In this work, we used a hydrothermal process to synthesize NiCo2O4 and Ni2CoS4 for flexible dye sensitized solar cell (FDSSC) and supercapacitor. The phase structures, functional groups and optical features of synthesized samples were confirmed by different characterization analytical techniques. The morphologies of NiCo2O4 are formed as nanoflakes and Ni2CoS4 formed as multiple interconnected nanosheets and nanoparticles, which were confirmed by FE-SEM and HR-TEM analysis. The fabricated FDSSC performances were analysed and the Jsc, Voc and FF% were obtained from J-V curves and were 6.75 mA cm−2, 0.6 V and 0.7209% for NiCo2O4 and 8.13 mA cm−2, 0.7 V and 0.73% for Ni2CoS4, respectively. The fabricated FDSSC displays a power conversion efficiency (PCE %) of 2.91% for NiCo2O4 and 4.16% for Ni2CoS4. After 50 bends and twists of the FDSSC the PCE% of the FDSSC remained at 70% (3.30%) and 74% (3.22%). Moreover, Ni2CoS4 showed exceptional photovoltaic activity in the reduction of triiodide (I−/I₃−) due to enhanced electronic conductivity and synergistic effects at the interfaces of NiCo2O4 and Na2S. Electrochemical performance of Ni2CoS4 electrodes in 1 M KOH showed a specific capacitance of 517.8 F/g at 1 A/g. A symmetric supercapacitor assembled with Ni2CoS4 attained an energy density of 26.85 Wh/kg, a power density of 699.9 W/kg and maintained 98.5% capacitance retention after 7000 cycles, highlighting its potential for energy storage applications. This study aims to provide novel synthesis and rational design of highly efficient NiCo2O4 and Ni2CoS4 materials for prospective FDSSC solar cell and supercapacitor applications.
Hydrogen production via water electrolysis is a promising route toward sustainable and carbon-free energy. Transition metal dichalcogenide (TMD) nanosheets have emerged as efficient electrocatalysts for the hydrogen evolution reaction (HER), owing to their tuneable electronic properties and abundant active sites. In this study, we report the in-situ solvothermal synthesis of a compositionally tuneable library of molybdenum sulfoselenide (MoS2(1-x)Se2x) nanosheets uniformly anchored on reduced graphene oxide (rGO). The resulting MoS2(1-x)Se2x/rGO nanocomposites exhibit significantly enhanced HER activity, with the optimal MoS0.6Se1.4/rGO sample achieving a current density of 10 mA cm−2 at a low overpotential of 118 mV and a Tafel slope of 46.6 mV dec−1 in acidic media. The improved performance is attributed to the synergistic effects of sulfur and selenium incorporation, which modulate hydrogen adsorption energy, enhance orbital hybridization (Mo 4d, S 3p, Se 4p), and facilitate charge separation. Density functional theory (DFT) simulations further reveal that the Janus-type configuration enhances electronic conductivity and reactivity. The rGO substrate provides a conductive framework, promoting efficient charge transport and mechanical stability. These findings demonstrate that interface-engineered MoS2(1-x)Se2x/rGO hybrids are highly efficient and tunable HER catalysts, offering valuable insights for the design of advanced electrocatalytic materials.
The addition of SnO2 with high electron mobility has the potential to improve Dye-Sensitized Solar Cell (DSSC) performance, especially SnO2 nanofiber, which has a direct electron path, and high porosity, thereby facilitating optimal dye and electrolyte absorption. This study examines the effect of annealing temperature (300 °C, 400 °C, 500 °C, and 600 °C) on the structural, morphological, optical, and performance characteristics of multilayer TiO2 nanoparticle/SnO2 nanofiber DSSC. The methods used were screen printing for TiO2 deposition and electrospinning to obtain SnO2 nanofiber. The results demonstrate that DSSC with TiO2 nanoparticles/SnO2 nanofiber photoanode annealed at 500 °C has the highest efficiency of 3.74%. This is attributed to the sample exhibiting the highest porosity of 68.14%, a small resistance (RCT), and an electron lifetime of 2.02 ms which indicates a low charge recombination rate and increased charge transfer.
