Bimetallic NiMnO₃-embedded laser-induced graphene: a high-performance catalytic filter for electrochemical pathogen...

Waterborne pathogens are among the most significant threats to public health, underscoring the need for advanced disinfection methods. Conventional methods often produce harmful disinfection by-products and demand high energy. As an emerging solution, electrochemical membrane filtration technology provides effective microbial disinfection. Due to its excellent electrical conductivity, large surface area, and mechanical strength, graphene shows enhanced disinfection performance. Bimetallic nanoparticles, such as nickel-manganese oxide (NiMnO₃), demonstrate synergistic physicochemical properties compared to their monometallic counterparts. This work focuses on fabricating and characterizing laser-induced graphene (LIG)-NiMnO₃ composites to act as electroconductive surfaces. The LIG-NiMnO₃ composite combines the redox and catalytic properties of nickel and manganese oxides, enhancing both electrochemical and antimicrobial efficiency. Bimetallic composites were synthesized with varying concentrations of NiMnO₃ at 1%, 5%, and 10% embedded into LIG, with the composite having 10% nanoparticle concentration demonstrating optimal performance. The characterization of composites confirmed their structural integrity, morphology, and electrochemical properties. Electrochemical characterization revealed a charge density of 1.86 × 10⁴ µC cm^-2 for the 10% composite, a ∼5.8-fold increase over pristine LIG, confirming significantly improved electrochemical performance. The charge density of the composite was ∼2.1 times higher than that of previously reported LIG composites, highlighting its superior electrochemical properties. The composite exhibited intense antimicrobial activity against microbes, including Escherichia coli and MS2 bacteriophage. In batch experiments, 6-log bacteria were removed within one hour, while viruses were inactivated within four hours of operation at 2.5 V. In flow-through mode, the 10% composite filter, operating at 2.5 V, demonstrated complete microbial removal. Our findings suggest that bimetallic NiMnO₃ composites improve LIG electrochemical properties via the combined effects of electrical fields and chemically induced oxidant effects. Thus, the newly developed LIG-NiMnO₃ composite exhibits excellent potential for environmental applications, including water and wastewater treatment, as well as disinfection.