FlatChem最新文献

Layered double hydroxides (LDHs) are attractive bidimensional materials for electrochemical applications because of their high activity in the oxygen evolution reaction (OER). However, their limited bifunctionality due to the slow kinetics of the oxygen reduction reaction (ORR) is a bottleneck for their use in secondary Zn-air batteries (ZABs). In this work, cobalt-free NiMn LDHs were rationally designed by optimizing the Ni composition and incorporating surface defects onto the LDH (oxygen vacancies, Ov) while performing interface engineering using a carbonaceous support enriched with nitrogen heteroatoms. The LDHs without induced defects presented the optimal activity for the OER at a 3:1 Ni/Mn atomic ratio (onset potential 1.47 V vs. 1.45 V for IrO₂/C), while the ORR was unfavorable. However, the further optimization by introducing Ov and N–heteroatoms (labeled as Ov-NiMn LDH/NCNTG) allowed bifunctionality by improving the onset potential to 0.90 V while decreasing the half-wave potential difference from 180 mV for the material without induced defects to 100 mV, and by improving the limiting current density by a factor of two. In this regard, density of states (DOS) calculations suggested that surface defects improved the electronic transfer while decreasing the oxygen adsorption energy. ZAB tests indicated that the interface-engineered material allowed a battery voltage of 1.47 V, and a power density of 64 mW cm⁻². The battery also maintained stability over 180 charge/discharge cycles at 10 mA cm⁻² (50 h), with ΔV below 150 mV between the initial and final cycles.

Graphene-based nanomaterials (GBNMs) are versatile due to their large surface area, great mechanical, chemical strength, and excellent electrical properties. The versatility of graphene has increased its applicability therefore several synthesis methods to produce high quality graphene simpler, faster, and cost-effectively are actively explored. The conventional synthesis methods however employ toxic chemicals, high temperatures, and lengthy synthesis times. On the other hand, the gamma (γ) irradiation approach is facile, occurs under ambient conditions and produces graphene composites of high purity. Noteworthy, this technique enables the user to control the synthesis time and total dose, hence minimising the aggregation of the nanomaterial, the main drawback hindering the commercial production of GBNMs. γ-radiolysis synthesized GBNMs exhibit superior optical and electrical properties and hence improved supercapacitance, catalytic, and sensing abilities. Although other reviews addressed the γ-ray synthesis of metallic nanomaterials, polymers, as well as usage of a variety of radiation techniques to fabricate graphene composites, this review focuses solely on the synthesis and modifications of GBNMs via the γ-synthesis technique. Properties of graphene and conventional methods used to reduce graphene oxide (GO) to graphene as well as their shortcomings are highlighted. This is followed by detailing the γ-radiation synthesis technique, its advantages over the conventional methods and the principles thereof. Effects of γ-irradiation and the conditions required for the structural modification of graphene to obtain different graphene composites are detailed. The influence of operational parameters on the fabricated graphene-based composites are discussed followed by summaries of recent developments in the applicability of γ-irradiated GBNMs in catalysis, energy, sensing, and biomedical fields. In addition, this paper presents insights into the challenges posed and provides future research directions and prospects in the field of γ-irradiated GBNMs.

This research explores the efficacy of photodynamic therapy (PDT) and photothermal therapy (PTT) in combating chemotherapy-resistant diseases. This study focuses on enhancing tumor treatment effectiveness by leveraging the synergetic effects of combining PDT and PTT through the development of Fe-nitrogen-carbon (FeNC) nanoparticles with superior photostability. These nanoparticles, functioning as photosensitizers for the combined PDT/PTT treatment, can generate both type I and type II ROS and heat upon 808 nm irradiation. Notably, the FeNC nanoparticles demonstrate an exceptional photothermal conversion efficiency (34 %), surpassing commonly used PTT photosensitizers. In vitro and in vivo experiments corroborate the efficiency of FeNC as a photosensitizer in achieving significant tumor inhibition. In conclusion, the FeNC nanoparticles present promising applicability in the synergistic PTT/PDT treatment of tumors.

