 F g(-1) and significantly decreased to 48% and 30%, respectively, under the same conditions. The outstanding performance of Au/Ni(OH)2 as a supercapacitor is attributed to the presence of metal Au NPs on the surface of semiconductor Ni(OH)2; this permits the creation of virtual 3D conducting networks via metal/semiconductor contact, which induces fast electron and ion transport by acting as a bridge between Ni(OH)2 nanostructures, thus eventually leading to significantly improved electrochemical capacitive behaviors, as confirmed by the EIS and I-V characteristic data.

By creating a p–n heterojunction of molybdenum sulfide (MoSx)/Ti-doped Fe2O3 (Ti-Fe2O3), we successfully addressed electron–hole transfer problems of hematite and thus achieved the enhanced photoelectrochemical (PEC) performance.

We present a facile yet efficient single-step pyrolysis method to prepare bulk-scale high-performance Ndoped 3D-graphitic foams with various length-scale pores. The iron precursors act as catalysts for the conversion of organic substances to a graphitic structure while simultaneously providing a rigid template that prevents the aggregation of organic components, and soluble polymers act as a carbon source for the formation of N-doped multilayer graphene under high-temperature and inert conditions. The 3Dgraphitic foams possess highly interconnected networks composed of micro-, meso-, and macropores with a specific surface area of up to 1509 m 2 g −1 and a high conductivity of 10 S m −1 . The resulting 3D-graphitic foams exhibited specific capacitance values of 330 and 242 F g −1 with outstanding cycling stability (a 23% loss after 100 000 cycles for a symmetric cell) in a three-electrode system and in a symmetric cell, respectively, when used as active materials in a supercapacitor. This study suggests the great potential of bulk-scale fabricated N-doped 3D-graphitic foams with a large surface area and excellent conductivity, as well as controlled porosity, for applications in various fields.

We have discovered a carbonized polymer film to be a reliable and durable carbon-based substrate for carbon enhanced Raman scattering (CERS). Commercially available SU8 was spin coated and carbonized (c-SU8) to yield a film optimized to have a favorable Fermi level position for efficient charge transfer, which results in a significant Raman scattering enhancement under mild measurement conditions. A highly sensitive CERS (detection limit of 10 M) that was uniform over a large area was achieved on a patterned c-SU8 film and the Raman signal intensity has remained constant for 2 years. This approach works not only for the CMOS-compatible c-SU8 film but for any carbonized film with the correct composition and Fermi level, as demonstrated with carbonized-PVA (poly(vinyl alcohol)) and carbonized-PVP (polyvinylpyrollidone) films. Our study certainly expands the rather narrow range of Raman-active material platforms to include robust carbon-based films readily obtained from polymer precursors. As it uses broadly applicable and cheap polymers, it could offer great advantages in the development of practical devices for chemical/bio analysis and sensors.

Graphene-enhanced Raman spectroscopy (GERS) is a technique to increase the Raman scattering of adsorbed probe molecules on graphene. Here we systematically explore the effect of the method used to transfer the CVD-grown graphene onto another substrate on Raman scattering. We have found that graphene transferred using poly methyl methacrylate (PMMA) produces 6 times the Raman scattering signal increase of that produced by graphene transferred using thermal release tape. The reason for this is that PMMA-transferred graphene contains a larger amount of defects such as carboxyl and hydroxyl groups that help the attachment of probe molecules to the graphene surface, leading to improved π-π* interactions and thus easier charge transfer between the probe molecules and graphene. Our results indicate the need for a much closer look at the functional groups of graphene which are different for the two transfer methods. 2 detection properties due to a high surface area, easy functionalization and stability in ambient environments. Graphene can be synthesized using epitaxial growth 1 , mechanical exfoliation 2 , chemical methods 3 and chemical vapor deposition (CVD) 4 . Among them, the CVD technique is extensively used to produce thin graphene films since it provides a relatively friendly synthesis route and also produces high quality graphene. In general, graphene films obtained by CVD needs to be transferred to desired substrates for further applications. Several transfer methods such as polymer-assisted 5 (PMMA, PDMS, thermal release tape), polymer-free 6 , electrochemical delamination 7 have been used to transfer the graphene films. Polymer-assisted transfer has been widely used due to its easy processing steps. Aside from surface-enhanced Raman scattering (SERS) 8,9 which is one of the most efficient detection tools utilizing metal substrate for a variety of common molecules, graphene-enhanced Raman spectroscopy (GERS) 10 is another efficient technique to increase the Raman scattering of adsorbed probe molecules adsorbed on graphene.The concept of GERS has been widely applied to graphene oxide 3b, 11 , hydrogen terminated graphene 12 , nano-mesh graphene 13 and nitrogen-doped graphene 14 . It has been reported that GERS depends on various factors such as the number of graphene layers 15 , the density of the probe molecules 16 , the space between graphene and the probe molecule, the Fermi level of graphene, which changes with doping 17 , an interference effect from the substrate, and molecular alignment 18 . Further, in GERS the contribution of the electromagnetic-enhanced plasmons is in the terahertz range, and Raman signals are solely due to the chemical mechanism (CM) which is closely related to the charge transfer between probe molecules and the graphene substrate. Here, we report the CM properties of graphene grown by CVD can be affected by the methods of transfer (i) PMMA-and (ii) TRT-assisted, by comparing their GERS of R6G probe molecules. To date there are, to the best of our knowledge, no comprehensive reports o...