Synthesis of BaTiO3/α-S8 composite for enhanced photocatalytic activity under UV/Solar light in comparison with α-S8 and BaTiO3 photocatalysts: Effect of spontaneous polarization

The BaTiO3/alpha-S-8 composite is fabricated via grinding method combined with melt-diffusion strategy. Non-centrosymmetric crystal structure of BaTiO3 induces a permanent spontaneous polarization which drives the electrons and holes to the opposite surfaces. This resultant surface polarization causes band bending based on C+/C- domain. Under the UV light, the C+ domain of BaTiO3 influences the energy bands to bend downwards and drives the CB electrons towards the CB of alpha-S-8 and the VB holes of BaTiO3 react with the surface adsorbed hydroxyl anions. Under the illumination of solar light, the charge carriers are generated only in the alpha-S-8. The photogenerated electrons from the CB of alpha-S-8 are trapped by the surface oxygen molecules and the holes move upwards to the VB of BaTiO3, as this energy level is located at 0.08 V higher than the VB of alpha-S-8. The composite exhibited enhanced photocatalytic activity for the degradation of fast red dye under UV/solar light due to the efficient vectorial charge carrier separation. The band bending at the junction of two semiconductors results in a spatially distinct redox chemistry. This favors the enhancement in the photocatalytic activity of the BaTiO3/alpha-S-8 composite.