The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nano...The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nanoparticles. In the present work, Au seeds （prepared by the reduction of Au3＋ solution with NaBI~ in the presence of cetyltrimethylammonium bromide （CTAB）） have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au＋ solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield （up to 92%） of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au＋, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au3＋ solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au＊ to the number of seeds.展开更多
The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation a...The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation and engineering of naturally abundant materials into efficient TENGs for mechanical energy harvesting is meaningful not only for fundamental scientific exploration,but also for addressing societal needs.Being an abundant natural biopolymer,chitosan enables exciting opportunity for low-cost,biodegradable TENG applications.However,the electrical outputs of chitosan-based TENGs are low compared with the devices built with synthetic polymers.Here,we explore the facile molecular surface engineering in chitosan to significantly boost the performance of chitosan-based TENG for enabling the practical applications,for example,self-powered car speed sensor.The molecular surface engineering offers a potentially promising scheme for designing and implementing high-performance biopolymer-based TENGs for selfpowered nanosystems in sustainable technologies.We further explore for the first time the feasibility of data mining approaches to analyze and learn the acquired triboelectric signals from the car speed sensors and predict the relationship between the triboelectric signals and car speed values.展开更多
基金Acknowledgements This work was supported by National Basic Research Program of China （973 Program No. 2009CB930703） and National Natural Science Foundation of China （No. 21033007）. We thank Dr. Jiawei Yan, Yongli Zheng, and Haixin Lin for helpful discussion. We also thank Zhaobin Chen for ICP-AES measurements.
文摘The appropriate choice of chemical composition of a metallic precursor, which produces the basic structure units in the growth process of nanocrystals, is a high priority in the synthesis of metal--especially Au--nanoparticles. In the present work, Au seeds （prepared by the reduction of Au3＋ solution with NaBI~ in the presence of cetyltrimethylammonium bromide （CTAB）） have been used to initiate the growth of Au nanoparticles from two different Au precursors. When an aqueous Au＋ solution prepared in the presence of CTAB micelles was treated with ascorbic acid in the presence of the gold seeds, a high yield （up to 92%） of gold nanoparticles was obtained. By varying the volume of the seed solution with a fixed amount of Au＋, we can effectively control the morphological transformation of the resulting Au nanoparticles from cubes to octahedra. When an aqueous Au3＋ solution was prepared in the presence of CTAB micelles and treated with ascorbic acid in the presence of the gold seeds, smaller yields of Au nanoparticles were obtained. A preliminary growth mechanism has been proposed based on the changes induced by varying the amount of ascorbic acid and the ratio of the concentration of Au＊ to the number of seeds.
基金W.Z.W.acknowledge the College of Engineering and School of Industrial Engineering at Purdue University for the startup support and the Ravi and Eleanor Talwar Rising Star Assistant Professorship.The support provided by the China Scholarship Council(CSC)during a visit of Chenxiang Ma to Purdue University is acknowledged.
文摘The state-of-the-art triboelectric nanogenerators(TENGs)are constructed with synthetic polymers,curtailing their application prospects and relevance in sustainable technologies.The economically viable transformation and engineering of naturally abundant materials into efficient TENGs for mechanical energy harvesting is meaningful not only for fundamental scientific exploration,but also for addressing societal needs.Being an abundant natural biopolymer,chitosan enables exciting opportunity for low-cost,biodegradable TENG applications.However,the electrical outputs of chitosan-based TENGs are low compared with the devices built with synthetic polymers.Here,we explore the facile molecular surface engineering in chitosan to significantly boost the performance of chitosan-based TENG for enabling the practical applications,for example,self-powered car speed sensor.The molecular surface engineering offers a potentially promising scheme for designing and implementing high-performance biopolymer-based TENGs for selfpowered nanosystems in sustainable technologies.We further explore for the first time the feasibility of data mining approaches to analyze and learn the acquired triboelectric signals from the car speed sensors and predict the relationship between the triboelectric signals and car speed values.
