Laser-Synthesized Co-Doped CuO Electrocatalyst: Unveiling Boosted Methanol Oxidation Kinetics for Enhanced Hydrogen Production Efficiency by In Situ/Operando Raman and Theoretical Analyses

The present study details the strategic development of Co-doped CuO nanostructures via sophisticated and expedited pulsed laser ablation in liquids (PLAL) technique. Subsequently, these structures are employed as potent electrocatalysts for the anodic methanol oxidation reaction (MOR), offering an alternative to the sluggish oxygen evolution reaction (OER). Electrochemical assessments indicate that the Co-CuO catalyst exhibits exceptional MOR activity, requiring a reduced potential of 1.42 V at 10 mA cm-2 compared to that of pure CuO catalyst (1.57 V at 10 mA cm-2 ). Impressively, the Co-CuO catalyst achieved a nearly 180 mV potential reduction in MOR compared to its OER performance (1.60 V at 10 mA cm-2 ). Furthermore, when pairing Co-CuO(+)ǀǀPt/C(-) in methanol electrolysis, the cell voltage required is only 1.51 V at 10 mA cm-2 , maintaining remarkable stability over 12 h. This represents a substantial voltage reduction of ≈160 mV relative to conventional water electrolysis (1.67 V at 10 mA cm-2 ). Additionally, both in situ/operando Raman spectroscopy studies and theoretical calculations have confirmed that Co-doping plays a crucial role in enhancing the activity of the Co-CuO catalyst. This research introduces a novel synthetic approach for fabricating high-efficiency electrocatalysts for large-scale hydrogen production while co-synthesizing value-added formic acid.

Architecting the High-Entropy Oxides on 2D MXene Nanosheets by Rapid Microwave-Heating Strategy with Robust Photoelectrochemical Oxygen Evolution Performance

High-entropy oxides (HEO) have recently concerned interest as the most promising electrocatalytic materials for oxygen evolution reactions (OER). In this work, a new strategy to the synthesis of HEO nanostructures on Ti₃ C₂ T_x MXene via rapid microwave heating and subsequent calcination at a low temperature is reported. Furthermore, the influence of HEO loading on Ti₃ C₂ T_x MXene is investigated toward OER performance with and without visible-light illumination in an alkaline medium. The obtained HEO/Ti₃ C₂ T_x -0.5 hybrid exhibited an outstanding photoelectrochemical OER ability with a low overpotential of 331 mV at 10 mA cm^-2 and a small Tafel slope of 71 mV dec^-1 , which exceeded that of a commercial IrO₂ catalyst (340 mV at 10 mA cm^-2 ). In particular, the fabricated water electrolyzer with the HEO/Ti₃ C₂ T_x -0.5 hybrid as anode required a less potential of 1.62 V at 10 mA cm^-2 under visible-light illumination. Owing to the strong synergistic interaction between the HEO and Ti₃ C₂ T_x MXene, the HEO/Ti₃ C₂ T_x hybrid has a great electrochemical surface area, many metal active sites, high conductivity, and fast reaction kinetics, resulting in an excellent OER performance. This study offers an efficient strategy for synthesizing HEO-based materials with high OER performance to produce high-value hydrogen fuel.

Couple of Nonpolarized/Polarized Electrodes Building a New Universal Electrochemical Energy Storage System with an Impressive Energy Density

Herein, we propose a new concept of energy storage system composed of a nonpolarized electrode and a polarized electrode (PPE) with an impressive energy density. It offered nearly 4 times higher energy density than that of carbon-based supercapacitor. Among the suggested potential PPE system, we introduced an electrodeposited nanozinc on the copper foam as the nearly nonpolarized electrode and a Zn-2,5-dihydroxyterephthalic acid (DHTA) metal-organic framework (MOF)-derived activated porous carbon as a nearly polarized electrode in KOH-ZnO electrolyte to constitute the C|Zn PPE system prototype. The C|Zn system achieved an impressive energy density of 84.5 Wh kg^-1 at 1000 W kg^-1, 4 times higher than that of the C|C supercapacitor. It also shows a high capacitance retention rate of 94.5% at 10 A g^-1 after 10 000 cycles. Therefore, the amazing results indicate that the PPE energy system integrates the advantages of supercapacitors and secondary batteries. It will be a promising and effective energy device for higher-performance electric vehicles.

