Identifying and rationalizing the morphological, structural, and optical properties of β-Ag₂MoO₄ microcrystals, and the formation process of Ag nanoparticles on their surfaces: combining experimental data and first-principles calculations

Abstract

We present a combined theoretical and experimental study on the morphological, structural, and optical properties of β-Ag2MoO4 microcrystals. β-Ag2MoO4 samples were prepared by a co-precipitation method. The nucleation and formation of Ag nanoparticles on β-Ag2MoO4 during electron beam irradiation were also analyzed as a function of electron beam dose. These events were directly monitored in real-time using in situ field emission scanning electron microscopy (FE-SEM). The thermodynamic equilibrium shape of the β-Ag2MoO4 crystals was built with low-index surfaces (001), (011), and (111) through a Wulff construction. This shape suggests that the (011) face is the dominating surface in the ideal morphology. A significant increase in the values of the surface energy for the (011) face versus those of the other surfaces was observed, which allowed us to find agreement between the experimental and theoretical morphologies. Our investigation of the different morphologies and structures of the β-Ag2MoO4 crystals provided insight into how the crystal morphology can be controlled so that the surface chemistry of β-Ag2MoO4 can be tuned for specific applications. The presence of structural disorder in the tetrahedral [MoO4] and octahedral [AgO6] clusters, the building blocks of β-Ag2MoO4, was used to explain the experimentally measured optical properties.

Fabrication of potato-like silver molybdate microstructures for photocatalytic degradation of chronic toxicity ciprofloxacin and highly selective electrochemical detection of H2O2

“…The calculated band gap energy value is 3.14 eV. On the other hand, the bandgap of Ag 2 MoO 4 is significantly altered compared to that of previous reports 36 43 44 50 . The oxygen vacancy created in the crystal lattice of the Ag 2 MoO 4 is leads to the distortion in the energy levels and influenced the bandgap which may be attributed to the effect of hydrothermal environment on the surface microstructures.…”

“…The photocatalytic activity mainly depends on the crystal and electronic structures of materials that affect the energy band structure and the efficiency of charge carrier transfer. Moreover, to improve their physicochemical properties of the photocatalyst, researchers have growled a number of approaches to obtain the different morphologies of Ag 2 MoO 4 including nanoparticles, nanorods, nanowires, wire-like nanostructures, nanoclusters, broom-like, flower-like microstructures and microcrystals 36 41 46 47 48 49 50 . However, to the best of our knowledge, we reported the synthesis of potato-like Ag 2 MoO 4 microstructure, its applications for the photocatalytic degradation of CIP and electrochemical detection of H 2 O 2 for the first time.…”

An experimental and theoretical investigation on the optical and photocatalytic properties of ZnS nanoparticles

“…Insights from theoretical calculations and experimental evidence can be related to develop a simple model that can be used to better understand crystal facet modulation with the aim of providing new insights into the structural design of the NPs as well as optical and photocatalytic mechanisms at the atomic level. The Wulff construction is a well-recognized method for determining the equilibrium morphology of complex functional materials [43][44][45][46][47][48][49][50]91,92], providing valuable thermodynamic information about frequent crystalline surface energies and constructing the most stable crystal shape. Fig.…”

“…First-principles calculations, mainly within the DFT framework, have proved invaluable in providing guidance and an atomistic understanding of the physical and chemical properties of emerging complex functional nanomaterials. Within this general framework, we are engaged in a joint experimental and theoretical project that is concerned with the synthesis, characterization, and technological applications of a series of Pb and Ag-based metal oxides, such as PbMoO 4 [43], α-Ag 2 WO 4 [44], β-Ag 2 WO 4 [45], β-Ag 2 MoO 4 [46], β-AgVO 3 [47], Ag 2 CrO 4 [48] or Ag-containing salts such as Ag 3 PO 4 [49,50].…”

Synthesis and morphological transformation of BaWO4 crystals: Experimental and theoretical insights

“…Using a specific methodology, which has been applied to study morphologies of various metal oxides such as SnO 2 [41], PbMoO 4 [42], and CaWO 4 [43], we developed a combination of experimental studies with first-principles calculations to deeper investigate electronic, structural, and energetic properties controlling the morphology and related transformation mechanisms of various metals and metal oxides such as Ag, anatase TiO 2 , BaZrO 3 , and α-Ag 2 WO 4 [44] as well as Co 3 O 4 , Fe 2 O 3 , and In 2 O 3 [45]. Based on the obtained results, we were able to explore facet-dependent photocatalytic and antibacterial properties of α-Ag 2 WO 4 crystals [46] as well as the relationship between the photoluminescence and photocatalytic properties of Ag 3 PO 4 microcrystals [47] and then identify and rationalize morphological, structural, and optical properties of β-Ag 2 MoO 4 microcrystals [48]. These cited papers contain a description of the method of calculating surface energies, which were used to characterize the corresponding surface morphologies.…”