Municipal solid waste incineration fly ash (MSWI-FA), a by-product of burning wastes at high temperatures for volume and mass reduction, is a promising, cost-effective, and sustainable adsorbent for phosphate (PO43–) removal due to its significant calcium oxide (CaO), silicon dioxide (SiO2), aluminum oxide (Al2O3), and iron oxide (Fe2O3) contents, which facilitate phosphate removal via adsorption and chemical precipitation reactions. This study investigates the efficiency of MSWI-FA for phosphate removal from wastewater through batch and continuous flow column experiments, with a particular focus on the influence of particle size, pH, contact time, and hydraulic retention time (HRT). Batch experiments showed that the –75 µm fraction achieved the highest phosphate removal (∼70%) at pH 6, with adsorption behavior controlled by chemisorption. Continuous flow column experiments revealed that a 25 mm bed provided 91.3% removal, while a 15 mL/min flow rate achieved ∼ 99% removal within 480 min. Fourier transform infrared spectroscopy (FTIR) analysis supported a dual removal mechanism of phosphate: (i) surface adsorption through hydroxyl and metal oxide functional groups (e.g., Al–OH, Fe–OH, Si–OH) (IR bands at ∼ 1050, ∼560 cm–1; ∼3000–3700 cm–1), and (ii) chemical precipitation with calcium ions forming calcium phosphate compounds (IR band at ∼ 1300–1600 cm–1). These findings underscore the practical potential of MSWI-FA in wastewater treatment and support its alignment with circular economy goals through waste valorization.
The goal of this critique is to examine the newer Flash Joule Heating (FJH) technique for the production of graphene and hydrogen to determine if either production method is sustainable. By conducting an in-depth evaluation into the FJH technique as well as other methods such as chemical vapor deposition, this review seeks to determine which is the most effective method. With high-voltage pulses, FJH can quickly transform waste materials rich in carbon, such as biomass and plastics, into superior quality graphene, while also producing hydrogen gas as a by-product. FJH has been estimated to use around 7.2 kJ/g of energy which is considerably lower than other methods, and it also has a higher scalability and a 90% lower carbon footprint than the classical methods and does not need as many costly catalysts and undergoes less energy demanding processes like electrolysis, which makes it more economically viable. Its usage has been extended to cover energy storage, hydrogen systems, and water purification. With such complex systems, there is bound to be variation in feedstock and defect control which can be solved using advanced AI/ML optimization and better pre-treatments. FJH is one step closer to achieving circular economy goals by turning waste products into materials of value, demonstrating the ability to mass produce hydrogen and graphene in an economical manner to aid in the ideal of a carbon–neutral energy future.
This study investigates the impact of carbon nanotube (CNT) incorporation on the electrochemical performance of polyvinyl alcohol (PVA)/HCl/TEOS-based solid polymer electrolytes for rechargeable aluminium-air batteries. CNTs were introduced in varying quantities (0–0.05 g), while a polylactic acid (PLA) nanofiber layer containing carbon quantum dots (CQDs) was integrated as a separator to enhance ion transport. The inclusion of CNTs improved the amorphous structure, as evidenced by X-ray diffraction (XRD), and optimized ionic pathways within the polymer-silica network. The PHT0.05CNT membrane exhibited the highest ionic conductivity of 6.25 × 10−3 S cm−1, while transference number analysis confirmed predominant ionic conduction (Tion = 0.923). Among the tested compositions, PHT0.02CNT achieved the best battery performance, delivering a capacity of 0.4168 mAh g−1 and an energy density of 0.145 mWh g−1. Cyclic voltammetry further demonstrated enhanced redox reversibility with the addition of CNTs. These findings underscore that controlled CNT incorporation significantly enhances ion transport and electrochemical performance, suggesting strong potential for developing high-efficiency aluminium-air batteries.
