The Elimination of N-Chloropiperidine in Aqueous Solution by Using Ni/NiO-C3N4 Under Visible Light Illumination

One of the main challenges in environmental remediation is the creation of stable and effective photocatalysts to eliminate organic contaminants when exposed to visible light. For the degradation of N-chloropiperidine, a persistent organic pollutant with multiple dangerous issues, we provide the synthesis, characterization, and photocatalytic evaluation of a Ni/NiO-incorporating carbon nitride (Ni/NiO-C3N4) composite in this work. The Ni/NiO-C3N4 photocatalyst was created by a single step of thermally polymerizing nickel nitrate and melamine. Four samples are ranged in Ni concentration from 0% to 10%. The coexistence of the Ni and NiO phases was confirmed by structural and morphological analyses using X-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and Fourier-transform infrared spectroscopy (FTIR). UV−Vis diffuse reflectance spectroscopy (DRS) also demonstrated an enhanced capacity to absorb visible light. A study of photocatalytic performance under visible light illumination showed that the Ni/NiO-C3N4 composite degraded N-chloropiperidine at a much faster rate than either pure carbon nitride (0.0231 min−1), with a first-order rate constant of 0.0456 min−1. The reaction rate nearly quadrupled when 10% Ni was added to the C3N4 matrix. Furthermore, the Ni/NiO-C3N4 composite’s photocatalytic activity performed better than its counterparts Ni-C3N4 (0.0315 min−1) and NiO-C3N4 (0.0386 min−1). The synergistic interaction between Ni and NiO, which promotes effective charge separation and lowers electron–hole recombination, is responsible for the higher activity of Ni/NiO-C3N4, increasing the production of reactive oxygen species. Furthermore, reusability experiments conducted over four successive cycles showed a slight decrease in activity, indicating the prepared samples are stable and reusable.