The optical quantification measurement on aggregated aqueous ZnO nanostructures upon exposure to tannic acid

Herein, a facile eco-friendly green hydrothermal approach was developed in the preparation of pristine, stable and safer aqueous zinc oxide (ZnO) nanostructures at high yield in the presence of tannic acid (TA) conducted both at low and high reaction temperatures (50, 70 and 90 °C). The TA acted as a reducing agent and also a stabiliser which later capped around the ZnO nanostructures. The absorption spectrum confirmed the formation of ZnO nanostructures with the intense peak range at ~365 to 405 nm. The acid-driven solvent based on the Brønsted-Lowry acid/base theory described the acid solvent interaction in pristine ZnO-TA samples which caused the proton mechanism transfer between the Zn and oxygen components. Based on TEM and SEM analyses, pristine ZnO-TA nanostructures are well distributed and formed nanoplatelet hexagonal aggregate morphology upon the addition of TA with the smallest mean diameter size of 7 ± 1.2 nm. A surprising role of TA was also found out where the presence of TA could influence the formation of smaller ZnO-TA nanostructures upon the addition of TA (increased the H+ concentration) at lower pH value (pH = 5) in pristine ZnO-TA samples which further influence the morphological formation of smaller nanostructures according to the pH of the aqueous solution. The complexation of reaction between Zn2+ and TA occurred mainly at pH = 7. At pH = 4, the presence of higher amount of H+ molecules was responsible for the increased of Zn2+ which caused the formation of larger size aggregates of ZnO-TA nanostructures. These results indicated that the TA caused the dissolution of ZnO nanostructures due to the effects of combined pH solution modification and alteration of complexation reaction

Late transition metal nanocomplexes: Applications for renewable energy conversion and storage

Energy conversion is one of the keys to the world’s future renewable and sustainable energy infrastructure systems. The use of multidimensional late transition metal complexes-based nanostructures to realise the self- powered or energy-autonomous systems have led to the creation of mechanistic-catalytic synergies of mate- rials functions. The system requires enhance interface architectures to recover and revolutionise those valuable materials-based resources. Hence, the purpose of the present work is to highlight the importance and the current progress of these latest generations of late transition metal nanocomplexes as a material source in renewable energy structure development. This paper reviews the fundamental mechanism steps in catalytic reactions with the focus of attention limited to the characteristic features of these late transition metals. Further on this, the developments in the field of self-powered of the late transition metal nanocomplexes, mainly focusing on their electrocatalytic reactions for energy conversion technology, comprises ORR, OER, and HER is reviewed. This is followed by a discussion on the current demand for the past five years in high-capacity renewable energy storage applications. Through the discussions, the optimisation and evolutionary changes in terms of selection, stability and scalability of late transition metal nanocomplexes are the factors that make them as a leader to suit the current energy landscape and for the next 25 years for prosperous, sustainable and affordable global energy future. This review will complement other papers on the energy transformation processes and storage that involve modern micro and nanotechnology, thus further boosting the over-all specific properties of transition metal complexes -based nanostructur

Tunable Functionality of Pure Nano Cu- and Cu-based Oxide Flexible Conductive Thin Film with Superior Surface Modification

Flexible and soft conductive thin film using pure Cu and Cu-based oxide nanostructures equally benefit from the versatility of their assembling individual materials and robustness of device design components. Their small-scale soft conductive thin film made of curved elastomeric bilayers driven by the responsive forces acting by the embedded printed liquid of pure Cu and/or Cu-based oxide nanostructures channels carrying alternating currents of those compact integrated circuits. As such, the localised oxide growth of those complex multiphase thin film architectures is the empirical knowledge that guides to further understanding of many interrelated factors of their intrinsic multiscale physical-electro-chemical interactions characteristics. Although not much literatures have been reported on the soft, flexible pure Cu and Cu-based oxide nanostructured thin films, still, the compelling unusual shapes/forms/construct of such nanostructures in the preparation of those superior functionalities thin film using various curvilinear shapes would seem to establish a predominant foundation in technologically important MEMS/NEMS devices. Herein, this article attempts to summarise the recent advances, challenges, and prospects of employing pure Cu and Cu-based oxide nanostructures in both fundamental and applied tunable functionality of varying dimensionality. Also, special emphasis on the emerging related critical issues and outlook of technical challenges that pave to research improvement opportunities are included

