Mohammad Mansoob Khan

Developing cost-effective, methanol-tolerant oxygen reduction reaction (ORR) electrocatalysts is critical for alkaline fuel cells and metal–air batteries. This study presents the synthesis of CoTiO3 and Co1–xNixTiO3 (x = 0.1 and 0.2) ilmenite oxides via a sol–gel method and thoroughly examines the influence of Ni substitution in CoTiO3 on its ORR performance. XRD, FTIR, Raman, and XPS analyses confirmed the formation of the ilmenite CoTiO3 framework, successful Ni incorporation, and Ni-induced modulation of the metal–oxygen environment. TEM and FE-SEM analyses revealed nearly spherical nanoparticles, while EDAX verified the expected constituent elements. BET analysis showed that Co0.9Ni0.1TiO3 possessed the highest surface area and pore volume, supporting improved active-site accessibility. Electrocatalytic ORR studies in O2-saturated 1 M KOH demonstrated that Co0.9Ni0.1TiO3 exhibited the best ORR activity among the investigated oxides, with higher cathodic current density, lower charge-transfer resistance, lower Tafel slope, higher exchange current density, increased ECSA, and an apparent near-four-electron ORR pathway, comparable to Pt/C. Co0.9Ni0.1TiO3 also showed excellent methanol tolerance, retaining 84.36% current after 10,000 s in 1 M KOH containing 1 M methanol and 89.98% after 20,000 s in methanol-free 1 M KOH, highlighting its potential as a cost-effective ORR electrocatalyst.

The photocatalytic conversion of CO ₂ into sustainable fuels is a key strategy for mitigating climate change and meeting energy demands. This review comprehensively covers recent progress in CO ₂ capture and photoreduction using advanced two‐dimensional (2D) materials, including g‐C ₃ N ₄ , graphene‐based photocatalysts, MXenes, transition metal dichalcogenides (TMDs), bismuth oxyhalides (BiOX), porous metal–organic frameworks (MOFs), covalent organic frameworks (COFs), and hydrogen‐bonded organic frameworks (HOFs). These materials exhibit high surface area, tunable band structures, and strong interfacial interactions, enabling efficient CO ₂ adsorption, light absorption, and charge‐carrier separation. The roles of heterostructure engineering, defect modulation, cocatalysts, and surface functionalization in enhancing photocatalytic performance are critically analyzed. Particular emphasis is placed on charge–transfer pathways, the coupling between CO ₂ capture and photocatalytic conversion, and the stabilization of key reaction intermediates. Key parameters influencing catalytic efficiency, including band alignment, adsorption affinity, intermediate‐binding strength, reaction conditions, and product desorption, are systematically discussed. Furthermore, synergistic integration of semiconductors with porous frameworks is emerging as a strategy to optimize both adsorption and catalytic processes. Despite significant progress, challenges related to stability, scalability, standard benchmarking, and product selectivity remain. Finally, future directions incorporating operando characterization, density functional theory, and artificial intelligence‐guided modeling are proposed to accelerate catalyst discovery and rational design.

Sunlight facilitates photosynthesis in plants and serves as a significant source of Vitamin D for humans. However, excessive sun exposure has substantial adverse consequences, including skin damage, skin cancer, and photoaging. Ultraviolet (UV) radiation is one of the key environmental risk factors for skin cancer, which is the most common type of cancer in the world. Despite the widespread use of synthetic sunscreens to mitigate UV exposure hazards, growing concerns regarding their potential adverse effects on human health, bioaccumulation, and the environment have spurred the exploration of natural product-based alternatives. This review outlines the distinct categories of sunscreens, the adverse effects of UV radiation on humans, and the disadvantages of inorganic and organic sunscreens compared to natural product-based sunscreens. This review gathers evidence from a comprehensive Scopus search (2017–2025) to evaluate the photoprotective, antioxidant, and anti-inflammatory activities of various plant-derived products ideal for sunscreen formulation. We highlight the multimodal mechanism of action of sunscreens in skin cancer prevention and summarize in vitro and formulation data for representative natural products. We discuss formulation strategies to overcome the limitations of natural product-based sunscreens and identify critical gaps, particularly the need for rigorous in vivo and clinical validation and scalable standardization methods. Finally, future prospects are outlined to highlight the stability and efficacy of natural sunscreens as commercially viable, broad-spectrum products that meet customer demands for safety and environmental sustainability.

