Solid-state synthesis of Pt/C cathode catalysts for direct methanol fuel cells

Abstract

To alleviate the world's current energy demand, there is a need for alternative energy sources and fuel cells play a significant role. The efficiency of a fuel cell primarily depends on the electrochemical catalytic activity of the catalysts used. Herein, we have synthesized a highly dispersed and efficient carbon-supported platinum-based cathode catalyst (Pt/C) with an excellent oxygen reduction reaction (ORR) for direct methanol fuel cell (DMFC) applications. The 20 wt% Pt/C catalysts are synthesized using a solid-state process at different thermal decomposition temperatures of platinum(II)–acetylacetonate (Pt(acac)₂), where Pt(acac)₂ is used as a precursor for the production of platinum metal and Vulcan-carbon black is used as a support material for platinum loading. The analysis of XRD, Raman, XPS, BET, SEM, TEM and EDX techniques confirmed that the Pt/C cathode catalyst synthesized at 500 °C (Pt/C-500) has a higher crystallinity of platinum, a lower degree of carbon graphitization, a higher surface area of Pt/C and weaker oxyphilic nature, which are highly essential to promote a high ORR activity. In addition, the cyclic voltammetry analyses confirmed a lower onset potential and higher half-wave potential of the ORR in the RDE polarization curve in the Pt/C-500 catalyst along with long-term electrochemical durability as observed in the chronoamperometry curve. Furthermore, the peak power densities of a single DMFC with Pt/C-500 are 82.28 and 92.87 mW cm⁻² at an oxygen backpressure of 0 and 10 psi, respectively, which are 95.9% and 101% higher than those of the commercial 40 wt% Pt/C. Overall, the results demonstrate that the Pt/C catalysts synthesized using the solid-state process have promising applications in DMFCs.