Formation of ZnO nanoparticles in the presence of Tannic acid

Zinc Oxide nanoparticles (ZnO NPs) have received abundance attention due to their ability to provide as a good semiconductor and UV absorbance materials. In this research, ZnO NPs are synthesised by hydrothermal method which employed a green synthesis method of which fully assisted by the Tannic Acid (TA). The controllable morphologies and mean sizes of ZnO NPs are observed to increased due to aggregation that occurred due to the influence of acidic medium (TA molecule). The morphological properties are discussed based on the TEM and FESEM images which indicated the average size of 14 nm and 32.7 nm for ZnO NPs and ZnO-TA NPs obtained, respectively. Meanwhile, the optical properties are discussed based on the UV-Vis absorbance spectroscopy results. The UV absorbance performance showed the behavior of absorbance peak at shorter wavelength as the ZnO NPs are capped with TA. The absorbance peak is shifted from UV-A region to UV-C region which indicated the transition from ZnO NPs to ZnO-TA respectively

The optical and structural of the synthesised cu nanostructure using hydrothermal microwave-assisted method

Cu nanostructure is a potential cost-saving conductive material that might be used in the development of nano-electronic devices. However, the development of Cu nanostructure as an alternative source for silver or gold is hampered not only by its stability in atmospheric surroundings in the nanometer range but also by the lack of a straightforward synthetic approach to create them in excellent yield as well as enhance their optical and structural properties. Therefore, a hydrothermal microwave-assisted method is used to synthesize Cu nanostructure using PVP as a structure-directing agent and PEG as a reducing agent. The absorbance range of Cu nanostructure is observed between 300 to 400 nm. The energy bandgap rises when the concentration increases. While, the average crystallite diameter of each sample is obtained less than 50nm

Morphological changes of ZnO nanostructures upon addition of Trisodium Citrate (Na3C6H5O7) at different reaction temperatures

Due to its interesting physical and chemical properties, zinc oxide (ZnO) is considered one of the front runners of numerous metal oxide semiconductors. In this paper, ZnO nanostructure are synthesised by hydrothermal method with trisodium citrate (TC) as the emulsfying agent. The mean diameetr of ZnO nanostructure are observed with increment of reaction temperature. The mean size results into no change to mean diameter upon increment of reaction temperature but the cumulative frequencies of size distribution showing ZnO nanostructure synthesised in higher temperature to have narrower size distribution. The addition of TC also results into much smaller ZnO nanostructure with mean diameter 8nm

Truncated and Spheroidal Ag Nanoparticles: A Matter of Size Transformation

The ordered arrays of anisotropic mesostructure metal nanoparticle (diameter size in the range of 15 to 200 nm) characteristics are indeed influenced by the combined effect of packing constraints and inter-particle interactions, that is, the two morphological factors that strongly influence the creation of the particles’ shape. In this work, we studied on how the degree of truncation of Ag nanoparticles authorised the mesostructured morphologies and particle orientation preferences within the mesosparticle arrays. The Ag represented the best and most versatile candidate and known for its highest electrical conductivities among other transition metals in periodic table. The interest is motivated by the need to understand the inevitable morphological transformation from mesoscopic to microscopic states evolve within the scope of progressive aggregation of atomic constituents of Ag system. The grazing information obtained from HR-TEM shows that Ag mesosparticles of highly truncated flake are assembled in fcc-type mesostructure, similar to the arrays formed by microscopic quasi-spherical structure, but with significantly reduced packing density and different growth orientations. The detailed information on the size and microstructure transformation have been gathered by fast Fourier transform (FFT) of HR-TEM images, allowing us to figure out the role of Ag defects that anchored the variation in crystallite growth of different mean diameter size particles. The influences on the details of the nanostructures have to be deeply understood to promote practical applications for such outstanding Ag material

