Method for preparing boron-and-nitrogen-doped cobalt-molybdenum-sulfur-oxygen compound/carbon composite material

A technology of sulfur-oxygen compounds and carbon composite materials, applied in chemical instruments and methods, chemical/physical processes, physical/chemical process catalysts, etc., can solve unseen problems

Active Publication Date: 2020-08-07

CHINA THREE GORGES UNIV

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Abstract

The invention provides a method for preparing a boron-and-nitrogen-doped cobalt-molybdenum-sulfur-oxygen compound/carbon composite material. The method comprises the following steps: dissolving a molybdenum salt and a nitrogen carbon source in a volatile non-aqueous solvent to obtain a Mo-N-C precursor solution, coating a substrate, on which a cobalt sulfide array structure grows, with the precursor solution, and carrying out drying; and with Ar or N2 as a shielding gas and a carrier gas and mixed powder of sublimed sulfur element and boric acid as a solid evaporation source, carrying out a chemical vapor deposition reaction to obtain the composite material. According to the invention, sulfur steam formed by evaporation of elemental sulfur and oxygen introduced by decomposition of boric acid react with cobalt sulfide and molybdenum ions to generate a cobalt-molybdenum-sulfur-oxygen compound; nitrogen and carbon are gradually carbonized in a protective atmosphere to form a carbon material; and meanwhile, boron atoms and nitrogen atoms can be respectively doped into the cobalt-molybdenum-sulfur-oxygen compound and the carbon material in a form of replacing sulfur-oxygen atoms or carbon atoms in the CVD reaction process. The boron-nitrogen-doped cobalt-molybdenum-sulfur-oxygen compound/carbon composite material obtained according to a technical scheme of the invention has excellent multifunctional electrocatalytic performance.

Application Domain

Physical/chemical process catalystsElectrodes

Technology Topic

Oxygen compoundComposite material +9

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Examples

Experimental program(8)

Example Embodiment

[0023] Example 1:

[0024] CoCl 2 ∙ 6H 2 O and urea are dissolved in 40 mL deionized water at room temperature, in which CoCl 2 The concentration of urea is 0.15 M, and the mass fraction of urea is 6.25 wt.%. After immersing the hydrophilic carbon paper in the solution, keep the reaction at 90℃ for 2 hours, cool to room temperature, take out the carbon paper and rinse with deionized water Three times, dry for later use. The carbon paper on which the basic cobalt salt array is grown is placed in the air at 500°C for 0.5 h, and then in an Ar+S atmosphere at 500°C for 1 h. After being naturally cooled, it is taken out for use. The carbon paper on which the cobalt sulfide array has been grown is soaked in a 400 mM molybdenum chloride solution. The solution is composed of a mixture of 50 mg bipyridine, 0.1 g glucose and 3 mL of N, N-dimethylformamide, soaked for about 1 min, take it out and dry it on a hot stage at 80°C for 10 min. Put the coated substrate into the tube furnace, use Ar as protective gas, and use boric acid (H 3 BO 3 ) And sublimated sulfur powder (S) to form a solid mixture as the evaporation reaction source, where H 3 BO 3 Both S powder and S powder are in excess, and their mass ratio is 1:5, reacted at 600°C for 2 h, and can be taken out after natural cooling to room temperature.

[0025] figure 1 The electrodes prepared in Example 1 (a) HER linear voltammetry (LSV) graph and (b) LSV graph of OER and ORR. Figure (a) shows that when the current density through the electrode is 10 mA/cm 2 When the overpotential required for hydrogen production by the HER reaction in the alkaline aqueous solution is only 70 mV; when the current density is 100 mA/cm 2 When, the corresponding overpotential is only 141 mV. It reflects the excellent catalytic hydrogen evolution performance of the material. Figure (b) shows that when the current density through the electrode is 10 mA/cm 2 When, the potential corresponding to oxygen production by OER reaction in alkaline aqueous solution is E 10 = 1.47 V, the corresponding OER reaction overpotential is only 240 mV (1.47 V-1.23V), the corresponding half-wave potential of ORR reaction in alkaline aqueous solution is E 1/2 = 0.77 V, the current density can reach ~6.0 mA/cm 2 ,Δ E = E 10 - E 1/2 = 0.70 V. It reflects the material's better ORR catalytic performance and excellent OER-ORR overall performance. figure 2 This is the SEM image of the electrode prepared in Example 1. It can be seen from the figure that the product grows firmly on the carbon fiber substrate.

