This study investigated the synthesis of ethaline-assisted iron sulfide on nickel foam (NF) using the electrode-position method to facilitate saline water splitting. The oxidization of iron and the formation of Fe(OH)3 on the cathode surface pose challenges for the electrodeposition of iron sulfide from aqueous solutions. To tackle these issues, deep eutectic solvent-assisted electrodeposition and ethaline-assisted sulfidation methods have been investigated for synthesizing FeS2. These approaches aim to enhance the efficiency of the iron sulfide electrode by preventing unwanted oxidation and ensuring the formation of high-quality coatings. Sulfidation in non-aqueous media was performed at varying durations, revealing that sulfur content significantly impacts the morphology of the prepared electrode. The optimum FeS2/NF catalyst offers the lowest overpotential of 194 mV at 10 mA cm-2 for oxygen evolution reaction (OER) and 176 mV at 10 mA cm-2 for hydrogen evolution reaction (HER) in saline water splitting. The enhanced catalytic activity is attributed to the formation of multiphasic components in the catalyst. The electrodes exhibited stability in saline water conditions for approximately 10 h for both OER and HER. Moreover, FeS2/NF exhibited stability for 50 h in OER and 20 h in HER when applied to pure water splitting. The investigation explores the unique synthesis of FeS2 in non-aqueous media and examines its catalytic activity in saline water electrolysis.

Perovskite solar cells (PSCs) play a pivotal role in advancing renewable energy to achieve United Nation's Sustainable Development Goal 7 (SDG 7), which aims to ensure universal access to affordable, sustainable, reliable and modern energy services. Aiming to enhance the performance of PSCs by replacing the typically used electron transport layers (ETLs: TiO2, SnO2, ZnO etc.), we theoretically investigated the viability of tungsten oxide (WOX) as a promising ETL for PSCs. Moreover, the effect of altering the energy levels of WOX on cell performance has also been analyzed through simulation. Initially, 12 (twelve) PSC structures having the combination of different perovskite (PSK: CsPbBr3, CsPbI3, FAPbBr(3), FAPbI(3)) absorber layers with different organic hole transport layers (HTLs: Spiro-OMeTAD, P3HT, PEDOT:PSS) and a fixed ETL of WOX were optimized numerically for comparing their performance. As CsPbBr3-based PSCs showed the best performance, further simulations were performed by varying some WOX/CsPbBr3 interface properties such as interface defect density, conduction band offset (CBO) between WOX and CsPbBr3, energy bandgap (E-g) of WOX etc. Finally, the best-performed PSCs were found for the E-g = 3.5 eV of WOX and the CBO of - 0.5 eV confirming the conduction band minimum (CBM) of WOX is lower than that of CsPbBr3 by 0.5 eV. A properly chosen WOX layer enhanced the efficiency of CsPbBr3-based PSCs up to 14.65 %, 14.52 % and 16.09 %, aproaching the Shockley-Queisser (S-Q) limit (16.37% for CsPbBr3-based solar cell) from the initial values of 11.39 %, 11.27 %, and 12.49 %, respectively. This study ensures WOX is a promising ETL for which a proper PSC structure having a suitable PSK and an HTL can improve cell performance. Moreover, the importance of modifying energy levels of ETL material in enhancing the performance of PSCs is explored. As a result, this study opens a path for the researchers to develop WOX having suitable CBM and E-g, so that it can be well-suited with a properly matched PSK material resulting in enhanced cell performance.

Perovskite solar cells (PSCs) show great potential for efficient solar energy conversion, but their long-term stability is still a concern. To address this issue, we developed a vacuum-deposited bismuth-based perovskite-like material (Cs3Bi2I9), which forms a high-quality thin film showing remarkable stability over 150 days of air exposure. When combined with a solution-processed MAPbI3 perovskite, the resulting device exhibits improved stability under varying environmental conditions. However, the power conversion efficiency (PCE) drops by 70% compared to the reference MAPbI3-based PSC. An advanced multiphysics optoelectrical device simulation combining 3D FDTD and FEM methods validates these findings, yielding results in excellent agreement with the experimental data. The study also provides insight into the device’s optics and electronic properties, revealing the factors that limit its performance. An optimized device design is proposed to reach an 18.81% PCE, higher than the reference device. The findings have significant implications for developing next-generation solar cells, including high-performance tandem solar cells.

