阅读说明：本技术 一种树枝状银-氧化铁复合光电极及其制备方法 (Dendritic silver-iron oxide composite photoelectrode and preparation method thereof ) 是由 李龙珠 吴浩宇 张伟庆 杨蓉 陈玉伟 陈小卉 唐惠东 于 2019-11-14 设计创作，主要内容包括：本发明公开了一种树枝状银-氧化铁复合光电极及其制备方法,该方法依次包括金属基底预处理、制备沉积有三维立体树枝状Ag导电骨架的金属基底、在沉积有三维立体树枝状Ag导电骨架的金属基底包覆FeOOH膜和热处理四个工序步骤,本发明的制备方法操作步骤简单,成本低廉,绿色环保,适合该技术的推广应用；本发明方法制备的一种树枝状银-氧化铁复合光电极,由于在金属基底外表面包覆有树枝状银-氧化铁复合膜,显著降低了传统的氧化铁光电极的开启电势,因此,该树枝状银-氧化铁复合光电极可以用作光电化学分解水技术中的光阳极,为光电化学分解水制氢奠定了应用基础。(The invention discloses a dendritic silver-ferric oxide composite photoelectrode and a preparation method thereof, wherein the method sequentially comprises four working procedures of metal substrate pretreatment, preparation of a metal substrate deposited with a three-dimensional dendritic Ag conductive framework, coating of a FeOOH film on the metal substrate deposited with the three-dimensional dendritic Ag conductive framework and heat treatment; according to the dendritic silver-iron oxide composite photoelectrode prepared by the method, the dendritic silver-iron oxide composite photoelectrode is coated on the outer surface of the metal substrate, so that the opening potential of the traditional iron oxide photoelectrode is remarkably reduced, and therefore, the dendritic silver-iron oxide composite photoelectrode can be used as a photoanode in a photoelectrochemical water splitting technology, and an application foundation is laid for hydrogen production through photoelectrochemical water splitting.)

1. A preparation method of a dendritic silver-iron oxide composite photoelectrode is characterized by comprising the following steps:

s1: pretreating a metal substrate, namely placing the metal substrate in an acid cleaning solution with a certain concentration, performing ultrasonic pretreatment for 5-30 s, washing with clear water and drying for later use;

s2: electrodepositing a three-dimensional dendritic Ag conductive framework on the metal substrate pretreated in the step S1 by using a three-electrode system to obtain the metal substrate deposited with the three-dimensional dendritic Ag conductive framework;

s3: coating the FeOOH film on the metal substrate deposited with the three-dimensional dendritic Ag conductive framework prepared in the step S2 by adopting a hydrothermal method;

s4: and (4) placing the metal substrate of the Ag conductive framework coated with the FeOOH film prepared in the step (S3) in a muffle furnace, and carrying out heat treatment at 600-700 ℃ for 0.5-1 h, wherein the heating rate is 10 ℃/min, so as to obtain the dendritic silver-ferric oxide composite photoelectrode.

2. The method for preparing a dendritic silver-iron oxide composite photoelectrode according to claim 1, wherein the metal substrate in the step S1 is made of Ti, Cu, Ni or Fe, and the acidic cleaning solution is formed by 40% by mass of HF and 68% by mass of HNO₃And H₂The O is prepared according to the volume ratio of 0.5-1: 1.5-4: 5-10.

3. A tree as claimed in claim 1The preparation method of the dendritic silver-iron oxide composite photoelectrode is characterized in that the specific operation of the step S2 is that the metal substrate pretreated in the step S1 is used as a working electrode, a Pt sheet is used as a counter electrode, an Ag/AgCl electrode is used as a reference electrode, and a constant current method is adopted to obtain a composite photoelectrode containing 0.02-0.06 mol/L Ag⁺Depositing for 60-120 s in the acidic electrolyte solution of ions, wherein the constant current value is 0.01-0.04A.

