FlatChem最新文献

The electrochemical energy conversion process must develop effective, long-lasting, and reasonably priced bifunctional electrocatalysts for the hydrogen evolution reaction (HER) and oxygen evolution reaction (OER). In this work, we present a simple, sustainable, economical, and scalable method for the preparation of stable and useful nickel nanoparticles on highly porous graphitic carbon doped with nitrogen. Direct pyrolysis followed by carbonization was used to create robust catalysts at different temperatures in an environment containing nitrogen (N₂). The carbon material generated at 600 °C (Ni@NPC-600) shows greater electrochemical efficiency when compared to other catalysts. The synthesized electroactive catalyst Ni@NPC-600 requires a less overpotential 280 mV (114 mV dec⁻¹) for OER and 151 mV (98 mV dec⁻¹) to conduct a HER at 10 mA cm⁻² in 1 M KOH. The active catalyst Ni@NPC-600 shows long-lasting robustness over 90 h with a current loss of <3.33 % and <4.9 % for OER and HER respectively. In addition, the overall water disintegration of Ni@NPC-600/NF//Ni@NPC-600/NF was achieved at 1.51 V with a continuous evolution of H₂ and O₂ at the cathode and anode respectively for approximately 150 h of prolonged robustness with a current reduction of < 4.6 %.

Incorporating iron nanoparticles into graphene oxide (GO) may enhance its potential for use in various applications. However, alterations to the GO structure could pose a risk to environmental organisms and should therefore be fully understood before their further use. In this paper, we prepared iron-doped graphene oxide from pure graphene oxide and two different iron sources with iron in two different oxidation states. Prepared samples were characterized in detail by SEM, EDS, XRF, Raman spectroscopy, XPS, and TEM. In the next step, these samples were subjected to ecotoxicological evaluation in three model organisms: mustard Sinapis alba, freshwater algae Desmodesmus subspicatus, and saltwater crustaceans Artemia salina. Our results showed a stimulatory effect of iron-doped GO on S. alba seeds and a modest degree of growth inhibition for D. subspicatus when compared to pure GO at a concentration of 100 mg/L. In the case of A. salina, mortality was observed at a concentration of 10 mg/L for all tested nanoparticles. However, the iron-doped nanoparticles exhibited a more than twofold decrease in mortality. Our findings suggest that iron-doped GO have a reduced toxicity compared to pure GO, but further research is necessary to enhance the understanding of their behaviour in the environment.

The Ti₃C₂T_x MXene has ignited a wave of excitement in the world of materials science due to its immense potential for diverse applications. However, a deeper understanding of the synthesis processes involved is crucial to unlock their potential. Here we review the various techniques for producing Ti₃C₂T_x MXene, covering everything from precursor selection to etching-exfoliation and intercalation-delamination steps. Furthermore, we also explore the oxidation stability of Ti₃C₂T_x and propose a reaction mechanism to help shed light on this critical aspect of Ti₃C₂T_x MXene. This review begins with the bibliography studies on Ti₃C₂T_x and then delves into the principle behind the chemical etching process. Followed by various etching strategies used for Ti₃C₂T_x synthesis and the impact of individual etching parameters on successful synthesis protocols. Finally, we address the challenges that still need to be overcome to fully realize the potential of Ti₃C₂T_x and highlight the exciting possibilities for its future development. We aim to inspire further research into this cutting-edge material and encourage the synthesis of Ti₃C₂T_x MXene with even more outstanding performance and a more comprehensive range of applications.

Graphene quantum dots (GQDs) are nanometer-sized fragments of graphene with unique characters, which make them as new interesting application candidates in the fields of chemical, environmental and energy engineering. In this paper, the four nitropyrenes with different nitration degree, such as mononitropyrene, dinitropyrene, trinitropyrene and tetranitropyrene, were successfully synthesized and used to rationally construct corresponding graphite phase quantum dots named GQD(1), GQD(2), GQD(3) and GQD(4) in turn. Subsequently, the relationship between the structure and photocatalytic activity of different intermediates for the preparation of GQD were systematically studied. Degree of polymerization and lateral size of GQDs prepared with different intermediates significantly affected their photocatalytic performance. Through comparision of the photocatalytic water splitting reaction of four GQDs, it was found that GQD(4) had the best photocatalytic efficiency among four GQDs.

