A Review of Rechargeable Zinc-Air Batteries: Recent Progress and Future Perspectives.

Zinc-air batteries (ZABs) are gaining attention as an ideal option for various applications requiring high-capacity batteries, such as portable electronics, electric vehicles, and renewable energy storage. ZABs offer advantages such as low environmental impact, enhanced safety compared to Li-ion batteries, and cost-effectiveness due to the abundance of zinc. However, early research faced challenges due to parasitic reactions at the zinc anode and slow oxygen redox kinetics. Recent advancements in restructuring the anode, utilizing alternative electrolytes, and developing bifunctional oxygen catalysts have significantly improved ZABs. Scientists have achieved battery reversibility over thousands of cycles, introduced new electrolytes, and achieved energy efficiency records surpassing 70%. Despite these achievements, there are challenges related to lower power density, shorter lifespan, and air electrode corrosion leading to performance degradation. This review paper discusses different battery configurations, and reaction mechanisms for electrically and mechanically rechargeable ZABs, and proposes remedies to enhance overall battery performance. The paper also explores recent advancements, applications, and the future prospects of electrically/mechanically rechargeable ZABs.

Bias-Modified Schottky Barrier Height-Dependent Graphene/ReSe2 van der Waals Heterostructures for Excellent Photodetector and NO2 Gas Sensing Applications.

Herein, we reported a unique photo device consisting of monolayer graphene and a few-layer rhenium diselenide (ReSe2) heterojunction. The prepared Gr/ReSe2-HS demonstrated an excellent mobility of 380 cm2/Vs, current on/off ratio ~ 104, photoresponsivity (R ~ 74 AW-1 @ 82 mW cm-2), detectivity (D* ~ 1.25 × 1011 Jones), external quantum efficiency (EQE ~ 173%) and rapid photoresponse (rise/fall time ~ 75/3 µs) significantly higher to an individual ReSe2 device (mobility = 36 cm2 V-1s-1, Ion/Ioff ratio = 1.4 × 105-1.8 × 105, R = 11.2 AW-1, D* = 1.02 × 1010, EQE ~ 26.1%, rise/fall time = 2.37/5.03 s). Additionally, gate-bias dependent Schottky barrier height (SBH) estimation for individual ReSe2 (45 meV at Vbg = 40 V) and Gr/ReSe2-HS (9.02 meV at Vbg = 40 V) revealed a low value for the heterostructure, confirming dry transfer technique to be successful in fabricating an interfacial defects-free junction. In addition, HS is fully capable to demonstrate an excellent gas sensing response with rapid response/recovery time (39/126 s for NO2 at 200 ppb) and is operational at room temperature (26.85 °C). The proposed Gr/ReSe2-HS is capable of demonstrating excellent electro-optical, as well as gas sensing, performance simultaneously and, therefore, can be used as a building block to fabricate next-generation photodetectors and gas sensors.

Stabilization of Perovskite Solar Cells: Recent Developments and Future Perspectives.

Exceptional power conversion efficiency (PCE) of 25.7% in perovskite solar cells (PSCs) has been achieved, which is comparable with their traditional rivals (Si-based solar cells). However, commercialization-worthy efficiency and long-term stability remain a challenge. In this regard, there are increasing studies focusing on the interface engineering in PSC devices to overcome their poor technical readiness. Herein, the roles of electrode materials and interfaces in PSCs are discussed in terms of their PCEs and perovskite stability. All the current knowledge on the factors responsible for the rapid intrinsic and external degradation of PSCs is presented. Then, the roles of carbonaceous materials as substitutes for noble metals are focused on, along with the recent research progress in carbon-based PSCs. Furthermore, a sub-category of PSCs, that is, flexible PSCs, is considered as a type of exceptional power source due to their high power-to-weight ratios and figures of merit for next-generation wearable electronics. Last, the future perspectives and directions for research in PSCs are discussed, with an emphasis on their commercialization.

Valorization of orange peel waste to tunable heteroatom-doped hydrochar-derived microporous carbons for selective CO2 adsorption and separation.

