Engineering Energy Level of Metal Center: Ru Single-Atom Site for Efficient and Durable Oxygen Reduction Catalysis

Abstract

Emerging as a new frontier in heterogeneous catalysis, single-atom site catalysts (SSCs) have sparked enormous attention and bring about new opportunities to oxygen reduction electrocatalysis. Despite considerable progress achieved recently, most of the reported SSCs suffer from either insufficient activity or unsatisfactory stability, which severely retards their practical application. Here, we demonstrate a novel Ru-SSC with appropriate adsorption free energy of OH* (ΔG OH*) to confer excellent activity and low Fenton reactivity to maintain long-term stability. The as-developed Ru-SSC exhibits encouraging oxygen reduction reaction turnover frequency of 4.99 e– s–1 sites–1, far exceeding the state-of-the-art Fe-SSC counterpart (0.816 e– s–1 sites–1), as a result of Ru energy level regulation via spontaneous OH binding. Furthermore, Ru-SSC exhibits greatly suppressed Fenton reactivity, with restrained generation of reactive oxygen species directly observed, thus endowing the Ru-SSC with much more superior stability (only 17 mV negative shift after 20 000 cycles) than the Fe-SSC counterpart (31 mV). The practical application of Ru-SSC is further validated by its excellent activity and stability in a real fuel cell device.

Ru and RuOxdecorated carbon nitride for efficient ammonia photosynthesis

“…22 All the above characterizations confirm the preservation of carbon nitride's structure after loading Ru species, while the specific peaks assigned to Ru species are not observed, again due to the highly dispersed and low amount of Ru loaded. 23,24 TEM was applied to analyse the microstructures of photocatalysts after loading Ru and RuO 2 (Fig. 2).…”

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

“…The above results suggested that the presence of abundant atomically dispersed Ru-O 2 sites is responsible for the significant performance enhancement, as will be discussed later. Moreover, compared to the reported Ru SA catalysts (including single-, dual-, or trifunctional catalysts), [15,16,19,20,27,29,50] our designed Ru single-site catalyst exhibits a competitive advantage in acidic media (Details have been provided in Tables S2-S7, Supporting Information), highlighting the importance of engineering the coordination environment of a single site on its catalytic activity.…”

Recent Advances in Single-Atom Electrocatalysts for Oxygen Reduction Reaction

“…Theoretical calculations revealed that ORR activity of Ru-N/G-750 originated from the Ru-oxo-N 4 moieties rather than Ru-N 4 moieties [ 148 ]. Xiao et al further reported that a Ru-based SAEC (Ru-SSC) showed unprecedented TOF up to 4.99 e − s −1 site −1 , far surpassing the benchmark Fe-SSC counterpart (0.816 e − s −1 site −1 ) [ 149 ].The excellent ORR activity of Ru-SSC could be attributed to the suitable OH∗ adsorption-free energy. In addition, Ru-SSC showed low Fenton reactivity, which enables the Ru-SSC much better durability (only 17 mV negative shift after 20000 cycles) than the corresponding Fe-SSC catalyst (31 mV).…”