Reduced Graphene Oxide‐Cadmium Sulfide Nanorods Decorated with Silver Nanoparticles for Efficient Photocatalytic Reduction Carbon Dioxide Under Visible Light

Abstract

Photocatalytic CO2 reduction is an attractive approach for the direct conversion of solar energy into chemical fuels. In this study, we synthesized a composite material that consists of Ag, reduced graphene oxide (RGO), and CdS nanorods as a photocatalyst for CO2 reduction. The morphological, structural, optical, and electrochemical properties of the resultant nanocomposite (Ag‐RGO‐CdS) were investigated by using various physical techniques (e.g., XRD, SEM, TEM, X‐ray photoelectron spectroscopy, UV/Vis diffuse reflectance spectroscopy, and electrochemical impedance spectroscopy). Our results indicate that the Ag‐RGO‐CdS nanocomposites exhibit an enhanced photocatalytic activity for the conversion of CO2 into CO, and the optimum activity is achieved over 1.0 wt %Ag‐3.0 wt %RGO‐CdS. This enhanced performance can be ascribed to the multifunctional promoting effects of RGO and Ag in the composite. On one hand, RGO and Ag can act as electron acceptors, which enhances the separation efficiency of photogenerated carriers. On the other hand, the incorporation of RGO and Ag can improve the adsorption and activation of CO2, which results in the enhancement of the photocatalytic reduction of CO2 to CO. Furthermore, a possible mechanism for photocatalytic CO2 reduction over the Ag‐RGO‐CdS nanocomposites was proposed. This study demonstrates a semiconductor‐based hybrid for efficient photocatalytic CO2 reduction by virtue of the combinational effect of dual cocatalysts.

Unraveling Photoexcited Charge Transfer Pathway and Process of CdS/Graphene Nanoribbon Composites toward Visible‐Light Photocatalytic Hydrogen Evolution

“…Particularly, newly emerged semiconducting materials with tunable bandgap and wide wavelength response were explored. Examples are: In 2 S 3 , SnS 2 , CdS, BiOX (X = Cl, Br, I), ZnIn 2 S 4 , g‐C 3 N 4 , etc. Among these promising photocatalysts, CdS has attracted considerable interest with merits such as a direct‐bandgap (2.4 eV) for visible‐light absorption and a negative potential of the conduction band edge for proton reduction.…”

“…However, CdS suffers from photocorrosion and low quantum efficiency. To this end, viable approaches, such as coupling CdS with other semiconductors of complementary attributes, tuning the morphology and structure, and loading cocatalysts, have been devised to improve the photocatalytic activities of CdS.…”

“…Ultrathin 2D nanosheets often possess distinct physicochemical properties and offer a versatile platform that allows to assemble diverse nanoscale composites with attractive optical, electronic, and catalytic properties, among others. For example, graphene, an atomic sheet of sp 2 ‐bonded carbon atoms that are arranged into a honeycomb structure, has been extensively explored in photocatalysis due to its high surface area, unique electron reserve and electron transfer property as well as chemical stability . As a cocatalyst and support for a given semiconductor, graphene could restrain the aggregation of semiconductor particles and speed up the separation and transportation of photogenerated charge carriers, and thus enhance photoactivity.…”

Sub‐10 nm Ag Nanoparticles/Graphene Oxide: Controllable Synthesis, Size‐Dependent and Extremely Ultrahigh Catalytic Activity

“…Among NMNPs/GO, Ag nanoparticles/GO (AgNPs/GO) have gradually become a hot topic of general concern . In addition to the extraordinary electronic/optical properties, the low cost of Ag relative to other noble metals renders AgNPs/GO feasible yet qualified alternatives for diverse advanced materials .…”

“…In addition to the extraordinary electronic/optical properties, the low cost of Ag relative to other noble metals renders AgNPs/GO feasible yet qualified alternatives for diverse advanced materials . Numerous AgNPs/GO‐based materials have thus far been manufactured by various methods, including chemical, electrochemical, sonochemical, or solvothermal reduction; electron beam, gamma ray, microwave, or light irradiation; biosynthesis; etc . These strategies, however, are disadvantaged by the use of toxic chemicals, multistep/long‐time operations, complex GO premodification steps, AgNP presynthesis or bioextract prepurification procedures, high pressure/temperature, rigorous experimental conditions, or bulky setups.…”