Constrained by the extortionately expensive carbon sources, low carbon yields, inadequate adsorption capacities, and corrosive chemical activating agents, the commercialization of carbonaceous CO2 adsorbents remains a challenging task. Herein, potassium oxalate (K2C2O4), an activating agent with less corrosive properties, was used for the synthesis of activated carbons from inexhaustibly available "orange peel biowaste." For the first time, a comprehensive report is presented on the effect of hydrothermal treatment, hydrochar/K2C2O4 ratio, activation temperature, and melamine modification in tailoring the porosity and surface functionalization of activated carbons. The optimized sample, OPMK-900, exhibited large specific surface area ~2130 m2/g; micropore volume ~1.1166 cm3/g, and a high pyrrolic nitrogen content (~ 46.1 %). Notably, melamine played the dual role as a promoter to K2C2O4 porosity generation and a nitrogen dopant, which synergistically led to an efficient CO2 uptake of ~6.67 mmol/g at 273 K/ 1 bar via micropore-filling mechanism and Lewis acid-base interactions. Moreover, remarkably high IAST CO2/N2 selectivity (105 at 273 K and 96 at 298 K) surpasses most of the biomass-derived carbons. Furthermore, the moderately high isosteric heat of adsorption (∆Hads ~ 38.9 kJ/mol) revealed the physisorption mechanism of adsorption with a limited energy requirement for the regeneration of the spent adsorbents.

Valorization of shrimp shell biowaste for environmental remediation: Efficient contender for CO2 adsorption and separation.

Over the years, single heteroatom-doped biowaste-derived activated carbons were studied for effective CO2 adsorption. However, binary or ternary heteroatoms-doping is equally important and could significantly affect the CO2 adsorption and flue gas (i.e., CO2/N2) separation. Herein, for the first time, shrimp shell-derived chitosan was used to design a series of ternary (N, S, O)-doped hierarchically porous carbons. The resultant carbons exhibit a large specific surface area (up to 2095 m2/g), micropore volume (up to 1.2647 cm3/g), and high heteroatoms content i.e., N up to 4.1 at. %, S up to 4.6 at. %, and O up to 13.4 at. %. Consequently, high CO2 uptake of 236.80 mg/g at 273 K/1 bar and an excellent CO2/N2 gas selectivity (84.3) was observed, attributed to the synergistic role of narrow micropores (<1 nm) and optimum heteroatom content. Furthermore, the stable CO2 adsorption-desorption cyclic behavior under flue gas conditions i.e., 15% CO2/85% N2 reveals the physisorption mechanism of CO2 adsorption and appears to be an energy-efficient regeneration process. Concluding, our work demonstrates a facile route of valorization of biowaste for environmental remediation to combat biowaste accumulation and mitigating atmospheric CO2 levels, simultaneously.

Energy-Efficient Tunneling Field-Effect Transistors for Low-Power Device Applications: Challenges and Opportunities.

Conventional field-effect transistors (FETs) have long been considered a fundamental electronic component for a diverse range of devices. However, nanoelectronic circuits based on FETs are not energy efficient because they require a large supply voltage for switching applications. To reduce the supply voltage in standard FETs, which is hampered by the 60 mV/decade limit established by the subthreshold swing (SS), a new class of FETs have been designed, tunnel FETs (TFETs). A TFET utilizes charge-carrier transportation in device channels using quantum mechanical based band-to-band tunneling despite of conventional thermal injection. The TFETs fabricated with thin semiconducting film or nanowires can attain a 100-fold power drop compared to complementary metal-oxide-semiconductor (CMOS) transistors. As a result, the use of TFETs and CMOS technology together could ameliorate integrated circuits for low-power devices. The discovery of two-dimensional (2D) materials with a diverse range of electronic properties has also opened new gateways for condensed matter physics, nanotechnology, and material science, thus potentially improving TFET-based devices in terms of device design and performance. In this review, state-of-art TFET devices exhibiting different semiconducting channels and geometries are comprehensively reviewed followed by a brief discussion of the challenges that remain for the development of high-performance devices. Lastly, future prospects are presented for the improvement of device design and the working efficiency of TFETs.

Synthesis using natural functionalization of activated carbon from pumpkin peels for decolourization of aqueous methylene blue.

