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How to measure AQY?

Equipment operation 2022-06-08 1 245

Apparent Quantum Yield (AQY) refers to the ratio of the number of electrons participating in the reaction to the total number of incident photons under a specific wavelength condition [1]. In the photocatalytic reaction system, AQY is a measure of the photocatalytic reaction. One of the important indicators of reactivity.

In the photocatalytic splitting of water for hydrogen production, the formula for calculating the apparent quantum yield of H2 as the product is as follows [2]

PLR-QY1000光催化反应量子产率测量系统测AQY.jpg

v:reaction speed(mol·s-1);

I:Optical power density(W·m-2); 

A:Incident light area(m2); :

λ:Incident light wavelength(nm)。

Click to view the details“Quantum yield (AQY) calculation nanny tutorial, you deserve it!”。 

In order to meet the experimental requirements for the measurement of apparent quantum yield in the photocatalytic decomposition of water for hydrogen production, Porphyra Technology has launched the PLR-QY1000 photocatalytic reaction quantum yield measurement system, as shown in Figure 1.

图1. PLR-QY1000光催化反应量子产率测量系统.jpg

Figure 1. PLR-QY1000 photocatalytic reaction quantum yield measurement system

The PLR-QY1000 photocatalytic reaction quantum yield measurement system uses a laser light source with good monochromaticity as the reaction light source, and the spherical black body reactor can effectively ensure that all photons are irradiated into the reaction system.

The PLR-QY1000 photocatalytic reaction quantum yield measurement system has a built-in temperature and pressure control module, which is convenient for the study of photocatalytic quantum yield under different temperature and pressure conditions.

The PLR-QY1000 photocatalytic reaction quantum yield measurement uses a high-precision sensor to quickly detect the H2 molecule. While ensuring the measurement accuracy, it can monitor the quantum yield of the photocatalyst in real time with the reaction time.

The PLR-QY1000 photocatalytic reaction quantum yield measurement system has a built-in data processing module, which can directly read out the quantum yield, gas production rate, total gas production and photon quantum number through the system interface, which can realize the measurement of photocatalytic quantum yield. direct measurement.

一、Technical parameters of PLR-QY1000 photocatalytic reaction quantum yield measurement system

1. Replacement gas:N2; 

2. Replacement gas:20 ~ 130 kPa,adjustable; 

3. Temperature reflex:5 ~ 60℃ ;

4. Laser light source: standard 405 nm laser generator, other wavelengths are optional; 

5. Reactor volume: 150 mL, see factory calibration value for details.

二、The use of PLR-QY1000 photocatalytic reaction quantum yield measurement system

1. Components

The PLR-QY1000 photocatalytic reaction quantum yield measurement system is mainly composed of the system host, reaction bottle, reaction bottle cap and related accessories as shown in Figure 2.

图2. PLR-QY1000光催化反应量子产率测量系统零部件组成图示.jpg

Figure 2. Components of the PLR-QY1000 photocatalytic reaction quantum yield measurement system

2. Assemble the reaction vial

2.1 Before use, ensure that the inside of the reaction flask and the U-shaped light window are in a clean state; 

2.2 Fill the powder photocatalyst and sacrificial agent aqueous solution into a glass container, and then disperse them uniformly by an ultrasonic machine to form a suspension; 

2.3 After pouring the suspension into the reaction bottle, slowly put the A-type magnet into the reaction bottle; 

2.4 Place the PTFE inner ring at the mouth of the reaction flask, then set the O-ring and the PTFE outer ring in sequence as shown in Figure 3(a), and then use the chain clamp to lock the reaction flask cap and reaction flask. 

Note: The chain clamp should not be too tight to prevent the reaction bottle from being crushed.

图3. PLR-QY1000光催化反应量子产率测量系统反应瓶的组装示意图.jpg

Figure 3. Schematic diagram of the assembly of the reaction flask of the PLR-QY1000 photocatalytic reaction quantum yield measurement system

3. boot operation 

3.1 Adjust the N2 cylinder pressure reducing valve connected with the PLR-QY1000 photocatalytic reaction quantum yield measurement system to make the output pressure 0.42 MPa; 

3.2 Turn on the power switch on the rear panel of the PLR-QY1000 photocatalytic reaction quantum yield measurement system host, click anywhere on the screen, and the system will automatically perform self-checking operations;

3.3 After the self-test is completed, the Self-test Complete Click the Screen to Continue dialog box will pop up, and then click anywhere on the screen again to enter the system operation interface.

