In this study, we report the synthesis of ZnO nanoparticles from Zn dross via hydrometallurgical method by using acetic acid as a leaching agent. D205 dye molecules were then adsorbed onto Zn dross originated ZnO nanoparticle film. The optical absorption confirms the photosensitization of the synthesized ZnO nanoparticles with dye. The photoluminescence spectra reveal the excitonic- and defect-related emission of ZnO nanoparticles. Compared to ZnO nanoparticles only, the longer emission lifetime of ZnO nanoparticles with adsorbed dye indicates the transfer of photoexcited electrons from dye to the ZnO nanoparticles. Furthermore, photodetection characterization of ZnO film show the enhanced current density with the presence of dye under simulated solar illumination, while that measured at dark is similar in both films with and without dye. This result confirms the potentiality of Zn dross to be recycled into valuable ZnO nanoparticles particularly for the applications in the visible light region, especially for sensing.
Semiconducting colloidal quantum dots (CQDs) represent an emerging class of thermoelectric materials for use in a wide range of future applications. CQDs combine solution processability at low temperatures with the potential for upscalable manufacturing via printing techniques. Moreover, due to their low dimensionality, CQDs exhibit quantum confinement and a high density of grain boundaries, which can be independently exploited to tune the Seebeck coefficient and thermal conductivity, respectively. This unique combination of attractive attributes makes CQDs very promising for application in emerging thermoelectric generator (TEG) technologies operating near room temperature. Herein, recent progress in CQDs for application in emerging thin‐film thermoelectrics is reviewed. First, the fundamental concepts of thermoelectricity in nanostructured materials are outlined, followed by an overview of the popular synthetic methods used to produce CQDs with controllable sizes and shapes. Recent strides in CQD‐based thermoelectrics are then discussed with emphasis on their application in thin‐film TEGs. Finally, the current challenges and future perspectives for further enhancing the performance of CQD‐based thermoelectric materials for future applications are discussed.
Metal implant coating engineering is needed to improve the surface biocompatibility properties of metals. For this, coating metal surfaces with bioactive and biocompatible biomaterials will be an option. Having high biocompatibility as well as similarity in chemical properties, nanohydroxyapatite may be a candidate as biomaterials for coating the metal implant. The key to the success of metal implant plating is the formation of pores which increase the bioactivity and biocompatibility properties of the implant. In this study, nanohydroxyapatite was used to be coated on stainless steel type 316L (SS316L). To ensure that the coating works properly on the surface, an appropriate measure of gas and distance is required. The purpose of this study was to determine the possible firing distance and gas pressure of the flame spray coating technique. The X-ray diffractometer (XRD), scanning electron microscope - energy dispersive X-ray spectroscopy (SEM-EDS), and optical microscopy (OM) characterizations were carried out to determine the phase, morphology, and presence of pores. After coated product, hydroxyapatite dehydroxylation occurred which led to the tetracalcium phosphate (TTCP) and β-tricalcium phosphate (β-TCP) phases. The thickness decreases with the addition of gas pressure and the farther the firing distance the layer thickness decreases. Nanohydroxyapatite coating on a bone implant substrate can increase the porosity of the layer.
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