ZnO/CuO/g-CN heterojunctions with enhanced photocatalytic activity for removal of hazardous antibiotics.

In view of the environmental pollution caused by antibiotics, the creation of an efficient photocatalytic material is an effectual way to carry out water remediation. Herein, we developed a smart strategy to synthesize ZnO/CuO/g-CN heterojunction photocatalysts for the photodegradation of hazardous antibiotics by one-pot synthesis method. In this system, the CuO nanoparticles with electrons reducing capacity were coupled with g-CN composites. The photocarriers were generated from the electric field of type Ⅰ heterojunction between ZnO and g-CN and type Ⅱ heterojunction between CuO and g-CN. ZnO as a co-catalyst was doped to CuO/g-CN catalyst system for removal of broad-spectrum antibiotics with the condition of visible light to protect CuO from photocorrosion, which thereby accelerated photocatalytic reactivity. Benefiting by new p-n-n heterojunction, the resulting ZnO/CuO/g-CN composites had an excellent degradation performance of broad-spectrum antibiotics such as tetracycline (TC), chlortetracycline (CTC), oxytetracycline (OTC) and ciprofloxacin (CIP), the degradation of which were 98.79%, 99.5%, 95.35% and 73.53%. In particular, ZnO/CuO/g-CN photocatalysts showed a very high degradation rate of 98.79% for TC in first 30 min under visible light, which was 1.35 and 10.62 times higher than that of CuO/g-CN and g-CN, respectively. This work gives a fresh visual aspect for simultaneously solving the instability deficiencies of traditional photocatalysts and improving photocatalytic performance.