Photo-induced charge separation Z-scheme mechanism in ternary bismuth sulfide coupled SnS/Al 2 O 3 nanostructure

The establishment of a solid-state Z-scheme heterojunction photocatalytic system to efficiently tailor photoinduced charge separation is of great significance to water purification. A structure of metal sulfide nanoparticles, tin monosulfide (SnS) and bismuth sulfide (Bi 2 S 3 ) in host alumina (Al 2 O 3 ) was developed by the sol–gel method. FTIR confirmed complete dispersion of SnS and Bi 2 S 3 nanoparticles in Al 2 O 3 having a cubic structure. The band gap energy ( E g ) of the ternary nanocomposite was found to be 1.85, 1.68 and 1.10 eV for 4.0, 8.0 and 12.0% bismuth sulfide coupled SnS/Al 2 O 3 respectively. The marked decrease in E g can be attributed to the tenacious agglomeration among SnS, Bi 2 S 3 and Al 2 O 3 . 99.0% methyl orange (MO) removal was achieved with 12.0% bismuth sulfide coupled SnS/Al 2 O 3 due to efficient and quick charge transfer among Al 2 O 3 and chalcogenides via Z-scheme electron transfer mechanism. Electrochemical measurements such as those of linear sweep voltammetry and cyclic voltammetry manifested that bismuth sulfide coupled SnS/Al 2 O 3 exhibited several times more current density than pristine Al 2 O 3 which is very well corroborated with the photocatalytic analysis. Investigation of radical scavengers manifested that O 2 ˙ − and OH˙ have important roles in the degradation of MO. This innovative and uniquely designed hybrid ternary nanocomposite will open new horizons as an economical and effective material for photocatalysis.