Constructing nanoflower-like semiconductor-insulator SrCO3/SrTiO3 heterojunction photocatalyst for the efficient removal of TC by the synergistic effect of adsorption and photocatalysis

A combination of adsorption and photocatalysis is a promising method to degrade organic pollutants. Herein, the work adopts SrTiO3 semiconductor coupled with insulator SrCO3 via an in-situ solvent method to construct a heterojunction with built-in electric field (IEF) photocatalyst, which improves excellently the electrons-holes (h+-e-) separation and adsorption performance on SrTiO3. The close heterojunction and the IEF formed at the heterojunction interface enhance the transfer and separation of photogenerated carriers, generating more active substances. Meanwhile, the unique nanoflower structure of SrCO3/SrTiO3 and the introduction of SrCO3 provide more adsorption sites and active centers, which is conducive to the adsorption and activation of TC. Thus, the maximum adsorption capacity of SrCO3/SrTiO3 could be up to 47.15 mg/g-1 within 30 min. Compared with pure SrTiO3, SrCO3/SrTiO3 exhibited the excellent removal of tetracycline hydrochloride (TC) (120 min, 90.5 %) via the synergistic effect of adsorption and photocatalysis under visible light, and its photocatalytic reaction rate was 24.79 and 3 times higher than SrCO3 and SrTO3, individually. h+and center dot O2- played a pivotal role in TC degradation. Additionally, the adsorption behavior of TC on SrCO3/SrTiO3 composite and the photocatalytic degradation mechanism of SrCO3/SrTiO3 were investigated in detail. This work provides a new idea for improving the photocatalytic performance of SrTiO3 and the application of insulators in photocatalysis.