A highly efficient bifunctional Z-scheme photocatalyst with spatially-separated and synergistically-enhanced adsorption and photodegradation

Adsorption-enhanced photodegradation and its unique kinetics are studied in a bifunctional Z-scheme photocatalyst. MoS₂ nanoflakes are selectively deposited on the edges of TiO₂ nanosheets to form an edge-connected MoS₂/Au/TiO₂ Z-scheme heterostructured photocatalyst, with rapid pollutant adsorption on MoS₂ surfaces and subsequent degradation on TiO₂ surfaces. The spatial separation of two components promotes the formation of Z-scheme charge transfer and maintains the effective bifunctions. As a result, the optimal system (10 %MoS₂/Au/TiO₂) could remove up to 90 % of pollutant within 30 mins and subsequently eliminates the residue to a level below ppm. Detailed study on the synergistic effects of adsorption and photodegradation indicates that the system exhibits an adsorption-enhanced photodegradation due to the pre-concentration effect by MoS₂ and a surface-diffusion mechanism of pollutant molecules migrating from MoS₂ to TiO₂. This work provides a novel strategy in designing the bifunctional photocatalyst for effective water treatment.