Structural regulation of ZnGa2O4 nanocubes for achieving high capacity and stable rate capability as an anode material of lithium ion batteries

Synthesis and Nanostructure Investigation of Hybrid β-Ga2 O3 /ZnGa2 O4 Nanocomposite Networks with Narrow-Band Green Luminescence and High Initial Electrochemical Capacity

The material design of functional "aero"-networks offers a facile approach to optical, catalytical, or and electrochemical applications based on multiscale morphologies, high large reactive area, and prominent material diversity. Here in this paper, the synthesis and structural characterization of a hybrid β-Ga₂ O₃ /ZnGa₂ O₄ nanocomposite aero-network are presented. The nanocomposite networks are studied on multiscale with respect to their micro- and nanostructure by X-ray diffraction (XRD) and transmission electron microscopy (TEM) and are characterized for their photoluminescent response to UV light excitation and their electrochemical performance with Li-ion conversion reaction. The structural investigations reveal the simultaneous transformation of the precursor aero-GaN(ZnO) network into hollow architectures composed of β-Ga₂ O₃ and ZnGa₂ O₄ nanocrystals with a phase ratio of ≈1:2. The photoluminescence of hybrid aero-β-Ga₂ O₃ /ZnGa₂ O₄ nanocomposite networks demonstrates narrow band (λ_em  = 504 nm) green light emission of ZnGa₂ O₄ under UV light excitation (λ_ex  = 300 nm). The evaluation of the metal-oxide network performance for electrochemical application for Li-ion batteries shows high initial capacities of ≈714 mAh g^-1 at 100 mA g^-1 paired with exceptional rate performance even at high current densities of 4 A g^-1 with 347 mAh g^-1 . This study provides is an exciting showcase example of novel networked materials and demonstrates the opportunities of tailored micro-/nanostructures for diverse applications a diversity of possible applications.

The Effect of Annealing Ambience on the Material and Photodetector Characteristics of Sputtered ZnGa2O4 Films

Spinel ZnGa₂O₄ films were grown on c-plane sapphire substrates at the substrate temperature of 400 °C by radio-frequency magnetron sputtering. Post thermal annealing was employed at the annealing temperature of 700 °C in order to enhance their crystal quality. The effect of thermal annealing on the microstructural and optoelectronic properties of ZnGa₂O₄ films was systematically investigated in various ambiences, such as air, nitrogen, and oxygen. The X-ray diffraction patterns of annealed ZnGa₂O₄ films showed the crystalline structure to have (111) crystallographic planes. Transmission electron micrographs verified that ZnGa₂O₄ film annealed under air ambience possesses a quasi-single-crystalline structure. This ZnGa₂O₄ film annealed under air ambience exhibited a smooth surface, an excellent average transmittance above 82% in the visible region, and a wide bandgap of 5.05 eV. The oxygen vacancies under different annealing ambiences were revealed a substantial impact on the material and photodetector characteristics by X-ray photoelectron spectrum investigations. ZnGa₂O₄ film exhibits optimal performance as a metal-semiconductor-metal photodetector when annealed under air ambience. Under these conditions, ZnGa₂O₄ film exhibits a higher photo/dark current ratio of ~10⁴ order, as well as a high responsivity of 2.53 A/W at the bias of 5 V under an incident optical light of 240 nm. These results demonstrate that quasi-single-crystalline ZnGa₂O₄ films have significant potential in deep-ultraviolet applications.

Enticing 3D peony-like ZnGa2O4 microstructures for electrochemical detection of N, N-dimethylmethanamide chemical

We demonstrate the hydrothermal synthesis of three dimension (3D) peony-like morphology of zinc gallate (ZnGa₂O₄), dominated by assembled nanosheets and applied as electrode material in electrochemical detection of N,N-dimethylmethanamide chemical. The crystalline, structural and compositional characterizations deduced the formation of high quality ZnGa₂O₄ with spinal crystal structure. Peony-like 3D ZnGa₂O₄ was benefited by a high surface area of ~62.3 m² g^-1, good pore distribution (mean pore diameter of ~23.3 nm) and large pore volume of ~0.3622 cm³ g^-1. N,N-dimethylmethanamide chemical sensor based on peony-like 3D ZnGa₂O₄ electrode presented a linear curve in the working dynamic range of 1 nM-10 mM. Significantly improved chemical sensitivity of ~154.2 mA mM^-1 cm^-2 with low detection limit value of ~0.14 μM were achieved. The fabricated sensor based on peony-like 3D ZnGa₂O₄ electrode endorsed real sample analysis and ascertained the selectivity towards N,N-dimethylmethanamide chemical by analyzing a range of interfering analytes, viz. ethanol, tetrahydrofuran, methyl amine chemical.

Zinc Gallium Oxide-A Review from Synthesis to Applications

Spinel ZnGa2O4 has received significant attention from researchers due to its wide bandgap and high chemical and thermal stability; hence, paving the way for it to have potential in various applications. This review focuses on its physical, optical, mechanical and electrical properties, contributing to the better understanding of this material. The recent trends for growth techniques and processing in the research and development of ZnGa2O4 from bulk crystal growth to thin films are discussed in detail for device performance. This material has excellent properties and is investigated widely in deep-ultraviolet photodetectors, gas sensors and phosphors. In this article, effects of substrate temperature, annealing temperature, oxygen partial pressure and zinc/gallium ratio are discussed for device processing and fabrication. In addition, research progress and future outlooks are also identified.

Electrogenerated chemiluminescence resonance energy transfer between ZnGa2O4/g-C3N4 and gold nanoparticles/graphene and its application in the detection of thrombin

A label-free ECL sensor for thrombin was fabricated based on ECL resonance energy transfer occurred between ZnGa₂O₄/g-C₃N₄ and AuNP/GR nanocomposites, which revealed a new role of spinel-type semiconductor oxides in the fabrication of ECL sensors.

Porous ZnO/Co3O4/N-doped carbon nanocages synthesized via pyrolysis of complex metal–organic framework (MOF) hybrids as an advanced lithium-ion battery anode

Metal oxides have a large storage capacity when employed as anode materials for lithium-ion batteries (LIBs). However, they often suffer from poor capacity retention due to their low electrical conductivity and huge volume variation during the charge–discharge process. To overcome these limitations, fabrication of metal oxides/carbon hybrids with hollow structures can be expected to further improve their electrochemical properties. Herein, ZnO-Co3O4 nanocomposites embedded in N-doped carbon (ZnO-Co3O4@N-C) nanocages with hollow dodecahedral shapes have been prepared successfully by the simple carbonizing and oxidizing of metal–organic frameworks (MOFs). Benefiting from the advantages of the structural features, i.e. the conductive N-doped carbon coating, the porous structure of the nanocages and the synergistic effects of different components, the as-prepared ZnO-Co3O4@N-C not only avoids particle aggregation and nanostructure cracking but also facilitates the transport of ions and electrons. As a result, the resultant ZnO-Co3O4@N-C shows a discharge capacity of 2373 mAh g−1 at the first cycle and exhibits a retention capacity of 1305 mAh g−1 even after 300 cycles at 0.1 A g−1. In addition, a reversible capacity of 948 mAh g−1 is obtained at a current density of 2 A g−1, which delivers an excellent high-rate cycle ability.