The valorization of hazardous spent potlining (SPL) waste into functional ceramics remains a formidable challenge due to its thermodynamic inertness and structural heterogeneity. This study presents a novel mechanochemical–thermal synthesis route enabling phase-pure formation of (Ca3Al2(SiO4)3 grossular (GSR)) garnet directly from SPL, employing Na2CO3 and CaCO3 as mineralizing additives. Post-synthesis calcination at 1200–1300 °C (at 25 °C intervals) for 5 h facilitated complete transformation into a highly ordered cubic Ia-3d garnet phase. Thermogravimetric analysis revealed sequential carbonate decomposition and volatile evolution above 1100 °C, while XRD confirmed sharp reflections characteristic of GSR garnet crystallinity. SEM analysis of the product exhibited dense, polygonal microstructures with minimal porosity and an average grain size of 2.8 µm. Elemental profiling revealed thermally activated incorporation of Ca, Al, and Si, with maximal oxide stabilization (Al2O3, CaO, and SiO2). FTIR spectra showed distinct Si-O stretching (875–1083.5 cm−1) and bending (529.88 cm−1) modes, alongside Ca-O and Al-O lattice vibrations, confirming complete oxide incorporation. Optical spectroscopy indicated a strong UV absorption edge and an indirect bandgap of 4.86 eV, consistent with DFT-predicted 4.59 eV. First-principles calculations verified high thermodynamic stability (E0 = −34347.433 eV, B0 = 192.878 GPa, ΔHf = -5755 kJ/mol) and a lattice parameter of a = 12.16 Å. The material exhibited strong UV absorption (5.6 × 103 cm−1), dielectric constant (ɛ1 = 4.8), and refractive index (n = 1.8). This work pioneers a sustainable materials design strategy, merging waste remediation with the creation of optoelectronic garnet materials for next-generation energy-related optoelectronic and ceramic applications.
Global energy security has been destabilized by post-pandemic disruptions, geopolitical instability, and climate-related events, accelerating the need for sustainable alternatives such as solar technologies. Dye-sensitized solar cells (DSSCs), a cost-effective and environmentally friendly third-generation photovoltaic technology, have attracted significant research interest in recent decades, particularly in enhancing the properties of the photoanode material. This review emphasizes the role of green synthesis approaches as promising alternatives to conventional chemical methods. These eco-friendly strategies utilize biological compounds as reducing and capping agents, enabling better control over particle size and morphology, improving DSSC performance by enhancing electron transport properties and dye-loading capacity. However, product consistency and reproducibility issues remain significant challenges, particularly for scaling up and commercialization. This paper also outlines future directions, including extract fingerprinting, hybrid nanostructure development, and integrating artificial intelligence and machine learning for synthesis optimization. The green synthesis of TiO2 nanoparticles holds strong potential for advancing DSSC performance while supporting the transition toward sustainable energy technologies.
Plastic pollution and water scarcity are urgent global challenges that demand sustainable solutions. Municipal solid waste (MSW), including plastic waste, is a crucial environmental challenge that contributes to global pollution and threatens ecosystems. MSW can be used in various applications beyond disposal, such as energy recovery systems, biogas production, the development of construction materials, and desalination. For instance, in interfacial solar evaporation (ISE), waste plastic efficiently produces water through solar-driven steam generation. Plastic materials possess properties such as low thermal conductivity and hydrophobicity that can enhance water evaporation efficiency. This review evaluates recent advances in plastic upcycling strategies and fabrication techniques for enhancing ISE. ISE systems using plastic garbage bags with direct repurposing reached a water evaporation rate of 8.96 kg⋅m−2⋅h−1. Repurposing plastic waste into solar evaporators, transparent solar stills, and insulation materials significantly improves water evaporation efficiency. In addition, the integration of plastic waste in ISE contributes to multiple Sustainable Development Goals (SDGs), including Clean Water and Sanitation (SDG6), Responsible Consumption and Production (SDG12), and Climate Action (SDG13). Furthermore, integrating waste management strategies with innovative water purification technologies enables scholars to assess the potential of waste plastic in advancing ISE for more sustainable water evaporation.