Petroleum-produced wastewater (PPW) represents a major source of environmental pollution but remains an untapped energy resource. In this study, the performance of microbial fuel cells (MFCs) was investigated as a dual solution for wastewater treatment and electricity generation using bioelectrochemical systems (BES). MFC parameters (current, charge, voltage, power production, substrate consumption, and suspended and attached biomass growth) were simulated under various operational conditions. We engineered Escherichia coli (E. coli) to form polyhydroxyalkanoate (PHA) nanowire-based thick biofilms through targeted modification of PHA biosynthesis genes (phaA, phaB, phaC) and the global regulatory network (arcA, fnr). The engineered strain, E. coli PHA-NW, exhibited a 12.4-fold increase in biofilm thickness (215 ± 18 μm vs. 17.3 ± 2.1 μm for wild-type as control), with highly ordered, conductive nanowire networks bridging the cell-electrode interface. Metabolic flux analysis revealed a 3.8-fold enhancement in intracellular NADH/NAD⁺ ratio and a 5.2-fold increase in formate and H2 production, collectively increasing metabolic electron production from 0.82 to 4.27 μmol electrons·mg⁻¹ protein·h⁻¹. Electrochemical characterization showed that PHA nanowires function as biological electrocatalysts, reducing charge transfer resistance from 1,820 Ω to 247 Ω and increasing maximum power density from 48.3 to 412.6 mW·m⁻² – an 8.5-fold improvement over wild-type E. coli and 58% higher than previous synthetic biology approaches. Continuous-flow MFC operation with real PPW (COD 12,400 ± 850 mg·L⁻¹) achieved 89.7 ± 3.2% COD removal and sustained a power output of 385.2 ± 12.4 mW·m⁻² over 720 h, representing 92% retention of initial performance. Metagenomic and proteomic analyses confirmed stable colonization of the engineered strain without plasmid loss or horizontal gene transfer to native PPW microbiota. These principles are generalizable to other wastewater streams and hydrocarbon-rich effluents, offering a paradigm shift in bioelectrochemical wastewater valorization.

The development of eco-friendly composites using recycled high-density polyethylene (rHDPE) and date palm leaf (DPL) fibers is often hindered by poor interfacial bonding. This incompatibility arises from the hydrophobic nature of the polymer matrix versus the hydrophilic nature of the natural fibers. The aim of this study is to investigate the effects of fiber treatment and nanoparticle modification on the microstructure and performance of rHDPE/DPL/ZnO composites, prioritizing efficient fiber-side treatments over matrix processing. This study was carried out by chemically treating DPL fibers with sodium hydroxide (NaOH) and stearic acid, followed by modification with zinc oxide (ZnO) nanoparticles to improve adhesion. The composites were then subjected to a comprehensive suite of characterization tests, including tensile testing for mechanical strength, thermogravimetric analysis (TGA) for thermal stability, differential scanning calorimetry (DSC) for thermal transitions, X-ray diffraction (XRD) for crystalline structure, and optical microscopy for morphological evaluation. The findings show that the treatments significantly enhanced the material properties across all metrics. Tensile testing revealed that the A5 composite achieved the highest mechanical performance, with a Young’s modulus of approximately 1.2 GPa and an elongation at break of roughly 9%. TGA results indicated improved thermal stability; specifically, sample A4 showed a degradation temperature (Td) increase of 8.7 °C (+1.83%) over A3, while sample A6 showed a gain of 5.1 °C (+1.07%) over A5. XRD analysis confirmed an efficient structural reinforcement, reaching a maximum crystallinity of 74.06%. Furthermore, melt flow index (MFI) analysis demonstrated that while fiber reinforcement naturally increases viscosity, stearic acid treatment provides a lubricating effect that maintains MFI values between 6 and 7 g/10 min, ensuring excellent processability for injection molding and 3D printing. Finally, optical microscopy and morphological studies observed superior fiber dispersion and cleaner interfaces, indicating that the fibers were evenly spread and well-separated within the rHDPE structure. It was concluded that the combination of chemical treatments and ZnO nanoparticle modification effectively bridges the compatibility gap between rHDPE and DPL fibers. These findings underscore the viability of these modified composites for high-performance structural and industrial applications.

Microplastics (MPs) are plastic particles with a size of ≤ 5 mm.[1] The small size of MPs poses several challenges for their detection, characterization, and monitoring in environmental systems. No...