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Project #1: Solar CO2 reduction using heterogenized molecular catalysts

In this project, diimine-tricarbonyl Re(I) and macrocyclic Co(III) complexes are covalently attached onto solid-state surfaces including SiO2, TiO2, and C3N4. Structures and complexation of the heterogenized molecular catalysts are investigated using in situ infrared, UV-visible, and X-ray absorption spectroscopies (XAS). The long-term goal of this project is to template intermolecular reactivity and enable cooperative activation of CO2 via low-energy pathways. Supported by NSF CAREER Award #1352437 (2014 – 2020).

Re-SiO2 synthesis.png

More recently, we have focused on enabling visible-light CO2 reduction using macrocyclic Co(III) complexes on surfaces. A representative macrocyclic Co(III) complex, [Co(cyclam)Cl2]Cl, requires the use of p-terphenyl and UV light in photocatalytic CO2 reduction. Visible-light CO2 reduction has been achieved using C3N4 as a light-absorbing surface.  Supported by DOE Award #DE-SC0016417 (2016 – 2020).

Co-SiO2.png
Project #2: Solar CO2 reduction using single atom catalysts

Single atom catalysts (SACs) combine the advantages of homogeneous and heterogeneous catalysis. This project is focused on constructing single-site cobalt catalysts in C3N4 for selective CO2 reduction under visible-light irradiation. We combine catalyst synthesis and spectroscopy with  computation modeling to understand the structures and properties of Co SACs. Supported by NSF Award #2102655 (2021 – 2024).

Co SAC.png
Project #3: Spectroscopic investigation of interfacial sites in metal/TiO2 photocatalysts

Heterogenous photocatalysis on many TiO2 materials is relatively inefficient due to electron-hole recombination. This project utilizes interfacial metal sites to improve photocatalysis on TiO2. We utilize spectroscopic techniques to investigate how such metal sites promote charge separation and photocatalysis. The figure below shows infrared spectra of CO spontaneously formed on Cu/TiO2 containing oxygen vacancies in the absence (left) and presence (right) of isotopically labeled CO2.  Supported by NSF Awards #1705528 (2017 – 2022) and #1510810 (2015 – 2018).

Cu-TiO2.png
Project #4: Electrocatalytic CO2 reduction using supported nanocatalysts

In collaboration with colleagues at UMass Lowell, we design and synthesize a series of covalent liners to attach nanocatalysts (metal oxide nanoparticles, metal nanoclusters) onto graphene-based electrodes. A combination of computational modeling, electrochemistry, and spectroscopy will be employed to investigate how the linker structures affect the electrocatalytic properties using CO2 reduction as a model reaction.  Supported by NSF Award #2247575 (2023 – 2026).

TiO2-3DG_edited.png

Collaborators

Prof. Anatoly Frenkel, Stony Brook University/Brookhaven National Lab
Prof. N. Aaron Deskins, Worcester Polytechnic Institute
Prof. Dunwei Wang, Boston College
Prof. Jier Huang, Boston College
Prof. Mingdi Yan, UMass Lowell
Prof. Jonathan Rochford, UMass Boston
Prof. Jie He, University of Connecticut
Prof. Christine Caputo, UNH Chemistry
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