The development of alternative energy sources and, in particular, chemical pathways that will contribute to diverting the energy crisis are highly desired in modern scientific procedures. Given the finite, global fossil fuel resources and volatile crude oil prices, current interest has been placed on the development of materials that can effectively harvest solar energy, reducing the overall carbon footprint of catalytic materials, while providing similar, if not better, overall results. Implementing heterogeneous catalysis in the development of sustainable chemistry procedures offers the added benefit of both catalyst recovery and potential recyclability in subsequent reactions, thereby reducing the generation of chemical waste. Semiconductor photocatalysis has rapidly emerged as a possible solution that satisfies many of these highly sought after chemical properties.
Functionalization of semiconductors with noble metal nanostructures, such as gold (AuNP) or silver nanoparticles (AgNP), provides an opportunity to extend composite response into the solar region of the electromagnetic spectrum and possible applications in the sector of renewable energy resources. Within the past decade, considerable attention has been placed on nanoparticle light-driven reactions due to the ability of both Au- and AgNP to efficiently absorb visible light as a result of surface plasmon resonance. This electronic phenomenon, which is essentially associated with rapid oscillation of the NP surface electrons results in absorption of AuNP and AgNP at ~530 nm and 420 nm, respectively. Plasmon, visible light, excitation has been suggested to enhance the electron donating and accepting properties of AuNP, largely exploited in the study of AuNP@TiO2 photocatalysts. In addition, nanoparticle-doping has been suggested to improve photoconversion efficacy of semiconductor materials by extending the photoresponse of the catalyst into the visible (by plasmon excitation with visible light LEDs), improving charge separation (via semiconductor excitation using UV LEDs), and by improving the electron storage capacity the material. The implementation of perovskites and, in particular, niobium oxide derivatives of this class of materials is interesting due to (a) their underdeveloped photocatalytic activities and (b) improved ease of separation from reaction mixtures (compared to traditional semiconductor materials) attributed to their unique crystallinity and size.
Within our group, we are currently investigating a variety of photocatalytically induced organic transformations using nanoparticle-doped semiconductors using both UV and visible light sources. We are primarily focused on using more economical means of excitation, with a large focus on the exploitation of LED photoreactors in our experimental procedures. Students in our lab will be involved in all aspects of their research project, from conception, to methods development, analysis and finally scientific writing in manuscript preparation to ensure an understanding and valuable experience is gained from all aspects of their undergraduate or graduate research.
Our current team is actively researching in several different areas of heterogeneous photocatalysis, including:
AuNP-doped semiconductors as catalysts in biomass conversion
Green chemistry applications of supported Ru complex@AuNP hybrids (in collaboration with the MacLean Group at StFX)
Photocatalytic applications of novel semiconductor/dye composites (in collaboration with the Dr. Brian MacLean and Dr. Manuel Aquino, StFX)
Development and applications of niobium oxide thin films (with Dr. Balaji Subramanian, Dept. of Physics, Trent University and Dr. Brian MacLean, StFX)
Natural product photoconversion (Dr. C.O.L. Crites, Université du Moncton, Edmundston Campus)