CN103111285B - Visible light-responsive composite oxide photocatalyst LiBiMo2O8 and its preparation method - Google Patents

Abstract

The invention discloses a visible light responsive composite oxide photocatalyst LiBiMo ₂ O ₈ and a preparation method thereof. The chemical composition formula of the composite oxide photocatalyst is: LiBiMo ₂ O ₈ . The invention also discloses the preparation method of the above-mentioned materials: (1) weighing and compounding 99.9% analytically pure chemical raw materials Li ₂ CO ₃ , Bi ₂ O ₃ and MoO ₃ according to the chemical formula of LiBiMo ₂ O ₈ ; (2) mixing the steps ( 1) Mix the prepared raw materials, put them into a ball mill jar, add zirconia balls and absolute ethanol, ball mill for 8 hours, mix and grind, take out and dry, and pass through a 200-mesh sieve; (3) The powder obtained in step (2) The material is pre-fired at 500-520°C, kept at a temperature of 6 hours, cooled to room temperature naturally, and then ball milled to make the particle diameter smaller than 2 μm, and the composite oxide LiBiMo ₂ O ₈ powder is obtained. The preparation method of the invention is simple and low in cost, and the prepared photocatalyst has excellent catalytic performance, has the function of decomposing harmful chemical substances under visible light irradiation, has good stability, and has good application prospects.

Description

Visible light-responsive composite oxide photocatalyst LiBiMo2O8 and its preparation method

technical field

The invention relates to a visible light-responsive composite oxide photocatalyst LiBiMo ₂ O ₈ and a preparation method thereof, belonging to the field of inorganic photocatalytic materials.

Background technique

Environmental pollution is a matter of great concern to all countries in the world. It has led to the continuous decline in the quality of people's drinking water and industrial water sources, resulting in increasing air pollution, resulting in continuous destruction of the ecological environment, and posing a serious threat to human survival. In order to solve these problems, people control and control environmental pollution through various methods.

Since the end of the 1970s, people have proposed the use of photocatalysts to decompose organic substances such as pesticides and odorous substances in water and the atmosphere, as well as self-cleaning of solid surfaces coated with photocatalysts; at present, the photocatalysts used are mainly titanium dioxide. Titanium dioxide is used to decompose organic substances such as pesticides and odorous substances in water and the atmosphere. However, the band gap of titanium dioxide is 3.2eV, and it can only show activity under the irradiation of ultraviolet rays shorter than 400nm. It can only be used indoors or with ultraviolet lamps. Working in places where visible light can hardly be utilized, this greatly limits the use of titanium dioxide photocatalysts.

Considering the practicability of photocatalysts in decomposing harmful substances, it is indispensable to use sunlight as a light source. Among the sunlight irradiated to the surface, the intensity of visible light with a wavelength near 500nm is the highest, and the energy in the visible light region with a wavelength of 400nm-750nm is about It is 43% of the total energy of sunlight, so in order to efficiently use the solar spectrum, people have paid attention to finding photocatalysts with visible light responses. The development and research of some composite oxide photocatalysts have achieved a series of significant results, such as BiVO ₄ , Bi ₂ WO ₄ and Bi ₂ MoO ₆ are reported to have good absorption under visible light.

The types of photocatalysts with visible light response reported at present are still very limited, so it is necessary to research and develop new high-efficiency photocatalysts with visible light response. The literature [Di Zhou, Clive A. Randall, Hong Wang, etc. Microwave Dielectric Ceramics in Li ₂ O–Bi ₂ O ₃ –MoO ₃ System with Ultra-Low Sintering Temperatures, Journal of the American Ceramic Society. 2010, 93(4):1096–1100] reported the preparation and structure of composite oxide LiBiMo ₂ O ₈ ceramics Considering that there is no research report on the photocatalytic performance of this compound, we conducted a photocatalytic performance study on LiBiMo ₂ O ₈ and found that the compound has excellent photocatalytic performance in response to visible light.

Contents of the invention

The object of the present invention is to provide a visible light responsive composite oxide photocatalyst LiBiMo ₂ O ₈ and a preparation method thereof.

The chemical composition formula of the composite oxide photocatalyst with visible light response involved in the present invention is: LiBiMo ₂ O ₈ .

The specific steps of the preparation method of the composite oxide are:

(1) The 99.9% analytically pure chemical raw materials Li ₂ CO ₃ , Bi ₂ O ₃ and MoO ₃ were weighed and dosed according to the chemical formula of LiBiMo ₂ O ₈ .

(2) Mix the raw materials prepared in step (1), put them into a ball mill jar, add zirconia balls and absolute ethanol, ball mill for 8 hours, mix and grind until fine, take it out and dry it, and pass through a 200-mesh sieve.

(3) Pre-fire the powder obtained in step (2) at 500-520°C, keep it warm for 6 hours, cool it down to room temperature naturally, and then pass it through a ball mill to make the particle diameter smaller than 2 μm, and then obtain the composite oxide LiBiMo ₂ O ₈ powder.

The preparation method of the invention is simple and the cost is low, and the prepared photocatalyst has excellent catalytic performance, and has the functions of decomposing harmful chemical substances, organic biomass and sterilizing under the irradiation of visible light.

