阅读说明：本技术 一种掺杂石墨状氮化碳材料的制备方法 (Preparation method of doped graphite-like carbon nitride material ) 是由 江治 戚荣杰 于 2018-08-07 设计创作，主要内容包括：本发明公开了一种掺杂石墨状氮化碳材料的制备方法；采用具有升华或低沸点特性的金属有机物(如乙酰丙酮配合物、双(2,2,6,6-四甲基-3,5-庚二酮)化铜、双(六氟乙酰丙酮)合铜、二茂铁,甲酸铜、金属羰基化合物)在石墨状氮化碳富氮前驱体的缩聚过程进行金属离子与阴离子气相共掺杂调控；加热缩聚过程中,金属有机盐和石墨状氮化碳的前驱体分区,控制压力为0.1-20MPa,升温速率为1-30℃/min,在450-600℃下保温2-6h,即得所述石墨状氮化碳。本方法基于气相共掺杂方法,可高效、快速得到多级孔结构的掺杂后石墨状氮化碳；所得材料对水的光催化分解和有机物的催化降解具有很高的活性。(The invention discloses a preparation method of a doped graphite-like carbon nitride material; metal ions and anions are subjected to gas-phase co-doping regulation and control in the condensation polymerization process of the graphite-like carbon nitride nitrogen-rich precursor by adopting metal organic matters with sublimation or low boiling point characteristics (such as acetylacetone complexes, bis (2,2,6, 6-tetramethyl-3, 5-heptanedionato) copper, bis (hexafluoroacetylacetone) copper, ferrocene, copper formate and metal carbonyl compounds); in the heating polycondensation process, the precursor of the metal organic salt and the graphite-like carbon nitride is partitioned, the pressure is controlled to be 0.1-20MPa, the heating rate is 1-30 ℃/min, and the heat is preserved for 2-6h at the temperature of 450-600 ℃ to obtain the graphite-like carbon nitride. The method is based on a gas-phase co-doping method, and can efficiently and quickly obtain doped graphite-like carbon nitride with a hierarchical pore structure; the obtained material has high activity on photocatalytic decomposition of water and catalytic degradation of organic matters.)

1. A method for preparing modified graphitic carbon nitride, comprising: taking organic metal salt with sublimation or low boiling point as a gas phase doping agent, and carrying out gas phase co-doping regulation and control on metal cations and organic anions in the heating polycondensation process of the graphite-shaped carbon nitride nitrogen-rich precursor; the heating polycondensation is to heat up to 450-600 ℃ at the heating rate of 1-30 ℃/min and keep the temperature for 2-6h under the condition that the reaction pressure is 0.1-20 MPa; in the heating polycondensation process, the organic metal salt and the graphite-shaped carbon nitride nitrogen-rich precursor are heated in a subarea mode.

2. The method of claim 1, wherein the nitrogen-rich precursor is selected from one or more of urea, melamine, dicyandiamide, cyanamide and thiourea.

3. The method for producing modified graphitic carbon nitride according to claim 1, wherein said organic metal salt is selected from one or more of acetylacetone complex, copper bis (2,2,6, 6-tetramethyl-3, 5-heptanedionate), copper bis (hexafluoroacetylacetone), ferrocene, copper formate, and metal carbonyl compound.

4. The method for preparing modified graphitic carbon nitride according to claim 1, wherein the mass ratio of said graphitic carbon nitride nitrogen-rich precursor to said organic metal salt as a gas-phase dopant is 50-10000: 1.

5. the method of claim 1, wherein the zoned heating comprises physical and/or temperature field zoning; the physical partition is that the graphite-shaped carbon nitride nitrogen-rich precursor and the organic metal salt are separated in a physical area, and mass transfer is completed by means of a gas phase diffusion process; the temperature field partition means that the temperature field areas of the graphite-like carbon nitride nitrogen-rich precursor and the organic metal salt are different, so that the gas-phase mass transfer diffusion rate is different.

6. Use of the modified graphitic carbon nitride prepared according to the preparation method of claim 1 in photocatalytic decomposition of water to produce hydrogen or photocatalytic decomposition of organic pollutants.

7. Use according to claim 6, wherein the photocatalytic decomposition of organic pollutants comprises photocatalytic decomposition of VOCs, S-VOCs.