4. The method for preparing the dendritic silver-iron oxide composite photoelectrode of claim 3, wherein the composition of the acidic electrolyte solution is 0.01-0.03 mol/L Ag₂SO₄1.0 to 1.5mol/L KSCN and 0.5 to 1.0mol/L H₂SO₄。

5. The method for preparing the dendritic silver-iron oxide composite photoelectrode of claim 1, wherein the specific operation of the step S3 is that the metal substrate deposited with the Ag conductive framework is placed into a reaction kettle containing Fe-containing precursor water solution, then the reaction kettle is placed into a muffle furnace heated to 80-100 ℃ for hydrothermal heat preservation treatment for 0.5-2 h, the metal substrate deposited with the Ag conductive framework is taken out and placed into an inert gas dryer, and is dried for 2-5 h at 60-80 ℃ to form the metal substrate of the Ag conductive framework coated with the FeOOH film, wherein the Fe-containing precursor water solution is FeCl with the concentration of 0.1-0.2 mol/L₃Or Fe (NO)₃)₃An aqueous solution.

6. The dendritic silver-iron oxide composite photoelectrode is obtained by the preparation method of the dendritic silver-iron oxide composite photoelectrode according to any one of claims 1 to 5.

Technical Field

The invention relates to the technical field of photoelectric materials, in particular to a dendritic silver-iron oxide composite photoelectrode and a preparation method thereof.

Background

With the global warming, energy shortage and environmental pollution, the photoelectrochemical water splitting hydrogen production is receiving attention as a way of converting clean solar energy into chemical energy, and the high-efficiency photoanode is the bottleneck of photoelectrochemical water splitting technology and the research hotspot. The iron oxide semiconductor material is a photo-anode material with the most potential in the photoelectrochemistry water splitting technology due to the advantages of narrow band gap (2.2eV), good photoelectrochemical stability, low price, no pollution and the like. But the photoelectrochemical property and the theoretical value thereof { the opening potential is 0.4V (vs. RHE), the saturation current is 12.6mA/cm and the like due to the factors of short service life, low minority carrier mobility, poor conductivity, insufficient oxygen output power and the like of the photo-generated carriers^-2The difference is large.

When the iron oxide semiconductor material is used as a photoanode to carry out photoelectrochemical water decomposition, photogenerated holes in the iron oxide generate water oxidation reaction at a semiconductor/electrolyte interface, and photogenerated electrons are collected by a substrate and are transmitted to a cathode to generate reduction reaction. One effective way to improve the charge separation efficiency of iron oxide photoanode is to add a conductive framework to the iron oxide nanostructure, through which the photo-generated electrons can be more easily transported to the cathode, thereby reducing the recombination probability of the photo-generated electron-hole pairs in the semiconductor. Lin et al describe TiSi₂The dual role of the nanotubes as structural scaffolds and efficient charge collection electrodes allows the highest photocurrent (2.7 mA/cm) obtained with undoped iron oxide^-2) And IPCE reached 46% (λ 400 nm). (Lin Y, Zhou S, Sheehan S W, et al. Nanonet-based hectorite heterostructures for influencing water splitting [ J]Journal of the American Chemical Society,2011,133(8): 2398-. The metal Ag has good conductivity and stability, and is wide in application rangeThe conductive skeleton is applied to an electrocatalyst and a sensor, but is also rarely reported as a conductive skeleton applied to a photoelectrochemical water splitting photo-anode.

Disclosure of Invention

The invention aims to overcome the defects in the prior art and provide the dendritic silver-iron oxide composite photoelectrode and the preparation method thereof, and the preparation method has the advantages of simple operation steps, low cost, environmental protection and suitability for popularization and application of the technology; the dendritic silver-iron oxide composite photoelectrode prepared by the method obviously reduces the opening potential of the traditional iron oxide photoelectrode because the dendritic silver-iron oxide composite photoelectrode is coated on the outer surface of the metal substrate, so the dendritic silver-iron oxide composite photoelectrode can be used as a photoanode in a photoelectrochemical water splitting technology, and lays an application foundation for hydrogen production by photoelectrochemical water splitting.

