Visible-Light-Driven Photocatalytic Activity of SnO(2)–ZnO Quantum Dots Anchored on g-C(3)N(4) Nanosheets for Photocatalytic Pollutant Degradation and H(2) Production

[Image: see text] A zero-dimensional/two-dimensional heterostructure consists of binary SnO(2)–ZnO quantum dots (QDs) deposited on the surface of graphitic carbon nitride (g-C(3)N(4)) nanosheets. The so-called SnO(2)–ZnO QDs/g-C(3)N(4) hybrid was successfully synthesized via an in situ co-pyrolysis approach to achieve efficient photoactivity for the degradation of pollutants and production of hydrogen (H(2)) under visible-light irradiation. High-resolution transmission electron microscopy images show the close contacts between SnO(2)–ZnO QDs with the g-C(3)N(4) in the ternary SnO(2)–ZnO QDs/g-C(3)N(4) hybrid. The optimized hybrid shows excellent photocatalytic efficiency, achieving 99% rhodamine B dye degradation in 60 min under visible-light irradiation. The enriched charge-carrier separation and transportation in the SnO(2)–ZnO QDs/g-C(3)N(4) hybrid was determined based on electrochemical impedance and photocurrent analyses. This remarkable photoactivity is ascribed to the “smart” heterostructure, which yields numerous benefits, such as visible-light-driven fast electron and hole transfer, due to the strong interaction between the SnO(2)–ZnO QDs with the g-C(3)N(4) matrix. In addition, the SnO(2)–ZnO QDs/g-C(3)N(4) hybrid demonstrated a high rate of hydrogen production (13 673.61 μmol g(–1)), which is 1.06 and 2.27 times higher than that of the binary ZnO/g-C(3)N(4) hybrid (12 785.54 μmol g(–1)) and pristine g-C(3)N(4) photocatalyst (6017.72 μmol g(–1)). The synergistic effect of increased visible absorption and diminished recombination results in enhanced performance of the as-synthesized tin oxide- and zinc oxide-modified g-C(3)N(4). We conclude that the present ternary SnO(2)–ZnO QDs/g-C(3)N(4) hybrid is a promising electrode material for H(2) production and photoelectrochemical cells.