Technical Field

The invention relates to preparation of graphite-phase carbon nitride, in particular to a one-step preparation method of a metal organic salt gas phase doping and regulation modified graphite-like carbon nitride material based on sublimation characteristics, which is used in the fields of hydrogen production by water decomposition by a photocatalytic technology and organic pollutant such as VOC and S-VOC decomposition by photocatalysis.

Background

In the modern society, among the ways to find renewable energy sources, the photocatalytic technology is considered as one of the most promising technologies for converting solar energy into hydrogen energy, and a feasible idea is provided for solving the environmental problem. Graphitic carbon nitride, as a non-metallic n-type semiconductor polymer, possesses a number of excellent electrical, optical and physicochemical properties. More and more attention is being paid to photocatalysts based on graphitic carbon nitride.

The modification around the graphite-like carbon nitride material is mainly embodied in the aspects of surface sensitization, heterojunction construction, defect construction, pore channel design and the like at present. The specific preparation method is embodied as a solvothermal method, a chemical vapor deposition method, an electrochemical deposition method, a thermal polycondensation method and the like. The thermal polycondensation method utilizes the pyrolysis nitrogen-rich organic matter to prepare the graphite-like carbon nitride through the self polycondensation process of the precursor, and has the advantages of simple and direct reaction process, low cost and small environmental pollution.

However, the graphite-like carbon nitride material prepared by traditional pyrolysis of nitrogen-rich organic matters has small specific surface area and low photocatalytic activity, and almost has no photocatalytic activity in a near infrared region.

The existing method for preparing the doped modified graphite-shaped carbon nitride material is complex in steps, and co-doping regulation and control of metal cations and anions are difficult to realize, so that the performance of the doped modified graphite-shaped carbon nitride material is limited. For example, the bimetallic ion doped graphite-like carbon nitride material mentioned in patent CN105214709B requires a series of complicated steps such as dissolving, stirring, drying, grinding and mixing, and co-doping of metal cations and anions cannot be controlled. Also, as the preparation method of the inorganic ion-doped carbon nitride photocatalyst mentioned in patent CN103301867A, the preparation process is also complicated, and the co-doping control of metal cations and anions cannot be realized only by considering the doping of specific ions.

Disclosure of Invention

The present invention aims to provide a one-step preparation method of a modified graphitic carbon nitride photocatalytic material (or doped graphitic carbon nitride material) capable of realizing environmental purification and solar energy chemical energy conversion, aiming at the defects of the prior art. During preparation, in the process of liquid phase polycondensation of the nitrogen-rich organic matter precursor, the products of gas phase decomposition and sublimation diffusion of the organic metal salt with sublimation or low boiling point characteristics can perform gas phase co-doping regulation and control of metal cations and anions on the formed graphite-shaped carbon nitride material, so that the photocatalytic activity of the prepared graphite-shaped carbon nitride material is improved. The method is simple, convenient and rapid, and the prepared metal and anion co-modified graphite-phase carbon nitride has high photocatalytic activity and high photon efficiency in a near infrared region, and can be used for hydrogen production by photolysis and degradation of organic pollutants, such as VOC, SVOC and other fields.

The purpose of the invention is realized by the following technical scheme:

the invention relates to a preparation method of modified graphite-like carbon nitride; the method comprises the following steps: taking organic metal salt with sublimation or low boiling point as a gas phase doping agent, and carrying out gas phase co-doping regulation and control on metal cations and organic anions in the heating polycondensation process of the graphite-shaped carbon nitride nitrogen-rich precursor; the heating polycondensation is to heat up to 450-600 ℃ at the heating rate of 1-30 ℃/min and keep the temperature for 2-6h under the condition that the reaction pressure is 0.1-20 MPa; in the heating polycondensation process, the organic metal salt and the graphite-shaped carbon nitride nitrogen-rich precursor are heated in a subarea mode.

In the above method, the temperature rise rate is controlled to be 1-30 ℃/min. Too high a temperature rise rate, e.g., above 30 deg.C/min, can reduce the crystallinity of the resulting modified graphite phase carbon nitride material, while too low a temperature rise rate, e.g., below 1 deg.C/min, can reduce the yield of the resulting modified graphite phase carbon nitride material.

