Analysis of Ruthenium Electrodeposition in the Nitric Acid Medium

The electrochemical redox and electrodeposition behaviors of nitrosyl ruthenium in nitric acid solution were systematically investigated by electrochemical quartz crystal microbalance analysis and cyclic voltammetry. The results show that the reduction of ruthenium is carried out in steps. The reduction current of Ru(III) to Ru(II) was observed at 0.05 V. A cathode current peak was recorded between -0.2 and -0.5 V, accompanied by a significant mass gain, which was confirmed to be the electrodeposition of metal ruthenium. During the oxidation process, the deposited Ru was slowly oxidized at a low oxidation potential, and the Ru dissolved violently at 0.75 V, resulting in a rapid degradation of the surface quality of the electrode. The electrodeposition kinetic parameters and nucleation growth mechanism of ruthenium in the nitric acid system were revealed by means of electrochemical measurement and model fitting, and the electrocrystallization of ruthenium was determined as instantaneous nucleation. After potentiostatic deposition on different substrates, it is found that the coating on the glassy carbon (GC) sheet presents a crumbly and coiled structure, while the surface of the coating on the Pt sheet is smoother and has a neat fracture edge.