Pd micro-nanoparticles electrodeposited on graphene/polyimide membrane for electrocatalytic oxidation of formic acid

A novel Pd electrocatalyst with flowerlike micro-nanostructures was synthesized by electrochemical deposition on a flexible graphene/polyimide (Gr/PI) composite membrane and characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD). The Pd micro-nanoparticles were prepared on a COOH-CNTs/PI membrane as a comparative sample. The XRD and SEM investigations for Pd electrodeposition demonstrate that the particle size of Gr/PI composite membrane is smaller than that of COOH-CNTs/PI membrane, while the uniform and dense distribution of Pd micro-nanoparticles on the Gr/PI composite membrane is greater than that on the COOH-CNTs/PI membrane. The electrocatalytic properties of Pd/Gr/PI and Pd/COOH-CNTs/PI catalysts for the oxidation of formic acid were investigated by cyclic voltammetry (CV) and chronoamperometry (CA). It is found that the electrocatalytic activity and stability of Pd/Gr/PI are superior to those of Pd/COOH-CNTs/PI catalyst. This is because smaller metal particles and higher dense distribution desirably provide abundant catalytic sites and mean higher catalytic activity. Therefore, the Pd/Gr/PI catalyst has better catalytic performance for formic acid oxidation than the Pd/COOH-CNTs/PI catalyst.