Formic acid electrooxidation on Ni-supported platinum thin film catalyst

Abstract

Pollution caused by the usage of fossil fuels is a consequence of industrialization, urbanization, and technological development, having a huge impact on the environment and human health. Thus, one of the biggest challenges that currently confront not only the scientific community but also humanity is reducing the use of fossil fuels, as well as the production and consumption of energy using renewable energy sources. In the last decades, small organic molecules such as methanol, ethanol and formic acid have attracted attention due to their properties that make them convenient for use in fuel cells. Among other precious metals, Pt is the most investigated as a promising catalyst for the anodic electrooxidation reaction of small organic molecules. However, high price, scarceness and susceptibility to poisoning are some of the limiting factors for the commercial use of pure Pt. There are two ways to mitigate those problems: lower the content of a noble metal present or make the catalyst more active for the particular reaction. To address the first problem nanocatalyst, produced by the deposition of platinum onto high surface area supports were introduced. A far greater challenge is to modify the catalyst to make it not just more active, but more stable as well, for a particular reaction. It is now well known that bimetallic catalysts fulfill these requirements quite well, and currently, they are widely used in many catalytic and electrocatalytic processes. In this study, a thin Pt film was electrochemically deposited on nickel support (Pt/Ni) and afterward subjected to the controlled thermal treatment in an attempt to reduce the proneness of Pt to poisoning species (CO) and therefore improve its catalytic performance at low potentials in the formic oxidation reaction. All produced catalysts were electrochemically characterized using cyclic voltammetry and oxidation of CO monolayer, while the influence of thermal annealing on the morphology was monitored using an atomic force microscope (AFM). Finally, catalyst performance was tested in a formic acid electrooxidation reaction. The obtained results clearly show that the exceptional activity for formic acid electrooxidation, measured on annealed Pt/Ni is a direct consequence of the nature of the substrate which manifests itself after controlled heat treatment through surface reconstruction and bifunctional effect.