In-situ fabrication of 3D/1D p-NiO/p-ZrO2 heterojunction composites with enhanced photo-degradation activity towards methyl orange and benzimidazole

Abstract

In current work, p-p type NiO/ZrO2 composites (NZO-1 and NZO-2) were fabricated with the help of single step co-precipitation route. NiO to ZrO2 ratio was kept 9:1 and 8:2 for NZO-1 and NZO-2, respectively. As prepared composites were characterized by different physiochemical techniques. XRD data confirmed that cubic and monoclinic crystal phases of NiO and ZrO2 were present in both NZO-1 and NZO-2 composites. With the increase in concentration of ZrO2, crystallite size of NiO/ZrO2 was decreased from 16 nm to 14 nm. SEM analysis showed the formation of 3D quasi spherical particles of NiO and 1D nanoneedles of ZrO2. With FT-IR investigations different M − O bonds related to Ni–O and Zr–O were observed in NZO-1 and NZO-2. When used for photocatalytic activities, NZO-2 outperformed as compared to NZO-1 and pure constituents (NiO and ZrO2). In brief, NZO-2, NZO-1, NiO and ZrO2 removed 93, 80, 62 and 45% of Methyl orange (MO) dye in presence of natural sunlight within 120 min. Clearly, NZO-2 hold optimum concentrations of NiO and ZrO2 with a kinetic rate constant value of 0.019 min−1. Scavenging experiments disclosed electrons, superoxide radicals and holes were the main species involved in the photo-removal of MO. For benzimidazole, sufficient photo-degradation activity (57%) was observed in presence of NZO-2. Photo-catalytic investigations suggested that NZO-2 can be used as efficient photocatalyst for the treatment of multiple pollutants from contaminated water.