In recent decades, emerging water contaminants have raised significant global concern due to their impact on water quality, driving the need for more effective treatment strategies. In this work, magnetically separable samarium-incorporated cobalt ferrite supported on reduced graphene oxide (SmCoFe2O4/rGO) nanocomposites were prepared using a dual co-precipitation–hydrothermal approach for the photocatalytic degradation of bisphenol A (BPA). The synthesized samples were characterized using; FTIR, XRD, SEM, TEM, UV-DRS and BET adsorption–desorption measurements. The photocatalytic activity of SmCoFe2O4/rGO was increased under visible-light irradiation and in the presence of peroxydisulfate (PDS), with a maximum BPA removal efficiency of 96.4

Erbium (Er3+)-doped and ytterbium (Yb3+)-Er3+ co-doped Sodium yttrium fluoride (NaYF4) nanoparticles were synthesized via a solution combustion method and systematically investigated as rare-earth doped spectral conversion materials. X-ray diffraction (XRD) confirmed the coexistence of cubic (alpha) and hexagonal ((3) phases, with rare-earth incorporation inducing lattice strain and modification of crystallite size while preserving the structural integrity of the host lattice. Electron microscopy revealed that Er3+ doping produced relatively uniform particles, whereas Yb3+ co-doping led to broader size distributions and increased morphological irregularity. Ultraviolet-visible-near-infrared (UV-Vis) absorption spectra showed characteristic Er3+ intra-4f transitions and a dopant-induced modification of the absorption edge. Under 980 nm excitation, strong up-conversion (UC) emission was observed, with Yb3+ enhancing excitation efficiency through effective energy transfer to Er3+ and enabling tunable visible emission. Thermoluminescence (TL) measurements demonstrated dose-dependent response and stable repeatability, indicating that rare-earth incorporation modifies trap distribution without compromising structural robustness. Density functional theory (DFT) calculations revealed dopant-induced band-gap narrowing and the emergence of localized electronic states near the valence band edge, consistent with experimental absorption trends. These combined findings demonstrate that rare-earth doping enhances the structural, optical, and electronic response of NaYF4 while maintaining host stability, highlighting its potential relevance for spectral conversion and related photonic applications.

Herein, we report on unique surface, structural and adsorption properties for nitrogen-doped graphene oxide (NGO) nanosheets containing a low content of N produced via a low-temperature (35 °C) one-pot Hummer’s method. Graphene oxide (GO) and NGO were successfully synthesized and characterized using different techniques. The results from X-ray photoelectron spectroscopy confirmed that N atoms were introduced, with concentrations ranging from 0.5 to 1.0

Hydroxyapatite (HAP) was synthesized under varying pH conditions and temperatures to investigate the influence of synthesis parameters on its structural properties and potential application in perovskite-based solar cells. The structural characteristics of the synthesized materials were systematically analyzed using X-ray diffraction (XRD). Key parameters including crystallite size, microstrain, dislocation density, crystallinity index, texture coefficient, and lattice parameters were evaluated. The morphology was examined using SEM and the lead absorption capability of the HAP material was confirmed with ICP-OES analysis. The results revealed that variations in both pH and synthesis temperature significantly affected the structural properties of HAP which in turn impacted the lead absorption. Increasing the pH and temperature led to a reduction in crystallite size and a corresponding increase in structural defects and lattice strain. These findings demonstrate that careful control of synthesis conditions can effectively tailor the crystallographic and microstructural properties of HAP which demonstrated improved absorption of the lead ions. This observation provides valuable insight into its optimization for potential applications in perovskite-based photovoltaic devices.

Graphitic carbon nitride (g-C3N4), a polymeric semiconductor with a graphite-like layered structure, has gained significant attention in electrochemical sensing and energy storage applications due to its large surface area, abundant active sites, metal-free nature, low cost, and simple synthesis. However, pristine g-C3N4 suffers from poor electrical conductivity and significant irreversible capacity loss, which limit its practical performance. This review highlights recent advances in modification strategies aimed at improving the properties of g-C3N4-based materials for enhanced electrochemical detection of emerging pollutants and energy storage applications. Key approaches include heteroatom doping, defect engineering, heterojunction construction, and surface modification through various synthesis techniques. In addition, the review discusses current challenges and provides future perspectives for researchers exploring modified g-C3N4 materials in electrochemical sensing and energy storage technologies.

