Highly efficient sulfur production in hydrogen sulfide conversion over Fe3O4 with {111} crystal facets: Unveiling the promotion of oxygen vacancies and basic sites.

High-performance catalysts for the selective catalytic oxidation of hydrogen sulfide (H2S-SCO) are required to achieve the conversion of hazardous H2S into harmless and valuable sulfur for environmental protection and resource utilization. Herein, three different morphologies of Fe3O4 were synthesized and used for H2S-SCO. Octahedral Fe3O4 dominated by {111} crystal facets exhibited excellent performance for H2S-SCO with an H2S conversion of ∼ 100 % and a sulfur selectivity exceeding 94.5 % in stability tests at 150 °C over 60 h. The {111} crystal facets provided weakly to moderately basic sites to promote H2S adsorption and dissociation, as well as abundant oxygen vacancies (OVs) due to lower OV formation energies on this facet, which significantly enhanced the oxidation performance of the catalyst. By revealing the promotions of OVs and basic sites, the relationship between the {111} crystal facets of Fe3O4 and the performance in the H2S-SCO was clarified. This study provides new insights into the design of efficient and stable Fe-based catalysts for the conversion of hazardous H2S from blast furnace gas into valuable sulfur.