Photoelectrode containing interface exposed CrOx cluster promoter and preparation method and application thereof

Abstract

The invention belongs to the technical field of electrocatalysis, and particularly relates to a photoelectrode containing an interface exposed CrOx cluster cocatalyst and a preparation method and application of the photoelectrode. A CrOx cluster with an EJI structure is prepared by a simple dispensing method and an alkali etching method to serve as an efficient cocatalyst, so that the preparation method of a novel cocatalyst (cluster, group and quantum dot) is greatly simplified and the preparation method of the novel cocatalyst (cluster, group and quantum dot) is greatly simplified. The structure with the exposed interface in the electrocatalyst is applied to the OEC, so that the catalytic activity of the OEC is further improved, and the performance of the photo-anode is improved. In atoms in In2S3 are introduced into CrOx in situ, so that the electron state of a CrOx cluster interface is regulated and controlled, the transfer of photo-generated holes is promoted, the surface overpotential is reduced, and the surface OER kinetic process is improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electrocatalysis, and particularly relates to a photoanode containing interfacially-exposed CrO x cluster cocatalyst, a preparation method thereof, and an application thereof. Background Art

[0002] Photoelectrochemical water splitting can achieve the direct conversion between solar energy and hydrogen energy, and is one of the effective means to solve the energy crisis and environmental pollution. Compared with the hydrogen evolution reaction involving two electrons, the oxygen evolution reaction (OER) involving four electrons is more complex. Therefore, developing a high-performance photoanode device is of great significance. Generally speaking, means such as element doping, crystal plane control, constructing heterojunctions, and loading cocatalysts can promote the transfer of photo-generated carriers. Among these strategies, loading an oxygen evolution cocatalyst (OEC) is widely regarded as one of the most direct and effective strategies to solve the poor OER kinetics on the surface of the photoanode.

[0003] In electrocatalysis, researchers have explored an electrocatalytic design with an exposed junction interface, in which the electronic state changes to generate abundant active sites and accelerate the OER kinetics. However, this strategy has not been successfully applied to OECs. This is because the formation of such an interface requires heteroatom doping or high-temperature treatment, which will change the entire bulk phase and damage the light absorption performance. In addition, the formation of such an interface will inevitably introduce defects, which are beneficial as activation / adsorption / anchoring sites for electrocatalysts, but may also act as electron-hole recombination centers in photocatalysis, resulting in the suppression of photocatalytic performance. Therefore, it is crucial to prepare CrO x clusters with exposed cluster-cluster junction interfaces on the photoanode, making the photoanode competitive with electrocatalysts, improving the OER kinetics, and promoting the transport of photo-generated carriers.

[0004] Using an efficient OEC on the photoanode can accelerate the OER kinetics. Some OECs (such as MXene quantum dots, CoNiP, Co 3 O 4 、Au, and FeOOH, etc.) have been anchored on the photoanode in the form of islands or particles to increase the surface catalytic active sites and pursue improved reaction kinetics. However, due to the incomplete coverage of the OEC on the surface of the photoanode, the stability of photo-generated carriers is poor and the transfer ability is insufficient. To break through these limitations, conformal-coated OECs loaded on the photoanode have been developed (for example, NiFe-LDH on BiVO 4 、Fe 2 O 3 、HfO x 、Fe 2 O 3 or BiVO 4of NiFe(OH) x etc.) to avoid direct exposure of the photoanode to the electrolyte, thereby simultaneously improving charge transfer kinetics and operational stability. Although this conformal coating structure of the OEC lacks exposed active sites, slowing down the reactions on the OEC surface and limiting further performance improvement. Therefore, constructing an ideal cocatalyst remains challenging, which can simultaneously have a low photoinduced water dissociation barrier, sufficient photoexcited carrier transfer, reduced carrier recombination, and optimal operational stability. Summary of the Invention

[0005] In the prior art, the conformal coating of the OEC lacks exposed active sites, while the island-like OEC is not conducive to improving the stability of the photoanode. Introducing some novel cocatalysts (such as Fe-In-S clusters) is too complex and not conducive to implementation. At the same time, introducing electrocatalysts on the photoanode surface will introduce more interface defects, which is not conducive to improving the overall performance of the photoanode.

