Solid solution palladium-nickel bimetallic anode catalysts by co-sputtering for direct urea fuel cells (DUFC)

A solid solution Pd-Ni alloy co-sputtered on carbon paper (Pd-Ni/C) is explored as a catalyst in the flow-through porous anode of a direct urea fuel cell (DUFC). The catalytic performances of urea electro-oxidation in an alkaline medium are investigated by cyclic voltammetry and chronoamperometry. In order to minimize the effect of morphological variation by the Pd-Ni composition, the island structure with a uniform size or electrochemical surface area was prepared. The Pd-Ni/C electrode shows a much higher electrocatalytic activity and lower onset oxidation potential toward urea electro-oxidation compared to the Ag-Ni/C and Pt-Ni/C electrodes prepared by the same procedure. When the DUFC with a cell configuration of Pd-Ni/C anode and Pd/C cathode operates at room temperature, an open circuit voltage of 0.59 V was obtained with 0.33 molL(-1) urea solution as anolyte and humidification oxygen as the catholyte. The DUFC also exhibits a maximum power density of 1.12 mWcm(-2). The electrocatalytic activity by the developed solid solution is largely attributed to high intrinsic electronic conductivity, excellent porous network structures and a synergetic effect by the constituting bimetallic elements. This work develops a simple type of anode catalyst for DUFC, which can possibly open a promising approach for urea-rich wastewater treatment.