Heterolayered TiO2@layered double hydroxide-MoS2 nanostructure for simultaneous adsorption-photocatalysis of co-existing water contaminants

• Published in: Applied surface science 2021-07, Vol.553, p.149577, Article 149577
• Main Authors: Panchal, Deepak, Sharma, Abhishek, Mondal, Prasenjit, Prakash, Om, Pal, Sukdeb
• Format: Article
• Language: English
• Subjects: Heterolayered-nanostructure; Layered double hydroxide (LDH); Molybdenum sulfide (MoS2); Multifunctional; Self-regeneration; Water treatment
• ISSN: 0169-4332; 1873-5584
• DOI: 10.1016/j.apsusc.2021.149577

[Display omitted] •Eliminating various pollutants with diversity using single material is a huge task.•Multifunctional T@L/M is synthesized by assembly of defect-rich MoS2 and TiO2@LDH.•Achieved removal of multiple pollutants of different physicochemical properties.•Strong self-regeneration is achieved with extended photoactivity in visible-region.•Exhibited excellent affinity and selectivity (Kd ~ 107 mL/g) towards metal-ions. The highly ordered heterolayered-nanostructure TiO2@Layered double hydroxide/Molybdenum disulfide (TiO2@LDH/MoS2; T@L/M) is formed by electrostatically-driven self-assembly of positively charged TiO2-dispersed-LDH layers (T@L) and negatively charged MoS2 nanosheets. TiO2 are incorporated in-situ across the LDH during synthesis yielding exfoliated TiO2-dispersed-LDH layers (T@L). Prior to MoS2 assembly, its interlayer spacing is enlarged and defects are created in basal-plane exposing sulfur-rich sites. Visible-light-active MoS2 and TiO2 synthesized heterostructure extending the T@L/M photoactivity in visible spectrum (2.92 eV) for enhanced degradation capacity. This enables a strong adsorptive-photocatalytic dual modality removal of both cationic and anionic organic dyes (97–99%) that usually cannot be achieved using one material facilitating visible-light-driven self-regeneration of exhausted adsorption sites. While dye removal efficiency varies within (4–7) % of the first cycle over 5 repeated uses, it simultaneously enables excellent affinity and selectivity for heavy metal ions (distribution coefficient ~107 mL/g for Ag+, Pb2+) with enormous adsorption capacity for single metal ion 421.8 mg/g (Ag+) which is at the top of materials known for such removal. It rapidly lowers toxic Pb2+ (from 10 mg/L to ≤0.8 µg/L) well below the standard drinking water limit. The self-regenerating heterostructure for targeting and removing multiple water pollutants of diverse physicochemical properties has not been reported until now.