阅读说明：本技术 溴调节的生物质衍生氧还原及析氢催化剂制备方法和应用 (Preparation method and application of bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst ) 是由 吕雪慧 陈艳丽 肖作旭 于 2019-09-29 设计创作，主要内容包括：本发明属于能源材料领域,具体涉及一种溴调节的生物质衍生氧还原及析氢催化剂的制备方法,并将此催化剂材料在金属(锌)-空气电池中作为阴极材料的应用。采用一锅共热解的方法将5,10,15,20-四(4-溴苯基)卟啉钴化合物与蘑菇粉进行充分混合得到的前驱体在氮气氛围下进行煅烧,由于热解过程中溴物种的离去,制备得到了比表面积大(604m<Sup>2</Sup>/g),孔径分布均匀的催化剂材料。发明的该催化剂材料表现出高效的氧还原性能(半波电位为0.85V,优于商业铂碳0.83V,vs.RHE),析氢性能(电流密度为10mA cm<Sup>-2</Sup>时具有小的过电势0.22V,vs.RHE)以及高于商业铂碳的稳定性。将该催化剂材料组装成锌-空气电池,具有最大的输出功率为100mW/cm<Sup>2</Sup>,优于商业铂碳(最大输出功率为78mW/cm<Sup>2</Sup>)。(The invention belongs to the field of energy materials, and particularly relates to a preparation method of a bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst, and an application of the catalyst material as a cathode material in a metal (zinc) -air battery. Fully mixing 5,10,15, 20-tetra (4-bromophenyl) porphyrin cobalt compound and mushroom powder by adopting a one-pot co-pyrolysis method to obtain a precursor, calcining the precursor in a nitrogen atmosphere, and obtaining the product with a large specific surface area (604 m) due to the leaving of bromine species in the pyrolysis process 2 Per g), catalyst material with uniform pore size distribution. The catalyst material of the invention shows high-efficiency oxygen reduction performance (the half-wave potential is 0.85V and is 0.83V, vs. RHE better than commercial platinum carbon),hydrogen evolution Performance (Current Density 10mA cm) ‑2 Small overpotential 0.22V, vs. rhe) and higher stability than commercial platinum carbon. The catalyst material is assembled into a zinc-air battery with the maximum output power of 100mW/cm 2 Is superior to commercial platinum carbon (the maximum output power is 78 mW/cm) 2 )。)

1. A preparation method and application of a bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst are characterized in that the catalyst is prepared by self-assembling halogen bromine-substituted cobalt tetraphenylporphyrin on a nanosheet layer of biomass mushroom powder and further performing one-pot pyrolysis under the protection of inert gas;

the preparation method of the oxygen reduction and hydrogen evolution catalyst is characterized by comprising the following specific steps of:

(1) preparation of a porphyrin and mushroom powder self-assembly precursor: weighing tetrabromophenyl porphyrin cobalt (CoTBrPP, 50-200mg) and dissolving in a dichloromethane solvent (20ml), uniformly stirring, weighing mushroom powder (800-950mg) and adding into the solution, stirring the mixture overnight so that the two can be fully assembled, uniformly dispersing porphyrin molecules on a mushroom powder nanosheet layer, and performing rotary evaporation on the obtained mixture to remove the solvent, thus obtaining precursor solid powder;

(2) preparation of the carbon-based catalyst: weighing a certain amount of precursor powder, placing the precursor powder in a clean magnetic boat, placing the magnetic boat in a high-temperature tube furnace, performing nitrogen protection in the whole pyrolysis process, firstly performing temperature programming to 700-900 ℃ at a speed of 5 ℃/min, keeping for 2 hours, and then performing temperature programming to 25 ℃ at a speed of 5 ℃/min to obtain the biomass-derived carbon-based catalyst material.

2. The cobalt tetrabromophenylporphyrin compound of claim 1, which is a 5,10,15, 20-tetrakis (4-bromophenyl) porphyrin cobalt compound.

3. The bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst as claimed in claim 1, wherein the mass percentage of the tetrabromophenylporphyrin compound and the mushroom powder required for self-assembly of the precursor is 5% -20%, and the pyrolysis temperature is 700-.

4. A bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst as claimed in claim 1 characterized by exhibiting high efficiency oxygen reduction performance (half-wave potential of 0.85V, better than half-wave potential of 0.83V, vs. RHE for commercial Pt-C electrode) at different pH conditions, high stability (98% of original current retained after 15000s, better than commercial Pt-C electrode) and good hydrogen evolution performance (current density of 10mA cm)^-2Is small in timeOverpotential 0.22V, vs. rhe).

5. A bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst as recited in claim 1 wherein said catalyst is employed in a metal (zinc) -air battery.

