Water splitting for hydrogen production using a high surface area RuO ₂ electrocatalyst synthesized in supercritical water

In water electrolysis, a major obstacle is the anodic reaction for water oxidation where substantial energy loss occurs mainly due to the large overpotential. Therefore, the electrocatalytic material of an anode is of importance to achieve a highly efficient water splitting reaction. Among the various requirements, the surface area of electrocatalysts has been considered a key factor in electrocatalytic reactions. In this study, to obtain a high surface area RuO₂ electrocatalyst, a supercritical hydrothermal synthetic method was applied. Indeed, RuO₂ particles with the surface area of 78.2 m²/g were successfully synthesized, which is 7 times higher compared with the commercial version. We also investigated the electrocatalytic activity of the synthesized high surface area RuO₂ by evaluating the number of active sites and hydrogen production rates and compared them with the commercial one as a reference. Based on the cyclic voltammetric measurements, the number of active sites was estimated to be 152.1 mC cm^-2 and 17.0 mC cm^-2 for the synthetic and the commercial RuO₂, respectively. More importantly, the hydrogen production rates measured by the water splitting device with RuO₂ films for the anode showed 4 times higher value for the synthetic RuO ₂ compared with the commercial one.