Synergistic Co/S co-doped CeO2 sulfur-oxide catalyst for efficient catalytic reduction of toxic organics and heavy metal pollutants under dark conditions

Abstract

The rising accumulation of pollutants, including heavy metals and toxic organics, necessitates effective environmental remediation to protect health and biological systems. In this study, a cubic cerianite CeO2-like Co/S co-doped CeO2 sulfur-oxide catalyst (labeled as CeCoOS) with super catalytic reduction performance of pollutants with NaBH4 as a reducing agent under dark was prepared via a green and facile preparation method. Transition metal Co2+-cation and S2−-anion co-doped CeO2 adjusted the energy bandgap and introduced oxygen vacancy (Vo), which converted Ce4+ around Vo into Ce3+ to maintain electric neutrality. The heterovalent Ce4+/Ce3+ states in Co/S-CeO2 enhance the electron lifetime and facilitate fast electron transfer. The valence transition between Ce4+/Ce3+ and Vo make the Co/S co-doped in CeO2 catalyst increase its electrochemically active surface sites and accelerate the pollutants reduction reaction. The CeCoOS-3 with Co/S dopants has an excellent catalytic reduction activity to completely reduce 20 ppm toxic 4-NP in 10 min, 50 ppm organic dyes of MB, RhB, and MO in 6 min, and 50 ppm heavy metal Cr6+ in 10 min. The CeCoOS-3 sulfur-oxide catalyst also exhibited excellent stability in the reusability test. Therefore, CeCoOS sulfur-oxide catalysts are expected to be used for dye decolorization, detoxification of organic toxins, and reduction of electroplating wastewater.