Synthesis and Characterization of RuO2 Anode Materials with Large Surface Areas for Oxygen Evolution Reaction

A novel olivary or petal-like RuO2 material with large surface area was successfully synthesized by surfactant-assisted homogeneous precipitation method using urea and dodecyl sulfate as the source reagent. The surface morphology, structural, and electrochemical properties of as-synthesized RuO2 materials were characterized by x-ray diffraction (XRD), field-emission scanning electron microscopy (FE-SEM), Cyclic voltammetry (CV), N-2 adsorption-desorption isotherms and polarization curve for oxygen evolution reaction (OER). It was found that the morphology and crystalline structures and electrochemical properties of as-synthesized RuO2 materials were strongly dependent on the calcining temperature. The ruthenium-surfactant mesophase with mesoporous structure transformed from network to regular olivary or petal-like RuO2 materials and remaining partial mesoporous character after calcination at lower temperature (i.e., 300 and 400 degrees C). However, the mesophase transformed into RuO2 agglomeration consisted of nanosized particles after calcination at 650 degrees C, which may be attributed to complete deorganization and porous structure collapse of RuO2 materials. In addition, the as-synthesized RuO2 materials showed higher specific surface area and better electrochemical activities for oxygen evolution reaction compared with the RuO2 prepared without surfactant. The electrochemical activity of as-synthesized RuO2 material calcined at 400 degrees C is about 3 times than that of RuO2 prepared without surfactant for oxygen evolution reaction. This can be attributed to the porous structure and large surface area of as-synthesized RuO2 materials.