ZnO hollow nanosphere (HNS) arrays decorated with Ag nanoparticles (NPs) were fabricated on silicon substrates using self-assembled monolayer polystyrene (PS) nanospheres as the template. The O 2 plasma etching was introduced to manipulate the diameters of the ZnO HNSs. This fabrication method has the advantages of simplicity, large scale production, easy size and shape manipulations, low cost and bio-compatibility. Scanning electron microscopy (SEM) images show that the obtained Ag NP-ZnO HNS hybrid structures are hexagonally arranged, with the uniform size and shape, and the X-ray diffraction (XRD) pattern shows that the ZnO HNS arrays are of high crystal quality and have a dominant orientation of <0001> direction. Resonant Raman scattering spectra reveal the multiphonon A1 (LO) modes of ZnO hollow nanospheres at 574, 1147 and 1725 cm À1 . Enhanced resonant Raman scattering from the Ag NP modified ZnO HNSs was observed, indicating a strong energy coupling effect located at the metal/semiconductor interface. Surface enhanced Raman scattering (SERS) application for the Ag NP decorated ZnO HNS arrays was verified using a Rhodamine 6G (R6G) chromophore as a standard analyte, which is proved to be an effective SERS template for Raman signal detection. SERS substrates with different structures have been compared, and the Ag NP modified ZnO HNS system exhibits superior Raman scattering enhancements induced by the local surface plasmon resonance (LSPR) effect. The SERS mechanism was well explained by theoretical calculation results. This study is helpful to fabricate controllable Ag NP arrays using the ZnO HNS as the supporting structure and to understand the mechanism of bio-sensing enhancements due to the LSPR effect originated from the metal NPs and metal/semiconductor interface.

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wileyonlinelibrary.compromoting the continued emergence or commercialization of the miniaturized autonomous devices such as wireless sensor networks in smart grid. [1][2][3][4] In order to operate independently, the micro/nanoautonomous electronic devices must have on-board power supply. The combination of energy harvesting system from ambient sources (solar, thermal, and vibrational) with a rechargeable battery has been proposed to create a completely self-sustaining power system. [ 5,6 ] However, the battery miniaturization still cannot keep pace with the size scaling-down of the complementary metal-oxide semiconductor (CMOS) electronic technologies, due to the poor electrochemical performance of the micro/ nanobatteries or the incompatible battery fabrication process with the IC technologies. Currently, the transition from 2D to 3D rechargeable lithium-ion batteries (LIBs) with better electrochemical properties in a small areal footprint was found to cope well with state-of-the-art semiconductor technologies conceptually providing new opportunities for micro/nanopower systems in the future. [7][8][9] Very recently, as an alternative energy storage technology to LIBs, the sodium-ion battery (SIB) drew signifi cant attention due to its unlimited sodium sources, low cost (about $150 ton -1 for sodium carbonate versus $5000 ton -1 for lithium carbonate [ 10 ] and the higher value of the Na/Na + potential (-2.7 V versus standard hydrogen electrode (SHE)) compared to Li/Li + (-3.0 V versus SHE), which can effectively reduce the electrolyte degradation at the surface of the electrode material. [ 11,12 ] But the major obstacle for the wide spread use of Na-ion batteries at room temperature is the larger ionic radius of Na + (0.98 Å) than that of Li + (0.69 Å), which makes them more diffi cult to reversibly insert into and extract from host materials. [ 11,13 ] Within the survey of the existing numerous electrode materials for LIBs, only a few cathode candidates borrowed or guided by the Li-ion chemistry are suitable to allow Na ions inserting/deinserting reversibly, and moreover, the availability of such anode host materials is even more rare. [14][15][16][17] Excitingly, the theoretical calculations predicted that the sodium could alloy with germanium (Ge) to form NaGe (Ge + Na + + e − ↔ NaGe), giving a theoretical capacity of 369 mAh g -1 . [ 18 ] 3D micro/nanobatteries in high energy and power densities are drawing more and more interest due to the urgent demand of them in integrating with numerous micro/nanoscale electronic devices, such as smart dust, miniaturized sensors, actuators, BioMEMS chips, and so on. In this study, the electrochemical performances of 3D hexagonal match-like Si/Ge nanorod (NR) arrays buffered by TiN/Ti interlayer, which are fabricated on Si substrates by a costeffective, wafer scale, and Si-compatible process are demonstrated and systematically investigated as the anode in sodium-ion batteries. The optimized Si/ TiN/Ti/Ge composite NR array anode displays superior areal/specifi c capaciti...