Abstract
Self-propelled catalytic microjets have attracted considerable attention in recent years and these devices have exhibited the ability to move in complex media. The mechanism of propulsion is via the Pt catalysed decomposition of H2O2 and it is understood that the Pt surface is highly susceptible to poisoning by sulphur-containing molecules. Here, we show that important extracellular thiols as well as basic organic molecules can significantly hamper the motion of catalytic microjet engines. This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing -SH, -SSR, and -SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines. It is essential that the presence of such molecules in the environment be taken into consideration for future design and operation of catalytic microjet engines. We show this effect on catalytic micromotors prepared by both rolled-up and electrodeposition approaches, demonstrating that such poisoning is universal for Pt catalyzed micromotors. We believe that our findings will contribute significantly to this field to develop alternative systems or catalysts for self-propulsion when practical applications in the real environment are considered.
Highlights
IntroductionCatalytic micro/nanomotors have attracted much interest amongst researchers.[1,2,3,4,5,6,7] It is hoped that these micro/nanomotors can be operated autonomously in various natural environments, such as biological liquids and environmental waters, in order for them to perform critical tasks which can include microsurgeries,[8,9,10] the discovery of natural resources[11] or aid in environmental remediation.[12,13] These catalytic micro/nanomachines can be powered by various mechanisms, such as self-electrophoresis, self-diffusiophoresis or bubble jet ejection.[3] While the feasibility of the former two phoretic mechanisms has been demonstrated, the bubble-jet mechanism has recently been heavily investigated as it allows fast motion of the micro/nanodevices with a signi cant power output
This is due to two different mechanisms: (i) molecules such as dimethyl sulfoxide can quench the hydroxyl radicals produced at Pt surfaces and reduce the amount of oxygen gas generated and (ii) molecules containing –SH, –SSR, and –SCH3 moieties can poison the catalytically active platinum surface, inhibiting the motion of the jet engines
We demonstrate that certain biomolecules and simple organic molecules containing sulphur moieties can signi cantly inhibit the motions of the microjets
Summary
Catalytic micro/nanomotors have attracted much interest amongst researchers.[1,2,3,4,5,6,7] It is hoped that these micro/nanomotors can be operated autonomously in various natural environments, such as biological liquids and environmental waters, in order for them to perform critical tasks which can include microsurgeries,[8,9,10] the discovery of natural resources[11] or aid in environmental remediation.[12,13] These catalytic micro/nanomachines can be powered by various mechanisms, such as self-electrophoresis, self-diffusiophoresis or bubble jet ejection.[3] While the feasibility of the former two phoretic mechanisms has been demonstrated, the bubble-jet mechanism has recently been heavily investigated as it allows fast motion of the micro/nanodevices with a signi cant power output. As for other sulphur containing compounds like sulphoxides, they may be present in environmental waters dedicated for remediation. Most of the current research is focused on fabrication of more
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