Highly Dispersed Ruthenium-Based Multifunctional Electrocatalyst

Abstract

A high-efficiency trifunctional electrocatalyst is required for practical applications of regenerative fuel cells, because the hydrogen evolution reaction (HER), oxygen reduction reaction (ORR), and oxygen evolution reaction (OER) are their core electrode reactions. However, implementation of both hydrogen and oxygen electrodes is hindered by low activity and poor stability of electrocatalysts for both water splitting and oxygen reduction. Herein, we report a high-temperature annealing strategy to fabricate a highly dispersed ruthenium-based catalyst embedded onto nitrogen-doped graphene (0.4-Ru@NG-750). The 0.4-Ru@NG-750 catalyst exhibits high trifunctional electrocatalytic activity and good stability in HER, ORR, and OER. The 0.4-Ru@NG-750 electrocatalyst exhibits a low overpotential of only 0.04 and 0.09 V at the current density of 10 mA·cm–2 for HER in 1.0 M KOH and 0.5 M H2SO4, respectively, and 0.372 V for OER in 1.0 M KOH. Moreover, it shows a high half-wave potential of 0.826 and 0.723 V for ORR in 0.1 M KOH and 0.1 M HClO4, respectively. Structural characterizations show that RuN4C x is one of the main structures in 0.4-Ru@NG-750. Density functional theory calculations indicate that the surface states of RuN4C x sites evolve in different reaction conditions. In HER, ORR, and OER, the most stable states should be RuN4C x , RuN4(OH)­C x , and RuN4(O)­C x , respectively, on which the theoretical overpotential is the lowest.

Trifunctional Single‐Atomic Ru Sites Enable Efficient Overall Water Splitting and Oxygen Reduction in Acidic Media

“…Meanwhile, the Ru loading of the Ru-SA/Ti 3 C 2 T x catalyst after 32 h electrolysis is determined to be 0.21 wt%, further confirming its rigorous stability. This finding can be ascribed to the strong interaction between Ru SAs and Ti 3 C 2 MXene support, [28,30] which is beneficial to stabilize the Ru SAs during electrolysis.…”

“…Until recently, only one study has confirmed that single-atomic Ru-N 4 sites can simultaneously catalyze HER, ORR, and OER. [30] However, trifunctional activities for these isolated Ru-N 4 sites in an acidic system still need to be improved for practical acidic electrolysis, and studies on this issue also are extremely limited. Previous studies have reported that the coordination effect of active sites can considerably affect their electronic structures, subsequently tuning their electrocatalytic activity.…”

Defect Electrocatalysts and Alkaline Electrolyte Membranes in Solid‐State Zinc–Air Batteries: Recent Advances, Challenges, and Future Perspectives

“…Atomically dispersed metal catalysts (ADMCs) have recently emerged as a new frontier in catalysis science and have attracted extensive research attention. [ 85–88 ] Traditional heterogeneous catalysts with a broad size distribution of metal particles suffer from a low metal utilization efficiency and poor selectivity. Homogeneous catalysts with well‐defined active sites and tunable coordination environments exhibit excellent activity and exclusive selectivity for a specific reaction.…”

Growth of Highly Active Amorphous RuCu Nanosheets on Cu Nanotubes for the Hydrogen Evolution Reaction in Wide pH Values

“…[18][19][20][21] In particular, rutheniumbased (Ru-based) electrocatalysts are believed to have the great potential to replace commercial Pt/C in HER process because of its highly active performance and lower cost compared to metal Pt. [22,23] Moreover, the effective design of highly active catalysts mainly includes the regulation of component and morphology, size control, the changing of electronic structure for active sites, and so on. At present, different shaped Ru-based catalysts, such as 0D nanoparticles, 1D nanowires (NWs), and 2D nanosheets, were reported to show excellent activity for water splitting.…”