Aerogels, as extraordinarily lightweight and porous functional nanomaterials, have garnered significant interest in both academia and industry over the past few decades. Graphene-based aerogels, in particular, stand out due to their excellent conductivity properties, high specific surface area, and efficient adsorption efficiency. Despite these advantageous properties, aerogels face challenges in mechanical durability, complicating their processing, especially in applications requiring complex structures. 3D printing technology holds promise for overcoming these limitations through its capabilities in microscale manufacturing, rapid prototyping, and arbitrary shaping. This review summarizes the advantages of graphene-based aerogels and compares various 3D printing techniques used for aerogel fabrication. Furthermore, it also highlights the energy and environmental applications of 3D-printed graphene and graphene-based composite aerogels, including batteries, supercapacitors, electromagnetic shielding, sensors, etc. The review concludes with an exploration of current challenges and provides an outlook on future developments in the 3D printing of graphene-based aerogels.

A straightforward and precise method was employed to generate Ti₃C₂ MXene/ZnO/CdSe photocatalysts by a simple synthesis process involving calcination at a temperature of 400 °C. Optical, structural, morphology, microstructure, and compositional properties of these catalysts were characterized. Results demonstrated that the presence of ZnO and CdSe doping sustained their existence inside the Ti₃C₂ MXene structure. Effects of catalyst powder, pollutant powder, and different degrading methods such as sonophotocatalytic, sonocatalytic, and photocatalytic methods on various antibiotic pollutants were then compared. The degradation efficiencies of sonophotocatalytic method were found to be highly efficient, resulting of 99.99, 99.98, and 99.90 % for ciprofloxacin, amoxicillin, and ofloxacin, respectively. Analysis of scavenger effect also illustrated the deterioration of ciprofloxacin and amoxicillin, suggesting that superoxide radicals (O₂⁻) had a substantial role in the sonophotocatalytic degradation process. Based on data obtained for ofloxacin, it was clear that the existence of holes (h⁺ quencher) affected the deterioration of ofloxacin in the system. Ti₃C₂ MXene/ZnO/CdSe had a performance in electrochemical sensing. Limits of detection (LODs) for ciprofloxacin, amoxicillin, and ofloxacin were 39.29, 4.49, and 13.04 ppm, respectively. Limits of quantification (LOQs) for ciprofloxacin, amoxicillin, and ofloxacin were 119, 13.61, and 39.52 ppm, respectively. Efficient degradation of pollutants using visible light can be achieved by employing straightforwardly manufactured Ti₃C₂ MXene/ZnO/CdSe photocatalysts, making them a practical and promising option.

Using Density Functional Theory, a newly synthesised 2-dimensional polyaramid (2dpa) system decorated with Li is explored for its hydrogen storage capability, and interesting results are obtained. Various sites on 2dpa are studied to ascertain the finest location for Li-decoration. The optimum configuration for hydrogen storage is then achieved by successively adding H₂ molecules, till it satisfies the adsorption energy window as prescribed by DoE (0.2–0.7 eV/H₂). Li has a good binding energy of −2.78 eV on 2dpa, higher than the cohesive energy for Li and thus prevents any possibilities of clustering. Yet the clustering has been checked by calculating the diffusion energy barrier for the Li atom which came to be around 1.92 eV. The average binding energy for H₂ on 2dpa + Li came to be −0.25 eV and the gravimetric weight percent with 3Li on 2dpa and 6H₂ molecules attached to each Li comes to be 10.62. Both values meet the conditions set by the US DoE for solid-state hydrogen storage systems. The thermal and dynamic stability of the system has been investigated using Ab initio Molecular Dynamics simulations and computing phonon spectra. Our theoretical results on newly synthesized 2D material may inspire the experimentalist to design a 2dpa-based high-capacity hydrogen storage device.