图4. PLR-QY1000光催化反应量子产率测量系统主机后面板及系统开机界面.jpg

Figure 4. PLR-QY1000 photocatalytic reaction quantum yield measurement system host rear panel and system startup interface

4. Assembly and calibration of laser light source 

4.1 Place the laser light source and optical power meter as shown in Figure 5; 

4.2 Place the light outlet of the laser light source at 1 cm in front of the optical power meter probe, and use the optical power meter to measure the optical power of the laser light source; 

4.3 Turn on the power switch on the laser light source panel, and turn the switch on the front panel of the laser light source to ON; 

4.4 Adjust the current adjustment knob of the laser light source until the value displayed by the optical power meter is the optical power value required by the experiment; Note: The value displayed by the optical power meter is the optical power, and the unit is W. When using it, pay attention to converting it to the optical power density. Unit conversion! 

4.5 After the measurement, turn the switch on the front panel of the laser light source to "OFF", and turn off the power switch at the same time. The measurement of specific optical power can be clicked to view“How to use PL-MW2000 strong light optical power meter”。

图5 激光光源光功率测量图示.jpg

Figure 5 Diagram of optical power measurement of laser light source

5. Setting parameters 

5.1 Click the parameter setting in the operation interface of the PLR-QY1000 photocatalytic reaction quantum yield measurement system as shown in Figure 6 to enter the setting interface, and enter the following parameters in the dialog box according to the experimental requirements: 

  • Light source power: the measured value of the optical power meter in 4.4, the unit is mW; 

  • Light source wavelength: the wavelength of the laser light source used in the experiment; 

  • Reaction temperature: the setting temperature of the cryostat; 

  • Reaction pressure: Set the reaction pressure according to the experimental situation, the range is 20~130 kPa, the system will adjust and control the pressure according to the set pressure; 

  • Solution volume: the suspension volume in 2.3; 

  • Atmospheric pressure: the value of the local atmospheric pressure in the laboratory, no need to set; 

  • Sampling period: the interval time for recording the experimental results, which can be set from 1 to 30 min; 

  • Number of samples: the number of data to be recorded in the current experiment, which can be set from 1 to 256; 

5.2 After the setting is completed, click the save button, and then the interface will jump out to the system operation interface again.

图6. PLR-QY1000光催化反应量子产率测量系统的系统操作界面和设置界面.jpg

Figure 6. System operation interface and setting interface of PLR-QY1000 photocatalytic reaction quantum yield measurement system

6. Gas calibration 

6.1 Prepare a bag of high-purity hydrogen and a syringe, as shown in Figure 7;

图7. 氢气袋和进样针.jpg

Figure 7. Hydrogen bag and syringe

6.2 Click the parameter setting button shown in Figure 8 in the system operation interface to enter the setting interface; 

6.3 After clicking Calibration, a dialog box for calibration will pop up. After clicking OK, the PLR-QY1000 photocatalytic reaction quantum yield measurement system will automatically perform gas replacement. After the replacement is completed, the system will automatically enter the calibration countdown interface; 

6.4 After 20 minutes of replacement, the system automatically pops up a prompt dialog box. According to the prompt content, enter the required volume of hydrogen from the standard sample port, and then click OK to complete the calibration; 

6.5 After calibration, the system jumps back to the setting interface again. After clicking save again, the interface will jump out to the system operation interface. 

Note: The operation mode of system calibration is guided operation mode, and each step can be operated according to the process according to the pop-up dialog box.

图8. PLR-QY1000光催化反应量子产率测量系统的系统标定操作流程.jpg

Figure 8. System calibration operation flow of PLR-QY1000 photocatalytic reaction quantum yield measurement system

7. preheating system 

7.1 In the operation interface of the PLR-QY1000 photocatalytic reaction quantum yield measurement system, click start operation to enter the operation interface; 

7.2 In the operation interface of the PLR-QY1000 photocatalytic reaction quantum yield measurement system, click start operation to enter the operation interface;

图9. PLR-QY1000光催化反应量子产率测量系统的运行界面.jpg

Figure 9. Operation interface of PLR-QY1000 photocatalytic reaction quantum yield measurement system

