Effect of GO phase in Zn(OH)2/GO composite on the extent of photocatalytic reactive adsorption of mustard gas surrogate

• Zn(OH)2/GO composites of relatively high surface areas were synthesized.
• Zinc hydroxide/GO composites show high photocatalytic activity for CEES degradation.
• Terminal hydroxyl groups govern reactive adsorption of CEES.
• GO increases the dispersion of active inorganic phase and surface heterogeneity.
• GO increases the photo-reactivity and thus the decontamination efficiency.

Composites of zinc hydroxide with various contents of graphite oxide (GO) were synthesized with a controlled precipitation rate. They were used at ambient conditions as adsorbents of a mustard gas surrogate, 2-chloroethyl ethyl sulfide (CEES). The samples’ surface features were characterized by various physical and chemical methods. The materials acted as photocatalysts upon light irradiation, degrading CEES to less- or no-toxic compounds. Exposure to visible light and the presence of GO in the composites improved the performance. The results indicated a paramount role of terminal OH groups as well as the porosity in the reactive adsorption process. The enhanced performance is linked to an increase in the degree of chemical and structural heterogeneity upon addition of GO. The surface characteristics strongly depend on the amount of the carbonaceous phase and 10 wt% was found as an optimal content. The CEES degraded mainly to ethyl vinyl sulfide by dehydrohalogenation and to hydroxyethyl ethyl sulfide via a hydrolysis pathway. The irradiation under visible light led to further transformation to vinyl vinyl sulfide and methyl vinyl sulfide through radical's reaction. The presence of GO promotes the electrons transfer and oxygen activation.

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