CN-122006771-A - Manganese-loaded gallium nitride nanowire photocatalyst, preparation method thereof and seawater photocatalytic conversion method

Abstract

The invention belongs to the technical field of photocatalysis, and in particular relates to a manganese-loaded gallium nitride nanowire photocatalyst, a preparation method thereof and a seawater photocatalytic conversion method, wherein the photocatalyst comprises a silicon substrate; and the manganese species are uniformly deposited on the surface of the gallium nitride nanowire, wherein the manganese species are MnO x (OH) y in which a plurality of Mn oxidation states coexist. Compared with the prior art, the invention solves the problems of high cost and low benefit existing in the prior art that noble metal is adopted as the photocatalyst. According to the scheme, manganese (Mn) nano particles are deposited on gallium nitride (GaN) nano wires of a silicon wafer substrate, a multifunctional catalytic system is constructed, and oxidation-reduction reactions in a water splitting process are driven together, so that the catalytic efficiency and long-term stability of the system are remarkably improved.

Inventors

• ZHOU BAOWEN
• LI YUMENG

Assignees

• 上海交通大学

Dates

Publication Date

20260512

Application Date

20250908

Claims (10)

1. 1. A manganese-supported gallium nitride nanowire photocatalyst, comprising: A silicon substrate; Gallium nitride nanowires vertically arranged on the surface of the silicon substrate; And the manganese species are uniformly deposited on the surface of the gallium nitride nanowire, wherein the manganese species are MnO x (OH) y in which a plurality of Mn oxidation states coexist.
2. 2. The manganese-supported gallium nitride nanowire photocatalyst according to claim 1, wherein the coverage rate of the gallium nitride nanowire on the silicon substrate is 0.2-0.4, and/or, The average height of the gallium nitride nanowire is 690-720nm.
3. 3. A manganese-supported gallium nitride nanowire photocatalyst according to claim 1, wherein the average size of the manganese species is 2-4nm, and/or, The deposition amount of the manganese species is not more than 0.322 mu mol cm -2 .
4. 4. A method for preparing the manganese-supported gallium nitride nanowire photocatalyst according to any one of claims 1 to 3, comprising the steps of: S1, growing gallium nitride nanowires on the surface of a silicon substrate in a mode of radio frequency plasma assisted molecular beam epitaxial growth under a nitrogen-rich condition; s2, using manganese sulfate aqueous solution as a precursor, and depositing manganese species on the surface of the gallium nitride nanowire under the irradiation condition of a full spectrum xenon lamp by a photochemical deposition method.
5. 5. The method for preparing a manganese-supported gallium nitride nanowire photocatalyst according to claim 4, wherein in step S1, the silicon substrate is degassed at 800 ℃ for 30 minutes.
6. 6. The method for preparing a manganese-supported gallium nitride nanowire photocatalyst according to claim 4, wherein in step S1, the rf plasma assists in molecular beam epitaxy: generating nitrogen plasma as a nitrogen source by a radio frequency power supply of 400W, and/or, A dual filament knudsen cell was used as the gallium source, and/or, The nitrogen flow rate was 1sccm, and/or, The gallium source vapor pressure is 5 x 10 -7 torr, and/or, The elemental ratio of nitrogen element to gallium element is 0.2, and/or, The growth temperature is 600 ℃, and/or, The growth rate of the gallium nitride nanowire is 300nm/h.
7. 7. The method for preparing a manganese-supported gallium nitride nanowire photocatalyst according to claim 4, wherein in step S2, the photochemical deposition method is as follows: the power of the full spectrum xenon lamp is 300W, and/or, Taking a mixed solution of methanol and water with the volume ratio of 1:5 as a light deposition medium, and/or, In a saturated argon atmosphere, and/or, The deposition time was 30 minutes.
8. 8. A method for photocatalytic conversion of seawater, comprising the steps of: Under the condition of no oxygen and illumination, the seawater is decomposed to prepare hydrogen under the catalysis of the photocatalyst as claimed in any one of claims 1-3.
9. 9. The method for photocatalytic conversion of seawater as recited in claim 8, wherein the irradiation intensity of the light under the irradiation condition is 2-6W cm -2 .
10. 10. The method for photocatalytic conversion of seawater as claimed in claim 8, wherein the hydrogen generation rate of the decomposed hydrogen production is 15.2mol g -1 ·h -1 under the illumination condition of 3.3W cm -2 , and the light-hydrogen conversion efficiency of the decomposed hydrogen production is 6.15%.

