Electrochemical Na-Insertion/Extraction Property of Ni-Coated Black Phosphorus Prepared by an Electroless Deposition Method

In-Situ Formation of High-Performance β-NiOOH OER Electrocatalysts Using Boron and Phosphorus-Enriched Ni Core-Shell Nanoparticles

Electrocatalytic water splitting is key to achieving UN Sustainable Development Goal 7, clean energy. However, electrocatalysts with increased activity and reasonable costs are needed. Ni-B, Ni-P, and Ni-B-P-based systems have recently been proposed as particularly promising candidates, but lacked either an active surface or sufficiently high B and P concentrations, which hindered their catalytic performance. Therefore, we developed a tailored synthesis of Ni-B-P electrocatalysts. The resulting core-shell nanoparticles featured a highly porous borate-phosphate shell and a metallic core. This design provided an abundance of active sites for the oxygen evolution reaction (OER) while ensuring high electrical conductivity. Furthermore, screening of the annealing temperature was performed, and significant changes in surface chemistry were observed, as revealed by X-ray photoelectron (XPS) and low-energy ion scattering (LEIS) spectroscopy. Comprehensive cyclic voltammetry (CV) and operando electrochemical impedance spectroscopy (EIS) measurements revealed that leaching of P and B facilitated the formation of β-NiOOH, a compound recognized for its highly active sites in the OER, leading to excellent performance. Our results present a facile and scalable chemical reduction procedure to obtain tailored mesoporous Ni-B-P core-shell nanoparticles, and we believe that their pronounced activation for the OER can inspire the development of in situ-activated electrocatalysts.

Carbon fibre production using an ecofriendly water-soluble precursor

Carbon fibre (CF) is a lightweight next-generation material with numerous applications. CF production is predominantly based on the polyacrylonitrile (PAN) precursor because of the high tensile strength of PAN-based CFs (PAN-CFs). However, expensive and toxic organic solvents are required for PAN-CF production. Moreover, the corresponding thermal stabilisation process is highly energy-intensive, leading to high CO2 emissions. Herein, aqueous polyacrylamide (aqPAM) fibre-prepared via polymerisation and dry spinning using water-is proposed as a water-soluble CF precursor that can be converted into high-performance CF at high carbon yields. The incorporation of small amounts of phosphoric acid into aqPAM considerably reduces the thermal stabilisation time and increases the carbon yield compared with that obtainable using PAN-CF. Moreover, the carbonised aqPAM-based CFs exhibit a high tensile strength and tensile modulus comparable with those of PAN-CFs. The developed process generates less CO2 emissions than PAN-CF production.

Fabrication of Ru-doped CuMnBP micro cluster electrocatalyst with high efficiency and stability for electrochemical water splitting application at the industrial-level current density

Electrochemical water splitting has been considered as a key pathway to generate environmentally friendly green hydrogen energy and it is essential to design highly efficient electrocatalysts at affordable cost to facilitate the redox reactions of hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this work, a novel micro-clustered Ru/CuMnBP electrocatalyst is introduced, prepared via hydrothermal deposition and soaking-assisted Ru doping approaches on Ni foam substrate. Ru/CuMnBP micro-clusters exhibit relatively low HER/OER turnover overpotentials of 11 mV and 85 mV at 10 mA/cm2 in 1 M KOH. It also demonstrates a low 2-E turnover cell voltage of 1.53 V at 10 mA/cm2 for the overall water-splitting, which is comparable with the benchmark electrodes of Pt/C||RuO2. At a super high-current density of 2000 mA/cm2, the dual functional Ru/CuMnBP demonstrates an exceptionally low 2-E cell voltage of 3.13 V and also exhibits superior stability for over 10 h in 1 M KOH. Excellent electrochemical performances originate from the large electrochemical active surface area with the micro cluster morphology, high intrinsic activity of CuMnBP micro-clusters optimized through component ratio adjustment and the beneficial Ru doping effect, which enhances active site density, conductivity and stability. The usage of Ru in small quantities via the simple soaking doping approach significantly improves electrochemical reaction rates for both HER and OER, making Ru/CuMnBP micro-clusters promising candidates for advanced electrocatalytic applications.

