Porous electrodes from self-assembled 3D jointed Pd polyhedra for direct formic acid fuel cells

The direct formic acid fuel cell (DFAFC) is recognized as a promising power source for its high electromotive force, easy fuel storage and transport. However, its power performance is low and the cost is high, which are known to originate from the sluggish formic acid oxidation (FAO) kinetics and poor mass transport within the DFAFC anode. Here, we present a new DFAFC anode design with a thin, porous, 3D-structured catalyst layer based on self-assembled jointed Pd polyhedra in-situ grown on the gas diffusion layer surface. The Pd polyhedra provide highly active jointed interfaces and high-index facets, boosting their catalytic activity towards FAO. The porous 3D catalyst layer facilitates the transport of reactants and products at the large current density region. Consequently, the present anode design exhibits a previously unachieved power density of 202 mW cm−2 at a Pd loading of 1.0 mg cm−2 in the HCOOH/air DFAFC test.