Oxygen and nitrogen plasma modifications of ZnCuCo LDH-graphene nanocomposites for photocatalytic hydrogen production and antibiotic degradation

Development of efficient, non-precious, and stable photocatalytic materials have become a prominent area of research in the energy production and environmental remediation fields. In this study, oxygen and nitrogen plasma-modified graphene (NOG) was used to support nitrogen-doped ZnCuCo layered double hydroxide (NLDH). The synergistic combination of oxygen functionalities and nitrogen doping significantly improved the photocatalytic activity of NLDH-NOG. The plasma modification introduced oxygen-containing functional groups on the surface of NOG, enhancing its hydrophilicity and facilitating efficient contact between NLDH and NOG. SEM and TEM images confirmed the uniform deposition of LDH and NLDH onto the plasma-modified graphene surface. Furthermore, nitrogen doping modified the Fermi levels, reducing the band gap of NLDH and promoting electron migration between NLDH and NOG, resulting in prolonged lifetimes of photogenerated charge carriers. Although the bare LDH was inactive in the photocatalytic hydrogen generation, NLDH-NOG produced a high amount of hydrogen under visible light illumination, benefiting from the large surface area (233 m²g⁻¹), improved light absorption, and enhanced charge separation. Additionally, the photodegradation of sulfanilamide (SA) was significantly enhanced compared to bare LDH. electron spin resonance (ESR) spectroscopy and scavenging experiments indicated that O₂^[rad]– and ^[rad]OH radicals played important roles in the photocatalytic degradation of SA. Based on the identification of intermediate compounds, a plausible reaction pathway for SA photodegradation was proposed. This study reveals the applicability of environmentally-friendly plasma modification of LDH-graphene nanocomposite with highly-efficient and durable photocatalytic activities towards hydrogen generation and pollutant degradation.