Example Embodiment

[0026] Example 2:

[0027] CoCl 2 ∙ 6H 2 O and urea are dissolved in 40 mL deionized water at room temperature, in which CoCl 2 The concentration of urea is 0.15 M, and the mass fraction of urea is 6.25 wt.%. After immersing the hydrophilic carbon paper in the solution, keep the reaction at 90℃ for 2 hours, cool to room temperature, take out the carbon paper and rinse with deionized water Three times, dry for later use. The carbon paper on which the basic cobalt salt array is grown is placed in the air at 500°C for 0.5 h, and then in an Ar+S atmosphere at 500°C for 1 h. After being naturally cooled, it is taken out for use. Soak the carbon paper on which the cobalt sulfide array has been grown in 400 mM molybdenum chloride solution. The solution is composed of 50 mg o-phenanthroline, 0.1 g glucose and 3 mL N, N-dimethylformamide. About 1 minute, after taking it out, dry it on a hot stage at 80°C for 10 minutes. Put the coated substrate into the tube furnace, use Ar as the protective gas, and use the solid mixture composed of boric acid and sublimated sulfur powder as the evaporation reaction source, where H 3 BO 3 Both S powder and S powder are in excess, and their mass ratio is 1:5, reacted at 600°C for 2 h, and can be taken out after natural cooling to room temperature.

[0028] image 3 The electrodes prepared in Example 2 (a) HER linear voltammetry (LSV) graph and (b) OER and ORR LSV graphs. Figure (a) shows that when the current density through the electrode is 10 mA/cm 2 When the overpotential required for hydrogen production by the HER reaction in the alkaline aqueous solution is only 72 mV; when the current density is 100 mA/cm 2 When, the corresponding overpotential is only 142 mV. It reflects the excellent catalytic hydrogen evolution performance of the material. Figure (b) shows that when the current density through the electrode is 10 mA/cm 2 When, the potential corresponding to oxygen production by OER reaction in alkaline aqueous solution is E 10 = 1.45 V, its corresponding OER reaction overpotential is only 220 mV (1.45 V-1.23V), the corresponding half-wave potential of ORR reaction in alkaline aqueous solution is E 1/2 = 0.71 V, the current density can reach ~7.9 mA/cm 2 ,Δ E = E 10 - E 1/2 = 0.74 V. It reflects the material's better ORR catalytic performance and excellent OER-ORR overall performance.

Example Embodiment

[0029] Example 3:

[0030] CoCl 2 ∙ 6H 2 O and urea are dissolved in 40 mL deionized water at room temperature, in which CoCl 2 The concentration of urea is 0.15 M, and the mass fraction of urea is 6.25 wt.%. After immersing the hydrophilic carbon paper in the solution, keep the reaction at 90℃ for 2 hours, cool to room temperature, take out the carbon paper and rinse with deionized water Three times, dry for later use. The carbon paper on which the basic cobalt salt array is grown is placed in the air at 500°C for 0.5 h, and then in an Ar+S atmosphere at 500°C for 1 h. After being naturally cooled, it is taken out for use. The carbon paper on which the cobalt sulfide array has been grown is soaked in a 400 mM molybdenum chloride solution. The solution is composed of 50 mg o-phenanthroline, 0.05 g glucose and 3 mL N, N-dimethylformamide. About 1 minute, after taking it out, dry it on a hot stage at 80°C for 10 minutes. Put the coated substrate into the tube furnace, use Ar as the protective gas, and use the solid mixture composed of boric acid and sublimated sulfur powder as the evaporation reaction source, where H 3 BO 3 Both S powder and S powder are in excess, and their mass ratio is 1:5, reacted at 600°C for 2 h, and can be taken out after natural cooling to room temperature.

[0031] Figure 4 The electrodes prepared in Example 3 (a) HER linear voltammetry (LSV) graph and (b) LSV graph of OER and ORR. Figure (a) shows that when the current density through the electrode is 10 mA/cm 2 When the overpotential required for hydrogen production by the HER reaction in the alkaline aqueous solution is only 79 mV; when the current density is 100 mA/cm 2 When, the corresponding overpotential is only 153 mV. It reflects the excellent catalytic hydrogen evolution performance of the material. Figure (b) shows that when the current density through the electrode is 10 mA/cm 2 When, the potential corresponding to oxygen production by OER reaction in alkaline aqueous solution is E 10 = 1.45 V, the corresponding overpotential of OER reaction is only 220 mV (1.45 V-1.23 V), the corresponding half-wave potential of ORR reaction in alkaline aqueous solution is E 1/2 = 0.73 V, the current density can reach ~5.3 mA/cm 2 ,Δ E = E 10 - E 1/2 = 0.72 V. It reflects the material's better ORR catalytic performance and excellent OER-ORR overall performance.

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