Batteries to the rescue: the formation of Pt bioelectrocatalysts with Shewanella oneidensis MR-1 and commercial batteries

Abstract

Platinum nanoparticles are active towards many reactions relevant to energy and environmental applications. The biosynthesis of platinum nanoparticles from ionic platinum solutions needs an electron donor to yield nanoparticles. Molecular hydrogen and formate are the electron donors of choice for generating platinum nanoparticles and can be used as reducing agents without microorganisms. We hypothesized that the metal ions adsorbed on a microorganism surface can be transformed to nanoparticles in the presence of an electron source, even in the absence of an organic electron donor. To test the hypothesis, a bioelectrochemical setup was designed that allowed the connection of a commercial 1.5 V battery to a bioelectrode in a platinum solution. The platinum reduction efficiency of the battery-bioelectrode system was compared to experiments that involved (1) a battery and an abiotic electrode, and (2) a bioelectrode that was not connected to the battery. The reduction efficiency was determined by a combined study of optical emission spectroscopy and atomic emission spectroscopy. Platinum nanoparticles were revealed by transmission electron microscopy. The electrochemical performance was evaluated by cyclic voltammetry. Platinum nanoparticles were formed only when the bioelectrode was connected to the battery, evidenced by the well-known platinum cyclic voltammetry.