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 PdPt nanoparticles (PdPt NPs) immobilized onto a carbon cloth-supported MWCNTs surface. The PdPt NPs were electrochemically formed under potentiodynamic conditions by using linear sweep voltammetry (LSV) by electroreduction of PtCl and Pd-(OAc) 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 PdPt catalyst has a high ECSA value (56.94 m/g) and at least 80% active site availability. These parameters explain its high activity and stability toward FA electrooxidation. The performance of the PdPt 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/cm load (14 h) for 3 M HCOOH showed excellent durability of the catalyst. DFAFC with a PdPt catalyst shows an excellent power density value of 64 mW/cm at 250 mA/cm.