Catalytic Activity of Atomic Metals Clusters Decorated Polyaniline Electrodes in Electrochemical Oxidation of 1-Propanol

Abstract

Electrochemical sensors are capable to fast-detect chemicals with a high sensitivity at a low cost. Thanks to these advantages, electrochemical sensors are promising for detections of biomolecules, such as glucose, dopamine, uric acid, etc. The catalytic electrode in a electrochemical sensor is composed of noble noble metals, such as Au and Pd,and a suppoorting material. Polyaniline (PANI)[ 1]is an ideal supporting material for noble metal clusters because of its good electrical conductivity, high stability, large active surface area, and simple preparation process. Recently, PANI decorated with atomic level noble metal clusters is report to show distinct catalytic activity for the electrochemical oxidation of alcohols.[1] However, the effects of the number of the metal atoms in such clusters and the sequence of the atomic level deposition step on their electrocatalytic activity for electrochemical alcohol oxidation remain unexplored.In this presentation, the effects of the number of the metal atoms and the sequence of the atomic level deposition step in the atomic level noble metal clusters on the catalytic activity in electrochemical oxidation of 1-propanol (1-PrOH) are reported. The PANI was deposited on a Pt disk electrode (ϕ = 3 mm) by electrochemical polymerization in a 2 M HBF4 aqueous solution containing 0.1 M of aniline. Then, the PANI deposited electrode was decorated with mono-atomic noble metal clusters, bi-atomic, tri-atomic, or tetra-atomic noble metal clusters. The atomic noble metal clusters are denoted as PdxAuy, where x represents the number of Pd atoms in a cluster and y is the number of the Au atoms. The sources of the Pd and Au were K2PdCl4 and KAuCl4, respectively.. Fig. 1 shows the schematic procedures for fabricating a bi-atomic pure Pd (Pd2) decorated PANI electrode and a PdAu decorated PANI electrode. The catalytic activity for the electrochemical oxidation of 1-PrOH was evaluated by performing cyclic voltammetry measurements with an aqueous solution containing 0.5 M 1-PrOH and 1 M KOH.The catalytic activtiy was found be higher for the Pd2 and Pd4 decorated PANI electrodes than those of the Pd1 and Pd3 decorated PANI electrodes, which revealed odd-even pattern effects as reported in a previous study.[ 1] Furthermore, the catalytic activity was found to be affected by the sequence in deposition of the atomic level noble metal clusters. Reference [1] A. P. Jonke, J. L. Steeb, M. Josowicz, J. Janata, Catal Lett 2013, 143, 531–538. Figure 1