The synthesis of multifunctional porous honey comb-like La2O3 thin film for supercapacitor and gas sensor applications

All-Solid-State Supercapacitors Based on Cobalt Magnesium Telluride Microtubes Decorated with Tellurium Nanotubes

Magnesium (Mg) has received very little exploration on its importance in the realm of battery-type energy storage technologies. They are abundantly present in seawater, and if successfully extracted and utilized in energy storage systems, it could lead to the long-term advancement of human civilization. Here, we fabricated an all-solid-state supercapacitor (ASSSC) using tellurium nanotubes decorated cobalt magnesium telluride microtubes (Te NTs@CoMgTe MTs) clad on nickel foam (NF). Owing to the unique mixed phase hierarchical structure, Te NTs@CoMgTe MTs showcases some advancement in energy storage performance. When tested in a three-electrode system, multiphasic hybrid of elemental Te and metal tellurides, Te NTs@CoMgTe MTs outperforms the monometallic telluride owing to the strong synergistic interaction effect triggered from conductive three components and delivers a long-life span performance up to 15,000 cycles. The fabricated Te NT@CoMgTe MT//AC solid-state device exhibits a maximum areal capacity of 59.2 μAh cm-2 (56.3 mAh g-1) at a current density of 6 mA cm-2 with a maximum energy density of 42.2 Wh kg-1 (46.5 μWh cm-2) at a power density of 6857.1 W kg-1 (7574.6 μW cm-2). The performance of the device is rigid even at different bending angles (0 to 180°) which validates the extensibility of the process for future applications.

Comprehensive Study on Ultra-Wide Band Gap La2O3/ε-Ga2O3 p-n Heterojunction Self-Powered Deep-UV Photodiodes for Flame Sensing

Solar-blind UV photodetectors have outstanding reliability and sensitivity in flame detection without interference from other signals and response quickly. Herein, we fabricated a solar-blind UV photodetector based on a La2O3/ε-Ga2O3 p-n heterojunction with a typical type-II band alignment. Benefiting from the photovoltaic effect formed by the space charge region across the junction interface, the photodetector exhibited a self-powered photocurrent of 1.4 nA at zero bias. Besides, this photodetector demonstrated excellent photo-to-dark current ratio of 2.68 × 104 under 254 nm UV light illumination and at a bias of 5 V, and a high specific detectivity of 2.31 × 1011 Jones and large responsivity of 1.67 mA/W were achieved. Importantly, the La2O3/ε-Ga2O3 heterojunction photodetector can rapidly respond to flames in milliseconds without any applied biases. Based on the performances described above, this novel La2O3/ε-Ga2O3 heterojunction is expected to be a candidate for future energy-efficient fire detection.

Fabrication of fullerene-supported La2O3-C60 nanocomposites: dual-functional materials for photocatalysis and supercapacitor electrodes

Nowadays, water pollution and energy crises worldwide force researchers to develop multi-functional and highly efficient nanomaterials. In this scenario, the present work reports a dual-functional La₂O₃-C₆₀ nanocomposite fabricated by a simple solution method. The grown nanomaterial worked as an efficient photocatalyst and proficient electrode material for supercapacitors. The physical and electrochemical properties were studied by state-of-the-art techniques. XRD, Raman spectroscopy, and FTIR spectroscopy confirmed the formation of the La₂O₃-C₆₀ nanocomposite with TEM nano-graphs, and EDX mapping exhibits the loading of C₆₀ on La₂O₃ particles. XPS confirmed the presence of varying oxidation states of La³⁺/La²⁺. The electrochemical capacitive properties were tested by CV, EIS, GCD, ECSA, and LSV, which indicated that the La₂O₃-C₆₀ nanocomposite can be effectively used as an electrode material for durable and efficient supercapacitors. The photocatalytic test using methylene blue (MB) dye revealed the complete photodegradation of the MB dye under UV light irradiation after 30 min by a La₂O₃-C₆₀ catalyst with a reusability up to 7 cycles. The lower energy bandgap, presence of deep-level emissions, and lower recombination rate of photoinduced charge carriers in the La₂O₃-C₆₀ nanocomposite than those of bare La₂O₃ are responsible for enhanced photocatalytic activity with low-power UV irradiation. The fabrication of multi-functional and highly efficient electrode materials and photocatalysts such as La₂O₃-C₆₀ nanocomposites is beneficial for the energy industry and environmental remediation applications.

Ultrathin Ce-doped La2O3nanofilm electrocatalysts for efficient oxygen evolution reactions

It is still highly desired to develop efficient, resource-abundant and inexpensive electrocatalysts to improve the sluggish kinetics of oxygen evolution reaction (OER) in electrochemical water splitting systems. In this work, the large-area ultrathin (2.52 nm thick) Ce-doped La₂O₃nanofilms were developed via a facile and reliable ionic layer epitaxy method with different Ce content. The ultrathin Ce-doped La₂O₃nanofilm with optimum composition of La_1.22Ce_0.78O₃exhibited an excellent OER performance with a very low overpotential of 221 mV at 10 mA cm^-2and a small Tafel slope of 33.7 mV dec^-1. A remarkable high mass activity of 6263.2 A g^-1was also obtained from ultrathin La_1.22Ce_0.78O₃nanofilm at the overpotential of 221 mV. Such a high mass activity was three orders of magnitude higher than state-of-the-art commercial IrO₂powders (3.8 A g^-1) and more than 30 times higher than La₂O₃nanofilm (196.7 A g^-1) without Ce doping at the same overpotential. This high mass activity was even significantly higher than other recently reported typical OER catalysts. The substantial OER performance gain by the Ce doping was attributed to the improved conductivity and electrochemical active surface areas of nanofilms as a result of favorable tuning on the charge transfer and electronic structures. This work provides a promising approach to develop high-performance two-dimensional (2D) electrocatalysts by effective heteroatom doping strategy.