7.3 Insert the U disk that comes with the system into the side panel of the PLR-QY1000 photocatalytic reaction quantum yield measurement system, as shown in Figure 10;

图10. PLR-QY1000光催化反应量子产率测量系统的侧面板.jpg

Figure 10. Side panel of the PLR-QY1000 photocatalytic reaction quantum yield measurement system

7.4 Click Confirm in the Start Gas Replacement dialog box on the right side of the running interface, the system will automatically enter the gas replacement stage, and the gas replacement operation is the vacuum pump and gas source built into the PLR-QY1000 photocatalytic reaction quantum yield measurement system to vacuum the reaction flask operation and inflation operation; 

7.5 After 6 times of gas replacement, the gas replacement complete dialog box as shown in Figure 11 will pop up, and then the system will automatically enter the preheating interface;

7.6 The warm-up time depends on the state of the system detector, generally 10 to 20 minutes.


图11. PLR-QY1000光催化反应量子产率测量系统的气体置换和预热流程.jpg

Figure 11. Gas replacement and preheating process of PLR-QY1000 photocatalytic reaction quantum yield measurement system

8. Preheating the laser light source Turn the switch on the rear panel of the laser light source to ON again to preheat the laser light source for 15 minutes. 

9. start experiment 

9.1 After preheating the system and the laser light source, put the laser light source probe into the U-shaped light window, and click the running interface ► as shown in Figure 11 to start the experiment. 

9.2 After the experiment starts, the values of quantum yield, gas production rate, gas concentration and total gas production on the screen interface will gradually increase from 0 and then stabilize. The stabilization time varies according to the reaction system. Generally, the stabilization time is 45 min or so.

图12. PLR-QY1000光催化反应量子产率测量系统的运行界面.jpg

Figure 12. Operation interface of PLR-QY1000 photocatalytic reaction quantum yield measurement system

10. End the experiment 

10.1 To end the experiment, click ■ to end the experiment as shown in Figure 13 in the running interface; 

10.2 Pull out the laser light source probe, turn the switch on the rear panel of the laser light source to OFF, and turn off the power switch of the laser light source; 

10.3 Click the button of the running interface to return to the system operation interface, click again to start running to enter the running interface; 

10.4 Click the last data to enter the historical data page, and click Download to download the experimental data to the U disk. The experimental data is stored in .csv format, including the quantum yield, gas production rate, gas concentration and total gas production at different times. Quantitative results.

图13. PLR-QY1000光催化反应量子产率测量系统的数据下载界面.jpg

Figure 13. Data download interface of PLR-QY1000 photocatalytic reaction quantum yield measurement system

10.5 After the experiment is over, loosen the nut at the air outlet on the rear panel of the system as shown in Figure 14 with a No. 12 wrench to release the pressure, remove the reaction bottle cap, and then tighten it with a No. 12 wrench; 

10.6 Clean the U-shaped light window and place it in the holder of the reaction flask.

图14. PLR-QY1000光催化反应量子产率测量系统的后面板.jpg

Figure 14. The rear panel of the PLR-QY1000 photocatalytic reaction quantum yield measurement system

三、Precautions for the use of PLR-QY1000 photocatalytic reaction quantum yield measurement system

1. The gas used must be N2, and the outlet pressure is between 0.4~0.45 MPa, otherwise it will affect the system self-check; 

2. The reaction bottle cap, O-ring and reaction bottle mouth should be kept clean, otherwise it will affect the air tightness of the system; 

3. If the system pressure changes too much during the preheating stage of the system, please pay attention to the air tightness prompt, which may be caused by the following operations: ① The chain clamp at the reaction bottle cap is too tight; ② The reaction bottle cap, O-ring and reaction There may be debris on the bottle mouth; ③The nut at the air outlet on the rear panel is loose.

[1]Wang Zheng, Li Can, Domen Kazunari*, Recent developments in heterogeneous photocatalysts for solar-driven overall water splitting[J]. Chemical. Society. Reviews, 2019, 48, 2109. 

[2]Lin Huiwen, Chang Kun*, Ye Jinhua* et. al., Ultrafine nano 1T-MoS2 monolayers with NiOx as dual co-catalysts over TiO2 photoharvester for efficient photocatalytic hydrogen evolution[J]. Applied Catalysis B: Environmental, 2020, 279, 119387.


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