Fabrication of binder-less metal electrodes for electrochemical water splitting - A review

The escalating demand for green hydrogen (H2) as a sustainable energy carrier has attracted intensive research into efficient water electrolysis methods. Promising candidates have emerged as binder-less metal electrodes, which enhance electrochemical performance and durability by reducing electron hindrance and avoiding binder degradation. Despite their potential, a comprehensive understanding of various binder-less fabrication techniques remains limited in the existing literature. As the main objective, this review paper aims to bridge this gap by providing an in-depth analysis of state-of-the-art fabrication methods for binder-less metal electrodes utilized in electrochemical water splitting. Recognizing the critical need for sustainable hydrogen production, the advantages of binder-less electrodes over conventional binder-based counterparts are elucidated, with emphasis placed on their role in promoting cost-effectiveness, improved stability, and enhanced catalytic activity. Techniques such as Hydrothermal/Solvothermal, Electrodeposition, Chemical/Vapor Deposition, and Laser-based fabrication are systematically examined, with their respective advantages, drawbacks, and comparison being highlighted. Drawing upon relevant examples from literature, insights on other aspects and recent trends are also provided, such as the performance of binder-less metal electrodes at industrial-scale current densities (0.1-1 A/cm2) or their potential as photoactive catalysts. Additionally, future directions in the field of binder-less electrode fabrication and the exploration of innovative techniques are also discussed, ensuring that the trajectory of research aligns with the evolving demands of sustainable energy production. The "what's next" section highlights areas of further investigation and potential avenues for technological advancement.

Synthesis of Ag3PO4/Ag4P2O7 by microwave-hydrothermal method for enhanced UV-visible photocatalytic performance

Ag₃PO₄/Ag₄P₂O₇ photocatalysts were successfully synthesized by microwave-hydrothermal method. Tuning the properties of photocatalysts was achieved using different amount of acetic acid (CH₃COOH) and sodium hydroxide (NaOH) to adjust pH value of precursor solution (pH = 4, 7, 10 and 12). The crystal structure, morphology and optical property of samples were characterized and explained. The photocatalytic activity of sample was determined by degradation of rhodamine B (RhB) and methyl orange (MO) under a wavelength range of 350-700 nm irradiation. The results demonstrated that the change in shape of particles was not observed whereas the average particle size was decreased with increasing pH value because of the high hydroxide ions (OH^-). The sample synthesized in the solution with the pH of 10 exhibited excellent photocatalytic performance and stability because of the highest surface area and the present of Ag₄P₂O₇ on the surface of particles. The highest photodegradation efficiency was 99.34 and 96.12% by degrading RhB and MO, respectively. The enhancement of photocatalytic performance of Ag₃PO₄/Ag₄P₂O₇ was discussed. The active species trapping experiments showed that the h⁺ was the main active species to decompose the dye molecules.

Antimonene: a tuneable post-graphene material for advanced applications in optoelectronics, catalysis, energy and biomedicine

The post-graphene era is undoubtedly marked by two-dimensional (2D) materials such as quasi-van der Waals antimonene. This emerging material has a fascinating structure, exhibits a pronounced chemical reactivity (in contrast to graphene), possesses outstanding electronic properties and has been postulated for a plethora of applications. However, chemistry and physics of antimonene remain in their infancy, but fortunately recent discoveries have shed light on its unmatched allotropy and rich chemical reactivity offering a myriad of unprecedented possibilities in terms of fundamental studies and applications. Indeed, antimonene can be considered as one of the most appealing post-graphene 2D materials reported to date, since its structure, properties and applications can be chemically engineered from the ground up (both using top-down and bottom-up approaches), offering an unprecedented level of control in the realm of 2D materials. In this review, we provide an in-depth analysis of the recent advances in the synthesis, characterization and applications of antimonene. First, we start with a general introduction to antimonene, and then we focus on its general chemistry, physical properties, characterization and synthetic strategies. We then perform a comprehensive study on the allotropy, the phase transition mechanisms, the oxidation behaviour and chemical functionalization. From a technological point of view, we further discuss the applications recently reported for antimonene in the fields of optoelectronics, catalysis, energy storage, cancer therapy and sensing. Finally, important aspects such as new scalable methodologies or the promising perspectives in biomedicine are discussed, pinpointing antimonene as a cutting-edge material of broad interest for researchers working in chemistry, physics, materials science and biomedicine.

