Shape-controlled synthesis of well-dispersed platinum nanocubes supported on graphitic carbon nitride as advanced visible-light-driven catalyst for efficient photoreduction of hexavalent chromium

Photocatalytic degradation of environmental pollutants by using semiconductor-based photocatalysts offers great potential for remediation of toxic chemicals. For an economical and eco-friendly method to eliminate hexavalent chromium (Cr(VI)), favourable catalysts own high efficiency, stability and capability of harvesting light. Combination of metal with semiconductor is a promising route to improve the photocatalytic performance for Cr(VI) reduction. Herein, well-dispersed platinum (Pt) nanocubes (NCs) were synthesized by a facile one-step hydrothermal method with poly- l -lysine (PLL) as the growth-directing agent, followed by their uniform dispersion on graphitic carbon nitride (g-C 3 N 4 ). Their morphology, crystal structure, chemical composition , and formation mechanism were mainly characterized by transmission electron microscopy (TEM), X-ray photoelectron spectroscopy (XPS), and X-ray diffraction (XRD). The hybrid nanocomposite was further explored for photocatalytic reduction of Cr(VI) to trivalent chromium (Cr(III)) under visible light at room temperature , by using formic acid (HCOOH) as a reducing agent, showing great improvement in photocatalytic activity and reusability, outperforming the referenced g-C 3 N 4 and home-made Pt black/g-C 3 N 4 catalysts. The effects of various experimental parameters and the proposed mechanism are discussed in detail.