High shear in situ exfoliation of 2D gallium oxide sheets from centrifugally derived thin films of liquid gallium

A diversity of two-dimensional nanomaterials has recently emerged with recent attention turning to the post-transition metal elements, in particular material derived from liquid metals and eutectic melts below 330 °C where processing is more flexible and in the temperature regime suitable for industry. This has been explored for liquid gallium using an angled vortex fluidic device (VFD) to fabricate ultrathin gallium oxide (Ga₂O₃) sheets under continuous flow conditions. We have established the nanosheets to form highly insulating material and have electrocatalytic activity for hydrogen evolution, with a Tafel slope of 39 mV dec^-1 revealing promoting effects of the surface oxidation (passivation layer).

Structural, thermal, and electronic properties of two-dimensional gallium oxide(ß-Ga2O3) from first-principles design

Two-dimensional (2D) materials with exotic electronic, optical and mechanical properties have attracted tremendous attention in the last two decades, due to their potential applications in electronics, energy storage and conversion technologies. However, only a few dozen 2D materials have been successfully synthesized or exfoliated. Motivated by the recent discovery of 2D gallenene, we have explored new 2D allotropes of ß-Ga 2 O 3 , an emerging wide-band gap transparent conductive oxide (TCO) with a wide range of semiconducting applications. All the possible 2D allotropes of ß-Ga 2 O 3 with high energetic stability have been predicted using particle swarm optimization, combined with density functional theory calculations. The structural and dynamical stability of the predicted 2D allotropes has been analyzed. Although ß-Ga 2 O 3 is not a van der Waals material, results predict that one or two allotropes of ß-Ga 2 O 3 are stable. In addition, the accurate band structures of these 2D semiconducting oxides have been calculated using both the GGA and LDA-1/2 approach. Remarkably, monolayer Ga 2 O 3 (100) has a larger indirect band gap of 4 eV, demonstrating a new avenue for the discovery of 2D ß-Ga 2 O 3 based nano-devices with enhanced electronic properties.

Energy storage properties of hydrothermally processed ultrathin 2D binder-free ZnCo2O4nanosheets

High energy-density supercapacitors (SCs) with long operating life, cost-effective, and competitive cycling performance is attracted great research attention to competing in the requirements of the modern age. However, despite these benefits, SC hampers inadequate rate-capability and structural deterioration, which primarily affects its commercialization. Herein, ultra-thin two-dimensional (2D) ZnCo₂O₄nanosheets arein situanchored on the conductive surface of nickel foam (denoted as ZCO@NF) by hydrothermal process. The binder-free ZCO@NF is employed as an electrode for SCs and shows impressive charge storage properties. ZCO@NF electrode exhibited a high capacitance of 1250 (750) and 733 F g^-1(440 C g^-1) at 2.5 and 20 A g^-1, respectively, demonstrating the outstanding rate-capability of 58.6% even at 8 times larger current density. Furthermore, the ZCO@NF electrode exhibits admirable capacitance retention of 96.5% after 10 000 cycles. This impressive performance of the ZCO@NF electrode is attributed to the high surface area which gives a short distance for ion/electron transfer, a high conductivity with extensive electroactive cities, and strong structural stability. The binder-free approach provides a strong relationship between the current collector and the active material, which turns into improved electrochemical operation as an electrode material for SCs.

Structural, electric and dielectric properties of perovskite based nanoparticles for energy applications

A nanocomposite electrode, obtained by combining two high performance perovskite materials, such as lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and gadolinium doped ceria, Ce0.85Gd0.15O1.5 (GDC), were investigated as a promising cathode for moderate temperature solid oxide fuel cells (SOFCs). The synthesized material has good conductivity and catalytic performance. The purpose of this synthesis was to prepare a stable and highly performing nanocomposite cathode material. In this research work, LSCF and GDC were separately synthesized by co-precipitation and solid-state reaction method to gain a homogeneous perovskite phase. Varying concentrations of LSCF–GDC composite with GDC (10 wt.%, 20 wt.% and 30 wt.%) were synthesized followed by calcination at 600 °C to remove water content and to achieve an adequate porous structure for oxygen absorption and desorption. These fabricated LSCF, GDC, and the nanocomposite specimens were characterized for microstructure, particle size etc. via. X-ray diffraction method (XRD), scanning electron microscope (SEM) and the laser particle size analyzer. This procedural approach helps to expand new methods for generating bi-functional duel nano-sized perovskites with great performance and stability which can be utilized for advancement of renewable energy sectors especially for rechargeable fuel batteries.

Structural, electric and dielectric properties of perovskite based nanoparticles for energy applications

A nanocomposite electrode, obtained by combining two high performance perovskite materials, such as lanthanum strontium cobalt ferrite, La0.6Sr0.4Co0.2Fe0.8O3−δ (LSCF) and gadolinium doped ceria, Ce0.85Gd0.15O1.5 (GDC), were investigated as a promising cathode for moderate temperature solid oxide fuel cells (SOFCs). The synthesized material has good conductivity and catalytic performance. The purpose of this synthesis was to prepare a stable and highly performing nanocomposite cathode material. In this research work, LSCF and GDC were separately synthesized by co-precipitation and solid-state reaction method to gain a homogeneous perovskite phase. Varying concentrations of LSCF–GDC composite with GDC (10 wt.%, 20 wt.% and 30 wt.%) were synthesized followed by calcination at 600 °C to remove water content and to achieve an adequate porous structure for oxygen absorption and desorption. These fabricated LSCF, GDC, and the nanocomposite specimens were characterized for microstructure, particle size etc. via. X-ray diffraction method (XRD), scanning electron microscope (SEM) and the laser particle size analyzer. This procedural approach helps to expand new methods for generating bi-functional duel nano-sized perovskites with great performance and stability which can be utilized for advancement of renewable energy sectors especially for rechargeable fuel batteries.

Exploring the Effect of Electron Withdrawing Groups on Optoelectronic Properties of Pyrazole Derivatives as Efficient Donor and Acceptor Materials for Photovoltaic Devices

Multifunctional pyrazole derivative, i.e. 3-amino-1-(5-hydroxy-3-methyl-1H-pyrazol-4-yl)-1H-benzo[f]chromene-2-carbonitrile (PBCC) has been synthesized and characterized. To shed light on various properties of interests, the ground state geometry was optimized by adopting Density Functional Theory (PBE/TZ2P). The effect of different functionals on the absorption wavelengths was studied by using Time-Domain DFT (TDDFT), e.g. GGA functional PBE, hybrid functionals B3LYP and PBE0, rang separated functionals CAM-B3LYP, LCY-PBE and CAMY-B3LYP, Dispersion Corrections PBE-D3 and B3LYP-D3. Among all these functionals PBE and PBE-D3 were found to be good choices which reproduced the absorption spectra of the PBCC. With the aim to enhance the electro-optical, charge transfer and photovoltaic properties, five new derivatives were designed by di-substituting the –F, –Cl, –Br, –COOH and –CN at benzochromene moiety. The electron injection barrier, band gap alignment and related calculated photovoltaic parameters revealed that PBCC and its newly designed derivatives would be proficient to be used in photovoltaic devices. These compounds can be used as donor materials in dye-sensitized solar cells (DSSCs) with favorable type-II band alignment. Moreover, PBCC and most of its derivatives might also be good choice as efficient acceptors with poly(dithieno[3,2-b:2,3-d]pyrrole thiophene) (PDTPr-T) and donor materials with Phenyl-C61-butyric acid methyl ester (PC61BM) in organic solar cells.