Anodic deposition of hydrous ruthenium oxide for supercapaciors: Effects of the AcO − concentration, plating temperature, and oxide loading

Abstract

Effects of the sodium acetate (NaCH 3COO, denoted as NaAcO) concentration, plating temperature, and oxide loading on the pseudocapacitive characteristics of hydrous ruthenium oxide (denoted as RuO 2· xH 2O) films anodically plated from aqueous RuCl 3· xH 2O media were systematically investigated in this work. The electrochemical behavior of RuO 2· xH 2O 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 2O 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 2O 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 2O. All RuO 2· xH 2O deposits show the ideal pseudocapacitive characteristics, definitely illustrating the merits of RuO 2· xH 2O prepared by anodic deposition without considering the advantages of its simplicity, one-step, reliability, low cost, and versatility for electrode preparation.