CN113772664B - Nickel black-graphene composite photo-thermal conversion film and preparation method thereof - Google Patents

Abstract

A nickel black-graphene composite light-to-heat conversion film and a preparation method thereof relate to the structure, preparation and seawater desalination application of the nickel black-graphene composite light-to-heat conversion film. A one-step electrochemical method is used to simultaneously deposit graphene and nickel black on the wall of nickel foam pores to obtain a nickel black-graphene composite light-to-heat conversion film. The plasmon resonance effect of metal nickel black and the advantages of graphene carbon materials in a wide range of light absorption wavelengths can be used to improve the light-to-heat conversion efficiency. Nickel black-graphene light-to-heat conversion film for seawater desalination under light conditions. Under the light intensity of 1 sun, the light-steam energy conversion efficiency can reach 162.4%, and the steam permeability can reach 2.37kg/m ² ·h.

Description

A kind of nickel black-graphene composite photothermal conversion film and preparation method thereof

technical field

The invention belongs to the field of photothermal conversion and its application in seawater desalination.

Background technique

Fresh water is an indispensable resource for human survival. Therefore, more and more countries adopt seawater desalination technology to alleviate the shortage of fresh water. However, high energy consumption is required in the desalination process. Solar energy, as an energy necessary for the survival of organisms, is ubiquitous and inexhaustible in life. People often think that the introduction of solar energy into seawater desalination technology has the effect of light-to-heat conversion and can effectively reduce energy consumption. By combining the two most abundant resources on the earth, seawater desalination can solve the problem of water shortage and achieve sustainable development, which is the general trend of seawater desalination technology in the future. At present, the commonly used solar thermal conversion materials are mainly divided into the following categories: various carbon materials, plasmonic metals, inorganic semiconductors, and organic polymers. Plasmonic metal materials have been used as solar energy absorbing materials due to their strong electromagnetic wave absorption ability. At present, precious metals such as gold and silver have been widely studied, but their high cost severely limits their wide application. Affordable nickel black can effectively replace expensive solar thermal conversion materials to achieve solar thermal conversion. At the same time, graphene is an emerging two-dimensional material, which has the characteristics of a wide range of solar absorption wavelengths and good photothermal conversion performance, and is widely used in photothermal conversion. Therefore, the present invention considers combining nickel black material and graphene to form a photothermal composite material and applying it in seawater desalination technology.

Contents of the invention

The purpose of the present invention is to provide a nickel black-graphene composite light-to-heat conversion film and its preparation method, aiming to improve the light-to-heat conversion efficiency and seawater desalination by synergistically utilizing the advantages of metal materials and carbon materials in light-to-heat conversion effect.

The steps of the present invention are:

A nickel black-graphene composite light-to-heat conversion film and a preparation method thereof, characterized in that the specific steps are:

(1) Add a certain amount of ammonium sulfate and nickel sulfate into the solvent, and keep stirring until fully dissolved to form an electrolyte;

(2) Nickel foam is used as the cathode, graphite foil is used as the anode, and the electrode distance is adjusted in the electrolyte;

(3) Under a certain DC voltage, the gas and hydroxyl radicals generated by the electrolyte intercalate the graphite foil, thereby peeling off the graphene; the nickel ions act as a carrier, transferring the graphene to the cathode while reducing itself Be nickel black; thereby generate uniform nickel black-graphene composite film on the cathode;

(4) Adjust the electrolyte concentration, deposition voltage and deposition time to control the content of nickel black-graphene composite material on the cathode;

In the step (1), the concentration of ammonium sulfate is 0-0.2 M, and the concentration of nickel sulfate is 0-0.08 M;

The electrode distance in the step (2) is 0.5-2 cm;

The voltage range in the step (3) is 5-15 V;

The deposition time in the step (4) is 5-40 min;

(5) After a certain period of electrodeposition, the nickel black-graphene light-to-heat conversion film was fully washed in deionized water, and dried in an oven at 60°C for 12 hours after taking it out.

The formation principle of a nickel black-graphene composite light-to-heat conversion film: After the system is energized, the gas and hydroxyl radicals generated by the electrolyte will intercalate the graphite foil, thereby peeling off the graphene. Nickel ions act as a charging salt, while transferring graphene to the cathode, it is reduced to nickel black itself; thus a uniform nickel black-graphene composite film is formed on the cathode.