Electrocatalytic water splitting is a promising solution to resolve the global energy crisis. Tuning the morphology and elemental composition is a crucial aspect in designing highlyefficient nanomaterials based electrocatalyst for water splitting. Herein, green synthesis using phytochemicals from aloe vera leaves extract was employed to hydrothermally synthesize copper oxide/cobalt oxide nanostructures on nickel foam. The reaction medium was performed in presence of mineralizers of different pH; hydrochloric acid (HCl), citric acid (CA), urea, diethyl amine (DEA) and sodium hydroxide (NaOH) to produce five different compositions of copper oxide/cobalt oxide on nickel foam. Based on FESEM and EDS analysis, it was verified that the plant mediated hydrothermal process yielded interesting morphologies and the elemental composition of the synthesized metal oxide nanostructures distinctly varied with effect to the different mineralizers used. Use of acidic mineralizers such as hydrochloric acid and citric acid favoured formation of copper oxide whereas basic mineralizers such as urea, diethyl amine and sodium hydroxide favoured formation of cobalt oxide. The green synthesis of metal oxide electrode in presence of urea exhibits the best OER electrocatalytic performance with an overpotential of 390 mV, and 453 mV for a current density of 50 mA cm-2 and 100 mA cm-2 respectively. The sample also exhibited sustained stability over 70 h, hence proving that the proposed electrode can serve as an efficient catalyst for electrocatalytic OER.(c) 2023 Hydrogen Energy Publications LLC. Published by Elsevier Ltd. All rights reserved.

This study emphasizes the synthesis of nickel oxide (NiOx + C) nanoparticles with varied graphite (C) proportions (1%, 2.5%, 5%, 7.5%, and 10%) using Aloe-Vera natural extract as a green reducing agent. Prepared NiOx + C nanostructures exhibited consistent X-ray diffraction patterns with no additional C peak, signifying enhanced interlayer spacing. The crystalline size (Dp) decreased from 27 nm to 20 nm with an increase in the amount of carbon (C). The determined bandgap (Eg) was 2 eV higher than bulk material due to formation extra energy level at defect sites. The shoulder peak at 1620 cm−1 agrees with the disorder-induced band from C and second-order bands of C at about 2700 cm−1 for NiOx + C. FESEM images confirm the hexagonal morphology. Not much particle aggregation was observed except for 10% C content. The selected area electron diffraction (SAED) confirms the existence of NiOx crystalline orientations including planes (111), (200), (220), (311), and (222).

The design and development of highly efficient electrocatalysts from transition metals have shown a great potential for substituting precious metal-based electrocatalysts in water-splitting processes.

This study investigates a sandwich-like CuSx/MnSx electrode fabricated through electrodeposition technique on nickel foam (NF) substrate for hydrogen evolution reaction (HER) in seawater splitting. The synthesized electrode exhibits plenty of active sites, substantial specific surface area, and a distinctive morphology reminiscent of a tuberose-type nanostructure. Moreover, synergistic activity between the copper and manganese components enhances the rate of electron transfer process, thereby augmenting the electrocatalytic performance. Partial oxidation serves to increase active sites and control the morphology of the nanoparticles. The optimized electrode exhibits a minimal overpotential of 144 mV at 10 mA/cm2 for saline water splitting. The Tafel slope of 197 mV/dec and a transfer coefficient (alpha) of 0.3 indicate that the rate-determining step for the HER is likely the initial Volmer reaction. A higher electrochemical surface area (ECSA) of 2268 cm2, a solution resistance of 0.84 S2, and a charge transfer resistance of 5.18 S2 suggest improved ion diffusion in the synthesized electrode. The electrocatalytic performance was also investigated by carrying out experiments with varying alkalinity in natural seawater electrolytes. The catalyst demonstrated robust stability for HER in natural seawater splitting with constant current density after 50 h of chronoamperometric analysis. The facile electrodeposited electrocatalyst exhibits energy-efficient and sustainable performance, effectively catalyzing reactions in a seawater-based electrolyte during the HER.