Technical Field

The invention belongs to the field of energy materials, and particularly relates to a preparation method of a bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst, and an application of the catalyst material as an air cathode material in a metal (zinc) -air battery.

Background

High energy consumption, severe pollution and non-renewable fossil fuels do not meet the requirements of sustainable development in human society. With the development of human society, clean, high-capacity and renewable energy storage and conversion technologies, such as fuel cells, metal-air batteries and water-splitting systems, are expected to become alternatives to conventional fossil fuels. Electrochemical oxygen reduction reaction (1/2O) due to the presence of large overpotentials and slow kinetics₂+2H⁺→H₂O, ORR) and hydrogen evolution reaction (H)₂O→1/2O₂+H₂HER) as the core reaction of the above mentioned renewable energy technology determines the efficiency of the whole conversion system. However, an effective catalyst is required to overcome these disadvantages. The noble metals platinum (Pt) and platinum-based catalysts are by far the most desirable ORR and HER catalysts, but their large-scale use is severely hampered by the scarcity of Pt resources (37 ppb in the crust), high price (over 55% of the total equipment cost), poor stability and poor methanol tolerance. Therefore, the development of a non-noble metal catalyst with low cost, environmental friendliness and high efficiency to replace the Pt-based catalyst for ORR and HER is considered to be a feasible path for ultimately realizing large-scale application, and has important practical application value.

Currently, transition metal nitride/carbide (TMN/TMCs) modified carbon materials are among the non-noble metal catalysts being the most promising catalyst to replace Pt-based catalysts for ORR and HER because their density of states (DOS) is closer to the fermi level due to the shrinkage of the d-band of the transition metal in TMN/TMCs, thus making the electron donor more prone to adsorb oxygen. Besides good physical properties such as high hardness, high melting point and corrosion resistance, the materials also have good conductivity and stability, and the advantages enable the materials to have catalytic properties not only under single electrolyte conditions (only under alkaline conditions or only under acidic conditions), but also under the full pH value range, which provides a research basis for various energy conversion systems. However, the methods for preparing TMN and TMC are complex, and have very strict requirements on the conditions of instruments, and the cost of the instruments is high, and besides, the specific surface areas of the TMN and TMC are small, so that the mass transfer and electron transfer processes are not facilitated, therefore, the carbon material with large specific surface area and TMN/TMCs modification is developed and prepared by using biomass with low cost through a simple one-pot method, the precursor source is wide, and the prepared catalyst has high catalytic property under the condition of multiple pH values.

Disclosure of Invention

Aiming at the problems in the prior art and the application requirements in the research field, the invention provides a preparation method and application of a non-noble metal-based catalyst which has low cost, simple preparation process, large specific surface area and high catalytic activity (ORR and HER) in the full pH value range without additional activating agent.

The preparation method of the catalyst comprises the steps of firstly designing and synthesizing bromine-substituted phenyl porphyrin as an active center, selecting biomass mushroom as a main carbon source precursor, and dispersing uniform porphyrin compounds in a lamella structure of mushroom powder through a simple self-assembly process to obtain uniformly mixed porphyrin and mushroom powder precursor. The precursor is pyrolyzed, during the pyrolysis process, a uniform pore structure is generated in a mushroom lamellar structure due to volatilization of bromine species, and a bromine substituent is arranged at the periphery of a porphyrin activity center, so that active sites are exposed to the maximum degree while pores are generated, and the prepared catalyst has high-efficiency oxygen reduction and hydrogen precipitation capabilities. It can be applied to a metal (zinc) -air battery or the like as a catalyst for an air electrode.

The molecular structure schematic diagram of 5,10,15, 20-tetra (4-bromophenyl) porphyrin cobalt is as follows:

synthesis of 5,10,15, 20-tetrakis (4-bromophenyl) porphyrin cobalt (CoTBrPP):

step 1: 0.16mmol (149mg) of tetrabromobenzenyl free porphyrin and 1.60mmol (399mg) of cobalt acetate tetrahydrate are taken and added into a 250ml three-necked flask, and 80ml of N, N-dimethylformamide is added;

step 2: starting stirring and heating to 155 ℃, refluxing for eleven hours, stopping heating, and cooling the reaction to room temperature;

and step 3: carrying out reduced pressure distillation by using an oil pump, evaporating the N, N-dimethylformamide in the flask to dryness, adding deionized water into the evaporated flask, and generating a brownish red precipitate in the flask;

and 4, step 4: carrying out suction filtration on the obtained precipitate, washing with deionized water until the filtrate becomes colorless, and carrying out vacuum drying on the obtained crude product at 60 ℃;

and 5: the crude product was further recrystallized from chloroform/methanol (volume ratio 1:8) and then filtered, the red-brown precipitate on filter paper was collected, this recrystallization step was carried out twice, and the resulting product was dried overnight in a vacuum oven at 40 ℃ to give cobalt tetrabromophenylporphyrin (CoTBrPP) in 79% yield.

