title: Influence of pH on the Motion of Catalytic Janus Particles and Tubular Bubble-Propelled Micromotors.
abstract: Self-propelled miniaturized machines harness the chemical potential of their environment for movement. Locomotion of chemically powered micromotors have been hugely dependent on the surroundings. The use of pH to alter the mobility of micromotors is demonstrated in this work through the manipulation of hydrogen peroxide chemistry in different acidity/alkalinity. The sequential addition of sodium hydroxide to increase the pH of the solution led to a consequent increase in activity of micromotors. Meanwhile, addition of hydrochloric acid compromised the structural integrity of the microstructures, culminating in locomotive changes. Such dramatic changes in activity and velocities of the micromotors allow the usage of this behavior for pH detection. This concept was illustrated with Janus silver micromotors and tubular bimetallic Cu/Pt micromotors. Alteration of pH serves as a useful general strategy for increasing hydrogen peroxide decomposition for enhanced oxygen-bubble propulsion in catalytic micromotors.
authors.affiliation: Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore), Fax: (+65) 6791-1961.
authors.forename: James Guo Sheng
authors.initials: JG
authors.lastname: Moo
authors.affiliation: Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore), Fax: (+65) 6791-1961.
authors.forename: Hong
authors.initials: H
authors.lastname: Wang
authors.affiliation: Division of Chemistry & Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University, Singapore 637371 (Singapore), Fax: (+65) 6791-1961. pumera@ntu.edu.sg.
authors.forename: Martin
authors.initials: M
authors.lastname: Pumera
keywords: Janus particles; hydrogen peroxide; micromotors; pH; sensors