Codeposited Bimetallic Pt-Pd Catalyst Supported on MWCNTs/Carbon Cloth as an Efficient DFAFC Anode Material

Direct formic acid fuel cell (DFAFC) is a promising energy source for portable devices due to its high theoretical open-circuit voltage (1.45 V), high power density, and the use of a nearly nontoxic fuel. To make DFAFC commercially feasible, it is necessary to develop an efficient catalyst for formic acid (FA) electrooxidation. Here, we present a nanostructured catalyst based on the Pd_0.64Pt_0.36 nanoparticles (Pd_0.64Pt_0.36 NPs) immobilized onto a carbon cloth-supported MWCNTs surface. The Pd_0.64Pt_0.36 NPs were electrochemically formed under potentiodynamic conditions by using linear sweep voltammetry (LSV) by electroreduction of PtCl₄ and Pd-(OAc)₂ precursors, previously immobilized inside the MWCNTs framework. The resulting catalyst forms ∼4 nm diameter spherical NPs, well-separated from each other and uniformly decorating the entire MWCNTs surface. XRD analysis showed the presence of Pd- and Pt-rich phases, while DRIFT measurements clearly indicate that the catalyst is resistant to CO poisoning and much more active compared to pure Pd and Pt metal catalysts. The Pd_0.64Pt_0.36 catalyst has a high ECSA value (56.94 m²/g) and at least 80% active site availability. These parameters explain its high activity and stability toward FA electrooxidation. The performance of the Pd_0.64Pt_0.36 catalysts as an anode was evaluated in a DFAFC cell at a temperature of 60 °C and cathodic airflow of 200 mL/min. A long-term stability study measured under a 50 mA/cm² load (14 h) for 3 M HCOOH showed excellent durability of the catalyst. DFAFC with a Pd_0.64Pt_0.36 catalyst shows an excellent power density value of 64 mW/cm² at 250 mA/cm².