Nanomaterials in 2 dimensions for flexible solar cell applications a review

This review presents the progress, challenges and prospects of ultrathin flexible photovoltaic devices based on 2 dimensional 2D nanomaterials. These devices have shown very high performance in bending stabilities for up to 90 of their power conversion efficiencies PCEs after multiple bending deformations. They are thin film PVs with lightweight and mechanically robust structures that allow use in the continual advancing solar cell applications. In this paper, comprehensive assessments of 2D nanomaterials, their syntheses methods, performance, degradation, mechanical and opto electronic characterization in flexible photovoltaic PV cells are highlighted. Semi conductor materials such as conjugated donor and acceptor polymers, small donor acceptor molecules and organometal halide perovskites for use as active layers in such flexible solar cell structures are reviewed. The challenges and prospects associated with the adoption of 2D nanomaterials in flexible solar cells are presented. The review highlights the need to transition laboratory results on 2D nanomaterials based flexible solar cells into scale up and commercialized products despite the existing and also opens research areas for researchers to explore and achieve robust and high efficient solar device

Interpenetrated Magnesium–Tricalcium Phosphate Composite: Manufacture, Characterization and In Vitro Degradation Test

Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test.Magnesium and calcium phosphates composites are promising biomaterials to create biodegradable load-bearing implants for bone regeneration. The present investigation is focused on the design of an interpenetrated magnesium–tricalcium phosphate (Mg–TCP) composite and its evaluation under immersion test. In the study, TCP porous preforms were fabricated by robocasting to have a prefect control of porosity and pore size and later infiltrated with pure commercial Mg through current-assisted metal infiltration (CAMI) technique. The microstructure, composition, distribution of phases and degradation of the composite under physiological simulated conditions were analysed by scanning electron microscopy, elemental chemical analysis and X-ray diffraction. The results revealed that robocast TCP preforms were full infiltrated by magnesium through CAMI, even small pores below 2 lm have been filled with Mg, giving to the composite a good interpenetration. The degradation rate of the Mg–TCP composite displays lower value compared to the one of pure Mg during the first 24 h of immersion test

Graphene for Flexible Photovoltaic Devices

Flexible photovoltaic devices (FPD’s) are emerging as next-generation technology in photovoltaic research. FPD’s have attracted great research attention because of their broad potential applications especially in wearable devices, portable electronics, integrated textiles, unmanned aerial vehicles, transportation, and military etc. The existing technologies have evolved over the years, improving efficiency and performance of photovoltaic devices. However, these technologies mostly rely on rigid electrodes that are brittle, costly and chemically unstable. For FPD’s to become practical, new materials that offer inherent flexibility without compromising on mechanical and optical properties must be the focus. Researchers have made significant advances over the past decade towards developing various aspects of FPD’s to improve its optical transmittance, mechanical stability, chemical stability etc. Graphene is increasingly been recognized as an excellent material for flexible photovoltaic devices because of its unique optical, electrical and mechanical properties. The prospects of introducing an inexpensive and abundant carbon-based material such as graphene in making flexible, low-cost, transparent PV cells cannot be over emphasized. However, the method to synthesize graphene to achieve the best performance is still complicated. This paper presents a brief overview of recent developments made in flexible photovoltaic devices using graphene

Recent Advancements in Chalcogenides for Electrochemical Energy Storage Applications

Energy storage has become increasingly important as a study area in recent decades. A growing number of academics are focusing their attention on developing and researching innovative materials for use in energy storage systems to promote sustainable development goals. This is due to the finite supply of traditional energy sources, such as oil, coal, and natural gas, and escalating regional tensions. Because of these issues, sustainable renewable energy sources have been touted as an alternative to nonrenewable fuels. Deployment of renewable energy sources requires efficient and reliable energy storage devices due to their intermittent nature. High-performance electrochemical energy storage technologies with high power and energy densities are heralded to be the next-generation storage devices. Transition metal chalcogenides (TMCs) have sparked interest among electrode materials because of their intriguing electrochemical properties. Researchers have revealed a variety of modifications to improve their electrochemical performance in energy storage. However, a stronger link between the type of change and the resulting electrochemical performance is still desired. This review examines the synthesis of chalcogenides for electrochemical energy storage devices, their limitations, and the importance of the modification method, followed by a detailed discussion of several modification procedures and how they have helped to improve their electrochemical performance. We also discussed chalcogenides and their composites in batteries and supercapacitors applications. Furthermore, this review discusses the subject’s current challenges as well as potential future opportunities

Facile synthesis and morphogenesis of superparamagnetic iron oxide nanoparticles for high-performance supercapacitor applications

A facile method has been developed for the synthesis of nearly mono-dispersed iron oxide nanocrystals. The structural analysis of the synthesized iron oxide nanocrystals reveals the magnetite phase of Fe3O4. The average particle size of the iron oxide was estimated to be 8 +/- 2 nm. The observed particle size is in good correlation with the particle size estimated by magnetic measurements. Furthermore, these nanocrystals showed bi-functional ferromagnetic and superparamagnetic behavior below and above the blocking temperature, respectively. The potential use of these nanocrystals as an electrode for supercapacitors was examined by investigating the electrochemical behavior of iron oxide using cyclic voltammetry (CV) and galvanostatic charge-discharge tests. The CV characteristics of the iron oxide electrode showed a typical pseudocapacitive behavior in 3 M KOH solution. Moreover, the specific capacitance of 185 F g(-1) at the current of 1 mA was observed with excellent cyclic stability, which is much higher than the reported value for iron oxide. The higher specific capacitance is due to the uniform nano-size of iron oxide. This work provides an ultimate facile method to synthesize nanostructured iron oxide for application in next generation energy storage materials

