Electronic structure modification of FeWO4 through F doping for enhanced oxygen reduction performance in zinc–air batteries

Abstract

Exploring efficient and stable oxygen reduction reaction (ORR) catalysts for zinc-air batteries (ZABs) holds tremendously significant. Tungsten-based materials have attracted the attention of researchers thanks to abundant resources and excellent stability. Nevertheless, due to the strong adsorption energy for O-containing intermediates, *O and *OH are difficult to desorb from tungsten-based materials during ORR. Here, an F-doping strategy was employed to construct F-doped FeWO4 species composited on a multi-dimensional N-doped carbon (F–FeWO4/NC) as the ORR catalyst for ZABs. The incorporation of F atoms into the main lattice of FeWO4 enhanced the polarity of chemical bonds in FeWO4 through hydrogen bond interactions between H2O molecules and F atoms, further enhancing the polarity and hydrophilicity of F–FeWO4/NC. These changes favored the adsorption and desorption of intermediates as well as the diffusion of electrolyte, and ultimately reduced the ORR overpotential. Therefore, the F–FeWO4/NC catalyst demonstrated excellent ORR activity (E1/2 = 0.85 V vs. RHE). Furthermore, the ZAB with F–FeWO4/NC yielded satisfactory a specific capacity of 800.2 mAh g−1, a peak power density of 173.5 mW cm−2, and charge-discharge cycling stability (over 170 h at 5 mA cm−2). This study is beneficial to improve the ORR intrinsic activity of cheap tungsten-based materials and provides theoretical guidance for their practical application in ZABs.