Description

Manganese-loaded gallium nitride nanowire photocatalyst, preparation method thereof and seawater photocatalytic conversion method Technical Field The invention belongs to the technical field of photocatalysis, and particularly relates to a manganese-loaded gallium nitride nanowire photocatalyst, a preparation method thereof and a seawater photocatalytic conversion method. Background The hydrogen energy is regarded as a clean energy carrier with the most potential because of the remarkable advantages, namely the hydrogen energy has the mass energy density of 142MJ/kg (about 3 times of that of traditional fossil fuel) and has outstanding energy storage advantages, and the hydrogen energy can realize full life cycle carbon neutralization by electrolyzing water through renewable energy sources, and the combustion product is only water, so that the problem of carbon emission is fundamentally avoided. However, the hydrogen yield of about 96% of the world still depends on the traditional technologies such as methane steam reforming (SMR) and coal gasification, and the technologies not only consume a large amount of stone raw materials, but also involve severe thermodynamic conditions such as high temperature and high pressure, and have inherent defects such as low energy efficiency, high carbon emission intensity and the like. Therefore, the development of renewable energy-driven green hydrogen production technology has become a critical path for breaking through energy conversion bottlenecks. Sunlight and water are used as natural resources which are most abundant, clean and renewable on earth, and an ideal foundation is provided for sustainable energy development. Among them, solar-driven water splitting technology provides a very promising solution for green hydrogen energy production and intermittent solar energy storage. In this system, the properties of the semiconductor material and the promoter directly determine photon absorption efficiency, carrier transport characteristics, and surface reaction kinetics, and thus become key factors in determining water splitting efficiency. The main challenges of current research are to explore semiconductor materials with excellent properties, develop efficient cocatalysts, and achieve reasonable synergy of the two. However, conventional water splitting systems are generally faced with inefficiency caused by too fast a photon-generated carrier recombination rate. Natural seawater provides a promising raw material for hydrogen production due to its richness. However, to date, the number of successful attempts to produce hydrogen by photocatalytic seawater cracking has been limited due to the problems of 1) competing anodic chlorine generating reactions (2cl—2e=cl 2, potential 1.49V versus standard hydrogen electrode), 2) severe corrosion of the photocatalyst by seawater impurities, and 3) the use of sacrificial reagents has been essential in photocatalytic seawater cracking reported to date. Furthermore, noble metal-based catalysts are often indispensable for the redox reaction of the overall water splitting in order to accelerate the slow kinetics, which is disadvantageous for the commercialization of this technology. By exploring a reasonable photocatalyst, achieving high efficiency, long-term stability and cost effectiveness of photocatalytic hydrogen production from seawater is a strong desire to break the above-mentioned bottlenecks. In recent years, vertically aligned gallium nitride (GaN) nanowires based on silicon substrates, i.e., gaN/Si nanowire structures, have been developed as research hotspots for new semiconductor platforms by virtue of their unique structural features, excellent photoelectric properties, and excellent catalytic activity. The nano structure provides an ideal semiconductor material system for solar driven water splitting technology by effectively solving the key scientific problems of low light capturing efficiency, high carrier recombination rate, slow surface reaction kinetics and the like commonly existing in the traditional photocatalytic material. As CN119746906a discloses a palladium-supported gallium nitride nanowire photocatalyst, a preparation method and application thereof, the palladium-supported gallium nitride nanowire photocatalyst comprises a silicon substrate, gallium nitride nanowires vertically grown on the silicon substrate, and palladium nanoparticles uniformly supported on the surfaces of the gallium nitride nanowires. However, the noble metal palladium is still adopted in the photocatalyst proposed by the scheme to realize the photocatalytic decomposition of the seawater, which hinders the reserve, the production quantity and the price of the palladium, so that the noble metal-based catalyst is difficult to meet the requirement of being applied to the hydrogen production by the photocatalytic decomposition of the seawater in a large scale, long-term and continuous manner with high benefit. Disclosure of Invention The