Optoelectrical Properties of NiInZnO (NIZO) Thin Films

This report presents the fabrication and characterization of x % Ni - InZnO (NIZO) Schottky diodes. The structural, optical and electrical properties of the fabricate Al/p-Si / x % Ni - InZnO /Au photodiodes were investigated. An average visible transmittance of about 75% - 85% has been obtained in the visible-light to near-infrared wavelength region. The optical bandgap was 3.17 ± 0.02 eV. Current-Voltage measurements were conducted to analyze the photodiode behavior under dark and light illumination. The reverse bias current increases together with increasing light illumination. The observed I-V results confirm the photoconductive and photovoltaic properties of the fabricated diode. There is an exponential relationship between the current and the voltage in the forward bias, confirming the rectification performance of the photodiode. The electrical properties of the fabricated photodiodes were evaluated using Cheung- Cheung and Norde’s methods. The transient photocurrent, capacitance-voltage-frequency and conductance-voltagefrequency plots indicate that the diode is very sensitive to light illumination. We also observe a strong correlation between capacitance and conductance on frequency, this was explained based on the presence of interface states. The obtained results suggest that the Ni-doped InZnO photodiodes can be useful in photovoltaic and optoelectronic applications

Optoelectrical properties of Al/p-Si/Fe:N doped ZnO/Al diodes

In this work, 3% Fe doped zinc oxide (ZnO) doped by Nitrogen thin films were grown by reactive radio frequency magnetron sputtering on p-Si substrates. The structural and optical properties of the 3% Fe doped ZnO doped by Nitrogen thin films were investigated by the scanning electron microscope and spectrophotometry. The diodes with the configuration of Al/p-Si/3% Fe-ZnO: N/Al have been fabricated and it has been observed that the diodes exhibit a good rectification. The optical band gap was found to be 3.98 +/- 0.02 eV for 3% Fe doped ZnO: N thin film deposited at the N-2 flow rate of 15 sccm. The electrical parameters of the diode were determined using Cheung's and Norde's method. The capacitance-voltage and conductance-voltage characteristics of Al/p-Si/3% Fe-ZnO: N/Al structure have been investigated in the frequency range 10 kHz-1 MHz. The increase in capacitance at lower frequency is attributed to the density of interface states. It is evaluated that the prepared diodes can be used as nanoscale electronic and optoelectronic devices.Scientific Project Unit of Kirklareli University [Klubap 76]; King Khalid University under the (Research Center for Advanced Materials Science) at King Khalid University, Kingdom of Saudi Arabia [RCAMS/KKU/007-18]This study was supported by Scientific Project Unit of Kirklareli University under project number: Klubap 76. Authors would like to acknowledge the support of the King Khalid University for this research through a grant RCAMS/KKU/007-18 under the (Research Center for Advanced Materials Science) at King Khalid University, Kingdom of Saudi Arabia.WOS:0004294098000342-s2.0-8504414751

Electrodeposited cobalt-based electrocatalysts for efficient oxygen evolution reaction and supercapacitors

Although transition metal oxides/hydroxides have gone through many modifications including heteroatoms doping to improve their performance towards electrocatalytic water splitting and supercapacitors, their superior performance is yet to come. Herein, cobalt hydroxide was calcined, sulfurized, and phosphorized, which was prepared via a facile electrodeposition process on nickel foam at −1.0 V. Based on the experimental results, the cobalt sulfide showed a lower overpotential of 282 mV to achieve a current density of 10 mA/cm2 for oxygen evolution process. Moreover, the prepared optimized cobalt sulfide sample displayed the highest specific capacitance of 3.7 F/cm2 along with the largest energy density (0.144 Wh/cm2) as well as high power density (8.28 W/cm2). The prepared optimized cobalt sulfide sample showed a very stable electrochemical performance suggesting that the facile electrodeposition process can produce efficient electrocatalysts for the oxygen evolution process

Machine learning based groundwater prediction in a data-scarce basin of Ghana

Groundwater (GW) is a key source of drinking water and irrigation to combat growing food insecurity and for improved water access in rural sub-Saharan Africa. However, there are limited studies due to data scarcity in the region. New modeling techniques such as Machine learning (ML) are found robust and promising tools to assess GW recharge with less expensive data. The study utilized ML technique in GW recharge prediction for selected locations to assess sustainability of GW resources in Ghana. Two artificial neural networks (ANN) models namely Feedforward Neural Network with Multilayer Perceptron (FNN-MLP) and Extreme Learning Machine (FNN-ELM) were used for the prediction of GW using 58 years (1960–2018) of GW data. Model evaluation between FNN-MLP and FNN-ELM showed that the former approach was better in predicting GW with R2 ranging from 0.97 to 0.99 while the latter has an R2 between 0.42 to 0.68. The overall performance of both models was acceptable and suggests that ANN is a useful forecasting tool for GW assessment. The outcomes from this study will add value to the current methods of GW assessment and development, which is one of the pillars of the sustainable development goals (SDG 6)