Highly visible-light active, eco-friendly artificial enzyme and 3D Bi4Ti3O12 biomimetic nanocomposite for efficient photocatalytic tetracycline hydrochloride degradation and Cr(VI) reduction

The removal of water pollution of persistent pharmaceutical products and heavy metals is highly demanded. It is urgently needed to develop highly efficient and eco-friendly photocatalysts to meet the requirements of current green environmental development. Eco-friendly enzymatic photocatalyst with potential solar light utilization is an effective alternative to environmental remediation. This work demonstrates the combined effect of artificial enzyme hemin immobilization on the surface of semiconductor photocatalyst Bi4Ti3O12 to fabricate a biomimetic photocatalyst hemin-Bi4Ti3O12 (HBTO) by using a facile solvothermal method. The HBTO nanocomposite photocatalyst showed high photocatalytic efficiency for the photodegradation of tetracycline hydrochloride (TCHCL) and photo-reduction of Cr(VI) to Cr(III). Under visible irradiation, the optimum ratio 1.0-HBTO showed 99.91% TCHCL photodegradation, and 99.97% Cr(VI) photo-reduction in contrast to pure BTO, which hardly achieved about 33.0% and 58.7%, respectively. Additionally, the photodegradation mechanism of TCHCL was monitored using HPLC-MS, and the photo-reduction performance was studied in detail. The photoabsorption and the photoelectrochemical performance of HBTO were highly improved with 3.8 times higher photocurrent density than pure BTO. The immobilization of hemin not only can improve the photoabsorption of HBTO but also act as an electron-conducting bridge and a surface oxygen absorption site. This work sheds light on an efficient approach of a synergistic effect of artificial enzyme and semiconductor photocatalyst to fabricate highly efficient biomimetic photocatalyst HBTO for environmental remediation.