Photochemically Activated Motors : From Electrokinetic to Diffusion Motion Control
Zhang, Kuan (Institut Català de Nanociència i Nanotecnologia)
Fraxedas, Jordi (Institut Català de Nanociència i Nanotecnologia)
Sepúlveda, Borja (Institut Català de Nanociència i Nanotecnologia)
Esplandiu Egido, Maria José (Institut Català de Nanociència i Nanotecnologia)

Data:	2017
Resum:	Self-propelled micro/nanomotors that can transform chemical energy from the surrounding environment into mechanical motion are cutting edge nanotechnologies with potential applications in biomedicine and environmental remediation. These applications require full understanding of the propulsion mechanisms to improve the performance and controllability of the motors. In this work, we demonstrate that there are two competing chemomechanical mechanisms at semiconductor/metal (Si/Pt) micromotors in a pump configuration under visible light exposure. The first propulsion mechanism is driven by an electro-osmotic process stemmed from a photoactivation reaction mediated by HO, which takes place in two separated redox reactions at the Si and Pt interfaces. One reaction involves the oxidation of HO at the silicon side, and the other the HO reduction at the metal side. The second mechanism is not light responsive and is triggered by the redox decomposition of HO exclusively at the Pt surface. We show that it is possible to enhance/suppress one mechanism over the other by tuning the surface roughness of the micromotor metal. More specifically, the actuation mechanism can be switched from light-controlled electrokinetics to light-insensitive diffusio-osmosis by only increasing the metal surface roughness. The different actuation mechanisms yield strikingly different fluid flow velocities, electric fields, and light sensitivities. Consequently, these findings are very relevant and can have a remarkable impact on the design and optimization of photoactivated catalytic devices and, in general, on bimetallic or insulating-metallic motors.
Ajuts:	Ministerio de Economía y Competitividad MAT2015-68307-P Ministerio de Economía y Competitividad PCIN-2016-093 Ministerio de Economía y Competitividad SEV-2013-0295
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Llengua:	Anglès
Document:	Article ; recerca ; Versió sotmesa a revisió
Matèria:	Catalytic motors ; Photoactivation ; Chemomechanical actuation ; Electro-hydrodynamics forces ; Light-driven motors
Publicat a:	ACS applied materials & interfaces, Vol. 9, Issue 51 (December 2017) , p. 44948-44953, ISSN 1944-8252

DOI: 10.1021/acsami.7b15855

Preprint 11 p, 1.2 MB

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Documents de recerca > Documents dels grups de recerca de la UAB > Centres i grups de recerca (producció científica) > Ciències > Institut Català de Nanociència i Nanotecnologia (ICN2)
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