The global transition toward a hydrogen economy has been projected to increase indefinitely over the next decade. Growing industrial and technological advancements have increased the need for sustainable energy solutions. In a quest to resolve the problem associated with Pt and Pt-based metal electrocatalysts towards hydrogen production, viz., material scarcity and high cost, this study evaluates the potential of a silver-modified cobalt ferrite (AgCoFe2O4) nanocomposite as an alternative non-platinum-based electrocatalyst for hydrogen production in an acidic medium. Both the catalyst and its control (CoFe2O4) were synthesized using a modified co-precipitation approach. The materials were characterized using various spectroscopic and microscopic techniques. Incorporating Ag nanoparticles enhanced the CoFe2O4 charge transfer activity and thus, electrochemical characterization in terms of Tafel slope (-215 mV/dec), overpotential at 10mA/cm2 (-0.52V vs. RHE) and hydrogen onset potential (-0.44V vs. RHE). In comparison with the activities of some previously reported electrocatalysts, the AgCoFe2O4 demonstrated a stronger potential for hydrogen production. The catalyst exhibited about 0.11 cm2 electrochemical active surface area with a polarization resistance of 40.1 Ω. This study reveals the potential of AgCoFe2O4 as a sustainable non-Pt alternative for hydrogen production, and thus its feasibility as a viable electrode material for industrial-based water splitting or integrated fuel cell device application.

Perovskite-based solar cells are the leading candidates in the next-generation of photovoltaic technologies because of their high-power conversion efficiency (PCE) that they possess and their ease of fabrication. Most of the highly efficient perovskite-based solar cells have lead (Pb) in their absorber layer which raises environmental, and health concerns should the device undergo degradation or Pb leakage. In this study we employ lead encapsulation techniques by incorporating a hydroxyapatite (HAP) scaffold layer into the device structure aiming at preventing the Pb leakage while maintaining the performance and the high PCE of the device. The influence of the key HAP parameters including the thickness of the layer, donor concentration, defect density and the bandgap on the device is systematically analyzed and simulated using SCAPS - 1D. In addition, the impact of aluminum-doped zinc oxide (AZO), which will be the devices electron transport layer, and the bottom electrodes, specifically copper nanowires (CuNWs) and indium-doped tin oxide (ITO), were assessed to give the optimized parameters that could be used in experimental fabrication of the device. The optimized device configuration includes an AZO layer (2.3 mu m), a HAP scaffold (0.25 mu m) with a defect density of 10 1 5 cm-3 , donor concentration of 1021 cm-3 , and a bandgap of 1.46 eV, alongside a perovskite absorber (CH3NH3PbI3) layer of 0.8 mu m, simulated at 300 K. Under these conditions, the simulated device reached a PCE of 25.08 %, a fill factor (FF) of 87.05 %, a short circuit current (Jsc) of 26.39 mA/cm2, and an open-circuit voltage (Voc) of 1.09 V demonstrating the potential of HAP as a functional scaffold in perovskite solar cell designs with the potential of preventing any lead leakage as well as improving the efficiency of the cell. This work is the first of its kind to simulate the usage of HAP in a solar cell device.

Effects of caffeine and titanium dioxide (TiO2) in methylammonium lead iodide (MAPbI3/CH3NH3PbI3) as a photon absorber are studied. XRD showed high crystallinity of TiO2:Caffeine:MAPbI3 with larger crystallite size of -3.9 nm compared to TiO2:MAPbI3 with -3.6 nm. Large grain size of -550 mu m was obtained for TiO2: Caffeine:MAPbI3 compared to -256 mu m of TiO2:MAPbI3. Rod-like structures were observed though TiO2: Caffeine:MAPbI3 morphology and was smoother compared to TiO2:MAPbI3. Reduced bandgap energy of -2.3 eV was observed from TiO2:Caffeine:MAPbI3 and PL quenching indicated the possibility of reduction of the electronhole recombination. TiO2:Caffeine:MAPbI3 showed better electrical conductivity compared to TiO2:MAPbI3. Density functional theory calculations showed increased charge transfer/redistribution which accounts for the slight enhanced electrical conductivity for TiO2:Caffeine:MAPbI3. The density of state calculations suggests the formation of unoccupied states and O 2p, Ti 3p, N 2p and C 2p as major contributors to the electronic and electrical properties of TiO2:Caffeine.

The chapter discussed the optical properties of ZnO phosphor for a wide-ranging emission application. The existing luminescence characteristics of ZnO phosphor can be enhanced by the introduction of native defects as well as electronic impurity doping. Special characteristics of ZnO phosphor, like its large exciton binding energy and wide bandgap, make it an interesting material to explore, especially when doped with various elements for various nanoscale lighting devices. Additionally, the distribution and interaction of defects in undoped and doped ZnO phosphors as well as their luminescence dynamics were discussed. We presented the experimental work for the undoped and doped ZnO phosphor materials as down- and up-converting phosphors. As a result, the advantages associated with advancing the luminescence characteristics of ZnO phosphor materials were discussed.

