Dynamics of Charge-Transfer Behavior in a Plasmon-Induced Quasi-Type-II p–n/n–n Dual Heterojunction in Ag@Ag₃PO₄/g-C₃N₄/NiFe LDH Nanocomposites for Photocatalytic Cr(VI) Reduction and Phenol Oxidation

Abstract

In this work, a series of heterostructure Ag@Ag 3 PO 4 /g-C 3 N 4 /NiFe layered double hydroxide (LDH) nanocomposites were prepared by a combination of an electrostatic self-assembly and in situ photoreduction method. In this method, positively charged p-type Ag 3 PO 4 was electrostatically bonded to the self-assembled negatively charged surface of the n–n-type g-C 3 N 4 /NiFe (CNLDH) LDH hybrid material with partial reduction of Ag + to metallic Ag nanoparticles (NPs) by the photogenerated electrons and available surface −OH groups of LDH under visible light irradiation. The presence of Ag 3 PO 4 as a p-type semiconductor, the surface plasmon resonance (SPR) effect of metallic Ag NPs, and oxygen vacancies as O v -type defects in NiFe LDH could greatly achieve the quasi-type-II p–n/n–n dual heterojunctions, which was revealed by the shifted conduction band and valence band potentials in Mott–Schottky (M–S) analysis. Among all the optimized heterostructures, CNLDHAgP4 could achieve the highest photocatalytic Cr(VI) reduction rate of 97% and phenol oxidation rate of 90% in 2 h. The heterostructure CNLDHAgP4 photocatalyst possesses a unique morphology consisting of cubic phases of both Ag NPs and Ag 3 PO 4 , which adhered to the thin and curvy layers of the CNLDH hybrid for smooth electronic and ionic charge transport. Furthermore, the intimate Schottky barriers formed at the interface of quasi-type-II p–n/n–n dual heterojunctions were verified by the photoluminescence, linear sweep voltammetry, M–S, electrochemical impedance study, high-resolution transmission electron microscopy, and X-ray photoelectron spectroscopy studies. The SPR effect of Ag NPs and oxygen vacancies as O v -type defect in NiFe LDH can effectively accelerate the threshold of charge separation and be the main reason for the enhanced activity achieved by the as-fabricated heterostructure photocatalyst.

NaBH4 induces a high ratio of Ni3+/Ni2+ boosting OER activity of the NiFe LDH electrocatalyst

“…S2A †) revealed four distinct peaks attributed to the surface hydroxyl groups attached to metal-oxygen (531.5 eV), lattice oxygen (530.5 eV), under coordinated lattice oxygen related to oxygen vacancies (531.6 eV), and adsorbed water (532.8 eV). 49 Indeed, a higher concentration of O vacancy was obtained from the deconvoluted O1s core-level spectra of NaBH 4 -NiFe LDH (Fig. S2B †) compared with NiFe LDH (Fig.…”

Preparation and application of metal ion-doped CoMgAl-hydrotalcite visible-light-driven photocatalyst

“…The degradation results revealed that the GA/CeMoPO 4 has better photocatalytic activity [23]. Many researchers have studied different synthesis methods through a lot of work on the preparation of LDHs, such as, ultra-sonication method [24], facile weight impregnation method [25] but mature synthesis methods include co-precipitation [26,27], hydrothermal synthesis [28][29][30], microwave radiation, ion exchange chromatography, sol-gel method [31,32], etc. Co-precipitation method is the most basic and commonly used synthetic method of hydrotalcite.…”

Strong Light–Matter Interactions in Au Plasmonic Nanoantennas Coupled with Prussian Blue Catalyst on BiVO4 for Photoelectrochemical Water Splitting

“…The 1/2 and 3/2 spin‐orbit doublet components of the V 5+ of the same electrode are located at 523.7 eV and 516.25 eV, respectively (see Figure d) . After the deposition of Au nanoislands, the V 2p and Bi 4f peaks are slightly blue shifted (≈0.1 eV) compared with the bare BiVO 4 , suggesting an electron transfer from Au to BiVO 4 , which could be attributed to the relatively high electronegativity of Au (see Figure c,d) . Moreover, the characteristics peaks at 87.18 eV and 83.5 eV in Figure S2 (in the Supporting Information) are ascribed to Au 4f 5/2 and Au 4f 7/2 , respectively, for Au‐BiVO 4 .…”