Dr. Valdes-Morales, Hector

The study investigates the influence of praseodymium (Pr) doping on bismuth ferrite (BiFeO3/BFO) nanofibers and their structural, morphological, magnetic, optical, and photocatalytic properties. A series of bismuth ferrite nanofibers with varying concentration of Pr (Bi1-xPrxFeO3, x = 0.00, 0.05, 0.10, and 0.15 mol%) were successfully synthesized using an electrospinning technique. XRD patterns revealed that structural transformation occurred from rhombohedral to orthorhombic upon effective doping of Pr3+ into BFO nanofibers. The X-ray photoelectron spectroscopy analysis confirmed that Bi, Fe, and O maintained their native oxidation states of +3 and -2, respectively in the bare and doped systems. Furthermore, the optical band gap value was significantly reduced from 2.35 to 2.22 eV as well as the recombination rates of charge carriers in the doped systems, especially in BP0.15O system. The photocatalytic performance of the prepared samples was studied by measuring the decomposition of rhodamine B (RhB) under sunlight irradiation. Outcomes showed that the doped-BFO nanofibers exhibited enhanced photocatalytic performance compared to pure BFO, with the BP0.15O system showing the 98 % degradation in 60 min. This enhancement could be attributed to the presence of Pr-energy levels, which facilitating enhanced separation, and charge transfer to the surface for the effective redox reactions.

Hydrogen energy possesses immense potential in developing a green renewable energy system. However, a significant problem still exists in improving the photocatalytic H2 production activity of metal-free graphitic carbon nitride (g-C3N4) based photocatalysts. Here is a novel Cu3P/CdS/g-C3N4 ternary nanocomposite for increasing photocatalytic H2 evolution activity. In this study, systematic characterizations have been carried out using techniques like X-ray diffraction (XRD), scanning electron microscopy (SEM), high resolution transmission electron microscopy (HR-TEM), Raman spectra, UV–Vis diffuse reflectance spectroscopy, X-ray photoelectron spectroscopy (XPS), surface area analysis (BET), electrochemical impedance (EIS), and transient photocurrent response measurements. Surprisingly, the improved 3CP/Cd-6.25CN photocatalyst displays a high H2 evolution rate of 125721 μmol h− 1 g− 1. The value obtained exceeds pristine g-C3N4 and Cu3P/CdS by 339.8 and 7.6 times, respectively. This could be the maximum rate of hydrogen generation for a g–C3N4–based ternary nanocomposite ever seen when exposed to whole solar spectrum and visible light (λ > 420 nm). This research provides fresh perspectives on the rational manufacture of metal-free g-C3N4 based photocatalysts that will increase the conversion of solar energy. By reusing the used 3CP/Cd/g-C3N4 photocatalyst in five consecutive runs, the stability of the catalyst was investigated, and their individual activity in the H2 production activity was assessed. To comprehend the reaction mechanisms and emphasise the value of synergy between the three components, several comparison systems are built.

The ZnTiO3 material was synthesized by sol–gel method with the assistance of ethanol as solvent. The oxidative polymerization method was used to synthesize polycarbazole (PCz). The ball milling technique was employed to synthesize the mechanically composited nanoparticles—ZnTiO3/PCz nanocomposite. The synthesized composites were analysed using powder X-ray diffraction (PXRD), Fourier transform infrared (FTIR) spectroscopy, X-ray photoelectron spectrum (XPS), UV–Vis absorption spectrum (UV–Vis), scanning electron microscope (SEM), and high-resolution transmission electron microscope (HRTEM). The degradation of crystal violet (CV) in water under visible-light irradiation was used to assess the photocatalytic behaviour of the synthesized catalyst. The result shows that the ZnTiO3/PCz composites exhibit greater photocatalytic activity than other materials. Polycarbazole in composite material acts as an electron reservoir, actively trapping the photogenerated electrons which considerably lowers the probability of recombination and increases the degrading effect of the catalyst.

A nanocomposite composed of α-Fe2O3/g-C3N4 is synthesized using a modified ultrasonication approach, which engineered a robust interfacial contact in the system. Phase formation and morphological features are confirmed via XRD and electron-microscopy techniques. XPS revealed the native oxidation states of the elements and chemisorption-mediated interactions in the system. This developed composite produced hydrogen at a rate of 1494 μmolg− 1 h− 1, which is around 6.6 times higher than the g-C3N4 system. The observed enhancement is attributed to the Z-scheme configuration, leading to the suitable band edge alignments, charge separation and extended lifetime of the carriers in the composite.

In this work, a novel low-cost electrochemical sensor involving copper bismuthate (CuBi2O4) microspheres embedded in reduced graphene oxide (rGO) is described for electrochemical determination of L-Tyrosine (L-Tyr) and photocatalytic degradation of methylene blue (MB) in Parkinson’s disease treatment and industrial waste treatment, respectively. The rGO improves the electrocatalytic behaviours of CuBi2O4 and enhances the sensing performance of L-Tyr. At the optimized conditions, the nanocomposites show good long-term stability, reproducibility, and fast response with nanomolar detection (6.9 nM) at wide linear ranges of 83–1234 × 10− 9 M (R2 = 0.9964) towards L-Tyr. Further, the photocatalytic dye degradation within 30 min was studied in the presence of CuBi2O4/rGO catalysts. The synthesized CuBi2O4/rGO composite enhances the dye degradation rate and shows good sensitivity to detect the L-Tyrosine compared to CuBi2O4. The results suggest that the self-assembled three-dimensional CuBi2O4/rGO microsphere is an excellent material for the detection of biomolecules and the removal of organic dyes.