Photoinduced Charge Transfer from Quantum Dots Measured by Cyclic Voltammetry
Micaela K Homer1, Ding-Yuan Kuo1, Florence Y Dou1
1Department of Chemistry, University of Washington, Box 351700, Seattle, Washington 98195-1700, United States.
Journal of the American Chemical Society
|July 27, 2022
Summary
Researchers developed a new method using cyclic voltammetry to measure charge transfer rates in quantum dot photocatalysts. This technique reveals long-lived charge states and provides rates relevant to chemical transformations.
Area of Science:
- Materials Science
- Electrochemistry
- Photocatalysis
Background:
- Quantum dots (QDs) are promising photocatalysts, but understanding charge transfer at their interfaces is key.
- Efficient charge separation and transfer are critical for photocatalytic activity.
Purpose of the Study:
- To develop a method for measuring photoinduced charge transfer rates at quantum dot interfaces.
- To investigate the influence of driving force on charge transfer rates.
- To correlate charge transfer dynamics with photocatalytic performance.
Main Methods:
- Utilized cyclic voltammetry under illumination to probe photoinduced charge transfer.
- Employed a library of molecular charge acceptors (hole and electron acceptors).
- Applied electrochemical modeling and the ErCi' zone diagram for mechanistic analysis.
Main Results:
- Demonstrated the measurement of charge transfer rates from CdS quantum dots.
- Observed long-lived charge donor states due to native photodoping.
- Found a positive correlation between driving force and charge transfer rate.
- Measured charge transfer rates on the order of 0.1 s⁻¹.
Conclusions:
- Cyclic voltammetry under illumination is effective for quantifying charge transfer in QD photocatalysts.
- The measured rates are more relevant to photocatalytic quantum yields than picosecond transient spectroscopy.
- This method provides insights into optimizing QD interfaces for enhanced photocatalysis.
More Related Videos
12:57Resonance Fluorescence of an InGaAs Quantum Dot in a Planar Cavity Using Orthogonal Excitation and Detection
Published on: October 13, 2017
9.3K
11:33All-electronic Nanosecond-resolved Scanning Tunneling Microscopy: Facilitating the Investigation of Single Dopant Charge Dynamics
Published on: January 19, 2018
9.8K
Related Concept Videos
01:10Voltammetric Techniques: Cyclic Voltammetry
673
Cyclic voltammetry (CV) is an electrochemical technique used to investigate the redox properties of a chemical species. It involves measuring the current response of an electrochemical cell as a function of the applied potential. The setup for cyclic voltammetry typically consists of a working electrode, a reference electrode, and a counter electrode—all immersed in an electrolyte solution. The working electrode is where the redox reaction of interest occurs, while the reference electrode...
673
01:17Voltammetric Techniques: Pulse Voltammetry
671
Differential-pulse voltammetry (DPV) is a type of voltammetry that involves applying a series of voltage pulses to an electrochemical cell while measuring the resulting current. In DPV, the differential pulse or small potential pulses are superimposed on a linear potential sweep. The magnitude of these pulses is typically small, often in the millivolt range. Each voltage pulse lasts a short duration, usually in the order of a few milliseconds, and is applied at regular intervals along the...
671
01:12Voltammetric Techniques: Linear-Scan (E vs Time)
503
Polarography is a classical voltammetric technique used to analyze electrochemical reactions. This method applies a linear potential sweep to a dropping mercury electrode (DME), and the resulting current is measured. A dropping mercury electrode is commonly used as the working electrode in polarography. It consists of a capillary tube filled with mercury, where the tiny droplet forms at the tip. This droplet continuously drops from the capillary, creating a new electrode surface for each...
503
01:21Voltammetry: Factors Affecting Measurements
207
A current produced due to the redox reactions of the analyte at the working and auxiliary electrodes is called a faradaic current. The reaction can be divided into two types. The current generated due to the reduction of the analyte is called cathodic current, and it carries a positive charge. In contrast, the current produced by analyte oxidation is known as an anodic current, and it has a negative charge. The applied potential at the working electrode determines the faradaic current flow, and...
207
01:00Coulometry: Overview
1.6K
Coulometry is one of the rapid, most accurate, and precise analytical techniques that determine the quantity of an analyte by measuring the electrical charge needed for its complete electrolysis without using any analytical standards. The total charge passed during electrolysis correlates with the analyte amount by Faraday's laws of electrolysis. For accurate coulometric measurements, a charge equal to Faraday's constant multiplied by the number of electrons involved in the relevant...
1.6K
01:20Voltammetry: Overview
2.0K
Voltammetry is an electroanalytical technique in which the current flowing through an electrochemical cell is measured as a function of applied potential, typically under conditions of concentration polarization. The technique provides valuable information about redox-active species, and the current response is plotted as a voltammogram.
A voltammetric cell uses three electrodes: a working electrode, a reference electrode, and an auxiliary electrode. The redox reactions occur in the working...
A voltammetric cell uses three electrodes: a working electrode, a reference electrode, and an auxiliary electrode. The redox reactions occur in the working...
2.0K