A method for preparing a bromine-modified biomass-derived carbon-based catalyst material, comprising the steps of:

step 1: grinding mushroom with planetary ball mill, sieving with 100 mesh sieve to obtain mushroom powder, washing mushroom powder with distilled water and ethanol respectively, and drying at 120 deg.C for 24 hr;

step 2: preparation of porphyrin and mushroom powder precursor: weighing CoTBrPP (50-200mg) and dissolving in a dichloromethane solvent (20ml), uniformly stirring, weighing mushroom powder (800-950mg) and adding into the solvent, stirring the mixture overnight so that the two can be fully assembled, uniformly dispersing porphyrin molecules on a mushroom powder nanosheet layer, and performing rotary evaporation on the obtained mixture to remove the solvent, thus obtaining precursor solid powder;

and step 3: preparation of the carbon-based catalyst: weighing a certain amount of precursor powder, placing the precursor powder into a clean magnetic boat, placing the magnetic boat into a high-temperature tube furnace, performing nitrogen protection in the whole pyrolysis process, firstly performing temperature programming at the rate of 5 ℃ per minute to 700-.

The invention relates to application of a bromine-regulated biomass-derived oxygen reduction and hydrogen evolution catalyst, which is mainly applied to a metal (zinc) -air battery as an air cathode electrode material.

The preparation method of the air cathode electrode comprises the following steps: mixing isopropanol and 5 wt% Nafion solution in a volume ratio of 10-25 to obtain a mixed solution, adding a small amount of ultrapure water for mixing, then weighing a biomass-derived carbon-based catalyst, dispersing the biomass-derived carbon-based catalyst in the mixed solution, spraying the biomass-derived carbon-based catalyst on an electrode substrate (the substrate is carbon paper or carbon cloth generally), and drying at room temperature to obtain the air cathode electrode, wherein the loading amount of the catalyst is as follows: 1mg/cm²。

The invention has the beneficial effects that: (1) the activating agent and the active center are designed on one porphyrin molecule for the first time, bromine species are evaporated from the porphyrin molecule along with the rise of temperature in the pyrolysis process, and the porphyrin molecule is uniformly dispersed in the mushroom powder lamellar structure, so that a uniform pore structure is formed on the mushroom powder lamellar structure, and the specific surface area of the carbon material is increased (604m²And/g) is more beneficial to mass transfer and electronic transmission processes. (2) The bromine substituent is arranged at the periphery of the porphyrin macrocycle, and the formed pore structure is near the active center of the macrocycle, so that the active sites are more effectively exposed while pores are formed, the active sites are more exposed, and the catalytic activity of the catalyst is increased. (3) The presence of bromine species promotes the formation of more transition metal nitrides and transition metal carbides in the carbon material, and the presence of this stable phase gives the catalyst higher stability and high catalytic activity over a variety of pH ranges. (4) The catalyst material of the invention shows high-efficiency oxygen reduction and hydrogen evolution performance, and the preferred half-wave potential of the oxygen reduction reaction of the catalyst is as follows: RHE of 0.85V vs. s is superior to that of commercial Pt-C catalyst of 0.83V, vs. RHE, the stability is much higher than that of commercial Pt-C catalyst, and the hydrogen evolution is carried out at the current density of 10mA cm^-2Has small over potential of 0.22V (vs. RHE), and the zinc-air battery assembled by the catalyst has maximum output power of 100mW/cm²Is superior to commercial platinum carbon (the maximum output power is 78 mW/cm)²)。

Drawings

The invention is further illustrated with reference to the following figures and examples.

FIG. 1 is a mass spectrum of cobalt tetrabromophenylporphyrin (CoTBrPP);

FIG. 2 is an SEM image of a biomass-derived carbon-based catalyst material of example 3 of the present invention;

FIG. 3 is a linear scan plot of oxygen reduction at 0.1M KOH for a biomass-derived carbon-based catalyst material in example 4 of the present invention;

FIG. 4 is a graph of stability time versus current (i-t) for a biomass-derived carbon-based catalyst material of example 4 of the present invention;

FIG. 5 is a plot of hydrogen evolution polarization at 1M KOH for the biomass-derived carbon-based catalyst material of example 4 of the present invention;

fig. 6 is a polarization curve of a zinc-air battery fabricated in example 5 of the present invention;

Detailed Description