Abstract
Bimetallic catalyst system of ruthenium oxide (RuO2) and niobium oxide (Nb2O5) was prepared using the Adams method and the hydrolysis method. Physical and electrochemical characterizations of the catalysts were studied using X-ray diffraction (XRD), Scanning electron microscopy (SEM), cyclic voltammogram (CV) and polarization measurements. Nb2O5 addition to RuO2 was found to increase the stability of RuO2. In Adams method the sodium nitrate was found to be forming complex with Nb2O5 at high temperature reaction. This makes Adams method unsuitable for the synthesis of RuO2–Nb2O5 bimetallic system. Hydrolysis method on other hand does not have this problem. But a proper mixture of two oxides was not obtained in hydrolysis method. A lower crystallite size for bimetallic system was obtained with Adams method compared to hydrolysis method. RuO2 prepared by Adams method had higher activity compared to the hydrolysis counterpart in electrolyzer operation with nafion membrane. A cell voltage of 1.62 V was obtained with RuO2 (A) at 1 A/cm2. A higher stability for Ru0.8Nb0.2O2(A) compared to RuO2(A) was observed in continuous cyclic voltammogram and electrolyzer cell test.
•RuxNb1−xO2 was prepared as anode catalyst for PEM-water electrolyzer.•Adams method gives a better mixture of RuO2 and Nb2O5 compared to hydrolysis method.•Nb2O5 form sodium complex with NaNO3 in Adams method at temperature above 400 °C.•Hydrolysis method gives poor mixture due to different hydrolyzing nature of precursors.•Addition of Nb2O5 stabilizes the RuO2 catalyst.