Facile green synthesis of ZnO/ZrO2 nanocomposite for photocatalytic degradation and chromium (VI) reduction

•ZnO/ZrO2 heterojunction were synthesized by green combustion method.•A variety of spectral approaches were used to analyze the NCs.•Methylene blue dye was used to examine the Photocatalytic activity of ZnO/ZrO2 heterojunction towards different parameters.•ZnO/ZrO2 heterojunction exhibits both recycling activity and Chromium (VI) reduction. In the field of nanoscience, using plant materials to create nanoparticles (NPs) is becoming growing in popularity and offers a number of benefits over physicochemical techniques. The green combustion approach effectively synthesized ZnO/ZrO2 nanocomposite (NCs) using powdered Butea monosperma (BM) leaf as the green fuel. The nature of NCs was confirmed through (X-ray Diffraction) XRD revealed that presence of hexagonal ZnO and cubic of ZrO2 phase. The morphology of NCs as seen by (Scanning Electron Microscopy) SEM and (Transmission Electron Microscopy) TEM reveals a fair distribution and non-uniform spherical shape. (Energy Dispersive X-Ray Analysis) EDAX pattern indicates the presence of zinc, zirconium and oxygen components. (Fourier Transform Infrared Spectroscopy) FT-IR spectrum obtained the metal–oxygen bonding in NCs. By applying the Tauc relation to calculate the optical energy band gap value of the sample is3.34 eV. UV light is used to conduct theinvestigation ofphotocatalyticdegradation of methylene blue (MB) dye. The NCs have superior degradation efficiency up to 99 % dye degradation is performed in 150 min. Furthermore, NCs exhibit a hazardous chromium (VI) decrease of up to 62 %. The collected results demonstrated that ZnO/ZrO2 NCs are the best photocatalyst for MB degradation and chromium reduction.