Visible-Light-Driven Photocatalytic Activity of SnO₂–ZnO Quantum Dots Anchored on g-C₃N₄ Nanosheets for Photocatalytic Pollutant Degradation and H₂ Production

Abstract

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.

Hydrogen production and photocatalytic activity of g‐C3N4/Co‐MOF (ZIF‐67) nanocomposite under visible light irradiation

“…The formed heterojunction interfaces are believed to make available the migration of photo‐induced h + to the ZIF‐67 by leaving the e − in the CB of g‐C 3 N 4 under visible light irradiation, which can be restraining the change of charge recombination and gather freer e − in the CB of g‐C 3 N 4. Generally, in the photocatalytic procedure, most of the photogenerated e − and h + will recombine inside the catalyst, and partial holes transferred to the catalyst surface will directly decompose dyes/react with the adsorbed H 2 O to produce (•OH) radicals to contribute in dye degradation . The remaining e − will react with O 2 to form • O 2 − and then react with protons to form HOO.…”

“…[47,48] Generally, in the photocatalytic procedure, most of the photogenerated e − and h + will recombine inside the catalyst, and partial holes transferred to the catalyst surface will directly decompose dyes/react with the adsorbed H 2 O to produce (•OH) radicals to contribute in dye degradation. [47] The remaining e − will react with O 2 to form • O 2 − and then react with protons to form HOO. Finally will produce •OH, degrades dyes efficiently.…”

Effect of Alloyed BiOClxBr1‐x Nanosheets Thickness on the Photocatalytic Performance

“…Many photocatalytic materials for decomposing toxic pollutants have been reported, such as TiO 2 , ZnO, SnO 2 . The narrow range of light response leads to a much lower photocatalytic activity of these semiconductor photocatalysts under sunshine irradiation, which limits their practical application . Therefore, photocatalysts with a wide range of light response need to be studied.…”

Nano-zirconia supported by graphitic carbon nitride for enhanced visible light photocatalytic activity

“…Some composite materials and degradation rates are shown in Table 1. Prabhakar vattikuti et al 41 have prepared SnO 2 -ZnO/g-C 3 N 4 composites. The degradation rate is 0.0184 min À1 , which is 5 times that of pure g-C 3 N 4 .…”