ERI: Engineering a Bi-Functional Heterostructured Photocatalyst for CO2 Photoconversion

University Of Massachusetts Boston, Dorchester MA

Investigators

Abstract

This award is funded in whole or in part under the American Rescue Plan Act of 2021 (Public Law 117-2). Demand for clean energy, combined with the global need for decreased emissions of greenhouse gases (especially carbon dioxide from fossil fuel combustion), has generated strong research impetus for sustainable, low carbon emission technologies. The project utilizes visible-light solar energy to react waste carbon dioxide (CO2) to value-added chemicals such as methanol and formic acid. Related research efforts to date have been hampered by low product selectivity, limitation to the UV light region, and inefficient photocatalytic mechanisms. To overcome those limitations, the project will investigate a bifunctional photocatalyst design known as a heterojunction. The heterojunction consists of a photothermal semiconductor photocatalyst interfaced with a metal-organic framework (MOF) material. Integrating the two components in the heterojunction architecture enhances both the capture and conversion of CO2 to value-added chemicals. Beyond the technical aspects, the project will include educational and outreach activities designed to excite students about careers in STEM, with emphasis on opportunities for women and other underrepresented groups in science and engineering. The overall project goal is to engineer a bi-functional heterostructured photocatalyst for efficient CO2 photoconversion utilizing visible-light energy. The project is built on the hypothesis that the MOF component will enhance the CO2 uptake and provide the pore space needed to promote access to the catalytic sites on the photocatalyst. Under visible light irradiation, the photoexcited electrons from the photocatalyst will then reduce CO2 to the desired hydrocarbon products. The project includes four aims: 1) synthesize and characterize families of MIL-101(Cr)-NH2 MOF and carbon@TiO2 photocatalyst of various particle size and core-shell properties; 2) develop a strategy to mediate MOF growth on the surface of the photocatalyst; 3) probe the interfacial structures of the carbon@TiO2@MIL-101(Cr)-NH2 photocatalyst; and 4) investigate the impact of the interface architecture on both selectivity control and the mechanism of photothermal catalytic CO2 conversion to C1 hydrocarbons. A key feature of the carbon@TiO2 photocatalyst design is to promote photothermal efficiency via the heat capture and transfer associated with the carbon core combined with the light-harvesting and photoelectron-generating properties of the TiO2 shell. Various methods will be employed in pursuing the four aims, including a range of photoelectrochemical techniques, spectroscopic methods, control and reaction experiments, and product analyses. Properties of the photocatalyst and MOF will be characterized at each stage of synthesis, up to and including the bifunctional performance of the component materials in the integrated heterojunction design. This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.