title: Graphene-Based Microbots for Toxic Heavy Metal Removal and Recovery from Water.
abstract: Heavy metal contamination in water is a serious risk to the public health and other life forms on earth. Current research in nanotechnology is developing new nanosystems and nanomaterials for the fast and efficient removal of pollutants and heavy metals from water. Here, we report graphene oxide-based microbots (GOx-microbots) as active self-propelled systems for the capture, transfer, and removal of a heavy metal (i.e., lead) and its subsequent recovery for recycling purposes. Microbots' structure consists of nanosized multilayers of graphene oxide, nickel, and platinum, providing different functionalities. The outer layer of graphene oxide captures lead on the surface, and the inner layer of platinum functions as the engine decomposing hydrogen peroxide fuel for self-propulsion, while the middle layer of nickel enables external magnetic control of the microbots. Mobile GOx-microbots remove lead 10 times more efficiently than nonmotile GOx-microbots, cleaning water from 1000 ppb down to below 50 ppb in 60 min. Furthermore, after chemical detachment of lead from the surface of GOx-microbots, the microbots can be reused. Finally, we demonstrate the magnetic control of the GOx-microbots inside a microfluidic system as a proof-of-concept for automatic microbots-based system to remove and recover heavy metals.
authors.affiliation: Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany.
authors.forename: Diana
authors.initials: D
authors.lastname: Vilela
authors.affiliation: Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany.|Institute for Bioengineering of Catalonia (IBEC), Baldiri I Reixac 10-12, 08028 Barcelona, Spain.
authors.forename: Jemish
authors.initials: J
authors.lastname: Parmar
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Yongfei
authors.initials: Y
authors.lastname: Zeng
authors.affiliation: Division of Chemistry and Biological Chemistry, School of Physical and Mathematical Sciences, Nanyang Technological University , 21 Nanyang Link, 637371 Singapore, Singapore.
authors.forename: Yanli
authors.initials: Y
authors.lastname: Zhao
authors.affiliation: Max-Planck Institute for Intelligent Systems, Heisenbergstr. 3, 70569 Stuttgart, Germany.|Institute for Bioengineering of Catalonia (IBEC), Baldiri I Reixac 10-12, 08028 Barcelona, Spain.|Institució Catalana de Recerca i Estudis Avançats (ICREA), Psg. Lluís Companys, 23, 08010 Barcelona, Spain.
authors.forename: Samuel
authors.initials: S
authors.lastname: Sánchez
mesh_terms: D006108:Graphite / Q000737:chemistry*; D056656:Lab-On-A-Chip Devices; D019216:Metals, Heavy / Q000737:chemistry*; D014874:Water Pollutants, Chemical / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*
chemical_list: D019216:Metals, Heavy; D014874:Water Pollutants, Chemical; D006108:Graphite
keywords: Graphene; catalytic microswimmers; environmental application; heavy metals; metal recovery; microbots; wastewater treatment