Manganese- and cobalt-based materials are considered promising cathode candidates for zinc-ion batteries (ZIBs) due to their environmental sustainability, high specific capacities, and the natural abundance of their constituent elements compared to those used in other metal-ion battery technologies. Nonetheless, their extensive utilization is impeded by sluggish kinetics and suboptimal durability. In addressing these challenges through nanostructure engineering, we present a novel approach by tailoring the Mn/Co ratio to synthesize MnCo2O4 (MCO) and CoMn2O4 (CMO) entrapped carbon nanofibers (CNFs) via the electrospinning technique and post-treatment. MCO-CNFs and CMO-CNFs exhibit excellent performance as zinc cathodes in ZIBs, achieving initial specific capacities of 501.94 mAh g−1 and 399.32 mAh g−1 at 0.05 A g−1, respectively. CMO-CNFs demonstrate superior rate performance at high current densities, whereas MCO-CNFs exhibit better cycle stability. This complementary behavior highlights the tunable electrochemical characteristics enabled by Mn/Co ratio adjustment. Insightfully, the influence of the Mn/Co ratio on the electronic stateof the elements and the electrochemical storage behavior of ZIBs during the charge/discharge process is convincingly explored using ex-situ techniques such as scanning electron microscopy and operando X-ray absorption near-edge structure, proving that MCO-CNFs are more stable and redox-reversible than CMO-CNFs.
A cross substrate counter diffusion (CSCD) process between the solutions of Zn(II) solution and 2-methyl imidazole (2-MIM)-ammonia solution (pH = 10) to in situ grow ZIF-8 particles was developed to enhance the performance of polyamide (PA)/polyethylene(PE) based thin film composite (TFC) total heat exchange membranes (THEMs). In situ grown ZIF particles from CSCD processes had effectively blocked CO2 leakages across the PA separating layer by sealing the defect points, and provided selective water vapor permeating channels and surface area to enhance energy recovery efficiencies. The effects of Zn(II) loading concentration, CSCD reaction time and ligand type on the structure, CO2 barrier property and heat exchange efficiencies were systematically investigated. Under optimized conditions, sealing with ZIF-8 particles could decrease the CO2 permeance from 7.5 GPU to 1.15 GPU, at the same time, increase the sensible heat, latent heat and heat exchange efficiencies from 80 %, 53 %, 68 % to 96 %, 73 % and 82 % respectively.
In the rapidly growing modern era, the advancement of electrochemical energy storage (EES) materials for electronic devices is a key challenge. Herein, we report the synthesis of novel redox-active polyureas (PUrs) bearing carbonyl functional group and repeated redox segments starting from the redox-active amine-capped trianiline (ACTA) and amine-capped tetraaniline (ACTAni). These materials are doped with 2 M HCl and designated as DPTA and DPTAni. The material properties and surface analysis are thoroughly analyzed by fourier transform infrared (FT-IR) spectroscopy, UV–Vis absorption spectroscopy, field emission-scanning electron microscopy (FE-SEM), X-ray diffraction (XRD) and Brunauer-Emmett-Teller (BET) techniques. In a three-electrode (3E) system, DPTA achieves a high specific capacitance (Csp) of 260.9 F/g, outperforming DPTAni of 239 F/g, as determined by galvanostatic charge–discharge (GCD) measurements. However, long-term cycling stability exhibits the capacitance retention for DPTA and DPTAni was about 59.12 % and 46.38 %, respectively, for 2000 cycles and with a significant decrement of Csp for 5000 cycles owing to an increase in the solution resistance, as confirmed by Electrochemical impedance spectroscopy (EIS). This study highlights the potential of carbonyl-functionalized PUrs as promising candidates for next-generation pseudo-capacitive materials, with further optimizations for enhancing cycling stability.
Layered Transition Metal Dichalcogenides (LTMDs)are now frequently employed as useful materials for catalysis, energy storage, and environmental applications. It is still extremely difficult to create synergistic bimetallic tellurides with great electrochemical performance, particularly in high-performance supercapacitors. Here, the standard self-flux technique isused to make high-capacity Cu intercalated and doped NiTe2. Both compounds feature a P3m1 space group and a CdI2-type trigonal structure, following the pattern of X-ray powder diffraction (XRPD). The transition electron microscope (TEM) also reveals the periodic arrangement of the crystalline structure. Additionally, the multilayer structures of this chemical are seen by the field emission scanning electron microscope (FESEM). We confirm the elemental composition and oxidation state analysis by using EDX and X-ray photoemission spectroscopy (XPS), respectively. Cu0.05NiTe2 and Ni0.95Cu0.05Te2 show specific capacitances of about 212 F/g and 478 F/g at 1 A/g. Ni0.95Cu0.05Te2 shows excellent cyclic stability (99.18 %) and coulombic efficiency (81.58 %) for 5000 cycles, which confirms that the doping of nickel enhances the electrochemical properties.
