Photocatalytic Generation of Solar Fuels and Commodity Chemicals

Title:

Photocatalytic Generation of Solar Fuels and Commodity Chemicals

Schedule:

Date: 22^nd May, 2024 (Wednesday)

Time: 5 - 6 pm (HKT)

Venue: Lecture Theatre P1, Chong Yuet Ming Chemistry Building

Speaker:

Prof. Francesca Arcudi

Department of Chemistry Sciences

University of Padova, Italy

Abstract:

This talk will describe two separate strategies to photocatalytically produce (i) CO from CO₂,^[1] and (ii) polymer-grade ethylene from an ethylene feed with acetylene contaminant.^[2] CO₂ reduction is accomplished in pure water with an unprecedented combination of performance parameters: turnover number (TON(CO)) >80,000, quantum yield (QY) >3% and selectivity >99%, using CuInS2 colloidal quantum dots (QDs) as photosensitizer and a Co-porphyrin catalyst. The amine/ammonium-terminated ligand shells of the QDs are responsible for the exception performance of this system by establishing (i) an electrostatic assembly with Co-porphyrin, which allow the colocalization of protons, CO₂, and catalyst at the QD core that serves at the source of the electrons; (ii) a dynamic equilibrium between carbamic acid and free CO₂ that increases the local concentration of available CO₂; and (iii) “second-sphere” effects that improve the efficiency of the Co-porphyrin catalyst. (Figure 1A).^[1] In a separate system based on a Co-porphyrin catalyst, acetylene is reduced to ethylene, an intermediate in the production of ~50-60% of all plastics. Our system reduces acetylene into ethylene with several advantages over the present hydrogenation technology, including (i) operation with near 100% conversion in an ethylene-rich gas feed and ≥99% selectivity under both non-competitive (no ethylene co-feed) and competitive (ethylene co-feed) conditions, the latter being industrially relevant; (ii) operation at room temperature using light and water in place of high temperature and an external H₂ feed, and (iii) use of cobalt in the catalyst in place of precious metal catalysts.^[2] Combining the high activity and selectivity of the homogeneous system with the ease of separability, recyclability, and robustness of a heterogeneous system lends advantages over the homogeneous catalyst, namely, facile recyclability and increased longevity.^[3] These features offer substantial advantages over current hydrogenation technologies with respect to selectivity and sustainability.

References:

[1] F. Arcudi L. Ðorđević; B. Nagasing; S. I. Stupp; E. A. Weiss, Journal of the American Chemical Society 2021, 143 (43), 18131–18138.

[2] F. Arcudi; L. Ðorđević; N. Schweitzer; S. I. Stupp; E. A. Weiss, Nature Chemistry 2022, 14, 1007–1012.

[3] A. Stone; L. Ðorđević; S. I. Stupp; E. A. Weiss; F. Arcudi*; J. T. Hupp*, ACS Energy Lett. 2023, 8, 4684–4693.