Combining rhombohedral dodecahedral ZnO with g-C3N4 nanosheets for enhanced photocatalytic activity

Photocatalysis technology is an effective method to remove pollutants in aquatic environment assisted by solar energy. Herein, the rhombohedral dodecahedral ZnO was dispersed on the g-C3N4 nanosheets for the construction of ZnO/g-C3N4 heterojunction via the combination of solvothermal method and calcination. The obtained ZnO/g-C3N4 heterojunction manifests excellent photocatalytic ability for methyl orange (MO). Especially, the optimal ZnO/g-C3N4 composite with the ZnO content of 10 wt% (ZC-3) exhibits the degradation efficiency of MO as high as 98.0 % under visible-light of 60 min. A series of factors were all-around investigated, such as initial pH, photocatalyst dosage, initial MO concentration, organic anions, humic acid and other dyes. The photocatalytic degradation behavior of MO complies with the first-order reaction kinetics, and the apparent rate constant (kapp) of ZC-3 is 2.3 and 13.4 times than that of pure g-C3N4 and pure ZnO. Meanwhile, the ZnO/g-C3N4 heterojunction exhibits satisfactory cyclic stability and its photocatalytic mechanism is postulated. Therefore, the ZnO/g-C3N4 heterojunction possesses great economic utilization value and is expected to be widely used for wastewater remediation. •The rhombohedral dodecahedral ZnO with g-C3N4 nanosheets composites heterojunctions were successfully constructed.•The heterojunctions improve surface area for active sites and promote the ability to separate photo-generated electron–hole pairs.•ZnO/g-C3N4 promoted the visible light photocatalytic performance of MO degradation.•Photocatalytic mechanism over ZnO/g-C3N4 was proposed.