Professor Gray's areas of expertise are environmental catalysis and physicochemical processes in natural and engineered environmental systems with particular focus on energy and urban sustainability applications. She studies the synthesis, characterization and performance of photo-active materials, principally TiO2-based nanocomposites for solar fuel production, resource recovery and water/air treatment.  Work in her group also involves the investigation of chemical fate in natural systems. She probes the role of periphyton (algal biofilms) in contaminant accumulation in stream sediments and in denitrification in wetlands.  She studies the ways in which detailed understanding of ecological relationships (periphyton structure, dynamic food web descriptions) improves our ability to predict chemical transfer (bioaccumulation) in aquatic systems and ultimately human health risks.  Application of this research is important in efforts to restore critical ecosystems (Great Lakes), to make ecological forecasts in the face of climate change and to employ ecosystem function for environmental protection (treatment wetlands). She is also studying the unintended ecotoxicological impacts of nanomaterial mixtures in aquatic systems and under light illumination. Recent work entails the adaptive and resilient design of urban systems to incorporate coupled ecological processes in response to climate change and demographic shifts.