This study delves into enhancing the efficiency and stability of perovskite solar cells (PSCs) by optimizing the surface morphologies and optoelectronic properties of the electron transport layer (ETL) using tungsten (W) doping in zinc oxide (ZnO). Through a unique green synthesis process and spin-coating technique, W-doped ZnO films were prepared, exhibiting improved electrical conductivity and reduced interface defects between the ETL and perovskite layers, thus facilitating efficient electron transfer at the interface. High-quality PSCs with superior ETL demonstrated a substantial 30% increase in power conversion efficiency (PCE) compared to those employing pristine ZnO ETL. These solar cells retained over 70% of their initial PCE after 4000 h of moisture exposure, surpassing reference PSCs by 50% PCE over this period. Advanced numerical multiphysics solvers, employing finite-difference time-domain (FDTD) and finite element method (FEM) techniques, were utilized to elucidate the underlying optoelectrical characteristics of the PSCs, with simulated results corroborating experimental findings. The study concludes with a thorough discussion on charge transport and recombination mechanisms, providing insights into the enhanced performance and stability achieved through W-doped ZnO ETL optimization.

The co-doping of vanadium pentoxide (V2O5) with rare-earth (RE) elements, namely 1.5 % holmium (Ho) and 1.5 % ytterbium (Yb) has been conducted using an eco-friendly, straightforward hydrothermal approach to assess the combined effects on structural, optical, and photocatalytic properties. The application of the density functional theory (DFT) approach effectively examined the impact of RE ions on the photocatalytic efficiency of co-doped V2O5. The stable orthorhombic crystal structure of co-doped V2O5 has been confirmed using DFT and X-ray diffraction without a secondary phase. It appears that homogeneous nucleation occurs while heterogeneous nucleation slows down in co-doped samples, as evidenced by the larger crystallite sizes in co-doped samples compared to doped ones. It means a result, the co-doped samples exhibit photodegrades more quickly and have a higher rate constant than the doped samples. This is because they have less dislocation density (4.26 x 10(-3) nm(-2)) and internal micro-strain (4.93 x 10(-3)). The bandgap and degradation efficiency are determined by the UV-vis spectroscopy and found to be 2.33 eV and 95 %, respectively, at the optimal pH of 7 in the visible range. The co-doped sample has a rate constant of 24 x 10(-3) min(-1), which is the highest in the RE-doped V2O5 system. This is a good reason to think of co-doped V2O5 as a possible catalyst.

Although perovskite solar cells (PSCs) have captured notable interest as a potential candidate for third-generation solar cells, due to their favorable optoelectronic properties, cost-effectiveness, and high efficiency, some issues related to device stability and toxicity of the perovskite (PSK) layer hinders the commercial viability of PSCs. The inherent instability of organic PSK halides and the toxicity of Pb has compelled researchers to focus on developing Pb-free all-inorganic PSCs by replacing the organic species with inorganic (Cs+) cations as a safer alternative. In this study, the SCAPS-1D simulator was employed to investigate the cell performances of all-inorganic Pb-free Cs-based PSCs with three different PSK layers (CsGeI3, CsSnI3, and Cs2TiI6) individually, where inorganic ZnO and CuSCN were used as the electron transport layer (ETL) and the hole transport layer (HTL), respectively. The Cs2TiI6-based PSC was found to have the best performance. Then, the defect tolerance level of the PSK layer and the impact of band offset on cell performances were investigated. The optimum values of the conduction band offset (CBO) and the valence band offset (VBO) were found to be 0 eV and between − 0.1 eV and 0 eV, respectively. Moreover, the effect of interface defects at the ETL/PSK and PSK/HTL interfaces on cell performance was also analyzed as a function of CBO and VBO and, for both cases, the interface defect tolerance limit was recorded as 1016 cm−2. This study observed a high rate of recombination for negative values of CBO and VBO at the interfaces. Thus, these findings will guide researchers in developing high-performance PSCs with suitable inorganic Pb-free perovskite and charge transport layers.