[0006] To solve the above existing technical problems, the present application provides the following technical solutions:

[0007] The present invention prepares an OEC with an exposed cluster-cluster junction interface (EJI) structure without damaging the photoanode material, making the photoanode competitive with electrocatalysts. This structure can accelerate the reactions and carrier transfer processes on the OEC surface. At the same time, the operational stability is also greatly improved. The characterization results show that the EJI exhibits an interpenetrating atomic distribution feature near the interface to manipulate the interfacial charge redistribution, activate abundant OER sites, and change the OER rate-determining step from * to *OH and *O to *OOH. In addition, the formed Cr-In bonds at the EJI can act as bridging atoms between clusters, successfully suppressing the formation of dangling bonds, thereby reducing photoexcited hole recombination and improving the stability of the CrO x clusters.

[0008] The present invention provides a method for preparing a photoanode containing an interfacially exposed CrO x cluster cocatalyst, comprising the following steps:

[0009] S11: Dropwise coat an organic solvent containing a chromium salt on the photoanode and preheat it;

[0010] S12: Anneal the preheated photoanode obtained in step S12 at 100 - 500 °C for 1 - 10 h to obtain an In 2 S 3 / Cr photoanode;

[0011] S13: Subject the In 2 S 3The / Cr photoanode is immersed in water containing alkali for 3 - 9 h to obtain the photo - electrode containing interfacial - exposed CrO x cluster cocatalyst.

[0012] Preferably, the preparation method of the photo - electrode is as follows:

[0013] S21: Mix indium trichloride, thiourea and water to obtain a precursor solution;

[0014] S22: Add the precursor solution into a container containing a conductive substrate, seal and heat at 140 - 200 °C for 4 - 8 h to obtain an In 2 S 3 photo - electrode; the conductive substrate is selected from fluorine - doped tin oxide conductive glass (FTO);

[0015] S23: Clean and dry the In 2 S 3 photo - electrode to obtain the photo - electrode.

[0016] Furthermore, the mass ratio of indium trichloride to thiourea is 2 - 4:1 - 3.

[0017] Furthermore, the conductive substrate is cleaned with acetone, ethanol and water 3 times for 30 min each before use.

[0018] Preferably, the chromium salt is selected from chromium trichloride, the organic solvent is selected from methanol, and the alkali is sodium hydroxide.

[0019] Preferably, in step S11, the pre - heating temperature is 30 - 70 °C.

[0020] Preferably, in the organic solution containing the chromium salt, the concentration of the chromium salt is 0.02 - 0.08 g / mL.

[0021] Preferably, in step S13, after soaking, it is washed with water and dried in vacuum.

[0022] Specifically, the preparation method of the photo - electrode containing interfacial - exposed CrO x cluster cocatalyst includes the following steps:

[0023] S1: Clean the fluorine - doped tin oxide conductive glass (FTO) conductive substrate: Use an ultrasonic instrument to clean FTO with acetone, ethanol and deionized water 3 times for 30 minutes each.

[0024] S2: In 2 S 3 Photo - electrode preparation: First, add 2 - 4 g of indium trichloride (InCl 3) Dissolve it in 200 mL of deionized water, and stir the mixture for 5 minutes. Then, mix 1 - 3 g of thiourea into the above - mentioned solution and stir vigorously. After that, place the clean FTO in a 15 - mL glass bottle with the conductive side facing down. Then, transfer 10 mL of the prepared precursor solution into each liner, seal it, and heat it to 180 °C for 6 hours. Construct In 2 S 3 nanopyramids, wash them with deionized water, and then store them in a vacuum oven.

