Phyto-engineered Pd-doped WO ₃ nanocomposite <i>via Anisomeles indica</i> leaf extract: a recyclable heterogeneous catalyst for aqueous Petasis reaction, photocatalytic dye degradation, and antibacterial applications

The development of multifunctional nanocomposites through green chemistry approaches has gained significant attention for promoting sustainable synthetic methodologies and environmental remediation. In this work, a green and sustainable route was employed for the synthesis of a Pd-doped-WO₃ nanocomposite using <i>Anisomeles indica</i> leaf extract as a natural reducing and stabilizing agent. The nanocomposite was synthesized under mild, aqueous-phase conditions without the use of toxic chemicals. Characterization by FTIR (Fourier Transform Infrared Spectroscopy), XRD (X-ray Diffraction), SEM (Scanning Electron Microscopy), and EDX (Energy Dispersive X-ray Spectroscopy) confirmed the successful formation of well-dispersed Pd nanoparticles within the WO₃ matrix. The XRD analysis revealed that the WO₃ crystallized in a monoclinic phase (JCPDS no. 00-043-1035). The optimized composition with ∼5 wt% Pd demonstrated superior multifunctional performance. Specifically, the (3 mol%) Pd-WO₃ nanocomposite served as an efficient recyclable catalyst for the Petasis reaction in aqueous medium, a highly active photocatalyst for dye degradation under sunlight, and a potent antibacterial agent against both Gram-positive and Gram-negative bacteria. The present work highlights its dual potential for environmental and biomedical applications. This green-synthesized Pd-doped WO₃ nanocomposite provides a sustainable solution for organic transformations, environmental remediation, and microbial control.