Abstract
Effects of the sodium acetate (NaCH 3 COO, denoted as NaAcO) concentration, plating temperature, and oxide loading on the pseudocapacitive characteristics of hydrous ruthenium oxide (denoted as RuO 2 ·xH 2 O) films anodically plated from aqueous RuCl 3 ·xH 2 O media were systematically investigated in this work. The electrochemical behavior of RuO 2 ·xH 2 O with annealing in air at 200 °C for 2 h is approximately independent of the NaAcO concentration and plating temperature although a negative shift in the onset and peak potentials of deposition with rising the plating temperature is found. The morphologies and adhesion of RuO 2 ·xH 2 O deposits strongly depend on the deposition rate which is obviously influenced by varying the above two deposition variables. The specific capacitance of RuO 2 ·xH 2 O is monotonously decreased from 760 to 505 F g -1 when the oxide loading is gradually increased from 0.34 to 1.0 mg cm -2 , due to the longer pathways of both electrons and protons during the redox transitions. The XRD and Raman spectroscopic analyses reveal the extremely localized crystalline nature of as-deposited RuO 2 ·xH 2 O. All RuO 2 ·xH 2 O deposits show the ideal pseudocapacitive characteristics, definitely illustrating the merits of RuO 2 ·xH 2 O prepared by anodic deposition without considering the advantages of its simplicity, one-step, reliability, low cost, and versatility for electrode preparation. © 2007 Elsevier Ltd. All rights reserved.