ZnO-SiO 2 nanocomposite thin films were prepared using the target-attached RF sputtering method without substrate heating. The PL measurements showed that the SiO 2 films containing uniformly dispersed ZnO nanoparticles emit white light consisting of violet, blue, and green-yellow band emissions. The presence of the blue emission is attributed to the large number of ZnO/SiO 2 interfaces, which enlarges the depletion layer width and then enhances the related transition. The Gaussian curve fitting of PL spectra revealed that the competition between the blue and green-yellow band emissions and the relative emission intensity is strongly associated with the number of ZnO nanoparticles embedded in the SiO 2 matrix. XPS analysis revealed that the main component of the oxygen defect species in the ZnO nanocomposite thin films is 'O − ' ions (531.1-531.7 eV) at the subsurface. Within the knowledge of the defect configuration, XPS data were also utilized to estimate the oxygen vacancies and the specific carrier concentration in ZnO nanoparticles and relate to the integrated intensities of emission bands. Further analyses indicated that the defect structure of samples could be manipulated by the number and distribution of ZnO nanoparticles in SiO 2 matrix to yield a distinct luminescence spectrum.

With the increasing demand for fuel causing serious environmental pollution, it is urgent to develop new and environmentally friendly energy conversion devices. These energy conversion devices, however, require good, inexpensive materials for electrodes and so on. The multifunctional properties of porphyrins enable framework materials (e.g., metal-organic frameworks and covalent organic frameworks) to be applied in energy conversion devices due to their simple synthesis, high chemical stability, abundant metallic active sites, adjustable crystalline structure and high specific surface area. Herein, the types of porphyrin structural blocks are briefly reviewed. They can be used as organic ligands or directly assembled with framework materials to generate high-performance electro-/photo-catalysts. These types of catalysts applied in electro-/photo-catalytic water splitting, electro-/photo-catalytic carbon dioxide reduction, and electrocatalytic oxygen reduction are also summarized and introduced. At the end of the article, we present the challenges of porphyrin-based framework materials in the above application and corresponding solutions. We expect porphyrin-based framework materials to flourish energy conversion in the coming years.

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ZnO quantum dots (QDs)-SiO2 nanocomposite films were prepared using the target-attached radio-frequency sputtering. The transmission electron microscopy revealed the uniform dispersion of ZnO QDs with diameters about 2–7nm in amorphous SiO2 matrix. The photoluminescence showed that small ZnO QDs are able to emit white light with luminescence spectra similar to those of the present GaN-based light emitting diode (LED). The calculated chromaticity coordinates of emitting light evidenced the feasibility of ZnO QDs-SiO2 nanocomposite films as the fluorescence material in optoelectronic devices.

Vanadium-based oxides with high theoretical specific capacities and open crystal structures are promising cathodes for aqueous zinc-ion batteries (AZIBs). In this work, the confined synthesis can insert metal ions into the interlayer spacing of layered vanadium oxide nanobelts without changing the original morphology. Furthermore, we obtain a series of nanomaterials based on metal-confined nanobelts, and describe the effect of interlayer spacing on the electrochemical performance. The electrochemical properties of the obtained Al 2.65 V 6 O 13 • 2.07H 2 O as cathodes for AZIBs are remarkably improved with a high initial capacity of 571.7 mAh • g À 1 at 1.0 A g À 1 . Even at a high current density of 5.0 A g À 1 , the initial capacity can still reach 205.7 mAh g À 1 , with a high capacity retention of 89.2 % after 2000 cycles. This study demonstrates that nanobelts confined with metal ions can significantly improve energy storage applications, revealing new avenues for enhancing the electrochemical performance of AZIBs.