Nanomaterial

Nanomaterials are materials with at least one external dimension in the nanoscale, usually 1 to 100 nanometers. At these sizes, materials often display properties that differ markedly from their bulk counterparts, in particular a higher surface area to volume ratio and, in some cases, quantum effects. These size-dependent properties enable new uses across various fields.

Nanomaterials can be described by dimensionality: zero-dimensional nanoparticles, one-dimensional nanowires and nanotubes, and two-dimensional nanosheets. They also can be categorized by composition, including carbon-based (such as graphene, carbon nanotubes, fullerenes), metal-based (gold, silver, metal oxides), ceramic, polymeric, and composite systems. Commonly studied examples include gold and silver nanoparticles for plasmonics, titanium dioxide nanoparticles for photocatalysis, and silicon-based quantum dots for optoelectronics.

Synthesis approaches are broadly classified as top-down or bottom-up. Top-down methods start from bulk material and size-reduce it, often by milling or lithography; bottom-up methods build material from atoms or molecules using chemical, vapor-phase, or biological routes. Fabrication can be followed by surface modification to tailor dispersibility, stability, and compatibility with specific environments.

Nanomaterials find applications in electronics, energy storage and conversion, catalysis, medicine and diagnostics, environmental remediation, and protective coatings. They enable improved sensors, more efficient solar cells, advanced imaging contrast agents, drug delivery systems, and durable materials. Adoption is accompanied by safety, environmental, and regulatory considerations.

Safety and environmental aspects include assessment of toxicity, exposure routes, and life-cycle impacts. Because properties often depend on size, coatings, and aggregation state, risk assessment can be complex. Regulatory guidance varies by jurisdiction, and researchers pursue responsible design and testing to minimize adverse effects.