AbstractGiven the increasing demand for electricity due to modernization and population growth, there is an urgent need to develop renewable energy conversion technologies such as photovoltaics. Among these technologies, CsPbIBr2, an all‐inorganic lead halide‐based perovskite, has shown promise due to its thermal stability, phase stability, and ease of fabrication. However, challenges remain, particularly in addressing device hysteresis and stability. Novel materials and optimized device designs could help overcome these challenges. This comprehensive review discusses strategies such as interface engineering, film quality improvement, compositional engineering, defect passivation, band alignments, and metal ion doping to enhance the performance of CsPbIBr2‐based perovskite films and, in turn, their potential for photovoltaic applications.

Organo-metal halide perovskite solar cells (PSCs) have received a lot of attention to the photovoltaic research community, mainly due to the rapid development of their cell performances. But industry-level production of PSCs is hindered for several reasons. At present, the use of high-temperature processed electron transport layer (ETL) such as TIO 2 , the use of chemically unstable ETL such as ZnO and SnO 2 , etc. are ETL-related obstacles behind this industrialization. Aiming to remove these problems, cerium oxide (CeO x ), one of the most Earth-rich metal oxides has been chosen as ETL for this study. In this study, the SCAPS-1D simulation package has been used for an intensive study on ETL/PSK interface for a methylammonium lead iodide (MAPbI 3 )-based PSC having CeO x as ETL. From this simulation, the effect of conduction band offset (CBO) between CeO x and MAPbI 3 has been found as the key player behind the cell performances. Defects at this interface have also been introduced and varied for studying their effects on cell performance at different CBO values. The temperature stability of a PSC is another important issue that has been considered in this study to find the effect of operating temperature on the PSC. This study would enlighten the researchers in implying some fantastic techniques at the ETL/PSK interface for improving the cell performance that will forward the research community a few steps to use CeO x as a promising ETL in PSC.

This paper presents the synthesis of copper sulfide (CuS) electrode utilizing chemical bath deposition (CBD) and the study of the effect of complexing agent on the morphology of CuS electrode. The aim of this study is to find the ideal time for the synthesis of CuS and to find the capacitance and highest potential of the CuS electrode synthesized at the ideal time. In this project, CuS solution is formed using copper (II) sulphate (CuSO4) solution, thioacetamide solution, and a complexing agent which is citric acid. Homogeneous ultrathin nanospheres of CuS thin films have been successfully developed on nickel foam (NF) by simple and low-cost CBD method which is a promising electrode material for high-performance supercapacitors. The CBD process was carried out at different time intervals which are 30, 60, 90 and 120 min to find the ideal deposition time for CuS/NF electrode fabrication. The surface morphological analysis showed uniform growth of CuS nanospheres on NF surface. Structural analysis confirms the formation of hexagonal crystal structure of CuS. The electrochemical performances were tested by cyclic voltammetry, galvanostatic charge/discharge and electrochemical impedance techniques. The best capacitance that was recorded by CuS fabricated at 60 min with a specific capacitance of 615 F/g at 1 A/g current density. Hence, the ideal deposition time of CuS/NF electrode fabrication for high supercapacitor performance is 60 min. The encouraging results suggest that CuS nanoflakes prepared by chemical bath deposition can serve as promising electrode materials for high performance supercapacitors in the future.