ZnTiO3:Er3+, Yb3+ thin film phosphors were successfully deposited by pulsed laser deposition (PLD) at different substrate temperatures. The distribution of the ions in the films was investigated and the chemical analysis showed that the ions were homogeneously distributed throughout the ZnTiO3 host lattice which indicated a successful incorporation of the Er3+ and Yb3+ ions. The optical response of the phosphors revealed that the reflectance percentages of the ZnTiO3:Er3+, Yb3+ vary with the silicon substrate temperature due to the differences in the thickness and morphological roughness of the thin films. Under 980 nm diode laser excitation, the ZnTiO3:Er3+, Yb3+ film phosphors displayed up-conversion emission from the Er3+ electronic transitions, with violet, blue, green, and red emission lines at 410, 480, 525, 545 and 660 nm from 2H9/2 → 4I15/2, 4F7/2 → 4I15/2, 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. The up-conversion emission was enhanced by increasing the silico (Si) substrate temperature during the deposition. Based on the photoluminescence properties and decay lifetime analysis, the energy level diagram was established and the up-conversion energy-transfer mechanism was discussed in detail.

ZnTiO3:Er3+,Yb3+ thin film phosphors were successfully deposited by pulsed laser deposition (PLD) at different substrate temperatures. The distribution of the ions in the films was investigated and the chemical analysis showed that the doping ions were homogeneously distributed in the thin films. The optical response of the phosphors revealed that the reflectance percentages of the ZnTiO3:Er3+,Yb3+ vary with the silicon substrate temperature due to the differences in the thickness and morphological roughness of the thin films. Under 980 nm diode laser excitation, the ZnTiO3:Er3+,Yb3+ film phosphors displayed up-conversion emission from the Er3+ electronic transitions, with violet, blue, green, and red emission lines at 410, 480, 525, 545 and 660 nm from 2H9/2 → 4I15/2, 4F7/2 → 4I15/2, 2H11/2 → 4I15/2, 4S3/2 → 4I15/2 and 4F9/2 → 4I15/2 transitions, respectively. The up-conversion emission was enhanced by increasing the silico (Si) substrate temperature during the deposition. Based on the photoluminescence properties and decay lifetime analysis, the energy level diagram was established and the up-conversion energy-transfer mechanism was discussed in detail.

Zinc gallate samples with varied solution concentrations were prepared successfully by solution combustion synthesis using nitrates of zinc and gallium fueled by urea. The samples were prepared at 400 oC and further calcined at 800 oC for 4h using a microwave assisted furnace. The effect of concentration on crystallinity and optical properties was investigated by X-ray diffraction (XRD), Photoluminescence (PL) and Thermoluminescence (TL) spectroscopic techniques. The formation of spinel structures was confirmed by XRD patterns on all samples. The sharp diffraction peaks indicate good crystallinity. The PL spectrum of these samples excited at 375 nm shows a greenish emission band centered at 528 nm, which corresponds to defects emission. The defect structure and corresponding electron kinetics of the samples were probed using a TL spectroscopic technique.

A key priority field of study over the years has been on the environmental application of nanotechnology (NT) in contaminated water laced with heavy metals (HMs) and dye treatment utilizing sorption techniques. To this end, various magnetic nanomaterials (MNMs) have been fabricated and functionalized to achieve superior nano-sorbents with an improved surface-to-volume ratio and active components to enhance the environmental remediation of industrial effluents containing HMs and dyes. The ideal sorption of various contaminants to MNMs was reported in the studies reviewed to be in the range of pH 2–9.6. Equilibrium sorption data showed that the Langmuir (LGR) and pseudo-second-order (PSOR) models mostly defined the sorption processes (SPs) of HMs and dyes to different MNMs. Thermodynamically, the interaction of most pollutants and MNMs were found to be spontaneous, and endothermic or exothermic. The fabricated MNMs were found to be effective in the sequestration of pollutants from an aqueous-medium and could be applied in the treatment of real industrial wastewater.

A leading cause of global death is cancer; hence its early detection and treatment are crucial. With the evolution and development of nanomaterials (NMs), there has been an amplified study on the advancement of modern detection and treatment methods using magnetic nanoparticles (MNPs') with theranostic (TC) potential as nano-medicine for cancer treatment. Recent research in nano-medicine has begun to explore the diagnostics and treatment combination (TC) as a technique to offer further adaptable, individual, and specific care for cancer treatment to better patient results. MNPs' have shown huge potential in this regard, as they have become key candidates to be employed in a TC platform to achieve this concept of total cancer treatment in humans owing to their extra benefit of being remotely identified and controlled by utilizing a peripheral magnetic field (MF).