The invention adopts a one-step electrochemical method, the preparation process is simple, and the film is formed at one time; the nickel black on the surface of the carrier can realize the photothermal conversion effect under the action of the plasma resonance effect, and the graphene has a wide range of light absorption wavelengths, and the synergistic effect increases its The production of water vapor in the desalination process to obtain more fresh water.

Description of drawings

Figure 1 SEM image of nickel black-graphene composite light-to-heat conversion film.

Figure 2 XRD pattern of nickel black-graphene composite light-to-heat conversion film.

Figure 3 Raman diagram of nickel black-graphene composite light-to-heat conversion film.

Implementation

In order to better illustrate the present invention, the present invention will be further described below by taking nickel black-graphene composite light-to-heat conversion film as an example in conjunction with the accompanying drawings.

Pre-experiment preparation:

1. Preparation of nickel black-graphene composite light-to-heat conversion film:

(1) Add 1.32g of ammonium sulfate and 0.42g of nickel sulfate to 200ml of deionized water, and keep stirring at room temperature until fully dissolved to form an electrolyte solution;

(2) Connect the nickel foam to the cathode, connect the graphite foil to the anode, adjust the distance between the connected electrodes and put them into the electrolyte;

(3) Turn on the switch of the external DC power supply, adjust the experimental voltage and experimental time to adjust the content of the nickel black-graphene composite material on the foamed nickel;

(4) Wash the plated nickel black-graphene light-to-heat conversion film in deionized water, take it out and dry it in an oven at 60°C for 12 hours.

Figure 1, Figure 2 and Figure 3 are the SEM, XRD and Raman diagrams of the nickel black-graphene composite light-to-heat conversion film, respectively. The existence of graphene and nickel black on the surface of the film can be clearly seen through the SEM image, and the characteristic peaks of nickel and graphene can be seen through the XRD and Raman images, which can effectively prove that the nickel black-graphene composite film is effectively prepared .

2. Experimental process:

The nickel black-graphene composite light-to-heat conversion film prepared above with an effective film area of 9 ^cm2 was placed on an evaporation cup with a concentration of 30 g/L NaCl solution, and was irradiated with simulated sunlight with a light intensity of 1 sun. Weigh the initial weight and end weight of the evaporation cup to calculate the vapor permeability.

Example 1

Add 1.32g of ammonium sulfate and 0.42g of nickel sulfate to 200ml of deionized water, and keep stirring at room temperature until fully dissolved to form an electrolyte solution; connect the foamed nickel to the cathode and the graphite foil to the anode, and connect the connected Adjust the electrode distance and put it into the electrolyte; turn on the switch of the external DC power supply, and react at 13V for 10 minutes; wash the plated nickel black-graphene light-to-heat conversion film in deionized water, take it out and bake it in an oven at 60°C Let dry for 12 hours. Placed on the evaporation cup under the light of 1 sun, the light-steam energy conversion efficiency is 136.94%, and the vapor permeability is 2.00 kg/m ² ·h.

Example 2

Add 1.32g of ammonium sulfate and 0.42g of nickel sulfate to 200ml of deionized water, and keep stirring at room temperature until fully dissolved to form an electrolyte solution; connect the foamed nickel to the cathode and the graphite foil to the anode, and connect the connected Adjust the electrode distance and put it into the electrolyte; turn on the switch of the external DC power supply, and react at 13V for 20 minutes; wash the plated nickel black-graphene photothermal conversion film in deionized water, take it out and bake it in an oven at 60°C Let dry for 12 hours. Placed on the evaporation cup under the light of 1 sun, the light-steam energy conversion efficiency is 138.49%, and the vapor permeability is 2.02 kg/m ² ·h.

Example 3

Add 1.32g of ammonium sulfate and 0.42g of nickel sulfate to 200ml of deionized water, and keep stirring at room temperature until fully dissolved to form an electrolyte solution; connect the foamed nickel to the cathode and the graphite foil to the anode, and connect the connected Adjust the distance between the electrodes and put them into the electrolyte; turn on the switch of the external DC power supply, and react at 13V for 30 minutes; wash the plated nickel black-graphene light-to-heat conversion film in deionized water, take it out and bake it in an oven at 60°C Let dry for 12 hours. Placed on the evaporation cup under the light of 1 sun, the light-steam energy conversion efficiency is 162.48%, and the vapor permeability is 2.37 kg/m ² ·h.