Interest in collecting waste heat from diesel generators, a substantial but underutilized energy source, has increased due to the growing demand for energy efficiency. By transforming heat gradients into electrical power, thermoelectric generators (TEGs) offer a clean alternative that improves fuel efficiency and lowers pollutants. In order to improve thermoelectric power generation, this work intends to construct and assess a hybrid system that combines Heating, Ventilating, and Air Conditioning (HVAC) condenser airflow with waste heat from diesel generator exhaust gases. The suggested system presents a new architecture that makes simultaneous use of condenser air and diesel exhaust, two easily accessible but infrequently coupled thermal sources and sinks. Compared to conventional setups, this method greatly increases TEG efficiency by taking advantage of high temperature differentials and passive sink flow. To mimic the behavior of the system under various operating situations, we developed a comprehensive thermal model. The effect of TEG plate dimensions, duct heights, and the TEG thickness-to-thermal-conductivity ratio (t/k) on temperature gradients and power output were investigated parametrically. The findings indicate that while larger cooling loads from the HVAC system result in worse performance, increasing the generator load and t/k ratio increases power output. With duct height = 0.04 m and a 5 m × 0.2 m TEG plate, the optimized arrangement produced a peak output of 4745 W, which translates to a 2.37 % increase in fuel efficiency. This work provides a scalable model for sustainable energy integration in industrial applications and validates the potential of hybrid TEG systems for efficient waste heat recovery.
This research has investigated the viability of valorizing Areca or Betel palm-shells into activated carbon, to be applied as an electrode active material in supercapacitors. The palm-shells are an agricultural waste from betel-nut production, an important economic crop in several regions around the world. The conversion process mainly involves pulverization, ZnCl2-activation, and carbonization. The effect of carbonization temperatures – 500, 600, 700, and 800 °C, was studied on the properties of the activated carbon. Microstructural characterizations like BET, Raman, and XPS were carried out. All the activated samples are microporous, have a specific surface area >1,000 m2 g−1, and possess an intensity ratio of D-to-G band close to 1. More than 80 % of the atomic concentration of the samples is carbon; the C 1s bonds include C=C or sp2, C–C or sp3, C–(O,N), C=O, and O–C=O or π– π*. The activated carbon synthesized at 700 °C shows the most favorable properties for being used as the electrode in supercapacitors. Its electrochemical properties, evaluated by galvanostatic charge–discharge and cyclic voltammetry deliver the maximum specific capacitances of 144.48F·g−1 at 1 A·g−1 and 169.21F·g−1 20 mV·s−1, respectively. The supercapacitors do perform stably at long-term cycling with the capacitance retention (>98 %) and the coulombic efficiency at almost 100 % over 50,000 cycles. The betel-palm-shell carbon has a very comparable capacitive performance to other biomass-derived carbons with the respective maximum energy and powder densities of 7.63 Wh·kg−1 and 5,849.93 W·kg−1. Converting the betel-palm-shell waste, one of the common agricultural wastes in Asia, Oceania, Africa, or Latin America to activated carbon is a pathway of waste valorization as well as leads to a new business opportunity of producing carbon electrodes for an energy application of supercapacitors. This will further go towards a circular carbon economy, not only reducing the carbon footprint and other pollution caused by currently widely practiced incineration, but also creating a sustainable loop of material utilization.
