Covalently linking CuInS₂ quantum dots with a Re catalyst by click reaction for photocatalytic CO₂ reduction

Abstract

Covalently linking photosensitizers and catalysts in an inorganic-organic hybrid photocatalytic system is beneficial for efficient electron transfer between these components. However, general and straightforward methods to covalently attach molecular catalysts on the surface of inorganic semiconductors are rare. In this work, a classic rhenium bipyridine complex (Re catalyst) has been successfully covalently linked to the low toxicity CuInS quantum dots (QDs) by click reaction for photocatalytic CO reduction. Covalent bonding between the CuInS QDs and the Re catalyst in the QD-Re hybrid system is confirmed by UV-visible absorption spectroscopy, Fourier-transform infrared spectroscopy and energy-dispersive X-ray measurements. Time-correlated single photon counting and ultrafast time-resolved infrared spectroscopy provide evidence for rapid photo-induced electron transfer from the QDs to the Re catalyst. Upon photo-excitation of the QDs, the singly reduced Re catalyst is formed within 300 fs. Notably, the amount of reduced Re in the linked hybrid system is more than that in a sample where the QDs and the Re catalyst are simply mixed, suggesting that the covalent linkage between the CuInS QDs and the Re catalyst indeed facilitates electron transfer from the QDs to the Re catalyst. Such an ultrafast electron transfer in the covalently linked CuInS QD-Re hybrid system leads to enhanced photocatalytic activity for CO reduction, as compared to the conventional mixture of the QDs and the Re catalyst.

Semiconductor Quantum Dots: An Emerging Candidate for CO2 Photoreduction

“…Here, we will mainly focus on how the unique properties of QDs and the interaction between QDs and cocatalysts would promote CO 2 photoreduction. Table 1 gave a detailed summary of the currently reported examples of utilization of QDs for CO 2 photoreduction . The recent advances of using semiconductor QDs in photocatalytic CO 2 reduction will be discussed in three categories: II–VI QDs, I–III–VI QDs and perovskite‐type QDs.…”

“…Recently, a cocatalyst of rhenium bipyridine complex (Re catalyst) had been covalently linked to the surface of CuInS 2 QDs by Click reaction ( Figure a) . Ultrafast TA spectroscopic analysis showed that the surface binding Re cocatalyst could quickly acquire an electron from the excited QDs within 300 fs (Figure b).…”

Nanostructured Metal Sulfides: Classification, Modification Strategy, and Solar‐Driven CO2 Reduction Application

“…[ 189–191 ] Because of the narrow bandgap (≈1.50 eV) and favorable photoabsorption (Figure 25d), CuInS 2 was developed to be a great potential and sustainable catalyst candidate in photocatalysis for H 2 evolution, CO 2 reduction, and degradation of pollutants. [ 192–195 ]…”

Study of Excited States and Electron Transfer of Semiconductor‐Metal‐Complex Hybrid Photocatalysts for CO2 Reduction by Using Picosecond Time‐Resolved Spectroscopies

“…Therefore, this concept could be applied to many combinations of photoactive semiconductors and metal‐complex catalysts. Several reports have indicated that the activity for CO 2 reduction could be improved by changing the photoactive semiconductor and metal‐complex catalyst [2–7] . Consequently, selective CO 2 reduction that utilizes only water and sunlight with water oxidation catalysts was successfully achieved using the hybrid photocatalysts concept [8–13] …”

“…Severalr eports have indicated that the activity for CO 2 reduction could be improved by changing the photoactive semiconductor and metal-complex catalyst. [2][3][4][5][6][7] Consequently,s elective CO 2 reductiont hat utilizes only water and sunlight with water oxidation catalysts was successfully achieved using the hybrid photocatalysts concept. [8][9][10][11][12][13] Time-resolved transientabsorption,e mission (TR-EM), and infrared absorption (TR-IR) spectroscopies are useful techniques for understanding fundamental photophysical and photochemicalp rocesses such as electron transfer.…”