Charge Transfer Dynamics between Photoexcited CdS Nanorods and Mononuclear Ru Water-Oxidation Catalysts

Tseng, Huan-Wei; Wilker, Molly B.; Damrauer, Niels H.; Duković, Gordana

doi:10.1021/ja400178g

Cited by 100 publications

(116 citation statements)

References 30 publications

Supporting

Mentioning

114

Contrasting

Order By: Relevance

“…13 For comparison with an aliphatic ligand that also makes QDs soluble in FA, a ligand exchange to 3-mercaptopropionic acid (MPA) was performed following previously published procedures. [29][30][31] These ligand-exchanged samples are referred to as CdSe-S, CdSe-Se, CdSe-Te, and CdSe-MPA, respectively.…”

Section: Resultsmentioning

confidence: 99%

Impact of Chalcogenide Ligands on Excited State Dynamics in CdSe Quantum Dots

2015

Self Cite

View full text Add to dashboard Cite

The ligands that passivate the surfaces of semiconductor nanocrystals play an important role in excited state relaxation and charge transfer. Replacement of native long-chain organic ligands with chalcogenides has been shown to improve charge transfer in nanocrystal-based devices. In this report, we examine how surface-capping with S 2-, Se 2-, and Te 2-impacts the excited state relaxation in CdSe quantum dots (QDs). We use transient absorption spectroscopy with state-specific pumping to reveal the kinetics of electron and hole cooling, band edge electron relaxation, hole trapping, and trapped hole relaxation, all as a function of surface-capping ligand. We find that carrier cooling is not strongly dependent on the ligand. In contrast, band edge relaxation exhibits strong ligand dependence, with enhanced electron trapping in chalcogenide-capped QDs. This effect is the weakest with the S 2-ligand, but is very strong with and Se 2-and Te 2-, such that the average band edge electron lifetimes for QDs capped with those ligands are under 100 ps. We conclude that, unlike the case of S 2-, improvements in electron transfer rates with Se 2-and Te 2-ligands may be overshadowed by the extreme electron lifetime shortening that may lead to low quantum yields of electron transfer.

show abstract

Section: Resultsmentioning

confidence: 99%

Impact of Chalcogenide Ligands on Excited State Dynamics in CdSe Quantum Dots

2015

Self Cite

View full text Add to dashboard Cite

show abstract

“…A multiexponential decay unsurprisingly indicates several processes at play in the complex M. thermoacetica-CdS hybrids. Rapid picosecond decays were previously measured with colloidal CdS that featured molecular acceptors with fast e − transfer behavior (24)(25)(26). As hot e − relaxation in Cd-chalcogenide quantum dots occurs in the subpicosecond regime, this process does not likely contribute to the TA kinetics in the measured time scale (27).…”

Section: −1mentioning

confidence: 97%

Spectroscopic elucidation of energy transfer in hybrid inorganic–biological organisms for solar-to-chemical production

Kornienko

Sakimoto

Herlihy

et al. 2016

Proc. Natl. Acad. Sci. U.S.A.

