Nitrogen-doped carbon nanoparticles (NCNPs) embedded with tungsten carbide/tungsten oxide (WC1-X/ WOX) nanohybrids are in situ synthesized via a solution plasma (SP) process using a tungsten electrode, with cyclohexane and aniline serving as dual solvents. By modulating the cyclohexane to aniline volume ratios (80:0, 75:5, and 70:10), the number of defect sites induced by nitrogen doping in carbon nanoparticles (CNPs) can be effectively regulated. In addition, the co-existence of WC1-X and WOX nanoparticles embedded on the surface of NCNPs is observed, which is attributed to the bombardment of tungsten electrodes during the SP process. The results reveal that the as-prepared NCNPs/ WC1-X/ WOX nanohybrids synthesized at the optimized cyclohexane/aniline volume ratio of 75:5 (5-NCNP) exhibit the highest electrochemical activity among the synthesized samples, with an onset potential of 0.72 V (vs. RHE), a current density of 2.13 mA cm−2, and an electron transfer number of approximately 3 in alkaline electrolyte, indicating a mixed two- and four-electron ORR pathway with appreciable HO2− generation. The enhanced ORR performance is associated with the optimized pyrrolic-N/pyridinic-N configurations in the carbon nanohybrids and their interfacial electronic coupling with WC1-X/ WOX, which may collectively contribute to the observed catalytic activity. Complementary density functional theory calculations on simplified W-decorated carbon model surfaces indicate that incorporating nitrogen into the CW environment lowers the Gibbs free-energy barriers of the ORR intermediates, qualitatively supporting the experimentally observed promotional effect of N doping. These combined experimental and theoretical insights suggest that the synergistic electronic coupling between the nitrogen configurations and the tungsten-based nanophases plays a key role in enhancing the ORR performance. Overall, these findings provide new insights into the rational design of carbon-metal nanohybrids for oxygen reduction catalysis.
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.
