Photochemical CO2 Reduction Driven by Water-Soluble Copper(I) Photosensitizer with the Catalysis Accelerated by Multi-Electron Chargeable Cobalt Porphyrin

Abstract

This study introduces a fully aqueous photochemical CO₂ reduction system that uses a water-soluble copper(I) photosensitizer (CuPS)Molecule with key PDVCFPPNDZGLBQ-UHFFFAOYSA-L does not exist. and a cobalt porphyrin catalyst (CoTMPyP). The system achieves high turnover numbers and selectivity for CO₂-to-CO conversion, outperforming other aqueous systems. The multi-electron chargeable property of CoTMPyP is key to its catalytic efficiency and selectivity.

Summary

A cop per(I) diimine complex serves as an efficient, water-soluble photosensitizer, enabling visible-light-driven CO₂-to-CO conversion in aqueous media. This system incorporates CoTMPyP, a cobalt porphyrin catalyst, achieving unprecedented catalytic performance. Key advances include a high turnover number (TON) and fast catalytic rates due to the multi-electron redox properties of CoTMPyP. The study demonstrates the potential of combining earth-abundant materials for sustainable photochemical CO₂ reduction.

Additional Remarks

The research underscores the importance of designing water-compatible, earth-abundant photocatalytic systems. CoTMPyP's multi-electron storage capability enables rapid intramolecular electron transfer, improving CO release. The CuPS-CoTMPyP system provides insights into addressing challenges like H₂ competition in aqueous CO₂ reduction systems​.

Content of the Published Article in Detail

• Design and preparation of the copper(I) photosensitizer CuPS.
• Photochemical studies demonstrating the CO₂ reduction mechanism in aqueous systems.
• Role of the multi-electron chargeable CoTMPyP in accelerating catalysis.
• Experimental results showing high TON and TOF under optimized conditions.
• Discussion of reaction selectivity, including negligible formation of undesired byproducts such as HCOOH.

Catalysts Tested in This Study

• CoTMPyP: A cobalt porphyrin catalyst with high catalytic efficiency (right).
• CoTPPS: Another cobalt porphyrin derivative used for comparison, with lower activity and selectivity compared to CoTMPyP​ (left) (100985).

(100985) (100986)

Photosensitizer

The copper(I) photosensitizer CuPS ([Cu(L1)(L2)]BF4), where L1 and L2 are ligands, features long-lived excited states, making it highly efficient in driving photochemical CO₂ reduction in aqueous media​.

Investigation

The study involved kinetic analysis of CO and H₂ production under various conditions. Control experiments confirmed the roles of CuPS, CoTMPyP, and ascorbate. The performance was evaluated by quantum yield and CO selectivity metrics, with additional insights provided by structural characterization of intermediates.

		cat	cat conc [µM]	PS	PS conc [mM]	e-D	e-D conc [M]	solvent A	additives	.	.	.	.	TON CO	TON CH4	.
(edit)	1.	Molecule:100985	5	Molecule:100987	500	Molecule:100989	0.1	H2O	NaHCO3					1085	127
(edit)	2.	Molecule:100988	5	Molecule:100987	500	Molecule:100989	0.1	H2O	NaHCO3					2680	820

Investigation-Name: Tabel 1

Further Information

The findings highlight the influence of ligand design in CuPS and the impact of peripheral groups in CoTMPyP. Future applications might involve integrating such catalysts into hybrid systems or scaling them for industrial CO₂ reduction​.

Sacrificial Electron Donor

In this study, the sacrificial electron donor was sodium ascorbate (AscHNa), which facilitated efficient electron transfer to drive the CO₂ reduction reaction​.

Additives

Additives such as bicarbonate buffer were used to maintain the pH and reaction environment, ensuring stability and efficiency of the photocatalytic system​.