156

126

View full text Add to dashboard Cite

The rise of inorganic-biological hybrid organisms for solar-to-chemical production has spurred mechanistic investigations into the dynamics of the biotic-abiotic interface to drive the development of nextgeneration systems. The model system, Moorella thermoaceticacadmium sulfide (CdS), combines an inorganic semiconductor nanoparticle light harvester with an acetogenic bacterium to drive the photosynthetic reduction of CO 2 to acetic acid with high efficiency. In this work, we report insights into this unique electrotrophic behavior and propose a charge-transfer mechanism from CdS to M. thermoacetica. Transient absorption (TA) spectroscopy revealed that photoexcited electron transfer rates increase with increasing hydrogenase (H 2 ase) enzyme activity. On the same time scale as the TA spectroscopy, time-resolved infrared (TRIR) spectroscopy showed spectral changes in the 1,700-1,900-cm −1 spectral region. The quantum efficiency of this system for photosynthetic acetic acid generation also increased with increasing H 2 ase activity and shorter carrier lifetimes when averaged over the first 24 h of photosynthesis. However, within the initial 3 h of photosynthesis, the rate followed an opposite trend: The bacteria with the lowest H 2 ase activity photosynthesized acetic acid the fastest. These results suggest a two-pathway mechanism: a high quantum efficiency charge-transfer pathway to H 2 ase generating H 2 as a molecular intermediate that dominates at long time scales (24 h), and a direct energy-transducing enzymatic pathway responsible for acetic acid production at short time scales (3 h). This work represents a promising platform to utilize conventional spectroscopic methodology to extract insights from more complex biotic-abiotic hybrid systems.energy conversion | spectroscopy | CO 2 reduction | biohybrid systems | catalysis

show abstract

“…(7) A growing body of spectroscopic work has examined charge transfer rates from QDs to molecular charge acceptors typically physisorbed onto the QD surface, exploring the parameter space in the Marcus equation. (8) Electron transfer studies (8)(9)(10)(11)(12)(13) outnumber hole studies, (14)(15)(16)(17)(18)(19) despite hole transfer being the limiting factor in the efficiencies of QD sensitized solar cells and in QD-based colloidal photocatalytic hydrogen evolving systems. (20,21) To establish a sound model for charge transfer from nanocrystals to molecular acceptors, we must address the features of this system that make the process more difficult to characterize than that of the pure molecular case.…”

Section: Introductionmentioning

confidence: 99%

Efficiency of Hole Transfer from Photoexcited Quantum Dots to Covalently Linked Molecular Species

Ding

Olshansky

Leone³

et al. 2015

J. Am. Chem. Soc.

131

172

View full text Add to dashboard Cite

Hole transfer from high photoluminescence quantum yield (PLQY) CdSe-core CdS-shell semiconductor nanocrystal quantum dots (QDs) to covalently linked molecular hole acceptors is investigated. 1H NMR is used to independently calibrate the average number of hole acceptor molecules per QD, N, allowing us to measure PLQY as a function of N, and to extract the hole transfer rate constant per acceptor, k ht. This value allows for reliable comparisons between nine different donor–acceptor systems with variant shell thicknesses and acceptor ligands, with k ht spanning over 4 orders of magnitude, from single acceptor time constants as fast as 16 ns to as slow as 0.13 ms. The PLQY variation with acceptor coverage for all k ht follows a universal equation, and the shape of this curve depends critically on the ratio of the total hole transfer rate to the sum of the native recombination rates in the QD. The dependence of k ht on the CdS thickness and the chain length of the acceptor is investigated, with damping coefficients β measured to be (0.24 ± 0.025) Å–1 and (0.85 ± 0.1) Å–1 for CdS and the alkyl chain, respectively. We observe that QDs with high intrinsic PLQYs (>79%) can donate holes to surface-bound molecular acceptors with efficiencies up to 99% and total hole transfer time constants as fast as 170 ps. We demonstrate the merits of a system where ill-defined nonradiative channels are suppressed and well-defined nonradiative channels are engineered and quantified. These results show the potential of QD systems to drive desirable oxidative chemistry without undergoing oxidative photodegradation.

show abstract

Charge Transfer Dynamics between Photoexcited CdS Nanorods and Mononuclear Ru Water-Oxidation Catalysts

Cited by 100 publications

References 30 publications

Impact of Chalcogenide Ligands on Excited State Dynamics in CdSe Quantum Dots

Impact of Chalcogenide Ligands on Excited State Dynamics in CdSe Quantum Dots

Spectroscopic elucidation of energy transfer in hybrid inorganic–biological organisms for solar-to-chemical production

Efficiency of Hole Transfer from Photoexcited Quantum Dots to Covalently Linked Molecular Species

Contact Info

Product

Resources

About