The implementation of titanium dioxide (TiO2) as a photocatalyst material in hydrogen (H2) evolution reaction (HER) has embarked renewed interest in the past decade. Rapid electron-hole pairs recombination and wide band gap of a photo-sensitive material of TiO2 are detrimental toward the targeted catalytical reaction. In this study, we present the rational design, fabrication, photocatalytic performance of TiO2-Cu/CuO/Cu2O heterostructures (CuTi) using viable chemical reduction method. The Z-scheme and S-scheme are succesfully generated across the TiO2/CuO/Cu2O interfaces, while the Schottky junction arises on the Cu perimeters. This is evidenced from the blue shifted about 0.3 eV of Cu 2p core level determined by using X-ray photoemission spectroscopy (XPS), in combination with the formation of inverse V-shape of the Mott-Schottky plots. In addition, we find that Cu/CuO/Cu2O facilitates photon absorption range up to the visible region. The multiple heterojunction and the large number of OHsurface enhanced charge carrier transfer are associated to the suppression of photoluminescence (PL) intensity, high surface hydroxyl (OHsurface) density in CuTi probed by XPS, and fast electron transfer based on the electrochemical measurements. The presence of OHsurface inhibits the recombination of electron. A significant H2 photogeneration rate enhancement is achieved when an optimized 5 wt% Cu/CuO/Cu2O concentration is used on TiO2 to achieve 7,157.19 μmol·g−1 (1,789.30 μmol·g−1·h−1). Based on this finding, zero emission energy innitiative could be materialized under multiple heterojunctions in photocatalytic process is beneficial for enhancing the H2 production.
This study aimed to enhance the effectiveness of the simultaneous combination of electrocoagulation and photocatalysis processes by modifying the configuration of the photocatalyst. A heterojunction mechanism was developed by integrating CdS with a photocatalyst usinga TiO2 nanotube array (TNTA) [1]. This mechanism is designed to enhance photocatalytic efficiency by reducing electron-hole recombination. The successful synthesis of CdS/TNTA nanocomposite was confirmed using various characterization methods, including XRD, HRTEM, FESEM, UV–Vis DRS, PL, transient photocurrent, and XPS. The results showed that CdS/TNTA worked better than TNTA in a single photocatalysis process, achieving improved Ciprofloxacin (CIP) removal (7.9 % to 13.8 %) and hydrogen gas production (0.006 to 0.156 mmol/m2plate). Simultaneously operating electrocoagulation and photocatalysis systems in the respective optimized settings resulted in significant enhancements. Hydrogen gas yield increased by 44 % (from 443 to 636 mmol/m2 plate) compared to using only TNTA, while CIP removal improved from 79 % to 83 %. This study demonstrates that the synthesis of CdS/TNTA photocatalysts may be a promising approach to achieving high performance of hydrogen recovery while simultaneously removing CIP from wastewater.
This study investigates the enhancement of thermoelectric properties in silver selenide (Ag2Se) via the cold sintering process (CSP) using dimethyl sulfoxide (DMSO) as a transient liquid phase. Unlike conventional sintering methods that require high temperatures and long processing times, CSP with DMSO enables densification at significantly lower temperatures while simultaneously tuning the microstructure and carrier transport properties. Bulk Ag2Se samples were fabricated with varying DMSO concentrations (5–12 %) and sintering temperatures (190 °C, 220 °C, and 250 °C) to evaluate the influence of these parameters on thermoelectric performance. X-ray diffraction (XRD) analysis confirmed the retention of the orthorhombic β-Ag2Se phase across all samples, with slight morphological changes observed due to DMSO concentration and sintering temperature. Optimal results were achieved at a DMSO concentration of 10 %, where a balance between electrical conductivity (σ) and Seebeck coefficient (S) yielded a high power factor. Thermal conductivity (κ) analysis showed a significant reduction attributed to enhanced phonon scattering from defects introduced via CSP with DMSO. Furthermore, the AS-DMSO250 sample (with 10 % DMSO and sintered at 250 °C) exhibited a stable ZT, ranging from 0.94 at 300 K to 1.10 at 380 K representing a 42–49 % enhancement over the reference sample, which had ZT values of 0.66 at 300 K and 0.74 at 380 K. The average ZT of the optimized sample with DMSO reached approximately 1.02 at 300–380 K, surpassing values commonly reported in the literature. These findings emphasize the critical role of DMSO concentration and sintering temperature in optimizing thermoelectric properties, offering a practical approach for advancing Ag2Se-based thermoelectric materials for efficient energy harvesting near room temperature.