In this study, a novel approach was applied for modification and functionalization of pumpkin peels (PP) derived carbon using natural beetroot extract. PP waste biomass was carbonized at 250 (AC250), 350 (AC350), 450 (AC450) and 550 °C (AC550) and used as adsorbent for the scavenging of methylene blue (MB). The adsorption results revealed that AC250 was the most efficient material. Thereafter, AC250 was further modified with different acids and natural beetroot extract to enhance the adsorption efficiency for MB removal. Modified and functionalized carbon materials were characterized to determine the functional groups, crystalline nature and surface morphology of adsorbents using Fourier Transformed Infra-Red spectroscopy, X-ray Diffraction and Scanning Electron Microscopy. The pore size distribution measurements by non-local density functional theory (NLDFT) revealed the presence of large number of mesopores in the beetroot activated carbon (BAC) with the BET specific surface area of 3.6 m2.g-1. The adsorption studies exhibited the highest adsorption (198.15 mg.g-1) for MB using 0.5 g.L-1 of adsorbent mass at 200 mg.L-1 MB concentration and 50 °C within 180 min. Reaction kinetics analysis of the experimental data revealed that adsorption followed pseudo second order kinetic model where BAC250 showed highest reaction rate constant value of 0.0095 and correlation coefficient value of 0.9992. The equilibrium data were tested by using Freundlich and Langmuir isotherm models. For both isotherms, the characteristic parameters were determined and the adsorption behaviour was found to fit well with the Langmuir isotherm model indicating monolayer adsorption of MB.

Butterfly cluster like lamellar BiOBr/TiO2 nanocomposite for enhanced sunlight photocatalytic mineralization of aqueous ciprofloxacin.

The present study for the first time reports facile in-situ room temperature synthesis of butterfly cluster like lamellar BiOBr deposited over TiO2 nanoparticles for photocatalytic breakdown of ciprofloxacin (CIP). The butterfly cluster arrangement of BiOBr resulted in an increase in surface area from 124.6 to 160.797 m2·g-1 and subsequently increased incident light absorption by the composite photocatalyst. The XRD indicated the existence of TiO2 as spherical ≈10-15 nm diameter particles with [101] preferential growth planes of anatase phase while the lamellar BiOBr showing growth along [110] and [102] preferential planes that were also confirmed by the HR-TEM images. DRS data implicated 2.76 eV as the energy band gap of the synthesized nanocomposite while PL spectroscopic analysis predicted it to be 2.81 eV. XPS measurements examined the chemical oxidation states of the constituents among the nanocomposite samples. The lameller structure of BiOBr in 15%BiOBr/TiO2 acts as a manifold promoting both visible light (λ > 420 nm) and direct sunlight catalytic degradation of 25 mg·L-1 aqueous CIP up to 92.5% and 100%, respectively within 150 min. The rate constant values suggested that the visible light photocatalysis of CIP with 15%BiOBr/TiO2 was 5.2 and 9.4 times faster compared to pristine TiO2 and BiOBr, respectively. The free radical scavenging study demonstrated that although photogenerated superoxide ions and holes contribute to the overall photocatalytic activity, yet, hydroxyl radicals predominantly control the CIP oxidation. The synthesized nanocomposite was re-used up to five cycles and retained 82.98% efficiency even after 5th use cycle showing a decline of only 12%. The catalyst stability and easy recovery adds to its reusability and value of the photocatalytic process.

Microporous carbons derived from melamine and isophthalaldehyde: One-pot condensation and activation in a molten salt medium for efficient gas adsorption.

In the present work, mixture of melamine and isophthalaldehyde undergo simultaneous polymerization, carbonization, and in situ activation in the presence of molten salt media through a single all-in-one route to design microporous carbons with high specific surface areas (~3000 m2/g). The effect of the activation temperature and molten salts on the polymerization process and final texture of the carbon was explored. Carbon materials prepared at 700 °C, in the presence of KOH (referred as MIK-700), exhibited a narrower pore-size distribution ~1.05 nm than those prepared in the presence of the eutectic KOH-NaOH mixture (MIKN). Additionally, MIK-700 possesses an optimum micropore volume (1.33 cm3/g) along with a high nitrogen content (2.66 wt%), resulting in the excellent CO2 adsorption capacity of 9.7 mmol/g at 273 K and 1 bar. Similarly, the high specific area and highest total pore volume play an important role in H2 storage at 77 K, with 4.0 wt% uptake by MIKN-800 (specific surface area and pore volume of 2984 m2/g and 1.98 cm3/g, respectively.) Thus, the facile one-step solvent-free synthesis and activation strategy is an economically favorable avenue for designing microporous carbons as an efficient gas adsorbents.