Pt-functionalized graphene shows promise for near-ambient hydrogen storage due to graphene’s potential as a hydrogen host and platinum’s role as a catalyst for the hydrogen evolution reaction and spillover effect. This study explores Pt cluster formation on epitaxial graphene and its suitability for hydrogen storage. Scanning Tunneling Microscopy reveals two growth pathways. Initially, up to $\sim$1 monolayer of Pt coverage, Pt tends to randomly disperse and cover the graphene surface, whereas the cluster height remains unchanged. Beyond a coverage of 3 monolayer, the nucleation of new layers on existing clusters becomes predominant, and the clusters mainly grow in height. Thermal Desorption Spectroscopy on hydrogenated Pt-decorated graphene reveals the presence of multiple hydrogen adsorption mechanisms. Two Gaussian peaks, which we attribute to hydrogen physisorbed (peak at 155°C) and chemisorbed (peak at 430°C) on the surface of Pt clusters are superimoposed on a linearly increasing background assigned to hydrogen bonded in the bulk of the Pt clusters. These measurements demonstrate the ability of Pt-functionalized graphene to store molecular hydrogen at temperatures that are high enough for stable hydrogen binding at room temperature.

Developing highly active, low-cost, and robust transition metal-based phosphide for alkaline overall water splitting is of utmost important to promote the practical application from fundamental. Herein, two-dimensional (2D) Mo-doped NiCoP nanoplates with novel amorphous/crystalline heterostructure (Mo(0.05)-NiCoP) in situ grown on three-dimensional nickel foam (NF) has been successfully constructed through hydrothermal reaction followed by the phosphorization treatment. Benefited from the synergy of amorphous/crystalline heterointerface, Mo doping, and unique 2D structure, the optimized Mo(0.05)-NiCoP exhibits outstanding electrocatalytic activity for hydrogen evolution reaction (HER) and oxygen evolution reaction (OER), achieving low overpotential of 67 mV at 10 mA cm⁻² for HER and 233 mV at 10 mA cm⁻² for OER. Meanwhile, there are only a cell voltage of 1.569 V was required to drive 10 mA cm⁻² when Mo(0.05)-NiCoP used as both anode and cathode for overall water splitting. Thus, this study provides a novel approach to construct efficient 2D bifunctional catalysts with amorphous/crystalline heterostructure and heterogeneous metal doping.

The hexagonal Boron Nitride (hBN) nanostructures with tuned physicochemical properties find huge applications in optoelectronic devices. Herein, we have synthesized nanocomposite of hBN with graphene oxide (GO) in various ratios to acquire composition-dependent variation in their structural, surface electronic, linear, and non-linear optical properties. The insertion of GO in hBN nanosheets has modified their strain landscape, the electronic charge transfers from GO to hBN, increased the working time of free charge carriers, and suppressed electron-hole recombination, thus modifying its work function (WF). GO-hBN nanocomposites observed to have reduced bandgap where creation of defect induced mid-gap states lead to enhancement in non-linear absorption of two photons. Herein, we have established a linear relationship between Urbach energy (E_u), a measure of disorders and non-linear absorption coefficient (α_NL). Additionally, we have observed that the tuned bandgap of the nanocomposites has significantly enhanced their performance as high-performance photocatalysts for the degradation of methyl orange, compared to bare hBN or GO. As a result, we discovered that E_u, α_NL, WF and photodegradation activity of GO-hBN nanocomposites exhibit analogous variations in response to changes in the content of GO. Thus, by strategically prioritizing the modification of a single parameter while considering the potential effects on other relevant properties for application purpose, GO-hBN can effectively harness large spectrum areas for catalytic and optoelectronic applications.

Highly determined materials have been applied to energy storage devices such as supercapacitors, batteries, etc., to investigate their electrochemical features and match them with ongoing technological developments. In this regard, electrodes based on graphene and layered double hydroxide with two divergent charge-storage mechanisms have been perused to expand the energy storage functionalities. Graphene materials as efficient electrodes have occupied a significant place in supercapacitors and batteries due to their outstanding electrical conductivity, flexibility, and large surface area. Additionally, according to the substantial electrochemical charge transport capabilities, layered double hydroxides are extensively employed in energy storage devices. This review comprehensively investigates the cooperation effect of the electrode composites of the graphene materials and layered double hydroxides and their optimization progress. The electrochemical characteristics of the electrodes have been considered, including specific capacitance, energy density, power density, and capacity retention, affected by pH, synthesis method, reaction temperature, and time. Eventually, the future trend of the electrode materials and their enhancing performance perspective is represented.

