Highly Efficient Carbon-Encapsulated ZnO Nanoparticles with Enhanced Light-Matter Interactions for Photocatalytic Applications

Rapid industrialization, urbanization, and unlimited human activities have caused severe environmental issues. Industrial chemical pollutants like methylene blue (MB) have become an environmentally undesirable element that is consequent to water contamination, posing serious risks to ecosystems and human health. Photocatalytic technology offers a sustainable environmental remediation for pollutant degradation using solar energy. In this study, a novel two-step synthesis method was successfully developed to fabricate ZnO@C core@shell nanoparticles (NPs) with uniform carbon encapsulation for the degradation of organic dyes, including MB. Finite Difference Time Domain (FDTD) simulations indicated enhanced light absorption and light–matter interaction (LMI), supported by experimental results. Under visible light irradiation, ZnO@C NPs achieved ~95% MB degradation within 90 minutes, significantly outperforming pristine ZnO (~38%). Electron paramagnetic resonance (EPR) spectroscopy identified superoxide radicals (O₂•⁻) as the dominant reactive species responsible for degradation, providing insights into highly selective radical-mediated pathways. ZnO@C NPs demonstrated excellent photostability and reusability over multiple cycles. Kinetic studies confirmed pseudo-first-order behavior. This work highlights the advantages of semiconductor@carbon architectures for enhancing charge separation and promoting reactive oxygen species (ROS)-driven catalysis, offering valuable insights for the rational design of next-generation photocatalytic systems for sustainable environmental remediation.