MXenes represent a revolutionary class of two-dimensional (2D) materials that have garnered significant attention due to their unique properties, including excellent electrical conductivity, and remarkable mechanical strength. This study investigates the influence of different etching agents on the synthesis of MXenes for electrochemical energy conversion applications, particularly in methanol oxidation reactions (MOR). Morphological characterization, particle distribution and sizing, elemental analysis, and surface chemistry assessments were conducted using field emission scanning electron microscopy (FESEM), elemental mapping, transmission electron microscopy (TEM), x-ray diffraction (XRD), and x-ray photoelectron spectroscopy (XPS). Electrochemical techniques such as cyclic voltammetry (CV), electrochemical active surface area (ECSA), Tafel analysis, electrochemical impedance spectroscopy (EIS), and long-term stability assessment were employed. The study reveals that PtRu/MXene synthesized with the FeF₃/HCl etching route exhibits the highest ECSA value and peak current density, being 12.3 times and 3.63 times higher than those achieved via the LiF/HCl etching route. The kinetic rate, tolerance to catalyst poisoning and long-term stability also show the better results for this etching route. These findings suggest promising potential for PtRu/MXene_FeF₃/HCl as an effective anodic electrocatalyst in direct methanol fuel cell (DMFC) applications.

We constructed SiC/borophene heterostructure based on the method of commensurate lattice with supercell approach and studied the structural, electronic and electrochemical properties using density functional theory (DFT). The interfacial binding energy of SiC/borophene is as high as −26.07 meV/Ų. Significant amounts of charge were found to drift from SiC to borophene, resulting in interfacial charge redistribution and increased Li binding affinity on the surfaces. The electronic properties of SiC/borophene showed pronounced metallic conductivity, a trait conducive to anodic applications in electrochemical cells. The calculated Li adsorption energy at the interface of SiC/borophene is −2.23 eV. Multiple layer adsorption is also observed, with the heterostructure retaining much of its structural integrity after adatom adsorption, indicating possible good cycling stability. At the maximum concentration, the Li storage capacity for SiC/borophene is 1980.63 mAh/g, surpassing a large variety of other reported 2D complexes. Also, an overall average operating voltage of 1.06 V is maintained in the structure, which is in proximity of the optimal 1.5 V threshold requisite for anodic operations. The diffusion energy barriers associated with lithium ion migration across the three distinct adsorption sites of the heterostructure all reveal a nominal magnitude with the lowest barrier energy of 0.54 eV at the top of borophene adsorption layer and site. These findings show that SiC/borophene could be used as an anode in very high-capacity lithium-ion batteries.

The 2-electron electrocatalytic oxygen reduction reaction (2e⁻ ORR) to hydrogen peroxide (H₂O₂) represents a promising strategy to resolve the high energy consumption and increasing environmental concerns inherent in the traditional anthraquinone process. The acidic 2e⁻ ORR has emerged as an exciting alternative for industrial-level H₂O₂ production, whereas is hampered by the inferior H₂O₂ selectivity due to the uncontrollable proton-coupled electron transfer processes in an acidic environment. Herein, an ultrathin 2D metal–organic frameworks (MOFs) nanosheet based on cobalt tetra(4-carboxyphenyl) porphine (Co-TCPP NSs) is designed to promote H₂O₂ selectivity up to 96.5 %, accompanied with a remarkable H₂O₂ generation rate of 4677.42 mg·L⁻¹·h⁻¹. Of note, the Co-TCPP NSs also demonstrate its potential for the electro-Fenton process with a cumulative H₂O₂ concentration of 1.21 wt%, highlighting its practical potential in portable H₂O₂ generation electrochemical devices for distributed applications. Our findings demonstrated that the efficient H₂O₂ electrosynthesis could be attributed to the attenuated *OOH adsorption over Co-N₄ moiety on the Co-TCPP NSs, which consequently suppresses its further reduction to form H₂O. This work highlights the potential of 2D MOF architecture for the 2e⁻ ORR and provides an atomic-level insight into the enhanced H₂O₂ selectivity.