Ru@RuO₂ Core‐Shell Nanorods: A Highly Active and Stable Bifunctional Catalyst for Oxygen Evolution and Hydrogen Evolution Reactions

Abstract

Ru@RuO2 core‐shell nanorods were successfully synthesized by heat‐treating Ru nanorods with air oxidation through an accurate control of the temperature and time. The structure, composition, dimension, and adsorption property of the core‐shell nanorods were well characterized with XRD and TEM. The catalytic activity and stability were electrochemically evaluated with a rotating disk electrode, a rotating ring‐disk electrode, and chronopotentiometric methods. The Ru@RuO2 nanorods reveal excellent bifunctional catalytic activity and robust stability for both oxygen evolution reaction (OER) and hydrogen evolution reaction (HER). The overpotentials for OER and HER are 320 mV and 137 mV at the current density of 10 mA cm−2, respectively. The catalytic activity of Ru@RuO2 nanorods for OER is 6.5 times higher than that of the state‐of‐the‐art catalyst IrO2 according to the catalytic current density measured at 1.60 V (versus RHE). The catalytic activity of Ru@RuO2 nanorods for HER is comparable to 40% Pt/C by comparing the catalytic current densities at −0.2 V.

Ru/RuO2 Nanoparticle Composites with N-Doped Reduced Graphene Oxide as Electrocatalysts for Hydrogen and Oxygen Evolution

“…However, the HER activity of RuO 2 is unfulfilled. For these reasons, some efforts were devoted to obtaining Ru/RuO 2 nanocomposite electrocatalysts for the overall water splitting. − Zhang et al designed Ru–RuO 2 hybrid nanoparticles decorating carbon nanotubes-based composites (Ru–RuO 2 /CNT) for a large scale of pH using aqueous electrolytes, which can electrolyze water to produce H 2 at an applied voltage of 0.73 V in an asymmetric-electrolyte electrolyzer. Jiang et al developed core–shell Ru@RuO 2 nanorods revealing excellent bifunctional catalytic activity and robust stability for both OER and HER in 0.1 M KOH.…”

“…43−45 Zhang et al 44 designed Ru−RuO 2 hybrid nanoparticles decorating carbon nanotubes-based composites (Ru− RuO 2 /CNT) for a large scale of pH using aqueous electrolytes, which can electrolyze water to produce H 2 at an applied voltage of 0.73 V in an asymmetric-electrolyte electrolyzer. Jiang et al 45 developed core−shell Ru@RuO 2 nanorods revealing excellent bifunctional catalytic activity and robust stability for both OER and HER in 0.1 M KOH. 3D graphene (3D rGO) 46,47 has drawn significant attention because of its unique structure and electronic properties, such as the hierarchical network, large specific surface area, various pore distribution, and excellent electrical conductivity.…”

High‐Index Faceted RuCo Nanoscrews for Water Electrosplitting

“…The selected area electron diffraction (SAED) pattern (Figure 1d) further confirmed the hcp structure of the single crystalline of RuCo NSs, in agreement with the diffraction pattern from the [100] zone axis of Ru ( P 63/ mmc ) (Figure S2, Supporting Information). [ 17–19 ] The atomic‐resolution transmission electron microscopy (TEM) image clearly shows the highly crystalline structure of RuCo NSs along the view of [100] zone axis with the hcp crystal structure (Figure 1e), in which the predominantly exposed crystal lattices spacing are determined to be 0.208 and 0.201 nm and can be attributed to the {002} and {101} planes and with many steps and edges. Both the 3D HAADF‐STEM surface plot image (Figure 1f) and the magnified aberration‐corrected HAADF‐STEM images of the RuCo (Figure 1g; and Figure S3, Supporting Information) clearly show that the nanocrystals with rough surfaces with many steps and edges, and the corresponding fast Fourier transform (FFT) pattern (Figure 1g, inset) also confirmed the hcp phase structure.…”

Earth-Abundant Fe and Ni Dually Doped Co2P for Superior Oxygen Evolution Reactivity and as a Bifunctional Electrocatalyst toward Renewable Energy-Powered Overall Alkaline Water Splitting

“…Water splitting includes two thermodynamically uphill half-reactions: anodic OER and cathodic HER, and requires a theoretical energy input of 1.23 V to ignite. In practice, the extra resistances on both electrodes force the cell voltage to be significantly larger. − Accordingly, electrocatalysts are in demand to lower the energy barrier and overcome the sluggish reaction kinetics. Pt and RuO 2 /IrO 2 are the benchmark electrocatalysts for HER and OER, respectively .…”

“…In practice, the extra resistances on both electrodes force the cell voltage to be significantly larger. − Accordingly, electrocatalysts are in demand to lower the energy barrier and overcome the sluggish reaction kinetics. Pt and RuO 2 /IrO 2 are the benchmark electrocatalysts for HER and OER, respectively . However, the high cost and scarcity of these noble materials hamper their large-scale applications.…”