Detailed ways

The present invention will be described in detail below:

1. In order to obtain the composite oxide used in the present invention, first use solid-phase synthesis to prepare powder, that is, mix various oxides or carbonates as raw materials according to the stoichiometric ratio of the target composition, and then mix them under normal pressure Synthesized in air atmosphere.

2. In order to effectively utilize light, the size of the photocatalyst in the present invention is preferably at the micron level, even nanoparticles, and has a larger specific surface area; the oxide powder prepared by the solid-phase synthesis method has larger particles and a larger surface area. Smaller, but the particle diameter can be reduced by crushing means such as a ball mill.

3. In the photocatalytic experiment of the present invention, methyl orange is used as a simulated organic pollutant, and its concentration is 20 mg/L; the addition amount of the composite oxide photocatalyst LiBiMo ₂ O ₈ is 1 g/L; the light source uses a 300W xenon lamp, and the reaction tank A vessel made of borosilicate glass is used to obtain light with a wavelength greater than 420nm through a filter, and then irradiate the photocatalyst; the catalytic time is set to 120 minutes.

Example 1:

(1) The 99.9% analytically pure chemical raw materials Li ₂ CO ₃ , Bi ₂ O ₃ and MoO ₃ were weighed and dosed according to the chemical formula of LiBiMo ₂ O ₈ .

(2) Mix the raw materials prepared in step (1), put them into a ball mill jar, add zirconia balls and absolute ethanol, ball mill for 8 hours, mix and grind until fine, take it out and dry it, and pass through a 200-mesh sieve.

(3) Pre-fire the powder obtained in step (2) at 500°C, keep it warm for 6 hours, cool it down to room temperature naturally, and then mill it with a ball mill to make the particle diameter smaller than 2 μm, and then obtain the composite oxide LiBiMo ₂ O ₈ powder.

The prepared photocatalyst can remove 98.7% of methyl orange in 120 minutes under the irradiation of visible light with a wavelength greater than 420nm.

Example 2:

(1) The 99.9% analytically pure chemical raw materials Li ₂ CO ₃ , Bi ₂ O ₃ and MoO ₃ were weighed and dosed according to the chemical formula of LiBiMo ₂ O ₈ .

(2) Mix the raw materials prepared in step (1), put them into a ball mill jar, add zirconia balls and absolute ethanol, ball mill for 8 hours, mix and grind until fine, take it out and dry it, and pass through a 200-mesh sieve.

(3) Pre-fire the powder obtained in step (2) at 510°C, keep it warm for 6 hours, cool it down to room temperature naturally, and then pass it through a ball mill to make the particle diameter smaller than 2 μm, and then obtain the composite oxide LiBiMo ₂ O ₈ powder.

The prepared photocatalyst can remove 99.3% of methyl orange in 120 minutes under the irradiation of visible light with a wavelength greater than 420nm.

Example 3:

(1) The 99.9% analytically pure chemical raw materials Li ₂ CO ₃ , Bi ₂ O ₃ and MoO ₃ were weighed and dosed according to the chemical formula of LiBiMo ₂ O ₈ .

(2) Mix the raw materials prepared in step (1), put them into a ball mill jar, add zirconia balls and absolute ethanol, ball mill for 8 hours, mix and grind until fine, take it out and dry it, and pass through a 200-mesh sieve.

(3) Pre-fire the powder obtained in step (2) at 520°C, keep it warm for 6 hours, cool it down to room temperature naturally, and then pass it through a ball mill to make the particle diameter smaller than 2 μm, and then obtain the composite oxide LiBiMo ₂ O ₈ powder.

The prepared photocatalyst can remove 99.0% of methyl orange in 120 minutes under the irradiation of visible light with a wavelength greater than 420nm.

The present invention is by no means limited to the above examples. Elements with similar structures and chemical properties to Bi, such as La, Nd, Sm, and Eu, and elements with similar structures and chemical properties to Mo, such as W and Cr, can also make photocatalysts with similar crystal structures and properties to the present invention. The upper and lower limits and interval values of each process parameter (such as temperature and time, etc.) can realize the present invention, and the examples are not listed here.

The photocatalyst powder prepared in the above invention examples can be loaded on the surface of various substrates. The substrate can be glass, ceramics, activated carbon, quartz sand, etc., and the photocatalyst can be loaded on the surface of the substrate in the form of a thin film.

Claims (1)

1. composite oxides are as an application for visible light-responded photochemical catalyst, it is characterized in that the chemical constitution formula of described composite oxides is: LiBiMo ₂o ₈;

Preparation method's concrete steps of described composite oxides are:

(1) by 99.9% analytically pure chemical raw material Li ₂cO ₃, Bi ₂o ₃and MoO ₃by LiBiMo ₂o ₈chemical formula weigh batching;

(2) raw material mixing step (1) prepared, put into ball grinder, add zirconia ball and absolute ethyl alcohol, ball milling 8 hours, is mixed and finely ground, and takes out and dries, and crosses 200 mesh sieves;

(3) by step (2) gained powder 500 ~ 520 DEG C of pre-burnings, and be incubated 6 hours, naturally cool to room temperature, then by ball mill ball milling, particle diameter is diminished, lower than 2 μm, namely obtain composite oxides LiBiMo ₂o ₈powder.