Tailoring the Electronic Structure of an Atomically Dispersed Zinc Electrocatalyst: Coordination Environment Regulation for High Selectivity Oxygen Reduction

Abstract

Accurately regulating the selectivity of the oxygen reduction reaction (ORR) is crucial to renewable energy storage and utilization, but challenging. A flexible alteration of ORR pathways on atomically dispersed Zn sites towards high selectivity ORR can be achieved by tailoring the coordination environment of the catalytic centers. The atomically dispersed Zn catalysts with unique O-and C-coordination structure (ZnO 3 C) or N-coordination structure (ZnN 4 ) can be prepared by varying the functional groups of corresponding MOF precursors. The coordination environment of as-prepared atomically dispersed Zn catalysts was confirmed by X-ray absorption fine structure (XAFs). Notably, the ZnN 4 catalyst processes a 4 e À ORR pathway to generate H 2 O. However, controllably tailoring the coordination environment of atomically dispersed Zn sites, ZnO 3 C catalyst processes a 2 e À ORR pathway to generate H 2 O 2 with a near zero overpotential and high selectivity in 0.1 M KOH. Calculations reveal that decreased electron density around Zn in ZnO 3 C lowers the d-band center of Zn, thus changing the intermediate adsorption and contributing to the high selectivity towards 2 e À ORR.

Oxygenated P/N co-doped carbon for efficient 2e−oxygen reduction to H2O2

“…The above results conclusively signify that O–P/N–C900 can produce H 2 O 2 at high current densities at a large scale. In addition, very high faradaic efficiencies (FEs) of 85% to 95% were achieved in a potential range of 0.1 to 0.3 V, which is higher than most reported values, 40,54,58–66 as compared in Fig. 4D.…”

Tafel Analysis Guided Optimization of ZnNP-O-C Catalysts for the Selective 2-Electron Oxygen Reduction Reaction in Neutral Media

“…Further electronic structure characterizations of M-Zn NP -O-C were performed by X-ray absorption near-edge structure (XANES) and extended X-ray absorption fine structure (EXAFS). As shown in the Zn K-edge XANES spectra (Figure c), the near-edge absorption threshold of M-Zn NP -O-C was located between those of Zn foil and ZnO, suggesting the coexistence of Zn 0 and its oxidation state on the surface. , The FT k 3 -weighted EXAFS spectrum in the R space of M-Zn NP -O-C (Figure d) presented two identifiable peaks of Zn–O (∼1.6 Å) and Zn–Zn (∼2.4 Å) scattering paths, coinciding with the X-ray photoelectron spectroscopy (XPS) (Figure S16). The above results clearly demonstrated that the catalyst featured Zn nanoparticles in which the surface Zn atoms were coordinated with O and uniformly dispersed on the carbon substrate (i.e., Zn–O–C bridge).…”

Low-temperature liquid reflux synthesis of core@shell structured Ni@Fe-doped NiCo nanoparticles decorated on carbon nanotubes as a bifunctional electrocatalyst for Zn–air batteries

“…, were also potential components of multi-metallic systems owing to their rich reserves, controllable electronic structures, and synergistic catalytic properties. 19–21 Typically, NiCo-based materials have attracted extensive attention in recent years owing to their excellent oxygen catalytic activity. 22–26…”