Effect of metal content on the electrocatalytic activity of AuxPdy mixtures and their use in a glucose membraneless microfluidic fuel cell

Abstract

Au_xPd_y bimetallic mixtures with different elemental contents were synthesized on glassy carbon electrodes using electrochemical techniques, which are easy, quick, versatile and cheap. Pulse potential and staircase techniques such as cyclic voltammetry (Au₆₀Pd₄₀), square-wave voltammetry (Au₅₀Pd₅₀ and Au₃₅Pd₆₅) and second harmonic AC voltammetry (Au₁₅Pd₈₅) were used to easily change the metal proportion and reduce the Au content in the Au_xPd_y mixtures. Au₆₀Pd₄₀ exhibited the most negative potential (−0.4 V vs. NHE) towards the glucose electro-oxidation reaction. For this reason, it was used in the anode compartment of a microfluidic fuel cell and compared with single Au and Pd materials by cyclic voltammetry. Au₆₀Pd₄₀ showed a greater negative potential than that of the Au anode; meanwhile, Pd showed no electrocatalytic activity. The lattice parameters were calculated by X-ray diffraction patterns resulting in values of 3.83 and 4.03 Å for Au and Pd, respectively, and 3.94 Å for Au₆₀Pd₄₀, which provides evidence for the internal structural changes due to the incorporation of Pd to the Au matrix. The maximum power density obtained with a glucose membraneless microfluidic fuel cell (GMMFC) using 10 mM glucose and Au₆₀Pd₄₀ as the anode was 0.28 mW cm⁻².