Hierarchical nanoporous microtubes for high-speed catalytic microengines

Abstract

Powerful micro-/nano-motors with high speeds and large driving forces in fluids are of great importance in propelling micro-/nanomachines for various tasks. Here, we achieved highly efficient catalytic locomotion in microtubular engines with hierarchical nanoporous walls. The sophisticated structures provide an enlarged surface area and improved reactant accessibility, which remarkably enhanced their catalytic activity toward H2O2 decomposition, accelerating the microengine’s speed. The fast catalytic locomotion of such hierarchical nanoporous microtubes makes them excellent candidates as efficient micro-machines for biomedical applications. Powerful micro-/nano-motors with high speeds and large driving forces in fluids are of great importance in propelling micro-/nanomachines for various tasks. Here, we achieved highly efficient catalytic locomotion in microtubular engines with hierarchical nanoporous walls. The sophisticated structures provide an enlarged surface area and better reactant accessibility, which remarkably enhances their catalytic activity toward H2O2 decomposition, accelerating the microengine’s speed. The fast catalytic locomotion of such hierarchical nanoporous microtubes makes them excellent candidates as efficient micro-machines for biomedical applications. Brownian motion and viscous forces become more important at micro- and nanoscales, significantly affecting the transport of micro- and nano-objects. This phenomenon has practical implications, for example for drug delivery devices in the biomedical field. A variety of synthetic nano-engines have been developed that run on chemical fuels. Typically in these engines, the catalytic decomposition of hydrogen peroxide (H2O2) into H2O and O2 leads to the emission of oxygen bubbles, which induces the device's self-propelling motion. A team of researchers at Fudan University, China, led by Gaoshan Huang and Yongfeng Mei has now devised microtubular engines that move at particularly high speed by enhancing the efficiency of the catalytic activity, which in turn accelerates the motion. The feature arises from the structure of the engines - microtubes rolled up from a titanium-chromium-platinum metallic trilayer with hierarchical porous walls of high surface area.