Nanomaterials are engineered at the molecular level to modify their structure and functional properties, which in turn, enables the development of innovative nano-enabled technologies. However, these same property manipulations have the potential to influence the adverse impacts of these engineered nanomaterials. It is therefore, critically important to drive the development of safe and functional nano-enabled products. This is accomplished through the identification of relationships between material structural features, physicochemical properties, functions, and hazards. These established relationships can then be used to inform rational sustainable material design. This approach will be applied in this project to carbon nanomaterials, which are one of the leading classes of engineered nanomaterials (based on production volumes). Their high surface area, electronic properties, and the ability to control the surface chemistry enable numerous environmental applications where the interactions of the carbon nanomaterial with environmental media are used to detect, remove, or degrade contaminants, for example. Realizing the performance of these next generation applications while precluding negative environmental impacts necessitates a fundamental understanding of the material properties that elicit both desirable and undesirable responses. These research efforts will: (i) identify design parameters for the synthesis of high performance carbon nanomaterials, taking into account structure and surface chemistry, (ii) define mechanisms that relate carbon nanomaterial surface chemistry, inherent structure, electrochemical and biological activity, and (iii) establish parametric relationships that identify how electrochemical activity can be selectively improved with minimal impact on inherent material hazard. The broader impacts of the proposed work will influence three key areas: (i) the development of fundamental scientific concepts crucial to understanding phenomena driving the interactions of nanomaterials in their applications and in the environment, (ii) accelerate the efforts of us and others in the education of undergraduate and graduate students throughout the scientific and engineering communities, and (iii) the professional development of K-12 science educators through training of prepared content modules, the success of which will be monitored through surveys to evaluate student engagement and learning gains.

The scientific objective of the proposed project is to resolve the molecular-level phenomena at the material surface that govern the chemical and biological reactivity of different allotropes of carbon nanomaterials, including carbon nanotubes and graphene. The central hypothesis is that the interplay between the surface functional group and the host carbon material is important and will present unique influences for different carbon nanostructures. Understanding the role of surface chemistry on the reactivity of carbon nanomaterials with inherently different electronic structure "semiconducting and metallic carbon nanotubes and grapheme" can elucidate design parameters to tailor the material functionality. The project rationale is that the performance of carbon nano-enabled electronic and electrochemical applications can be greatly improved through the establishment of parametric relationships that include the chemical nature of the host carbon nanomaterial. Furthermore, to safely enable carbon nanomaterial applications, it is necessary to gain a mechanistic understanding of how molecular level manipulations influence their intrinsic properties. The expected research outcomes are to (i) establish material design parameters, in the form of parametric relationships (structure-property-function and structure-property-hazard), that will inform the development of functional and safe carbon nano-enabled products, (ii) provide enhanced understanding of the underlying mechanisms of action of carbon nanomaterial electrochemical and biological reactivity by resolving the fundamental chemical properties and interactions with environmentally-relevant biological systems, and (iii) determine the extent to which the established parametric relationships are modulated by environmental conditions, providing an avenue towards determining the robustness of the relationships established under laboratory conditions.