Construction of LaNiO3 nanoparticles modified g-C3N4 nanosheets for enhancing visible light photocatalytic activity towards tetracycline degradation

Graphitic carbon nitride (g-C3N4) with a suitable bandgap (ca. 2.7 eV) has been regarded as one of the most promising photocatalysts for water purification. Nevertheless, pristine g-C3N4 still suffered from low photocatalytic performance due to the high recombination of the photoinduced charge carriers. To this end, we designed and constructed a direct Z-scheme LaNiO3/g-C3N4 hybrid composed of LaNiO3 nanoparticles and g-C3N4 nanosheets through a facile heat treatment method. As expected, the resultant LaNiO3/g-C3N4 hybrid demonstrated drastically improved photocatalytic performance of tetracycline (TC) degradation in aqueous solution under visible light irradiation (λ > 420 nm). Strikingly, the optimized LaNiO3(30 wt%)/g-C3N4 composite exhibited prominent photocatalytic activity for TC degradation under visible light irradiation, the TC degradation rate up to 0.00282 min−1, which was about 3.8 and 3.9 times larger than those of pure g-C3N4 and pristine LaNiO3, respectively. The enhanced photocatalytic activity was mainly ascribed to the formation of the direct Z-scheme LaNiO3/g-C3N4 heterojunction as a result of the synergistic effect between LaNiO3 and g-C3N4, which not only facilitated the interfacial charge transfer efficiency but also preserved the strong redox ability of the photogenerated electrons and holes. Furthermore, active species trapping experiments confirmed that the synergistic effect of superoxide radicals and holes was responsible for the photodegradation of TC. Eventually, a plausible Z-scheme charge transfer mechanism was put forward based on the experimental results. This work provides a new approach to construct highly efficient Z-scheme g-C3N4-based composite photocatalysts for environmental remediation and energy conversion.