Enhanced interfacial charge migration through fabrication of p-n junction in ZnIn2S4/NiFe2O4/biochar composite for photocatalytic doxycycline hydrochloride degradation

Photo-induced electron-hole pair recombination, light response ability and surface property of photocatalyst greatly affect its activity. In this paper, a p-n junction ZnIn2S4/NiFe2O4 with biochar (ZIS/NFO/BC) was prepared, presenting improved charge carrier mobility, excellent light absorption and hierarchical porous micro-structure. ZIS/NFO/BC exhibited good photodegradation efficiency and TOC removal rate towards doxycycline hydrochloride under simulated sunlight, as well as good stability and reusability after six cycles. Biochar inhibited the agglomeration of nanoparticles, improved charge carrier mobility and light absorption ability. The synergy between adsorption of biochar and photocatalytic degradation of p-n junction greatly promoted photodegradation efficiency. Photo-induced holes (h+) played a major role during photodegradation. The effects of pH, coexisting ions (Cl-, NO3–, CO32–) and humic acid on photodegradation were investigated. Furthermore, the photodegradation mechanism was proposed and possible pathway was illustrated. This work provides new route for the development of magnetic recyclable photocatalyst with high potential for wastewater treatment.