Example 4

Add 1.32g of ammonium sulfate and 0.42g of nickel sulfate to 200ml of deionized water, and keep stirring at room temperature until fully dissolved to form an electrolyte solution; connect the foamed nickel to the cathode and the graphite foil to the anode, and connect the connected Adjust the distance between the electrodes and put them into the electrolyte; turn on the switch of the external DC power supply, and react at 13V for 40 minutes; wash the plated nickel black-graphene photothermal conversion film in deionized water, take it out and bake it in an oven at 60°C Let dry for 12 hours. Placed on the evaporation cup under the light of 1 sun, the light-vapor energy conversion efficiency is 140.37%, and the vapor permeability is 2.05 kg/m ² ·h.

Comparative example 1:

Irradiate the evaporation cup with a concentration of 30g/L NaCl solution without a film on it with simulated sunlight with a light intensity of 1 sun. The initial weight and end weight of the evaporation cup were weighed, and the light-to-steam energy conversion efficiency was calculated to be 50.89%, and the vapor permeability was 0.75k g/m ² ·h.

Comparative example 2:

Add 1.32g of ammonium sulfate to 200ml of deionized water, and continue to stir at room temperature until fully dissolved to form an electrolyte solution; connect the foamed nickel to the cathode, and connect the two nickel plates to the anodes on the left and right sides of the foamed nickel respectively. Adjust the distance between the connected electrodes and put them into the electrolyte; turn on the external DC power supply and electrolyze for 20 minutes at 15V; wash the plated nickel black light-to-heat conversion film in deionized water, take it out and dry it in an oven at 60°C 12 hours. Under the light of 1 sun, the light-steam energy conversion efficiency is 91.87%, and the vapor permeability is 1.07kg/m ² ·h.

Comparative example 3:

Add 1.32g of ammonium sulfate into 200ml of deionized water, and continue to stir at room temperature until fully dissolved to form an electrolyte solution; put graphite foil on the cathode and anode respectively, and after peeling off for 1 hour, the obtained graphene is suction-filtered into a graphene film . Under the light of 1 sun, the light-steam energy conversion efficiency is 81.20%, and the vapor permeability is 1.19kg/m ² ·h.

in conclusion:

It can be seen from Table 1 that compared with nickel black film and graphene film, nickel black-graphene composite light-to-heat conversion film has achieved a synergistic promotion effect, and has a better effect in seawater desalination, and the electrolysis time is 30min The light-to-vapor energy conversion efficiency and vapor permeability of the film are maximized.

Table 1 The vapor permeability of nickel black-graphene composite light-to-heat conversion film with an effective film area of 9 cm ² and the comparative example under 1 sun light

membrane Comparative example 1 (without film) Comparative example 2 (nickel black film) Comparative example 3 (graphene film) 10min 20min 30min 40min <![CDATA[Steam Permeability (kg/m²·h)]]> 0.75 1.07 1.19 2.00 2.02 2.37 2.05

Claims (3)

1. The preparation method of the nickel black-graphene composite photo-thermal conversion film is characterized by comprising the following steps of:

(1) Adding a certain amount of ammonium sulfate and nickel sulfate into deionized water, and continuously stirring until the ammonium sulfate and the nickel sulfate are fully dissolved to form electrolyte with the concentration of ammonium sulfate of 0-0.2M and the concentration of nickel sulfate of 0-0.08M;

(2) Using foam nickel as a cathode and graphite foil as an anode, and adjusting the distance between electrodes in electrolyte to be 0.5-2 cm;

(3) Under the direct-current voltage of 5-15V, the gas and hydroxyl radicals generated by the electrolyte have intercalation effect on the graphite foil of the anode, so that the graphene is peeled from the anode into the electrolyte; meanwhile, nickel ions in the electrolyte transfer graphene stripped from the anode to the cathode under the action of an electric field force, and the nickel ions are reduced at the cathode; under the high current density generated by high voltage, the nickel-graphene composite deposition layer deposited on the cathode is burnt to form a nickel black-graphene composite photo-thermal conversion film;

(4) Adjusting the concentration of the electrolyte, the deposition voltage and the deposition time to control the component content of nickel black and graphene in the nickel black-graphene composite material on the cathode;

(5) And after electrodeposition for 5-40 minutes, the nickel black-graphene photo-thermal conversion film is fully cleaned in deionized water, and is taken out and dried in a 60 ℃ oven for 12 hours.

2. The method for preparing the nickel black-graphene photothermal conversion film according to claim 1, wherein graphene and nickel black are simultaneously deposited on the cathode by a one-step electrochemical method.

3. The nickel black-graphene composite photo-thermal conversion film obtained by the preparation method of claim 1 is applied to solar-driven seawater desalination and other water treatment processes.

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