The temperature is controlled to be 450-600 ℃. The control temperature is too low, e.g. below 450 ℃, the desired graphitic carbon nitride structure cannot be formed, and the control temperature is too high, e.g. above 600 ℃, the structure of the modified graphitic carbon nitride is destroyed due to thermal stability

The pressure is controlled to be 0.1-20 MPa. By controlling the control pressure within this range, the rates of gas phase diffusion and mass transfer can be regulated.

The heat preservation time is controlled to be 2-6 h. If the holding time is too short, for example, less than 2 hours, the crystallinity of the graphite-like carbon nitride structure is poor, and if the holding time is too long, for example, more than 6 hours, the structure of the modified graphite-like carbon nitride may be damaged due to thermal stability.

Preferably, the graphitic carbon nitride nitrogen-rich precursor is selected from one or more of urea, melamine, dicyandiamide, cyanamide and thiourea.

Preferably, the organic metal salt is selected from one or more of acetylacetone complex, bis (2,2,6, 6-tetramethyl-3, 5-heptanedionato) copper, bis (hexafluoroacetylacetonato) copper, ferrocene, copper formate, and metal carbonyl compound.

Preferably, the mass ratio of the graphite-like carbon nitride nitrogen-rich precursor to the organic metal salt is 50-10000: 1.

preferably, the zone heating comprises physical zone division and/or temperature field zone division; the physical partition is that the graphite-shaped carbon nitride nitrogen-rich precursor and the organic metal salt are separated in a physical area, and mass transfer is completed by means of a gas phase diffusion process; the temperature field partition means that the temperature field areas of the graphite-like carbon nitride nitrogen-rich precursor and the organic metal salt are different, so that the gas-phase mass transfer diffusion rate is different. Partitioning over a physical or temperature field can be achieved by placing the nitrogen-rich organic and the organometallic salt in separate vessels.

The invention also relates to application of the modified graphite-like carbon nitride prepared by the preparation method in hydrogen production by photocatalytic decomposition of water or organic pollutant photocatalytic decomposition.

Preferably, the photocatalytic decomposition of organic pollutants includes photocatalytic decomposition of VOCs, S-VOCs.

The technical principle of the invention is as follows: the nitrogen-rich organic matter undergoes a liquid phase process in the process of forming graphite-like carbon nitride through thermal polycondensation; and for organic metal salt with low boiling point or sublimation property, low boiling point or sublimation organic metal salt and decomposed gas phase products thereof, the gas phase co-doping of metal ions and anions can be realized in the process of nitrogen-rich organic matter liquid phase polycondensation, so that the photocatalytic activity of the graphite-like carbon nitride material is remarkably improved, and the graphite-like carbon nitride material also shows higher activity in a near infrared band.

Compared with the prior art, the invention has the following beneficial effects:

1) the mode of partitioned gas phase doping is adopted, the whole preparation process is realized in one step, and the method is simple, efficient, easy to operate and convenient for large-scale industrial production;

2) the raw material source is wide, the cost is low, and a complex pretreatment process is not needed;

3) the whole preparation process does not need to use organic solvents and protective gases, and is green and friendly;

4) the shape, structure and appearance of the modified graphite-like carbon nitride product can be regulated and controlled; by adjusting the proportion of the nitrogen-rich organic matter and the organic metal salt, graphite phase carbon nitride materials with different shapes and properties can be obtained;

5) the prepared graphite-phase carbon nitride co-modified by metal and anions has high photocatalytic activity and high photon efficiency in a near infrared region, and can be used for hydrogen production by photolysis and degradation of organic pollutants.

Drawings

Other features, objects and advantages of the invention will become more apparent upon reading of the detailed description of non-limiting embodiments with reference to the following drawings:

FIG. 1 is an XRD spectrum of a modified graphitic carbon nitride material prepared in example 1 of the present invention;

FIG. 2 is a TEM image of a modified graphitic carbon nitride material prepared in example 1 of the present invention;

FIG. 3 is a UV-VIS diagram of the modified graphitic carbon nitride material prepared in example 1 of the present invention.

Detailed Description

The present invention will be described in detail below with reference to specific embodiments and the accompanying drawings. The following examples will assist those skilled in the art in further understanding the invention, but are not intended to limit the invention in any way. It should be noted that variations and modifications can be made by persons skilled in the art without departing from the spirit of the invention. All falling within the scope of the present invention.