Title : Pt-Co/C catalysts for the oxygen reduction reaction: Effect of composition and preparation conditions
Abstract:
The development of highly active and durable catalysts for the oxygen reduction reaction (ORR) is of great importance for improving the performance and efficiency of proton exchange membrane fuel cells. Platinum-based catalysts are currently among the most effective electrocatalysts for the ORR; however, their high cost and limited availability provide a strong motivation for developing catalysts with reduced Pt content and improved utilization of the noble metal. Alloying Pt with transition metals such as Co represents a promising approach for modifying the electronic and structural properties of Pt-based catalysts and, consequently, their electrocatalytic performance.
In the present study, a series of Pt-Co/C catalysts with different compositions was prepared using a two-step approach based on electroless deposition and subsequent galvanic replacement. In the first step, a Co-P coating was deposited onto Vulcan XC72R carbon powder by an electroless process. In the second step, the Co-P/C precursor was immersed in a chloroplatinate solution, resulting in spontaneous partial replacement of Co by Pt and formation of a Co-rich core and Pt-enriched shell-like surface. Different preparation conditions were applied in order to obtain catalysts with varying Pt/Co ratios and modified structural and surface characteristics. The main objective was to investigate the influence of the preparation parameters on the composition and properties of the resulting Pt-Co/C catalysts and to identify conditions suitable for optimization of their catalytic performance.
The morphology, elemental composition and crystal structure of the prepared materials were investigated using scanning and transmission electron microscopy coupled with energy-dispersive X-ray spectroscopy (SEM/EDS and TEM/EDS), X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The electrochemical behavior of the catalysts was examined by cyclic voltammetry (CV), while their electrocatalytic activity towards the ORR was evaluated by linear sweep voltammetry (LSV). The obtained results will be used to establish relationships between the preparation conditions, Pt-Co composition, particle structure and surface properties of the catalysts. Particular attention will be paid to determining the composition and synthesis conditions that provide favorable characteristics for efficient ORR electrocatalysis.