The technical scheme of the invention provides a preparation method of a dendritic silver-iron oxide composite photoelectrode, which comprises the following steps:

s1: pretreating a metal substrate, namely placing the metal substrate in an acid cleaning solution with a certain concentration, performing ultrasonic pretreatment for 5-30 s, washing with clear water and drying for later use;

s2: electrodepositing a three-dimensional dendritic Ag conductive framework on the metal substrate pretreated in the step S1 by using a three-electrode system to obtain the metal substrate deposited with the three-dimensional dendritic Ag conductive framework;

s3: coating the FeOOH film on the metal substrate deposited with the three-dimensional dendritic Ag conductive framework prepared in the step S2 by adopting a hydrothermal method;

s4: and (4) placing the metal substrate of the Ag conductive framework coated with the FeOOH film prepared in the step (S3) in a muffle furnace, and carrying out heat treatment at 600-700 ℃ for 0.5-1 h, wherein the heating rate is 10 ℃/min, so as to obtain the dendritic silver-ferric oxide composite photoelectrode.

Preferably, in the step S1, the metal substrate is made of Ti, Cu, Ni, or Fe, and the acidic cleaning solution is formed by 40% by mass of HF and 68% by mass of HNO₃And H₂The O is prepared according to the volume ratio of 0.5-1: 1.5-4: 5-10.

Preferably, the specific operation of the step S2 is to use the pretreated metal substrate of the step S1 as a working electrode, a Pt sheet as a counter electrode, and an Ag/AgCl electrode as a reference electrode, and to use a constant current method to generate a constant current containing 0.02 to 0.06mol/L Ag⁺Depositing for 60-120 s in the acidic electrolyte solution of ions, wherein the constant current value is 0.01-0.04A.

Further preferably, the composition of the acidic electrolyte solution is 0.01-0.03 mol/L Ag₂SO₄1.0 to 1.5mol/L KSCN and 0.5 to 1.0mol/L H₂SO₄。

Preferably, the specific operation of the step S3 is to place the metal substrate deposited with the Ag conductive framework in a reaction kettle containing an Fe-containing precursor aqueous solution, then place the reaction kettle in a muffle furnace heated to 80-100 ℃ for hydrothermal heat preservation for 0.5-2 h, take out the metal substrate deposited with the Ag conductive framework and place the metal substrate in an inert gas dryer, dry the metal substrate at 60-80 ℃ for 2-5 h to form the metal substrate of the Ag conductive framework coated with the FeOOH film, wherein the Fe-containing precursor aqueous solution is 0.1-0.2 mol/L of FeCl₃Or Fe (NO)₃)₃An aqueous solution.

The dendritic silver-ferric oxide composite photoelectrode is obtained by the preparation method of the dendritic silver-ferric oxide composite photoelectrode. The dendritic silver-iron oxide composite membrane is coated on the outer surface of the metal substrate, so that the opening potential of the traditional iron oxide photoelectrode is remarkably reduced, and the dendritic silver-iron oxide composite photoelectrode can be used as a photoanode in a photoelectrochemistry water splitting technology, and lays an application foundation for photoelectrochemistry water splitting hydrogen production.

The invention has the advantages and beneficial effects that:

1. the preparation method disclosed by the invention is simple in operation steps, low in cost, green and environment-friendly, and is suitable for popularization and application of the technology.

2. According to the dendritic silver-iron oxide composite photoelectrode prepared by the method, the dendritic silver-iron oxide composite photoelectrode is coated on the outer surface of the metal substrate, so that the opening potential of the traditional iron oxide photoelectrode is remarkably reduced, and therefore, the dendritic silver-iron oxide composite photoelectrode can be used as a photoanode in a photoelectrochemical water splitting technology, and an application foundation is laid for hydrogen production through photoelectrochemical water splitting.

Drawings

FIG. 1 is an electron microscope scanning image of the dendritic silver-iron oxide composite photoelectrode in example 1.

Detailed Description

The following description of the embodiments of the present invention will be made with reference to the accompanying drawings. The following examples are only for illustrating the technical solutions of the present invention more clearly, and the protection scope of the present invention is not limited thereby.