A green, plant extract-mediated synthesis technique utilizing the Aloe Vera stem extract with Zinc acetate (Zn(CH₃CO₂)₂•2H₂O), and Tungsten chloride (WCl2) salt has been employed to grow Zinc Oxide (ZnO) and tungsten doped ZnO (W-ZnO) nanoparticles (NPs). The formation of NPs was confirmed by FESEM with EDX and TEM analysis. The synthesized NPs have been employed for fabricating ZnO and W-ZnO thin films and the electro-optical properties of the films have also been investigated in detail. The thin films have obtained via spin coating and followed by annealing at 350 °C for 3h in an ambiance atmosphere. The films showed smooth surfaces with a bandgap of 3.20 and 3.25eV for ZnO and W-ZnO respectively. Finally, a novel structure inverted perovskite solar cells (PSCs) has been numerically analyzed utilizing the films as an electron transporting layer (ETL) for realizing the device performance. The highest PCE of the device for synthesized ZnO and W-ZnO has been found to be 21.16% and 23.61%, respectively. All of the findings show that the W-ZnO film is more suitable for the fabrication of PSCs than the ZnO film. In a nutshell, the synthesis of W-ZnO NPs employing green and eco-friendly methods, mediated by Aloe Vera extract as the reducing agent, offers in this study a novel approach to enhancing solar cell efficiency with the simple spin coating fabrication technique.

Aiming to enhance the properties of gallium doped zinc oxide (GZO) for considering it as a promising electron transport layer (ETL) in perovskite solar cells (PSCs), GZO thin films were sputtered using radio frequency (RF) magnetron sputtering under different Ar gas flow from 2 sccm to 5 sccm. Then the variations of morphological, structural, optical and electrical properties of the GZO thin films were studied thoroughly. The sputtered GZO films showed polycrystallinity having a hexagonal wurtzite-type crystal structure with a preferred crystal orientation in the direction of (0 0 2). In terms of morphological analysis, EDX confirmed the presence of Ga and FESEM analysis revealed that the thickness and grain size of deposited films gradually increase with the increment of Ar flow. Further, the film deposited at 3 sccm showed the lowest electrical resistivity of 1.09 x 10-02 omega-cm and achieved the highest carrier concentration of 1.586 x 1019 cm -3. All the GZO films showed optical transmittances between -80 % and -90 %. Finally, the simulation study validated the use of sputtered GZO as ETL in PSCs. This study provides a significant path for the researchers to optimize the RF-sputtered GZO films by varying the Ar gas flow rate for confirming their use as promising ETL in PSCs.

The treatment of palm oil mill effluent (POME) poses a significant challenge for Malaysia’s palm oil industry, necessitating compliance with the Department of Environment (DOE) regulations prior to discharge. This study introduces an eco-friendly synthesis method utilizing mangosteen (Garcinia mangostana L.)-leaf aqueous extract to fabricate copper oxide (CuO), zinc oxide (ZnO) nanoparticles (NPs), and their nanocomposite (CuO-ZnO NCs). The physicochemical properties of these nanomaterials were characterized using various analytical tools and their effectiveness in reducing the chemical oxygen demand (COD) of palm oil mill effluent (POME) was assessed under the illumination of two types of light sources: monochromatic blue- and polychromatic white-light emitting diodes (LEDs). CuO-ZnO NCs demonstrated superior performance, with the lowest energy bandgap (1.61 eV), and achieved a COD removal efficiency of 63.27% ± 0.010 under blue LED illumination, surpassing the DOE’s discharge limit of 100 mg/L. This study offers a cost-effective and environmentally friendly method for synthesizing heterojunction materials, which show great potential as photocatalysts in reducing POME COD to permissible levels for discharge.

