Atomically Dispersed Selenium Sites on Nitrogen‐Doped Carbon for Efficient Electrocatalytic Oxygen Reduction

Abstract

Owing to their unique electronic structure and maximum atom utilization efficiency, single-atom catalysts have received widespread attention and exhibited efficient activity. Herein, we report the preparation of non-metal Se single atoms embedded in nitrogen-doped carbon (NC) via a high-temperature reduction strategy for electrocatalytic oxygen reduction reaction (ORR). Selenium dioxide is reduced to selenium by NC at high temperature and partially anchored to form CÀ SeÀ C bond. Impressively, the obtained single-atom catalyst exhibits outstanding ORR activity and stability that even surpasses state-of-the-art noble metal catalysts and many previously reported nanocatalysts. Experimental and theoretical calculations reveal that the Se single atoms can serve as the ORR active sites and contribute to lowering the reaction barrier. Our discoveries demonstrate the promising prospects for utilizing metal-free single-atombased materials for efficient electrocatalysis.

Facile synthesis of three-dimensional Co/N co-doped carbon nanocuboids for an enhanced oxygen reduction reaction

“…56,57 The largest value of I D /I G (0.99) is obtained for CoN/CNCs-800, further illustrating the existence of abundant defects and graphitic carbon, which is favorable to improve electron transfer efficiency and promote the electrocatalytic process. 58 As displayed in Fig. 1c and d, the nitrogen adsorption and desorption isotherms (BET) are also used to determine the BET specific surface area and the porous structure of these CoN/CNCs and ZIF-9-800.…”

Long-Range Regulation of Se Doping for Oxygen Reduction of Atomically Dispersed Sb Catalysts for Ultralow-Temperature Solid-State Zn–Air Batteries

“…The Fourier-transformed k 2 -weight-extended XAFS (FE-EXAFS) of Sb–SeNC did not detect the characteristic peak of Sb–Sb at about 2.7 Å (Figure d). Figure e shows that the adsorption edge of Sb–SeNC moves toward a higher energy than Se foil but lower than SeO 2 , indicating that the valence of Se in Sb–SeNC is higher than zero, ,, and also the Se–Se peak was absent in Figure f, demonstrating the atomically dispersed Sb and Se species in Sb–SeNC . Fitting analysis was then performed on the R -space and K -space to discriminate local coordination configurations (Figures g,h and S11).…”

“…Previous studies indicate that atomically dispersed Se is more likely to coordinate with two C atoms to form an energy-stable SeC 2 moiety on the jagged edges of graphene (Figure S28). ,,, Therefore, we also constructed five possible structures to represent the Sb–SeNC catalyst (Figure a). Among these structures, SbN 2 C 2 -1 is a tetra-coordinated structure in which Sb coordinates with two N and two C atoms, where two N and two C atoms are on the same side and in the six-membered ring.…”

“…During pyrolysis, Se species formed by evaporation of SeO 2 can be captured and anchored in NC to form Se−NC. 38 Then, SbCl 3 was adsorbed on the surface of Se−NC by vapor deposition to obtain Sb ad /SeNC. Finally, Sb−SeNC can be synthesized by the second-step pyrolysis of Sb ad /SeNC at 950 °C.…”

“…Figure 2e shows that the adsorption edge of Sb−SeNC moves toward a higher energy than Se foil but lower than SeO 2 , indicating that the valence of Se in Sb−SeNC is higher than zero, 45,47,48 and also the Se−Se peak was absent in Figure 2f, demonstrating the atomically dispersed Sb and Se species in Sb−SeNC. 38 Fitting analysis was then performed on the R-space and K-space to discriminate local coordination configurations (Figures 2g,h and S11). The results show that the Sb atom is coordinated with four (C or N) atoms (marked as SbN x C 4−x ), and the Se atom is coordinated with two C or N atoms (Table S3).…”