科研之友
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摘要
The catalytic performances, as well as the thickness and morphologies, of silver nanoshells have been facilely tuned in an eco-friendly manner via laser irradiation. The irradiation of nanosecond laser pulses has transformed silver seeds or nanoparticles adsorbed to the silica surfaces of Ag@SiO2 nanostructures into silver nanoshells, producing Ag@SiO2@Ag nanostructures having highly enhanced catalytic performances. The catalytic degradation of rhodamine B has been found to occur on silver nanoshells (k(1) process) or on core silver nanospheres (k(2) process); whereas the k(2) value hardly changes, the k(1) value increases largely by chemical reduction and/or laser treatment. Although the k(1) value of a nanocatalyst is smaller than the k(2) value, dye molecules are degraded mostly by the k(1) process because it takes a long induction time for the k(2) reaction to occur. Laser irradiation enhances the catalytic performances of silver-based sandwich nanostructures by lowering the energy barrier (E-a) of the k(1) process, and Ea is reduced by the energetically favorable formation of the activated complex. The increment of catalytic performances resulting from the decrease of Ea has been considered to arise from the surface restructuring process, as well as the coverage increase, of silver nanoshells during laser irradiation.
- 出版日期2016-2-25