Green synthesis of metal oxide nanoparticles is a cost-effective and sustainable approach that allows tailoring of the size and shape of the nanostructures for versatile applications. In this study, aloe vera extract-assisted sol-gel synthesis of nickel oxide nanoparticles (NiOx NPs) was explored for supercapacitor application. The NiOx NPs were synthesized at different aloe vera concentrations (2.5 and 5 wt%) and calcination temperatures (300, 400 and 500 C-degrees). The phytochemical-assisted synthesis yielded NiOx nanopyramids with pores on their surface which widens as calcination temperature increases. As confirmed by XRD analysis, NiOx crystallite size also increased at higher calcination temperatures. Upon electrochemical characterization, NiOx-400B which was synthesized with 5 wt% aloe vera extract at 400 C-degrees recorded the highest specific capacitance of 721 F g(-1) at 1 A g(-1) current density with the energy and power density of 10.38 Whkg(-1) and 241.08 W kg(-1) respectively. The charge storage mechanisms in the samples were gauged using Dunn's method which revealed that NiOx synthesized at higher calcination temperatures exhibited a greater contribution of the diffusion-controlled process. The optimized composition, NiOx-400B, also demonstrated excellent cycle stability by retaining up to 90.4 % of its original capacitance over 1500 cycles. This work is an attempt to investigate the viability of green synthesized nanoparticles in energy storage applications and the novel NiOx nanopyramid substantiates its prospect as a good electrode material for supercapacitors.

This study investigated the pseudocapacitive energy storage system of biphasic CuSx and CoSx electrodeposited on nickel foam (NF). XRD, FESEM, and EDX show the formation of nano-flower-shaped biphasic layer on NF. The biphasic electrode shows higher areal specific capacitance (Csp) than the single-layered NF/CuSx and NF/CoSx electrodes. The Csp of the NF/CuSx/CoSx drops by 42 % as the scan rate (& thetasym;) rises from 5 mV s- 1 to 20 mV s- 1. Electrode polarization and reduced ion migration occurring with rapid scan rates are responsible for this decrement. Galvanostatic charge-discharge (GCD) analysis showed that Csp declined from 11.42 to 9.63 F cm-2, and the retained Csp was 84 % as the current density shifted from 4 to 8 mA cm-2. The energy density of 0.30 mWh.cm- 2 and power density of 1.57 mW cm-2 imply significant energy storage capability of the electrode. The kinetic analysis indicates that 78 % of the capacitance is diffusion-controlled process in the NF/CuSx/CoSx electrode. The b-value of around 0.7 suggests that the pseudocapacitance mostly originates from diffusion-controlled processes. The poor cyclic stability of NF/CuSx/CoSx was demonstrated by only upholding 61 % of its original Csp after 500 cycles. However, the higher coulombic efficiency indicates that a greater proportion of the electrical charge is stored in the supercapacitor. The study explores the biphasic design of copper and cobalt sulphide-based electrodes as potential pseudocapacitive energy storage system applications such as super-capacitors and supercapatteries.

This study explores green-synthesized delafossite CuAlO2 as a hole transport layer (HTL) in a CH3NH3SnI3-based perovskite solar cells (PSCs) with an FTO/CuAlO2/CH3NH3SnI3/WO3/Au structure. The performances of the cell have been theoretically investigated using SCAPS-1D. Interface defects significantly impact cell efficiency, as defect density increases from 1014 cm−3 to 1020 cm−3 efficiency reducing from 25.3% to 24.45% in the HTL/perovskite junction and from 25.2% to 17.8% in the perovskite/electron transport layer (ETL) interface. PCBM as buffer layer at perovskite/ETL interface compensates for power conversion efficiency (PCE) losses. Optimizing parameters reveals the delafossite CuAlO2-based, lead-free perovskite solar cell achieving peak efficiency at 26.74%, with VOC, JSC, and FF values of 0.99 V, 33.43 mA cm−2, and 81.05%, respectively. This research underscores delafossite CuAlO2 as a promising HTL for eco-friendly, stable CH3NH3SnI3-based perovskite solar cells, emphasizing its potential in enhancing device performance.