Atomically Thin Holey Two-Dimensional Ru2P Nanosheets for Enhanced Hydrogen Evolution Electrocatalysis

The defect engineering of low-dimensional nanostructured materials has led to increased scientific efforts owing to their high efficiency concerning high-performance electrocatalysts that play a crucial role in renewable energy technologies. Herein, we report an efficient methodology for fabricating atomically thin, holey metal-phosphide nanosheets with excellent electrocatalyst functionality. Two-dimensional, subnanometer-thick, holey Ru₂P nanosheets containing crystal defects were synthesized via the phosphidation of monolayer RuO₂ nanosheets. Holey Ru₂P nanosheets exhibited superior electrocatalytic activity for the hydrogen evolution reaction (HER) compared to that exhibited by nonholey Ru₂P nanoparticles. Further, holey Ru₂P nanosheets exhibited overpotentials of 17 and 26 mV in acidic and alkaline electrolytes, respectively. Thus, they are among the best-performing Ru-P-based HER catalysts reported to date. In situ spectroscopic investigations indicated that the holey nanosheet morphology enhanced the accumulation of surface hydrogen through the adsorption of protons and/or water, resulting in an increased contribution of the Volmer-Tafel mechanism toward the exceptional HER activity of these ultrathin electrocatalysts.

Sodium storage mechanism of a GeP5/C composite as a high capacity anode material for sodium-ion batteries

The sodium storage mechanism of a GeP₅/C composite electrode was revealed. Metallic Ge formed during discharge enhances the electronic conductivity of the electrode, while Na_xP mitigates the agglomeration and volume change of Ge in the alloying process. The GeP₅ phase is regenerated after recharge along with elemental Ge and P, implying a reversible phase transition of GeP₅ during cycling.

Sub-level engineering strategy of nitrogen-induced Bi2O3/g-C3N4: a versatile photocatalyst for oxidation and reduction

Herein, the α-Bi₂O₃ nanocrystal decorated by nitrogen dopant and its heterojunction nanocomposite with g-C₃N₄ (N_0.1/Bi₂O₃/g-C₃N₄) is successfully fabricated for the first time, for photo-oxidation of RhB and photo-reduction of Cr(VI) to Cr(III). The resulting N_0.1/Bi₂O₃/g-C₃N₄ (3%) nanocomposite showed an optimal Cr(VI) photo-reduction and RhB photo-oxidation rates under visible-light irradiation, being 3-4 times higher than that of pure α-Bi₂O₃. The results from XPS confirmed the substitution of nitrogen with various oxidation states from N³⁺ to N^x+ (x < 5), due to the existence of different nitrogen oxides including N-O, O-N=O, and NO₃^- in the crystal structure. We investigated the reaction mechanism using catalytic tests, impedance spectroscopy, EPR technique, and density functional calculations. The DFT calculations presented the appearance of a new mid-gap hybrid of p states, comprised of N 2p, O 2p, and Bi 6P states, which enhance light absorption capacity and narrow band gap. The theoretical results were in excellent agreement with experimental UV-Vis data. The N_0.1/Bi₂O₃/g-C₃N₄ nanocomposite exhibited acceptable practical application value and recycling ability for removal of the contaminants. Such improved photocatalytic activity is originated from the modified band positions, new electron evolution pathway, introducing defects in α-Bi₂O₃ by insertion of N atoms into the Bi sites, and the enhanced charge carrier mobility between N_0.1/Bi₂O₃ and g-C₃N₄. The strategy to form nitrogen-doped bismuth-based nanocomposites may open a new opportunity to design atomic-level electronic defects by feasible methods to obtain a versatile photocatalyst material with simultaneous photo-reduction and photo-oxidation ability for removal of Cr(VI) and organic dyes from water.

A highly selective and stable cationic polyelectrolyte encapsulated black phosphorene based impedimetric immunosensor for Interleukin-6 biomarker detection

Due to the insufficiency of binding sites for the immobilized recognition biomolecules on the immunosensing platform, cancer detection becomes challenging. Whereas, the degradation of black phosphorene (BP) in the presence of the environmental factors becomes a concerning issue for use in electrochemical sensing. In this study, BP is successfully encapsulated by polyallylamine (PAMI) to increase its stability as well as to enhance its electrochemical performance. The successful encapsulation of BP is ensured through X-ray Photoelectron spectroscopy and Raman spectroscopy, whereas the stability of black phosphorus is ensured by Zeta potential measurements and cyclic voltammetry tests. The developed BP-PAMI composite showed high stability in the ambient environment and exhibited improved electrochemical performances. The impedimetric immunosensor was developed on a BP-PAMI modified laser burned graphene (LBG) to detect interleukin-6 biomarkers using electrochemical impedance spectroscopy (EIS). Under the optimized parameters, the fabricated immunosensor demonstrated a wide linear range of 0.003-75 ng/mL, limit of detection (LOD) of 1 pg/mL. Based on the experimental analysis, the developed sensing strategy can be employed as an easy, disposable, cost-effective and highly selective point-of-care cancer detection. In addition, the developed technique can be applied broadly for detecting other biomarkers after treating with suitable biomolecules.