Electrocatalytic Hydrogen Evolution Reaction with Multilayer Graphene-Covered Ni Particles Synthesized by Microwave-Assisted Catalytic Methane Decomposition

Abstract

It is known that the type of electrocatalysts used in the hydrogen evolution reaction (HER) are critical for energy technologies such as water splitting and hydrogen fuel cells. Thus, in recent years, increasing attention has been paid to the development of noble metal-free electrocatalysts. It has recently been reported that Ni–C-based catalysts exhibit HER activity comparable to that of Pt in an acidic medium. Moreover, we have recently developed a new metal–carbon powder, which contained multilayer graphene-covered Ni particles as the main component, synthesized by multimode microwave-assisted catalytic CH4 decomposition using a multimode microwave reactor. Thus, in this study, we investigated the electrocatalytic HER over the Ni–C powder using a digital potentiostat equipped with a potential sweep unit. Figure 1 shows the current–potential curve in the presence or absence of dissolved oxygen in an aqueous H2SO4 solution; the curve was obtained using a carbon paste electrode filled with the Ni–C powder. A reduction current based on HER was observed from approximately 0.0 V (referred vs. SHE), while the onset potential was shown to be slightly affected by the presence or absence of dissolved oxygen. Therefore, the Ni–C powder can be used as a noble metal-free electrocatalyst to implement the HER with excellent electrochemical performance in acidic medium. *Figure 1. Linear sweep voltammograms with the carbon paste electrode (Φ = 3 mm) filled with the Ni–C powder, synthesized by a multimode microwave-assisted process in an acidic solution under different atmospheres. SR = 10 mV/s. Figure 1