Graphene research has captivated researchers worldwide, propelling innovation across diverse industries. Through the liquid-phase exfoliation methodology of graphite powder, we have demonstrated a rapid route for obtaining few-layer and multi-layer graphene using a natural surfactant, cardanol. Aqueous phase exfoliation of graphite in the presence of cardanol as a surfactant was conducted to obtain pre-exfoliated graphite suspensions. The influence of different ultrasonication times, 10, 20, and 30 min, and contact times with the surfactant, 1 and 60 min, on the stability and concentration of dispersed exfoliated graphite was evaluated. Results indicate that ultrasonication for 20 min resulted in improved stability and reduced graphene flake sizes, making it suitable for scalable graphene production. Subsequently, the most stable dispersions of exfoliated graphite were subjected to CO₂-pressurized treatment. Promising results were obtained when employing cardanol at its critical micelle concentration. The graphene exhibited good structural quality, low defect density, and small stacking, with an average size of 15 nm, where 40 % of the stacked graphene was smaller than 5 nm. The findings provide valuable recommendations for the scalable production of graphene with multilayers and a few layers (FLG/MLG), using cardanol, a friendly surfactant, and a novel method of exfoliation utilizing supercritical CO₂. This technology represents an innovative approach, with potential applications in supercapacitors, solar cells, biosensors, polymer composites, and advanced materials.

The doping of lighter non-metals like boron and nitrogen into fullerene $\left(C_{60}\right)$ represents a promising advancement in the field of nanoelectronic devices. These doped two-dimensional (2D) materials offer improved stability and enhanced adsorption characteristics compared to pure form. Notably, It displays semiconducting behaviour, resulting in higher conductivity and carrier mobility. This study investigates the structural, electronic, optical, and conductivity/carrier transport properties of 2D polymer sheets made of fullerene, both with and without boron and nitrogen doping. We employ density functional theory (DFT) with PBE and HSE functionals, considering the inclusion of van der Waals (vdW) interactions. The research findings indicate that the $2D$ sheets of $C_{60},C_{58}{B}_1{N}_1$, and $C_{54}{B}_3{N}_3$ exhibit band gaps of approximately $0.97eV\left(1.51eV\right),1.08eV\left(1.65eV\right)$, and $1.05eV\left(1.56eV\right)$, respectively, as obtained from PBE (HSE) calculations. Moreover, according to the deformation potential theory, $C_{58}{B}_1{N}_1$ exhibit ultra-high conductivity (${10}^{14}{\Omega }^{-1}{cm}^{-1}{s}^{-1}$ at room temperature). These sheets display cohesive energies of −8.76, −8.72, and $-8.67eV$, respectively, indicating their stability. These results are promising and underscore the significance of a single pair of $BN$ dopants in fullerene monolayers for advancing next-generation 2D nano-electronic applications.

The preservation of Silicon nanoparticles (Si NPs)’ structural integrity and surface protection during cycling is vital for optimal Si-graphene electrodes, controlling volumetric changes during lithiation/delithiation. Weak physical adherence of Si NPs to the carbon matrix compromises electrode performance, highlighting the need for effective bonding mechanisms. This research focuses on Si/reduced graphene oxide (Si/RGO) composites, employing a scalable, low-temperature synthesis method to examine effect of bonding between Si NPs and RGO in mitigating the volumetric fluctuations during cycling. Characterization techniques, including FTIR, XRD, Raman spectroscopy, SEM, EDX and TGA confirm successful synthesis, offering structural and chemical insights. Electrochemical assessments, including EIS, CV, and GCD, reveal that covalently coupled Si/RGO composites outperform counterparts, demonstrating superior rate and cyclic performance. The first delithiation capacity of 1275 mAh g⁻¹ surpasses directly assembled Si/RGO and pristine RGO-based anodes, with corresponding values of 736 and 511 mAh g⁻¹, respectively and is retained to 670 mAh g⁻¹ (1.8 times the capacity compared to a graphite anode) at 0.1 A g⁻¹ after 100 cycles. Furthermore, the research challenges the notion that a high reduction temperature is obligatory for achieving high conductivity in RGO, as observed through improved charge/electron transfer kinetics, detailed in subsequent sections.