Boosting oxygen evolution of single-atomic ruthenium through electronic coupling with cobalt-iron layered double hydroxides

Abstract

Single atom catalyst, which contains isolated metal atoms singly dispersed on supports, has great potential for achieving high activity and selectivity in hetero-catalysis and electrocatalysis. However, the activity and stability of single atoms and their interaction with support still remains a mystery. Here we show a stable single atomic ruthenium catalyst anchoring on the surface of cobalt iron layered double hydroxides, which possesses a strong electronic coupling between ruthenium and layered double hydroxides. With 0.45 wt.% ruthenium loading, the catalyst exhibits outstanding activity with overpotential 198 mV at the current density of 10 mA cm −2 and a small Tafel slope of 39 mV dec −1 for oxygen evolution reaction. By using operando X-ray absorption spectroscopy, it is disclosed that the isolated single atom ruthenium was kept under the oxidation states of 4+ even at high overpotential due to synergetic electron coupling, which endow exceptional electrocatalytic activity and stability simultaneously.

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

“…The Ru XANES result revealed that the absorption edge of Ru-SA/Ti 3 C 2 T x is located between those of Ru foil and RuO 2 (Figure 2a and Figure S5, Supporting Information), indicating that the average valence for the Ru species in Ru-SA/Ti 3 C 2 T x is situated between Ru 0 and Ru 4+ . [28] In the Ru Fourier transform EXAFS (FT-EXAFS) of Ru-SA/Ti 3 C 2 T x , the main peak is observed at ≈1.50 Å (Figure 2b), which is 38% less than the RuRu bond length for the Ru foil (2.42 Å); [19] this result is in agreement with the HAADF-STEM characterization described above (Figure 1e and Figure S1, Supporting Information). Furthermore, the wavelet transform (WT)-EXAFS contour plot of Ru-SA/Ti 3 C 2 T x exhibits only one intensity maximum at 4.6 Å −1 , corresponding to RuO bonding.…”

“…[13] Ru-SA/Ti 3 C 2 T x exhibits a higher C dl (191.1 mF cm −2 ) than those of Ti 3 C 2 T x and Ru-NP/Ti 3 C 2 T x (43.5 and 80.7 mF cm −2 , respectively), indicating that the acidic HER activity for Ru-SA/Ti 3 C 2 T x is remarkably improved mainly related to the existence of Ru SAs. [19] To further investigate the intrinsic catalytic activity of Ru-SA/ Ti 3 C 2 T x , the turnover frequency (TOF), [25,42,43] a figure-of-merit that is independent of the surface area, is calculated according to our previous study (Figure 3d and Figures S8a and S9a, Supporting Information). Notably, the calculated TOF of Ru-SA/ Ti 3 C 2 T x is 2.67 H 2 s −1 (η = 100 mV), which is significantly greater than those of Ru-NP/Ti 3 C 2 T x and Pt/C (0.18 and 1.29 H 2 s −1 , respectively).…”

“…Single-atom (SA) catalysts, [14][15][16][17][18][19][20][21][22][23][24] which are isolated metal sites anchored onto appropriate supports, have been reported to exhibit superior catalytic performance and high selectivity for diverse electrochemical reactions. In this regard, the development of trifunctional SA catalysts can not only considerably reduce the use of noble metals required in electrolysis but also achieve optimized electrochemical performance.…”

“…In addition, Yang et al have reported remarkable acidic HER activity of Ru SA coordinated by fourfold N atoms, while its performance is subpar as compared to that of Pt/C. [19] Recently, Xiao et al have prepared a Ru-N 4 single-site catalyst confined on metal-organic-framework-derived carbon and reported satisfactory acidic ORR activity. [29] Although tremendous efforts have been focused toward the exploration of Ru-SA-based catalysts in acidic electrolytes, they have been used rarely as trifunctional catalysts.…”

Photo/electrocatalysis and photosensitization using metal nanoclusters for green energy and medical applications

“…Therefore, extensive efforts have been made on their miniaturization, the theoretical prediction of the activity and the mechanism. [35][36][37][38] Moreover, research regarding cluster-sized particles is progressing. Chen and Gao reported that dodecanethiolate (C12)protected Pd 6 /AC exhibits a current density 37 times higher than that of commercially available Pt/C at an applied voltage of 1.85 V ( Fig.…”