[0025] S3: In 2 S 3 / Cr:EJI photoanode preparation: Deposit CrO 2 S 3 cluster cocatalyst on the surface of In x by the drop - coating method. Prepare the Cr source solution through the following steps: Dissolve 0.1 - 0.4 g of chromium(III) chloride (CrCl 3 ) in 5 mL of methanol (CH 3 OH) and stir for 30 minutes. Next, place the In 2 S 3 sample on a hot stage at 60 °C, and then drop the prepared Cr source solution on the surface of In 2 S 3 and pre - heat for a few minutes. After pre - heating, anneal the sample at 350 °C for 4 hours to obtain In 2 S 3 / Cr photoanode. Finally, extract the sample and soak it in 1 M NaOH for 7 hours to obtain In 2 S 3 / Cr:EJI photoanode. Wash the sample with deionized water and store it in a vacuum oven.

[0026] The present invention also provides a photoanode containing an interfacial - exposed CrO x cluster cocatalyst prepared by the above - mentioned preparation method.

[0027] The present invention also provides a photoelectrochemical cell for water photolysis, using the above - mentioned photoanode containing an interfacial - exposed CrO x cluster cocatalyst as the working electrode.

[0028] The technical solution of the present invention has the following advantages compared with the prior art:

[0029] 1) The preparation method of the present invention is simple. By the methods of drop - coating and alkali etching, the problems of few active sites and insufficient hole - transport ability existing in the cocatalyst design are solved, avoiding excessive complex operations and making the device preparation process simple.

[0030] 2) Applying the structure with exposed interfaces in the electrocatalyst to the OEC is beneficial to enhancing the catalytic effect of the cocatalyst, enhancing the stability of the entire device, and further improving the performance of the photoanode.

[0031] 3) In-situ introduction of In on the surface regulates the electronic state of the CrOx clusters, promotes the transfer of photo-generated holes, reduces the surface overpotential, and enhances the surface OER kinetic process. Its excellent catalytic ability has greatly improved the resulting photoanode device. Description of the Drawings

[0032] Figure 1 is In 2 S 3 (a) Front view of the scanning electron microscope (SEM) and (b - c) transmission electron microscope (TEM) images of In

[0033] Figure 2 is In 2 S 3 and In 2 S 3 / Cr:EJI J - V curves.

[0034] Figure 3 are J - V curves with different chromium(III) chloride contents. Detailed Embodiments

[0035] The present invention will be further described below in conjunction with the drawings and specific embodiments, so that those skilled in the art can better understand the present invention and be able to implement it, but the embodiments given are not intended to limit the present invention.

[0036] Example 1

[0037] (1) Use an ultrasonic instrument to clean the conductive substrate fluorine - doped tin oxide conductive glass (FTO) 3 times successively with acetone, ethanol, and deionized water, 30 minutes each time.

[0038] (2) Dissolve 2.8105 g of indium(III) chloride (InCl 3 ) in 200 mL of deionized water, and stir the mixture for 5 minutes. Then, mix 1.4615 g of thiourea into the above solution and stir vigorously. After that, place the cleaned FTO in a 15 - mL glass bottle with the conductive side facing down. Then, transfer 10 mL of the prepared precursor solution into each liner, seal it, and heat it to 180 °C for 6 hours. Construct In 2 S 3 nanopyramids, wash them with deionized water, and then store them in a vacuum oven.

[0039] (3) Dissolve 0.266 g of chromium(III) chloride (CrCl 3) Dissolve it in 5 mL of methanol (CH 3 OH) and stir for 30 minutes. Next, place the In 2 S 3 sample on a hot stage at 60 °C, and then drop the prepared Cr source solution onto the surface of In 2 S 3 and preheat for several minutes. After preheating, anneal the sample at 350 °C for 4 hours to obtain the In 2 S 3 / Cr photoanode. Finally, extract the sample and soak it in 1 M NaOH for 7 hours to obtain the In 2 S 3 / Cr:EJI photoanode. Wash the sample with deionized water and store it in a vacuum oven.