A facile synthesis of nano AgBr attached potato-like Ag2MoO4 composite as highly visible-light active photocatalyst for purification of industrial waste-water

In recent times, silver (Ag) based semiconductors have been gained a lot of attention as photocatalysts for industrial waste-water treatment owing to their strong visible-light absorbing capability and small bandgap energy. Therefore, herein, we have designed and utilized a one-pot hydrothermal approach to the synthesis of nano-sized AgBr covered potato-like Ag₂MoO₄ composite photocatalysts for the elimination of organic wastes from the aquatic environment. To achieve a high-performance photocatalyst, a sequence of AgBr/Ag₂MoO₄ composites were acquired with varying CTAB from 1 to 4 mmol. Furthermore, the photocatalytic activity of these photocatalysts was confirmed from decomposing of Rhodamine B (RhB) dye via visible-light elucidation. It can be noticed that AgBr/Ag₂MoO₄ composites exhibited significantly increased photocatalytic behaviour as compared with pure AgBr and Ag₂MoO₄. Surprisingly, the AgBr/Ag₂MoO₄ composite obtained from 2 mmol CTAB was eliminated the entire RhB dye with 25 min. Also, the recycling experiment indicates the AgBr/Ag₂MoO₄ composite has an excellent photo-stability. Accordingly, the as-acquired AgBr/Ag₂MoO₄ composite would be a suitable photocatalytic material for industrial waste-water purification.

Hierarchical porous carbon derived from jujube fruits as sustainable and ultrahigh capacitance material for advanced supercapacitors

Herein, we propose a new highly porous natural carbon material from renewable and inexpensive jujube fruits as a carbon source applied in supercapacitors. The combination of pre-carbonization and chemical activation approaches is employed to product hierarchical porous carbon from natural jujube fruits. The specific surface area of the prepared porous carbon is increased from 85.4 to 1135 m² g^-1 after the completion of NaOH activation at an optimized condition, which is beneficial to enhancing electrochemical performance of supercapacitors. A 3-electrode configuration was utilized to explore the electrochemical ability of porous carbon in 6 M KOH electrolyte. The acquired results demonstrate that porous carbon displays the specific capacitance of 587, 460 and 324 F g^-1 at 0.1, 1 and 100 A g^-1, respectively, which is confirmed by its admirable capacitance and rate behaviors. The porous carbon also shows a wonderful durability with a capacitance retention of 92.2% after 130,000 cycles at 50 A g^-1. Moreover, the assembled symmetrical coin-like supercapacitors with wide potential window of 2.5 V in 1 M Et₄NBF₄/AN organic electrolyte offer a high energy density of 23.7 Wh kg^-1 at 0.629 kW kg^-1 with remaining 94% capacitance over 10,000 cycles at 30 A g^-1, indicating its practical application prospect. As a result, the present study proves the natural jujube fruits is a promising sustainable carbon source for making more economical and efficient electrode material of high performance supercapacitors.

A review on ZnO nanostructured materials: energy, environmental and biological applications

Zinc oxide (ZnO) is an adaptable material that has distinctive properties, such as high-sensitivity, large specific area, non-toxicity, good compatibility and a high isoelectric point, which favours it to be considered with a few exceptions. It is the most desirable group of nanostructure as far as both structure and properties. The unique and tuneable properties of nanostructured ZnO shows excellent stability in chemically as well as thermally stable n-type semiconducting material with wide applications such as in luminescent material, supercapacitors, battery, solar cells, photocatalysis, biosensors, biomedical and biological applications in the form of bulk crystal, thin film and pellets. The nanosized materials exhibit higher dissolution rates as well as higher solubility when compared to the bulk materials. This review significantly focused on the current improvement in ZnO-based nanomaterials/composites/doped materials for the application in the field of energy storage and conversion devices and biological applications. Special deliberation has been paid on supercapacitors, Li-ion batteries, dye-sensitized solar cells, photocatalysis, biosensors, biomedical and biological applications. Finally, the benefits of ZnO-based materials for the utilizations in the field of energy and biological sciences are moreover consistently analysed.