The Effect of SnO<sub>2</sub> and Rh on Pt Nanowire Catalysts for Ethanol Oxidation

In this study, we synthesized Pt-Rh nanowires (NWs) through chemical reduction of metallic precursors using formic acid at room temperature, excluding the use of surfactants, templates, or stabilizing agents. These NWs were supported on two substrates: carbon (Vulcan XC-72R) and carbon modified with tin oxide (SnO₂) via the sol-gel method (10 wt.% SnO₂). We explored the electroactivity of Pt/SnO₂/C, Pt-Rh/C, Pt-Rh/SnO_{2(commercial)}/C (commercial SnO₂), and Pt-Rh/SnO₂/C NWs toward electrochemical oxidation of ethanol in acidic media using various techniques, including CO-stripping, cyclic voltammetry, derivative voltammetry, chronoamperometry, and steady-state polarization curves. Physical characterization involved X-ray diffraction and transmission electron microscopy. The synthesized NWs exhibit higher ethanol oxidation activity than the commercial Pt/C (Johnson Matthey™) catalyst. Rh atoms are hypothesized to enhance complete ethanol oxidation, while the NW morphology improves ethanol adsorption at the catalyst surface for subsequent oxidation. Additionally, the choice of support material plays a significant role in influencing the catalytic activity. The superior catalytic activity of Pt-Rh/SnO₂/C NWs may be attributed to the facile dissociation of the C-C bond, low CO adsorption (electronic effect due to Rh presence), and the bifunctional mechanism facilitated by the oxophilic nature of the SnO₂ support.