A photocatalyst with an enhanced Schottky effect and an efficient electron-transfer channel fabricated by assembling Ni–WC heterojunction nanoparticles on g-C3N4 for highly efficient removal of chlorophenols

Abstract

Fabricating photocatalysts with optimized charge kinetics to improve carrier transfer and separation is critical for the removal of highly-toxic chlorophenol pollutants. Herein, a Mott–Schottky catalyst was fabricated by assembling nickel–tungsten carbide nanoparticles on two-dimensional g-C₃N₄ (Ni–WC/CN) for the photocatalytic removal of 4-chlorophenol (4-CP). The abundant interfacial contact and suitable Fermi level alignments between g-C₃N₄ and Ni–WC induced an enhanced Schottky effect and an efficient photogenerated electron transfer route from g-C₃N₄ to Ni–WC. The electron-rich Ni–WC surface could effectively activate oxygen/water molecules to generate active radicals. Consequently, Ni–WC/CN boosts the photodegradation and mineralization of 4-CP with 100% removal rate, 100% mineralization efficiency and fast rate constant (k_ap, 3.0 × 10⁻² min⁻¹) in 2.5 h under 100 W white light. The k_ap and mineralization efficiency of Ni–WC/CN are 30-fold and 49-fold higher than those of g-C₃N₄. The robust Ni–WC/CN also exhibited excellent substrate universality in CP removal and ensured biological safety of the treated water. This work provides evidential proof of the rational design of efficient Schottky photocatalysts via the regulation of electron transfer on heterostructure interfaces in practical environmental applications.