Discrete and aggregated nanoparticles offer tremendous design flexibility, yet methods to assemble them into extended 3-dimensional structures suffer from a number of limitations. Complex linker systems and multi-step procedures result in time intensive processes that are further increased by the removal of templates, often by chemically harsh methods. Another practical challenge of many porous metal materials has been the limitation and control of monolith size and shape, consequently impeding their use in actual devices. To address this challenge, a synthesis approach for 3-dimensional copper nanowire films is demonstrated using DNA as a biotemplate. The general approach described here is to 1) form a covalently cross-linked DNA hydrogel; 2) sensitize the DNA biotemplate gel using catalytic palladium ions to mediate electroless deposition; and 3) synthesize copper 3-dimensional networks via electroless deposition. Covalent crosslinking of DNA template molecules is achieved using ethylene glycol diglycidyl ether. A copper electroless deposition solution consisting of CuSO<sub>4</sub>●5H<sub>2</sub>O, ethylenediamino tetraacetic acid, disodium, dehydrate, 3-(N-morpholino) propanesulfonic acid buffer, and dimethyl amine borane reducing agent was used for metal deposition and to control final metal to biotemplate mass ratio via deposition time. Electroless deposition on palladium sensitized biomolecular templates resulted in 3-dimensional porous nanowire networks within macroscopic films approximately 10 µm thick as seen with scanning electron microscopy. X-ray diffractometry and energy dispersive X-ray spectroscopy confirms metal content in excess of 98% with minimal oxide presence. Electrochemical impedance spectroscopy, cyclic voltammetry, and nitrogen gas adsorption are used to determine surface area and pore structure. Biotemplating with electroless deposition is envisioned to facilitate a range of porous metal composite materials for energy storage, catalytic and sensor applications.

DNA biotemplated 3-dimensional copper nanowire composite films

2019 Spring National Meeting

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