ZnO/Cu2O/Si Nanowire Arrays as Ternary Heterostructure-Based Photocatalysts with Enhanced Photodegradation Performances

Abstract

Ternary ZnO/Cu 2 O/Si nanowire arrays with vertical regularity were prepared with all-solution processed method at low temperature. In addition to the detailed characterizations of morphologies and crystallographic patterns, the analyses of photoluminescence and photocurrents revealed the sound carrier separation owing from the established step-like band structures. By modeling the photodegradation process of the prepared heterostructures through kinetic investigations and scavenger examinations, the photocatalytic removal of MB dyes was found to follow the second-order kinetic model with reaction constant more than 15.3 times higher than bare Si nanowires and achieved 5.7 times and 3.4 times than ZnO/Si and Cu 2 O/Si binary heterostructures, respectively. Moreover, the highly stable photoactivity of ZnO/Cu 2 O/Si photocatalysts was evidenced from the repeated photodegradation tests, which demonstrated the robust photocatalytic efficiency after cycling uses. The facile synthesis along with in-depth mechanism study of such ternary heterostructures could be potential for practical treatment for organic pollutants. Keywords HeterostructurePhotocatalystSilicon nanowire arraysKinetic study Electronic supplementary material The online version of this article (10.1186/s11671-019-3093-9) contains supplementary material, which is available to authorized users.

Extending Absorption Edge through the Hybrid Resonator-Based Absorber with Wideband and Near-Perfect Absorption in Visible Region

“…It has been reported that the structures with metal pattern/dielectric layer/metal layer could proceeded the excellent photocatalytic oxidation of benzylamine [30]. In light of this finding, the present study unveiled the near-perfect and broadband light-absorption characteristics based on the simple sandwich-like design, and could be potentially used for efficient photocatalytic applications illuminated with visible light through replacing the middle SiO 2 layer with photochemical-active materials such as TiO 2 [30] or Cu 2 O [31], which might pave ways for organic synthesis, pollutant degradation and other photocatalytic applications.…”

Photochromic and Photocatalytic Properties of Ultra-Small PVP-Stabilized WO3 Nanoparticles

“…The reductive photodegradation of methyl orange is also confirmed by the absence of the influence of isopropyl alcohol (IPA) on the photodegradation rate. IPA is one of the most widely used inhibitors of photocatalytic processes, due to its reaction with hydroxyl radicals [34]. Figure 11a shows time-resolved methyl orange absorption spectra during methyl orange photodecomposition by WO 3 @PVP sols both in deionized water and in a 20% IPA solution.…”

“…As mentioned above, the increase in sodium concentration led to the formation of much more stable sodium tungsten bronzes and, subsequently, to the enhancement The reducing mechanism of photocatalytic activity of WO 3 @PVP nanoparticles was additionally confirmed by the introduction of HAuCl 4 in the reaction mixture. Here, the reduction of HAuCl 4 and the formation of gold nanoparticles was a competitive process and contributed to the organic dye discoloration rate [34]. Since the gold nanoparticles cause plasmon resonance effect, their absorption may interfere with the absorption of the methyl orange.…”

Electric and Photocatalytic Properties of Graphene Oxide Depending on the Degree of Its Reduction

“…The GO, GO AA and P25 TiO 2 samples followed a Langmuir–Hinshelwood mechanism during the photocatalysis ( Figure 10 B), which is indicated by the goodness of fitted line to the assumed pseudo first-order kinetics (Equation (1)). The behavior could be approximated by second-order kinetics ( Figure 10 C) as well (Equation (2)), with slightly better fitting [ 37 , 38 , 39 ]. The current and starting concentration of the dye is c and c 0 , respectively, A and A 0 is the measured and starting absorbance, k is the reaction rate constant and t is time, and the Lambert–Beer law holds true for these concentrations.…”