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In this research article, characterization and catalytic properties of manganese ion (Mn)-doped iron(III) oxide (Mn–Fe2O3) nanostructured particles have been reported. Mn–Fe2O3samples were synthesized via the co-precipitation - thermal decomposition (CPTD) method. Samples were analyzed by X-ray diffraction, spectroscopic, and microscopic techniques. The influence of the Mn-doping process in the phase and crystalline structure of Fe2O3was determined by powder X-ray diffractometry (p-XRD), and Fourier transform infrared (FTIR) spectroscopy. The optical energy band gap and fluorescence feature of Mn–Fe2O3samples were explored through UV–Visible absorption and fluorescence spectroscopies, respectively. The morphology and size of Mn–Fe2O3were determined through field emission scanning electron microscopy (FE-SEM). The influence of Mn3+ion concentration on the magnetic property of Fe2O3was determined. The dye pollutant removal ability of Mn–Fe2O3samples was examined by employing hydrogen peroxide (H2O2)-mediated degradation of Methylene blue (MB) and Congo red (CR) dyes under visible light conditions. The benefit of the Mn-doping process in the photocatalytic property of Fe2O3was discussed.

The strategic review explores the evolving landscape of electronic waste (e-waste) management in Saudi Arabia, shedding light on the strategies implemented, challenges faced, and emerging opportunities in the realm of sustainable waste management. The comprehensive analysis encompasses the environmental and human health implications in association with the inappropriate handling of electronic waste. Saudi Arabia, a rapidly advancing technological hub, has witnessed a surge in e-waste generation, prompting the need for robust management frameworks. The review delves into the existing strategies employed by Saudi Arabia to tackle the growing e-waste dilemma, evaluating their effectiveness and potential areas for enhancement. Key challenges, including regulatory gaps, technological obsolescence, and awareness gaps, are examined to provide a holistic understanding of the obstacles hindering optimal e-waste management practices. Furthermore, the document explores opportunities for innovation, collaboration, and policy refinement to address these challenges and build a more sustainable e-waste management ecosystem. A crucial aspect of this review is the examination of the direct and indirect impacts of e-waste on human well-being and the environment. Insights are drawn from existing studies and data to illuminate the potential risks associated with improper disposal and the liberation of dangerous substances. The review highlights the urgent need for comprehensive e-waste management strategies to mitigate adverse consequences on both human well-being and the environment. In total, this strategic review aims to contribute to the ongoing discourse surrounding e-waste management in Saudi Arabia, offering valuable insights for policymakers, researchers, and stakeholders. By identifying key strategies, challenges, and opportunities, it seeks to inform and guide future initiatives, fostering a sustainable approach to electronic waste management in the Kingdom.

Zinc oxide (ZnO) nanorods is widely investigated due to its high photoelectrochemical conversion performance. Further enhancement may be afforded by introducing a metal chalcogenide sensitization layer such as zinc selenide (ZnSe). In this study, ZnO nanorods were electrodeposited with ZnSe at potential range from -0.5 V to -0.9 V vs Ag/AgCl reference electrode. Structural, morphological and optical properties of ZnSe electrodeposited were investigated as a function applied potential by using X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis). ZnSe electrodeposited for 15 minutes at -0.7 V showed crystallite size of 20.13 nm with the lowest band gap energy of 2.97 eV. The existence of ZnSe particles with the size of 41.8 nm were proven by FESEM images, after ZnSe particles were electrodeposited onto ZnO nanorods that have an average diameter of 62.6 nm and length of 1.6 µm. The photocurrent density generated by samples were measured in a three-electrodes cell incorporated with halogen lamp. The photocurrent generated increased between -0.5 V to -0.7 V before dropped at higher applied potential due to hydrogen evolution process which affected the thin film quality, ultimately affecting photoconversion performance. The highest photocurrent density of 0.2621 mAcm-2 was recorded for samples prepared at -0.7 V vs Ag/AgCl.

Following successful growth of zinc oxide (ZnO) nanorods, a layer of zinc selenide (ZnSe) was electrodeposited onto the nanorods to further enhance its conversion efficiency in the photoelectrochemical (PEC) cell. The electrodeposited ZnSe layer onto the ZnO nanorods was subjected to heat treatment at 200, 250 and 300°C. The prepared films were characterized by X-ray diffractometry (XRD), field emission scanning electron microscopy (FESEM), and ultraviolet-visible spectroscopy (UV-Vis) to investigate the structural, morphological and compositional characteristics. Additionally, PEC conversion generated by the prepared thin films were tested with photocurrent measurements under calibrated visible illumination from a halogen lamp. Based on FESEM analysis, the thickness of ZnO thin film increased with temperature. However, the diameters of the ZnO nanorods were found to be in a decreasing trend upon heat treatment at higher temperature. The electrodeposited ZnSe layer at the potential of -0.7 V for 60 seconds (calcined at 200°C) possessed crystallite size of 20.1 nm. According to UV-Vis analysis, band gap energy measured was 2.8 eV, which is very close to standard ZnSe band gap value (2.7 eV). Additional layer of ZnSe electrodeposited enhanced thin film performance in terms of current density as much as 37.4% while having high photocurrent density of 0.2671 mAcm-2.

Mesoporous carbon (MPC) films were prepared by using spin coating self-assembly soft templating method onto titanium (Ti) foils as substrates. Carbon precursor of resorcinol (R), formaldehyde (F) and a surfactant of triblock copolymer Pluoronic F127 (F127) which may act as a structure directing agent (SDA) for the pore structure geometry tuning were used in the preparation of the mesoporous carbon films. The samples were then carbonised to obtain the final product of MPC films. The mesostructure was characterised by thermogravimetry (TGA), Fourier transform infrared spectroscopy (FTIR), X-ray diffraction (XRD) patterns, field emission scanning electron microscopy (FESEM) and electrochemical analyses. The MPC film showed excellent electrochemical property for supercapacitor application by achieving specific capacitance value of 15.23 mF cm-2at the scan rate of 5 mV s−1in 1.0 M potassium chloride (KCl) neutral aqueous electrolyte which was approximately 88 times higher than as prepared samples. F127/RF carbon film also displayed outstanding cycle stability with 98% capacitance retention after 1000 cycles. This has proven that the synthesised MPC film-coated titanium foil may be a promising candidate for high performance electric double layer capacitors (EDLC).

Tin seleno telluride thin film was deposited by pulse electrodeposition onto fluorine doped tin oxide coated glass from aqueous solution containing Sn-EDTA, Na2SeO3 and TeO2. The sample was deposited at a potential of-0.40 V vs Ag/AgCl with various duty cycle between 10% to 90% followed by annealing under nitrogen gas at 250°C for 30 minutes. The crystalline structure, morphology and photoresponse of the thin film was analyzed using X-ray diffraction (XRD), scanning electron microscopy and linear sweep photovoltammetry techniques. The XRD pattern shows polycrystalline cubic structure of SnSe0.4Te0.6 for film deposited at 50% duty cycle. The domain peak at 2θ=28.82o shows a high intensity and a better photoresponse due to the small crystalline size. The tin seleno telluride thin film reflects the loose short rod type aggregates at 10%-50% duty cycle and dendritic structure was formed at deposition of 75% and above. The deposited tin seleno telluride is a p-type semicoductor and the band gap was found to be 1.60 eV with direct transition.