Light harvesting and electron recombination are essential factors that influence photovoltaic performance of quantum dots sensitized solar cells (QDSSCs). ZnO hollow microspheres (HMS) as architectures in QDSSCs are beneficial in improving light scattering, facilitating the enhancement of light harvesting efficiency. However, this advantage is greatly weakened by defects located at the surface of ZnO HMS. Therefore, we prepared a composite hollow microsphere structure consisting of ZnO HMS coated by TiO2layer that is obtained by immersing ZnO HMS architectures in TiCl4aqueous solution. This TiO2-passivated ZnO HMS architecture is designed to yield good light harvesting, reduced charge recombination, and longer electron lifetime. As a result, the power conversion efficiency (PCE) of QDSSC reaches to 3.16% with an optimal thickness of TiO2passivation layer, which is much higher when compared to 1.54% for QDSSC based on bare ZnO HMS.Keywords:TiO2passivation layer;ZnO hollow microspheres;quantum dots sensitized solar cells
Surface chemistry can be modified by introducing another component on the surface of catalyst due to the regulation of configuration and electronic properties. Herein, the nanostructured ZnO hollow microspheres were fabricated for selective CO 2 reduction to CO. The addition of CuO weakens the strength of adjacent Zn-O bond and improves the formation of more zero-valence Zn. Small CuO entities can provide the active sites for CO 2 adsorption, and the presence of surface defects due to Zn 2+ reduction could enhance initial dissociation from CO 2 to CO. More interestingly, the 3CuO/ZnO catalyst underwent reconstruction during electrocatalysis , and multi-shelled hollow spheres evolved into a thin flaky structure. The extended surface area of flaky morphology enhances the catalytic stability despite the occurrence of ZnO reduction. This study highlights the importance of surface modification for CO 2 selective reduction to CO but also provides some insights on reconstruction during electrochemical reduction of CO 2 .
Yuan Qu,Ziwen Ding,Xiaotong Yuan,Feiyu Zhang,Ke Xu,Xiang Lu,Song Liu,Siqi Li,Wei Ji
The fabrication of gas sensors based on metal oxide semiconductors (MOS) with high sensitivity and low detection limits is a crucial research domain. Modulation of microstructural features is a critical strategy to enhance gas sensing performance, owing to its controllability and inherent design flexibility. The double-shell structure amplifies active surface sites and nested effects, further heightening gas-sensor interaction for escalated adsorption efficiency and reaction rates. In this paper, we fabricated hierarchical double-shell ZnO hollow microsphere (D-ZnO) sensors via a scalable technique, incorporating uniformly spherical carbon templates. These D-ZnO-based sensors demonstrated a high response (32.42) to 100 ppm n-butanol and achieved a low detection limit (DL) of 96 ppb at the optimized temperature of 240 °C. Such excellent gas sensing performance of D-ZnO can be attributed to the unique spatial structure of hierarchical double-shell for the modulation of gas diffusion pathways and collision frequency.
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