Jayeeta Chattopadhyay

Multi-shelled hollow nanomaterials with diverse compositions and architectures have garnered significant attention due to their unique structural advantages, including high surface-to-volume ratios, tunable inner cavities, and enhanced physicochemical properties. While single-shelled hollow structures have been extensively explored, multi-shelled architectures offer superior functionality, making them promising candidates for advanced applications. This review provides a comprehensive overview of recent advancements in the synthesis, classification, and biosensing applications of multi-shelled spherical nanomaterials. Various synthesis approaches, including hard templating, soft templating, sacrificial templating, and template-free methods, are critically analyzed with a focus on their advantages, limitations, and challenges. The potential of multi-shelled nanoparticles in biosensing is explored, particularly in electrode-based detection and surface-enhanced Raman scattering (SERS) techniques, enabling rapid, sensitive, and selective identification of harmful organisms, viruses, and contaminants. Furthermore, this review emphasizes the importance of developing greener, scalable, and cost-effective synthetic strategies to meet the growing demand for real-world applications. Future research directions are highlighted, including the integration of multi-shelled nanospheres into point-of-care diagnostic platforms, the design of multifunctional nanocomposites, and the enhancement of biosensing performance through novel hybrid materials. These advancements are expected to pave the way for next-generation biosensors capable of real-time, in vivo , and multiplexed detection, contributing significantly to healthcare, environmental monitoring, and food safety.

N‐doped multi‐shelled Ru‐Co/Co ₃ O ₄ graphene‐coated nanospheres were synthesized from metal‐organic frameworks (MOFs) using a hydrothermal method. The annealing process, conducted at temperatures of 250°C, 310°C, 380°C, 450°C, and 530°C with a heating rate of 2°C min ⁻¹ in the presence of melamine under a nitrogen atmosphere, led to the formation of multi‐shelled nanospheres. The annealing temperature played a crucial role in controlling the number of shells within the nanospheres and enhancing nitrogen incorporation into their structure. This study demonstrated that annealing at 530°C resulted in the formation of quintuple‐shelled nanospheres with the highest nitrogen incorporation. The number of shells and nitrogen content emerged as key factors influencing the electrocatalytic performance of these materials in water splitting. The quintuple‐shelled nanospheres demonstrated remarkable electrocatalytic efficiency, delivering the maximum current density with minimal overpotential for both hydrogen and oxygen evolution reactions (HER and OER) under acidic conditions. Conversely, reducing the number of shells led to a progressive decrease in the overall electrocatalytic performance.

The present study investigates the catalytic co‐pyrolysis of banana peel waste with plastic materials (HDPE, PP, and PET) using chicken eggshell‐derived CaO as a catalyst in a fixed‐bed reactor. The physical characterization of the synthesized CaO confirmed the successful formation of particles with a surface area of 186.45 m ² ·g ⁻¹ and an average size of 2–4 µm. The catalytic activity of CaO significantly enhanced both the yield and quality of the gaseous products. The effect of temperature and blend composition on product distribution was systematically analyzed. Results demonstrated a pronounced synergistic interaction between banana peel and plastics, with increasing plastic content leading to higher liquid and gaseous product yields. The highest hydrogen gas yield (71.2 vol%) was achieved during the catalytic co‐pyrolysis of a 3:2 (w/w) banana peel–plastic mixture, representing the optimum synergistic composition. The CaO catalyst derived from waste chicken eggshells effectively promoted dehydrogenation and water–gas shift reactions, resulting in improved hydrogen generation and superior product quality. This study highlights the potential of utilizing waste‐derived CaO as a sustainable and cost‐effective catalyst for enhancing hydrogen‐rich gas production through the co‐pyrolysis of biomass and plastic wastes.

The rapid advancement of 3D printing technology has revolutionized biomedical engineering, enabling the creation of complex and personalized prototypes. Thermal properties play a crucial role in the performance and safety of these biomedical devices. Understanding their thermal behavior is essential for ensuring their effectiveness, reliability, and compatibility with the human body. This review article aims to provide a comprehensive overview of the thermal properties of 3D printed biomedical prototypes. It categorizes these prototypes based on thermal characteristics, examines the thermal attributes of various 3D printing materials, explores the thermal considerations for different biomedical devices, and identifies the challenges and future prospects in this dynamic field.

Carbon quantum dots (CQDs) represent a category of carbon nanomaterials that have recently garnered attention as emerging contenders in the realm of traditional semiconductor quantum dots. CQDs offer several compelling advantages, including low toxicity, environmental friendliness, cost‐effectiveness, photostability, favorable charge transfer characteristics that enhance electronic conductivity, and easily reproducible synthesis procedures. This review aims to delve into the latest advancements in CQD research and development, with a primary focus on their synthesis, functionalization, and applications in the field of energy. An overview of various synthesis methods, each with its own set of advantages and disadvantages, has been depicted clearly. The subsequent section of this review is dedicated to exploring the wide‐ranging energy applications of CQDs, including their use in supercapacitors, lithium‐ion batteries, photovoltaic devices, the hydrogen evolution reaction (HER), and the oxygen evolution reaction. Further, primary emphasis has been given to their potential and effectiveness in contributing to advancements in HER as electrocatalysts. This article has been concluded with examination of the challenges that lie ahead and provide insight into future prospects in this dynamic and promising area of research.