Facile preparation of Fe3O4/Ag/RGO reusable ternary nanocomposite and its versatile application as catalyst and antibacterial agent

•Fe3O4/Ag/RGO ternary nanocomposites are successfully prepared by a facile one-pot solvothermal method.•The nanocomposites exhibit extraordinary catalytic performance and recyclability in reducing 4-NP into 4-AP.•The nanocomposites also show outstanding antibacterial activity against various pathogens.•The as-obtained nanocomposites could be a promising candidate for wastewater treatment and water purification.