Sulfur-doped Sb4Mo10O31 bimetallic sulfur-oxide catalyst for highly efficient reduction of toxic organic and hexavalent chromium under dark

Sulfur-doped Sb4Mo10O31 bimetallic sulfur-oxide catalyst (labeled as SbMoSO) was synthesized by thermal hydrolysis using different amounts of S precursor CH3CSNH2 (TAA). SbMoSO catalysts for reducing toxic organic pollutants (4-nitrophenol (4-NP)), organic dyes (Methyl orange (MO), Methylene blue (MB), Rhodamine B (RhB)), and heavy metal ions Cr(VI) in water were studied. SbMoSO-2 catalyst showed the best catalytic performance. 10 mg SbMoSO-2 ultimately reduced 100 mL of 10 ppm 4-NP within 10 min in the presence of 5 mg NaBH4, while 100 mL of 50 ppm MO, 20 ppm MB, and 50 ppm RhB solutions were reduced entirely within 10 min, 6 min, and 8 min, respectively. The activity of the used catalyst, which was recovered and dried, was tested again for the sixth time and was still up to 95.3%. SbMoSO also performed good stability and durability for reducing organic pollutants and heavy metal ions. The fact of heterovalent conversion of Mo4+ ↔ Mo6+ is conducive to electron transfer and lowers the electron-hole recombination efficiency. Likewise, the stack nanosheet-like morphology of the catalyst can also provide a larger specific surface area and more active sites to facilitate the reduction reaction. Therefore, this study illustrates that the S incorporation into metallic/bimetallic oxides is a promising approach for designing the tuned electronic structure of metallic/bimetallic sulfur-oxide catalysts with boosted catalytic performance.