Faculty Advisor or Committee Member

Aaron N. Deskins, Advisor

Faculty Advisor or Committee Member

Michael T. Timko, Committee Member

Faculty Advisor or Committee Member

Pratap M. Rao, Committee Member

Faculty Advisor or Committee Member

Andrew R. Teixeira, Committee Member

Identifier

etd-061218-115213

Abstract

Excessive CO2 emissions can negatively impact society and our planet. Reduction of CO2 is one potential avenue for its abatement. One of the most significant challenges to reducing CO2 is its extremely stable linear form. Experimentally, Cu/TiO2 has shown promise for CO2 photocatalytic reduction. Dispersed atomic catalysts can achieve high catalytic efficiency on a per atom basis. Active sites also typically having lower coordination number, and therefore may be more reactive. Using density functional theory and experimental techniques, we have investigated the role of surface oxygen vacancies (Ov) and photoexcited electrons on supported single atom catalysts and CO2 reduction. Cu atoms with Ov have shown to aid in the process of bent, anionic CO2 formation. In the first step involving CO2 dissociation (CO2* --> CO* + O*), a single Cu atom in Ov lowered the activation barrier to 0.10 - 0.19 eV, which could enable fast reduction of CO2 even at room temperature, in agreement with experimental findings. A photoexcited electron model was shown to readily promote Cu binding to the surface vacancy, and CO2 adsorption and direct dissociation. Finally, we briefly compare our results to calculations of supported single Pt atoms to determine how metals besides Cu may behave as photocatalysts for CO2 reduction, and we found a single Pt with Ov can promote CO2 dissociation. Our results show that tailoring TiO2 surfaces with defects in conjunction with atomic catalysts may lead to useful catalysts in the photoreduction of CO2.

Publisher

Worcester Polytechnic Institute

Degree Name

Thesis

Department

Chemical Engineering

Project Type

Thesis

Date Accepted

2018-07-18

Accessibility

Unrestricted

Subjects

Photocatalysis Supported Single Atom Catalysts CO2 Reduction Photoexcitation Surface Defects Oxygen Vacancy TiO2 anatase (101) CO2 Direct Dissociation

Available for download on Wednesday, June 12, 2019

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