METHOD FOR PREPARING CARBON NANODOT-MODIFIED NICKEL PHOSPHIDE NANOSHEET AND USE THEREOF IN WATER ELECTROLYSIS

Abstract

The present disclosure discloses a method for preparing a carbon nanodot-modified nickel phosphide nanosheet and a use thereof as auxiliary materials in water electrolysis. The preparation steps include: preparing water solution containing carbon nanodots; attaching the carbon nanodots to the surface of a hydrogen-producing electrode in water electrolysis; and annealing the hydrogen-producing electrode with carbon nanodots. The carbon nanodots obtained by this preparation method have extremely small sizes and relatively uniform diameters, facilitating the attachment with other materials, and the integration of these carbon nanodots with the hydrogen-producing electrode in water electrolysis significantly enhances the hydrogen production efficiency, substantially reducing the cost required for hydrogen production through water electrolysis.

Claims

1. A method for preparing a carbon nanodot-modified nickel phosphide nanosheet, comprising the following steps: S1: providing two graphite rods as positive and negative electrodes and deionized water as electrolyte, and applying a voltage of 20-25 V between the two graphite electrodes, by a constant voltage power supply, for 100-120 hours to obtain carbon nanodot solution; S2: immersing an array of Ni.sub.5P.sub.4 nanosheets into the carbon nanodot solution for a few seconds, then removing them for naturally drying; S3: placing the Ni.sub.5P.sub.4 nanosheets with carbon nanodots in a tube furnace, adjusting internal atmosphere of the tube furnace with argon gas, and heating the tube furnace to 480? C.-500? C. and maintaining it for 50-60 minutes, then cooling to obtain carbon nanodot-modified Ni.sub.5P.sub.4 nanosheets.

2. The method for preparing the carbon, nanodot-modified nickel phosphide nanosheet of claim 1, wherein, applying a voltage of 25 V between the two graphite electrodes, by the constant voltage power supply, for 120 hours.

3. The method for preparing the carbon nanodot-modified nickel phosphide nanosheet of claim 1, wherein, heating the tube furnace to 500? C. and maintaining it for 60 minutes.

4. A use of the carbon nanodot-modified nickel phosphide nanosheet of claim 1, wherein, the carbon nanodot-modified nickel phosphide nanosheet is directly employed as a water electrolysis cathode of a water electrolysis device, the water electrolysis device comprises the carbon nanodot-modified Ni.sub.5P.sub.4 nanosheet, a graphite paper counter-electrode, an Hg/HgO reference electrode, and potassium hydroxide electrolyte, wherein the potassium hydroxide electrolyte has a pH value of 14.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0015] FIG. 1 is a transmission electron microscope image of the carbon nanodots in the present disclosure; and

[0016] FIG. 2 is a polarization curve of a Ni.sub.5P.sub.4 nanosheet cathode for water electrolysis, modified with carbon nanodots in the present disclosure.

DETAILED DESCRIPTION

[0017] The technical solutions in the embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present disclosure. Apparently, the described embodiments are only part of the embodiments of the present disclosure, not all of them. Based on the embodiments of the present disclosure, all other embodiments obtained by those skilled in the art without inventive effort shall fall within the scope of protection of the present disclosure.

[0018] The present disclosure relates to a method for preparing a carbon nanodot-modified nickel phosphide nanosheet and a use thereof in terms of the cathode for water electrolysis, which includes the following steps: [0019] Step S1: Utilizing, two graphite rods as an anode and cathode, with deionized water serving as electrolyte, applying a voltage of 20-25 V between the two graphite electrodes using a constant voltage power supply, and continuing this for 100-120 hours to ultimately obtain a carbon nanodot solution. [0020] Step S2: Immersing an array of Ni.sub.5P.sub.4 nanosheets into the carbon nanodot solution for a few seconds, then removing them, for naturally drying. [0021] Step S3: Placing the carbon nanodot-attached Ni.sub.5P.sub.4 nanosheets at a central position within a tube furnace. Adjusting the internal atmosphere of the tube furnace with argon gas. Heating the central position of the tube furnace to 480-500? C. and maintaining it for 50-60 minutes. After cooling, stable carbon nanodot-modified Ni.sub.5P.sub.4 nanosheets are obtained.

[0022] In some embodiments, applying a voltage of 25 V between the two graphite electrodes using the constant voltage power supply, and continuing for 120 hours to obtain the carbon nanodot solution.

[0023] In some embodiments, heating the central position of the tube furnace to 500? C. and maintaining for 60 minutes to obtain the stable carbon nanodot-modified Ni.sub.5P.sub.4 nanosheet.

[0024] In some embodiments, the carbon nanodot-modified nickel phosphide nanosheet can be directly employed as the cathode for water electrolysis in a water electrolysis device/system, the water electrolysis device comprises the carbon nanodot-modified Ni.sub.5P.sub.4 nanosheet cathode for water electrolysis, a graphite paper counter-electrode, an Hg/HgO reference electrode, and a potassium hydroxide electrolyte, wherein the graphite paper can be replaced by other materials with similar electrochemical performance for the water electrolysis anode, and the pH value of the potassium hydroxide electrolyte is 14.

[0025] In some embodiments, carbon nanodot solution is obtained by the method for preparing the carbon nanodot-modified nickel phosphide nanosheet. The obtained carbon nanodot has a uniform size, with a diameter of approximately 5 nm, making it suitable for integration with other cathodes for water electrolysis. As shown in FIG. 2, the curvature of the corresponding curve for the Ni.sub.5P.sub.4 nanosheets modified with carbon nanodots is much higher than that of the corresponding curve for the Ni.sub.5P.sub.4 nanosheets, indicating that under the same applied voltage conditions, the Ni.sub.5P.sub.4 nanosheets modified with carbon nanodots result in higher current density, thus producing more hydrogen gas. That is, the obtained Ni.sub.5P.sub.4 nanosheets modified with carbon nanodots only require a relative potential of 63 mV to reach a current density of 10 mA/cm.sup.2, which is significantly lower than the 94 mV required by the conventional Ni.sub.5P.sub.4 nanosheets to reach a current density of 10 mA/cm.sup.2.

[0026] Although the present disclosure has been described in detail with reference to the foregoing embodiments, it should not be understood, as limiting the scope of the disclosure. Any modification and variation that can be made by those skilled in the art within the scope of the claims without inventive effort are still within the scope of protection.