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

Effects of the sodium acetate (NaCH3COO, denoted as NaAcO) concentration, plating temperature, and oxide loading on the pseudocapacitive characteristics of hydrous ruthenium oxide (denoted as RuO2·xH2O) films anodically plated from aqueous RuCl3·xH2O media were systematically investigated in this work. The electrochemical behavior of RuO2·xH2O 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 RuO2·xH2O deposits strongly depend on the deposition rate which is obviously influenced by varying the above two deposition variables. The specific capacitance of RuO2·xH2O 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 RuO2·xH2O. All RuO2·xH2O deposits show the ideal pseudocapacitive characteristics, definitely illustrating the merits of RuO2·xH2O prepared by anodic deposition without considering the advantages of its simplicity, one-step, reliability, low cost, and versatility for electrode preparation.