Photocatalytic degradation attracts considerable attention because it is a promising strategy to treat pollutants from industrial and agricultural wastes. In recent years, other than the development of e cient photoca...Photocatalytic degradation attracts considerable attention because it is a promising strategy to treat pollutants from industrial and agricultural wastes. In recent years, other than the development of e cient photocatalysts, much e ort has been devoted to the design of reliable and inexpensive photocatalytic platforms that work in various environment conditions. Here, we describe a novel photocatalytic platform that is able to float and freely move atop water while performing photodegradation. Compared to common platforms, such as slurry reactors and immobilized photoreactors, the proposed platform is advantageous in terms of easy recycling and energy saving. Furthermore, the special configuration resulting from a two-step synthesis route, semi-embedded photocatalysts, addresses some of the remaining challenges, for instance, the contamination from the loose photocatalysts themselves. For the probe pollutant, methylene blue(MB), a reproducible and remarkable degradation activity of the platform, is observed and the e ect of two primary factors, including surface area of the catalyst and mass transfer rate, is investigated. Besides, the piezo-photocatalysis e ect, serving as an additional functionality, is confirmed to further improve the degradability of the platform, which o ers an additional 20% of degraded MB. At last, the promising result of the degradation toward crude oil reveals the possibility of the platform to be used in gasoline pollution treatment.展开更多
Exploiting nonlinear characteristics in micro/nanosystems has been a subject of increasing interest in the last decade.Among others,vigorous intermodal coupling through internal resonance(IR)has drawn much attention b...Exploiting nonlinear characteristics in micro/nanosystems has been a subject of increasing interest in the last decade.Among others,vigorous intermodal coupling through internal resonance(IR)has drawn much attention because it can suggest new strategies to steer energy within a micro/nanomechanical resonator.However,a challenge in utilizing IR in practical applications is imposing the required frequency commensurability between vibrational modes of a nonlinear micro/nanoresonator.Here,we experimentally and analytically investigate the 1:2 and 2:1 IR in a clamped–clamped beam resonator to provide insights into the detailed mechanism of IR.It is demonstrated that the intermodal coupling between the second and third flexural modes in an asymmetric structure(e.g.,nonprismatic beam)provides an optimal condition to easily implement a strong IR with high energy transfer to the internally resonated mode.In this case,the quadratic coupling between these flexural modes,originating from the stretching effect,is the dominant nonlinear mechanism over other types of geometric nonlinearity.The design strategies proposed in this paper can be integrated into a typical micro/nanoelectromechanical system(M/NEMS)via a simple modification of the geometric parameters of resonators,and thus,we expect this study to stimulate further research and boost paradigm-shifting applications exploring the various benefits of IR in micro/nanosystems.展开更多
文摘Photocatalytic degradation attracts considerable attention because it is a promising strategy to treat pollutants from industrial and agricultural wastes. In recent years, other than the development of e cient photocatalysts, much e ort has been devoted to the design of reliable and inexpensive photocatalytic platforms that work in various environment conditions. Here, we describe a novel photocatalytic platform that is able to float and freely move atop water while performing photodegradation. Compared to common platforms, such as slurry reactors and immobilized photoreactors, the proposed platform is advantageous in terms of easy recycling and energy saving. Furthermore, the special configuration resulting from a two-step synthesis route, semi-embedded photocatalysts, addresses some of the remaining challenges, for instance, the contamination from the loose photocatalysts themselves. For the probe pollutant, methylene blue(MB), a reproducible and remarkable degradation activity of the platform, is observed and the e ect of two primary factors, including surface area of the catalyst and mass transfer rate, is investigated. Besides, the piezo-photocatalysis e ect, serving as an additional functionality, is confirmed to further improve the degradability of the platform, which o ers an additional 20% of degraded MB. At last, the promising result of the degradation toward crude oil reveals the possibility of the platform to be used in gasoline pollution treatment.
基金the Defense Advanced Research Projects Agency(Young Faculty Award D16AP00110)。
文摘Exploiting nonlinear characteristics in micro/nanosystems has been a subject of increasing interest in the last decade.Among others,vigorous intermodal coupling through internal resonance(IR)has drawn much attention because it can suggest new strategies to steer energy within a micro/nanomechanical resonator.However,a challenge in utilizing IR in practical applications is imposing the required frequency commensurability between vibrational modes of a nonlinear micro/nanoresonator.Here,we experimentally and analytically investigate the 1:2 and 2:1 IR in a clamped–clamped beam resonator to provide insights into the detailed mechanism of IR.It is demonstrated that the intermodal coupling between the second and third flexural modes in an asymmetric structure(e.g.,nonprismatic beam)provides an optimal condition to easily implement a strong IR with high energy transfer to the internally resonated mode.In this case,the quadratic coupling between these flexural modes,originating from the stretching effect,is the dominant nonlinear mechanism over other types of geometric nonlinearity.The design strategies proposed in this paper can be integrated into a typical micro/nanoelectromechanical system(M/NEMS)via a simple modification of the geometric parameters of resonators,and thus,we expect this study to stimulate further research and boost paradigm-shifting applications exploring the various benefits of IR in micro/nanosystems.
