Oxygen vacancy enhanced catalytic oxidation of H2S based on ZnO-incorporated N-doped hollow carbon nanofibers for cathode construction for high-performance Li–S batteries

Abstract

As one of the most toxic pollutants, hydrogen sulfide (H₂S) is hazardous to human health and the environment. Selective oxidation of H₂S to elemental sulfur (S) over carbon-based catalysts has emerged as an interesting solution owing to the advantages of low reaction temperature (20–30 °C), high desulfurization efficiency and accuracy. Interestingly, the produced carbon–sulfur composites could be directly used as cathodes for high-performance lithium–sulfur batteries (LSBs). Herein, a carbon-based catalyst consisting of nitrogen-doped hollow carbon nanofiber (NHCF) loading oxygen-deficient ZnO (O_d-ZnO/NHCFs) is fabricated to achieve this integrated application. The oxygen vacancy in O_d-ZnO/NHCFs is able to enhance the chemisorption of H₂S and generates a ZnO/ZnS heterostructure; besides, it can enrich O₂˙⁻ radicals through electrostatic interaction to improve the catalytic oxidation of adsorbed H₂S to elemental sulfur. Meanwhile, the hollow framework of NHCFs enables rapid gas diffusion and adequate storage space for solid sulfur; thus, the in situ construction of a high S-loading cathode (S@O_d-ZnO/ZnS/NHCFs) for LSBs is realized during the desulfurization process. More importantly, the formed ZnO/ZnS heterostructure can boost the electrochemical kinetic behavior in the discharge/charge processes of LSBs. Coupled with the physical confinement of hollow structures on polysulfides, the as-prepared S@O_d-ZnO/ZnS/NHCF cathode exhibits outstanding electrochemical performance in LSBs. This work opens up a new avenue for the synergistic application of high-performance LIB electrodes for the control and conversion of sulfur-containing pollutants.