The physical and optical investigations of the tannic acid functionalised Cu-based oxide nanostructures

The need for a mild, low-cost, green environment that is able to produce exotic properties of output nanostructures is appealing nowadays. Employing these requirements, the copper (Cu)—based oxide nanostructures have been successfully synthesised via one-pot reaction using biocompatible natural polyphenol, tannic acid (TA) as both the reducing agent and stabiliser at 60, 70 and 80 °C. The structural and optical studies disclosed the efect of TA on the surface morphology, phase purity, elemental composition, optical microstrain and optical intrinsic energy of this mixed Cu2O and CuO nanostructures. The optically based method describes the comparative details of the multi-band gap in the presence of more than one element with overlapping spectra from the frstderivative absorbance curve and the exponential absorbance of Urbach tail energy EU towards the conventional Tauc bandgap. The A demonstrates that the pronounced efect of TA that Cu2O and CuO nanostructures creates much sensitive frst-derivative bandgap output compared to the Tauc bandgap. The results also show that the EU reduced as the temperature reaches 70 °C and then experienced sudden increase at 80 °C. The change in the pattern is parallel to the trend observed in the Williamson– Hall microstrain and is evident from the variations of the mean crystallite size Dm which is also a cause response to the change in temperature or pH. Therefore, the current work has elucidated that the structural and optical correlations on the as-synthesised Cu2O and CuO nanostructures in the presence of TA were the combined reaction of pH change and the ligand complexation reactions. The acquired results suggest a more comprehensive range of studies to further understand the extent relationship between the physical and optical properties of TA functionalised Cu-based oxide nanostructures

A sensitive ac magnetometer using a resonant excitation coil for characterization of magnetic fluid in nonlinear magnetization region

In order to tailor magnetic nanoparticles (MNPs) for intended applications, it is important to unravel their dynamics with respect to excitation magnetic field. In this work, we report on the development of a sensitive AC magnetometer using a resonant excitation coil for this purpose. The excitation coil fabricated from a Litz wire is connected to a capacitor network to effectively reduce the impedance of the circuit. The high efficiency showed by the excitation coil enables investigation of MNP’s dynamics in the nonlinear magnetization region. We demonstrate the sensitivity of the developed system by measuring the harmonics of a multicore iron oxide nanoparticle solution down to 300 ng/ml of iron concentration. We experimentally show that the first harmonic component is not completely ‘transparent’ to the diamagnetic background of the carrier liquid compared to the higher harmonics. We also demonstrate the complex magnetization measurement of the iron oxide nanoparticles in solution and dry states from 3 Hz to 18 kHz. A highly sensitive exploration of MNPs’ dynamics can be expected using the developed AC magnetometer

Non-regularized reconstruction of magnetic moment distribution of magnetic nanoparticles using barnacles mating optimizer

Core size estimation of magnetic nanoparticles (MNPs) using magnetization curves has been reliably utilized to obtain a fast and simple size estimation technique compared to transmission electron microscopy. This estimation technique involves solving the inverse problem of the magnetization curve. However, conventional methods, such as the singular value decomposition (SVD) or non-negative least squares (NNLS) algorithms, require a regularization threshold to mitigate the overfitting issues of an ill-conditioned problem. This prior information on the regularization requirement may lead to inaccurate magnetic moment reconstruction if the regularization degree is high due to broad distributions of the reconstructed magnetic moment. This research proposes a non-regularized reconstruction technique of magnetic moment distribution using the recent machine learning technique of the Barnacles Mating Optimizer (BMO) algorithm. A simulated magnetization curve of unimodal moment distributions from 1 mT to 1 T is used to minimize a model-free magnetic moment distribution. A reconstruction comparison among the BMO, Particle Swarm (PSO), Genetic Algorithm (GA), Sine Cosine Algorithm (SCA) optimizers, and NNLS method is presented. The magnetic moment reconstruction using the BMO algorithm shows significantly less noise and smooth distribution compared to the PSO and GA algorithms with fewer computation times. Furthermore, the constructed peaks' position matches the original distribution and shows comparable performance with the conventional NNLS algorithm