Manavalan Rajesh Kumar

This work addresses major limitations of CdS photocatalysts through a strategy of involving substitutional Ni²⁺ doping and SLS assisted co-precipitation, exploiting their cooperative interaction to improve photocatalytic efficiency. Ni²⁺ incorporation introduces shallow trap states that facilitate charge carrier separation and prolong carrier lifetime, while SLS restricts particle size of (3.66–4.42 nm) and generates a hydroxyl-rich surface that promotes reactive oxygen species formation. The synthesized Ni-doped CdS nanocomposites (CN1–CN5) were characterized using XRD, TEM, and UV–Vis spectroscopy, confirming hexagonal wurtzite phase, lattice expansion, and bandgap narrowing to 2.23 eV with an absorption edge red-shifted to 556 nm. The optimally doped CN4 achieved 98% MB degradation within 90 min, while scavenger studies shows ·OH and h⁺ as the dominant oxidative species. Urbach energy shows that photocatalytic performance is governed by defect quality rather than defect quantity, and catalyst retained 60% activity after five cycles due to SLS mediated suppression of photo corrosion.

This research reports the challenge of effectiveness versus control in nanostructuring the photocatalysts based on cadmium sulphide and it proposes a dual engineering approach in which nickel doping and sodium lauryl sulphate mediated morphology optimization come together synergistically. The synthesized Ni doped CdS nanocomposites (CN1–CN5, 1-5% Ni 0.0059 g, 0.0119 g, 0.0178 g, 0.0238 g, 0.0297 g) were characterized using XRD, TEM, and UV-vis DRS, confirming lattice expansion, reduced crystallite size (3.66–4.46 nm), and a red-shifted absorption edge at 556 nm with a bandgap reduction to 2.23 eV. Photocatalytic performance was evaluated through methylene blue degradation under visible light, where the optimally doped CN4 sample achieved 98% degradation within 90 minutes, significantly outperforming pristine CdS. Scavenger experiments identified hydroxyl radicals and holes as the dominant reactive species, while reusability tests showed 60% activity retention after five consecutive cycles compared to 98% in cycle 1 with the scavenger contribution index values ·OH: 66.7%, h⁺: 53.3%. The dual engineered CdS exhibits improved charge separation, surface reactivity, and stability, offering a scalable and environmentally considerate approach for designing high performance photocatalysts. This work provides a general framework for co-optimizing defects and morphology in metal sulphides, aligning with green chemistry principles through the use of low cost, biodegradable SLS, and highlights its potential for environmental remediation applications. The findings offer a practical pathway toward visible-light-driven photocatalytic purification of dye-contaminated wastewater using cost-effective, scalable semiconductor materials.

Sodium tripolyphosphate has been demonstrated to act as a highly effective kinetic controller in the aqueous synthesis of cadmium sulphide nanoparticles, Redefining its conventional role as a stabilizing agent. By analytically tuning the Sodium tripolyphosphate concentration as 0.5 - 2.5 g, precise control over the nucleation and growth phases was achieved, enabling the formation of cadmium sulphide nanoparticles with a mean diameter of 5.1 nm. High-resolution TEM confirmed excellent crystallinity with lattice spacings of 0.14 nm and 0.15 nm, while XRD revealed a mixed hexagonal cubic phase, with the cubic phase dominating at higher Sodium tripolyphosphate concentrations. UVVis analysis exhibited a tuneable quantum-confined band gap, reached as minimum of 2 eV. XPS measurements verified surface passivation through CdS bond formation and the presence of POCd linkages at 532.1 eV (O 1s), confirming strong coordination between Sodium tripolyphosphate and the CdS surface. Raman spectroscopy further identified the longitudinal optical phonon mode at 148 cm¹ for cadmium sulphide and a symmetric stretching mode at 932 cm¹corresponding to phosphate groups. Collectively, these findings reveal that Sodium tripolyphosphate not only suppresses Ostwald ripening but also modulates crystal phase evolution and surface electronic structure, offering a new kinetic pathway for designing high quality, stable semiconductor nanomaterials through inorganic polyphosphate-assisted synthesis.

In the present day, photocatalysis has become the primary and most promising technology to generate renewable energy and degrade environmental pollutants. Remarkable efforts have been made to improve photocatalytic efficiency. Among these, introducing an external magnetic field is considered a promising strategy to boost photocatalytic performance. This review explores the dynamic realm of improving photocatalytic efficiency, with a particular emphasis on the strategic integration of external magnetic fields. Examining recent breakthroughs, we reviewed the influence of magnetic fields on diverse catalyst materials, including both magnetic and nonmagnetic variants, 2D materials, and semiconductors. Comprehensive coverage is provided on the mechanisms governing photocatalytic dye degradation, materials utilized for catalysis, and the profound impact of magnetic fields on enhancing reaction kinetics. This review also focuses on recent advances in the application and effect of magnetic fields in the magnetic and nonmagnetic catalysts towards dye degradation. This review provides a forward‐looking view, highlighting the potential of magnetic field‐enhanced photocatalysis to play a central role in sustainable energy and environmental management.

Apart from our imagination, the nanotechnology industry is rapidly growing and promises that the substantial changes that will have significant economic and scientific impacts be applicable to a wide range of areas, such as aerospace engineering, nanoelectronics, environmental remediation, and medical healthcare. In the medical field, magnetic materials play vital roles such as magnetic resonance imaging (MRI), hyperthermia, and magnetic drug delivery. Among them, manganese oxide garnered great interest in biomedical applications due to its different oxidation states (Mn²⁺, Mn³⁺, and Mn⁴⁺). Manganese oxide nanostructures are widely explored for medical applications due to their availability, diverse morphologies, and tunable magnetic properties. In this review, cogent contributions of manganese oxides in medical applications are summarized. The crystalline structure and oxidation states of Mn oxides are highlighted. The synthesis approaches of Mn-based nanoparticles are outlined. The important medical applications of manganese-based nanoparticles like magnetic hyperthermia, MRI, and drug delivery are summarized. This review is conducted to cover the future impact of MnO_x in diagnostic and therapeutic applications.

The development of a heterojunction nanocomposite leads to improved optoelectronic properties. Herein, ceria (CeO₂), copper oxide (CuO), and ceria–copper–copper hydroxide (CeO₂-CuO-Cu(OH)₂) nanocomposites were prepared via a facile chemical method and their structural, morphological, and optical properties were studied using various characteristic techniques such as X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDAX), transmission electron microscopy (TEM), ultra-violet visible light absorption (UV-visible), photoluminescence, and thermogravimetry differential thermal analysis (TG-DTA). In the integration of CeO₂ and CuO with Cu(OH)₂, the band gap is modified to 2.64 eV; this reduced band gap can improve the photocatalytic efficiency of the nanocomposite. The CeO₂ can increase light absorption in the nanocomposite, while CuO acts as an electron trap in the composite and this leads to a good enhancement of the optical properties of the CeO₂-CuO-Cu(OH)₂ nanocomposite. In addition, the heterojunction combination at the interfaces of the CeO₂-CuO-Cu(OH)₂ nanocomposite facilitates the photo-generated charge separation in the composite, which increases the charge participation in the catalyzed conversion reactions of the prepared composite. The highest photocatalytic degradation efficiencies of 96.4% and 92.7% were achieved for fast green (FG) and bromophenol blue (BP), respectively, using the CeO₂-CuO-Cu(OH)₂ nanocomposite.

The integration of metal oxides into MXene structures has been instrumental in boosting high surface area, electrical conductivity, stability, and sensitivity. This points to a promising future for biomedical applications.