[0040] The morphology of the In 2 S 3 / Cr:EJI composite electrode is as shown in Figure 1 . It can be seen from Figure 1 that there is a flocculent substance on the surface of In 2 S 3 , and this substance on the surface is determined to be CrO x , which is beneficial to the transport of photo-generated carriers and the progress of the photocatalytic reaction.

[0041] Assemble the above-prepared photoelectrode into a photoelectrochemical cell, and then carry out water photolysis at different voltages. For comparison, use the FTO loaded with In 2 S 3 as the working electrode and a platinum mesh as the counter electrode to carry out water photolysis under the same conditions. The results are shown in Figure 2 . It can be seen from Figure 2 that at a voltage of 1.23 V RHE , the dark current (the dotted line in Figure 2 ) can be basically ignored, and the photocurrent of the photoelectrode prepared by the method of this embodiment can reach 6.26 mA / cm 2 , while the photocurrent of the In 2 S 3 thin film is only 0.68 mA / cm 2 .

[0042] Example 2

[0043] Prepare the In 2 S 3 / NS photoelectrode according to the method of steps (1) to (3) in Example 1, except that in step (3), by controlling the amount of chromium trichloride added, different CrO x -active In 2 S 3 / Cr:EJI photoelectrodes are obtained.

[0044] Assemble the above-prepared photoanode into a photoelectrochemical cell, and then perform water photolysis at different voltages. At a voltage of 1.23 V RHE , the photocurrent of the best photoanode prepared by the method of this embodiment can reach 6.26 mA / cm 2 , and the results are shown in Figure 3 .

[0045] Obviously, the above embodiments are only examples given for clear illustration and are not limitations on the implementation manners. For those of ordinary skill in the art, other different forms of changes or modifications can be made based on the above description. It is not necessary and impossible to enumerate all implementation manners here. And the obvious changes or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A method containing interface exposed CrO x A method for preparing a photoelectrode with a cluster promoter, characterized in that: The steps include: S11: drop-coating an organic solvent containing a chromium salt onto the photoelectrode and preheating; S12: annealing the photoelectrode preheated in step S12 at 100-500° C. for 1-10 h to obtain an In2S3 / Cr photoanode; S13: Soak the In2S3 / Cr photoanode in water containing alkali for 3-9 hours to obtain the photoanode containing interface exposed CrO x Cluster-promoted photoelectrodes.

2. The preparation method according to claim 1, characterized in that The preparation method of the photoelectrode is as follows: S21: mixing indium trichloride, thiourea and water to obtain a precursor solution; S22: adding the precursor solution into a container containing a conductive substrate, sealing and heating at 140-200° C. for 4-8 hours to obtain an In2S3 photoelectrode; the conductive substrate is selected from fluorine-doped tin oxide conductive glass; S23: Clean and dry the In2S3 photoelectrode to obtain the photoelectrode.

3. The preparation method according to claim 2, characterized in that: The mass ratio of indium trichloride to thiourea is 2-4:1-3.

4. The preparation method according to claim 2, characterized in that: The conductive substrate was cleaned with acetone, ethanol and water three times in sequence before use, each time for 30 minutes.

5. The preparation method according to claim 1, characterized in that: The chromium salt is selected from chromium trichloride, the organic solvent is selected from methanol, and the alkali is sodium hydroxide.

6. The preparation method according to claim 1, characterized in that: In the step S11, the preheating temperature is 30-70°C.

7. The preparation method according to claim 1, characterized in that: In the organic solution containing the chromium salt, the concentration of the chromium salt is 0.02-0.08 g / mL.

8. The preparation method according to claim 1, characterized in that: In the step S13, after immersion, the sample is washed with water and vacuum dried.

9. A CrO-containing material with interface exposure prepared by the preparation method according to any one of claims 1 to 8 x Cluster-assisted photoelectrodes.

10. A photoelectrochemical cell for photolysis of water, characterized in that: The method according to claim 9 containing interface exposed CrO x The cluster-assisted catalyst photoelectrode was used as the working electrode.

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