Construction of a Z-Scheme Dictated WO_3–X/Ag/ZnCr LDH Synergistically Visible Light-Induced Photocatalyst towards Tetracycline Degradation and H₂ Evolution

Abstract

Herein, we have designed nonstoichiometric WO3, coupled with ZnCr layered double hydroxide (LDH) nanosheeet through Ag nanoparticle as the solid-state electron mediator to form WO3–X/Ag/ZnCr LDH Z-scheme photocatalyst. The presence of oxygen defect levels in as-synthesized materials was confirmed by Raman, X-ray photoelectron spectroscopy (XPS), and photoluminescence (PL) analyses. The photocatalytic performance of the catalysts was investigated by the tetracycline degradation and H2 energy production under visible light irradiation. The WO3–X/Ag/ZnCr LDH ternary heterostructure exhibits superior activity toward tetracycline degradation and hydrogen evolution. The excellent photocatalytic performance of the catalyst was attributed to the synergistic effects among three species (WO3–X, Ag, and ZnCr LDH) and the enhanced separation efficiency of photoinduced charge carriers through the Z-scheme WO3–X/Ag/ZnCr LDH system. In addition, the created oxygen deficiency on WO3–X could improve the photocatalytic behavior of ZnCr LDH in heterostructure by delaying the recombination efficiency of photoexcited electron–hole pairs. Furthermore, the higher affinity of tetracycline at the oxygen defect levels of the photocatalyst supports the high rate of tetracycline degradation. The enhanced photocatlytic activity of the catalysts was further supported by PL spectra and photoelectrochemical studies (electrochemical impedance spectroscopy (EIS) and linear sweep voltammetry (LSV) plot). The present research opens up a new strategy for designing highly efficient visible light-induced Z-scheme-based photocatalysts with high population of active sites for energy and environmental applications in a sustainable manner.

Precious Metal‐Free Photocatalytic Water Oxidation by a Layered Double Hydroxide‐Prussian Blue Analogue Hybrid Assembly

“…Although LDHs have been actively used for photocatalytic water splitting due to their high quantum yield and efficiency, only a limited number of studies involve the utilization of ZnCr‐LDH as a narrow bandgap semiconductor for the photocatalytic water oxidation process [14] . ZnCr‐LDH has been employed either as an individual photocatalyst [15–17] or as part of a heterostructure consisting of a combination of suitable semiconductors for overall water splitting [18–20] . Although ZnCr‐LDH exhibits a suitable band energy alignment for visible light‐driven water oxidation, poor charge mobility in LDHs leads to unavoidable recombination of photo‐induced charge carriers, which yields relatively poor efficiency and stability [14] .…”

One-step controllable synthesis of three-dimensional WO3 hierarchical architectures with different morphologies decorated with silver nanoparticles: enhancing the photocatalytic activity

“…Additionally, Ag NPs shown known surface plasmon resonance (SPR) effect, which extended and enhanced the light absorption and enhanced the separation efficiency of the photogenerated electron-hole pairs. [61][62][63] As a results, these photogenerated electrons (e À ) and electrons from the reservoir on the Ag NPs could be trapped by O 2 molecules in the solution and generate the cO 2 À radical specie. [64][65][66][67] On the other hand, the photogenerated holes (h + ) are capable to react with H 2 O or OH À molecules, generating the cOH radical specie (Scheme 2).…”

Evaluation of polymeric g-C3N4 contained nonhierarchical ZnV2O6 composite for energy-efficient LED assisted photocatalytic mineralization of organic pollutant

“…⋅ OH∕ ⋅ O − 2 ∕h + + TC → Degradation products(CO 2 + H 2 O) the photo-induced charges attack the TC molecule, first, the parent molecule is disintegrated into smaller molecules and eventually breaks down into simpler products like water, carbon dioxide, ammonium-cation and nitrate ions [43]. Primarily, the deprotonation reaction occurs that split the parent chain.…”

“…Second, the demethylation may take place due to the lower bond energy of C-N [37]. Finally, there may be deamidation reactions of TC molecules with complementing deethylation, dihydroxylation, addition, and ring-opening reactions to degrade TC [43].…”