Nanoflakes-like nickel cobaltite as active electrode material for 4-nitrophenol reduction and supercapacitor applications

Catalytic reduction of nitroaromatic compounds present in wastewater by nanostructured materials is a promising process for wastewater treatment. A multifunctional electrode based on ternary spinal nickel cobalt oxide is used in the catalytic reduction of a nitroaromatic compound and supercapacitor application. In this study, we designed nanoflakes- like nickel cobaltite (NiCo₂O₄) using a simple, chemical, cost-effective hydrothermal method. Nanoflakes- like NiCo₂O₄ samples are tested as catalysts toward rapid reduction of 4-nitrophenol and as electrode materials for supercapacitors. The conversion of 4-nitrophenol into 4-aminophenol is achieved using a reducing agents like sodium borohydride and NiCo₂O₄ catalyst. Effect of catalyst loading, 4-nitrophenol and sodium borohydride concentrations on the catalytic performance of 4-nitrophenol is studied. As sodium borohydride concentration increases the catalytic efficiency of 4-nitrophenol increased due to more BH₄^- ions available which provides more electrons for catalytic reduction of 4-nitrophenol. Catalytic reduction of 4-nitrophenol using sodium borohydride as a reducing agent was based on the Langmuir-Hinshelwood mechanism. This mechanism follows the apparent pseudo first order reaction kinetics. Additionally, NiCo₂O₄ electrode is used for energy storage application. The nanoflakes-like NiCo₂O₄ electrode deposited at 120 °C shows a higher specific capacitance than samples synthesized at 100 and 140 °C. The maximum specific capacitance observed for NiCo₂O₄ electrode is 1505 Fg^-1 at a scan rate of 5 mV s^-1 with high stability of 95% for 5000 CV cycles.

Nanoparticle-Decorated Ultrathin La2O3 Nanosheets as an Efficient Electrocatalysis for Oxygen Evolution Reactions

Electrochemical catalysts for oxygen evolution reaction are a critical component for many renewable energy applications. To improve their catalytic kinetics and mass activity are essential for sustainable industrial applications. Here, we report a rare-earth metal-based oxide electrocatalyst comprised of ultrathin amorphous La₂O₃ nanosheets hybridized with uniform La₂O₃ nanoparticles (La₂O₃@NP-NS). Significantly improved OER performance is observed from the nanosheets with a nanometer-scale thickness. The as-synthesized 2.27-nm La₂O₃@NP-NS exhibits excellent catalytic kinetics with an overpotential of 310 mV at 10 mA cm^-2, a small Tafel slope of 43.1 mV dec^-1, and electrochemical impedance of 38 Ω. More importantly, due to the ultrasmall thickness, its mass activity, and turnover frequency reach as high as 6666.7 A g^-1 and 5.79 s^-1, respectively, at an overpotential of 310 mV. Such a high mass activity is more than three orders of magnitude higher than benchmark OER electrocatalysts, such as IrO₂ and RuO₂. This work presents a sustainable approach toward the development of highly efficient electrocatalysts with largely reduced mass loading of precious elements.

A chemiresistor sensor modified with lanthanum oxide nanoparticles as a highly sensitive and selective sensor for dimethylamine at room temperature

An interdigitated microelectrode coated with La₂O₃ metal oxide for the detection of dimethylamine gas has high stability in response, fast response, low recovery time, low energy consumption and low manufacturing cost.

Ultrasound assisted growth of NiCo2O4@carbon cloth for high energy storage device application

The nanostructure of metal oxides attracts great attention in the field of supercapacitors because of fast charge transport process. The hydrothermal method is used for development of NiCo₂O₄nanostructure on carbon cloth as current collector backbone. The stepwise study of various structural, morphological and electrochemical properties of NiCo₂O₄electrode is studied. The ultrasonic treatment is used to obtain nanowire-like morphology of NiCo₂O₄ which exhibits hierarchical nanostructure, which provides surface properties such as high surface area and appropriate pore capacity. NiCo₂O₄ nanostructure with specific capacitance of 1460 F g^-1 with high electrochemical stability of 84% after 3000 cycles in 3 M KOH aqueous electrolyte at 100 mV s^-1. The electrochemical property shows NiCo₂O₄is one of the potential candidates for energy storage application. The specific capacitance and energy density for NiCo₂O₄@CC//NiCo₂O₄@CC symmetric supercapacitor device is of 124 F g^-1 and 16.18 Wh.kg^-1, respectively at current density of 5 mA.

The electrochemical applications of rare earth-based nanomaterials

This review presents a general description of the synthesis and electrochemical properties of rare earth-based nanomaterials and their electrochemical applications.