Carbon catalyst, electrode, and battery
Provided are a carbon catalyst, an electrode, and a battery that exhibit excellent activity. A carbon catalyst according to one embodiment of the present invention has a carbon structure in which area ratios of three peaks f broad , f middle , and f narrow obtained by separating a peak in the vicinity of a diffraction angle of 26° in an X-ray diffraction pattern obtained by powder X-ray diffraction satisfy the following conditions (a) to (c): (a) f broad : 75% or more and 96% or less; (b) f middle : 3.2% or more and 15% or less; and (c) f narrow : 0.4% or more and 15% or less.
1. A carbon catalyst, comprising a transition metal, a nitrogen atom and a carbon structure including low-crystalline components and a high-crystalline component,
wherein the carbon structure exhibits a peak within a range of a diffraction angle of from 23° to 27° in an X-ray diffraction pattern obtained by powder X-ray diffraction, the peak including three peaks of f broad and f middle corresponding to the low-crystalline components and f narrow corresponding to the high-crystalline component, the three peaks are obtained by separating the peak within the range of the diffraction angle of from 23° to 27°,
wherein area ratios by area-under-the curve of the three peaks satisfy the following conditions (a) to (c):
(a) f broad observed within a range of diffraction angle of 24.0°±4.0° and having a half width of 10°±5.0°: 75% or more and 96% or less;
(b) f middle observed within a range of diffraction angle of 26.3°±1.5° and having a half width of 3.5°±3.0°: 3.2% or more and 15% or less; and
(c) f narrow observed within a range of diffraction angle of 26.5°±1.0° and having a half width of 1.0°±0.9°: 0.4% or more and 15% or less,
wherein the peak separation is performed by the following steps:
(i) the X-ray diffraction pattern is subjected to intensity correction of a polarization factor, a Lorentz factor, and an atom scattering factor of carbon, and is also subjected to background correction in which a straight line connecting the diffraction angle of around from 10° to 20° to the diffraction angle of around from 30° to 40° is defined as a background, and the background is subtracted from each diffraction intensity after the intensity correction; and
(ii) in the corrected X-ray diffraction pattern, the peak having a peak top within a range of the diffraction angle of from 23° to 27° is superimposed onto a Gaussian basic waveform to be approximated, to thereby optimize a peak intensity, a peak half width, and a peak position, and each of three superimposed peaks included in the peak is subjected to curve fitting,
wherein the curve fitting is performed so that a residual sum of squares becomes smallest,
wherein the residual square refers to a square of a residual error at each measured diffraction angle,
wherein the residual sum of squares refers to a sum of residual squares,
wherein the residual error refers to a difference between the intensity of the peak having a peak top within a range of the diffraction angle of from 23° to 27° in the corrected X-ray diffraction pattern, and the sum of intensities of the three separated peaks f broad , f middle , and f narrow .
2. The carbon catalyst according to claim 1 , wherein the carbon catalyst comprises the carbon structure that exhibits an oxygen adsorption heat of 13 kJ/mol or less in oxygen adsorption and desorption measurement.
3. The carbon catalyst according to claim 1 , wherein the carbon catalyst comprises the carbon structure in which a carbon dioxide desorption amount at from 150° C. to 900° C. exhibits a maximum value within a range of from 200° C. to 340° C. in a temperature programmed desorption method including measuring a desorption amount of carbon dioxide at from 0° C. to 1,000° C.
4. The carbon catalyst according to claim 1 , wherein the carbon catalyst comprises the carbon structure that exhibits a carbon monoxide desorption amount at from 150° C. to 1,000° C. of 0.30 mmol/g or more and a carbon dioxide desorption amount at from 150° C. to 900° C. of 0.10 mmol/g or more in a temperature programmed desorption method including measuring desorption amounts of carbon monoxide and carbon dioxide at from 0° C. to 1,000° C.
5. An electrode, comprising the carbon catalyst of claim 1 .
6. A battery, comprising the electrode of claim 5 .
7. The carbon catalyst according to claim 1 , wherein
(a) f broad observed within a range of diffraction angle of 24.0°±4.0° and having a half width of 10°±5.0°: 75% or more and 95% or less;
(b) f middle observed within a range of diffraction angle of 26.3°±1.5° and having a half width of 3.5°±3.0°: 3.5% or more and 15% or less; and
(c) f narrow observed within a range of diffraction angle of 26.5°±1.0° and having a half width of 1.0°±0.9°: 0.4% or more and 12% or less.
8. The carbon catalyst according to claim 1 , wherein
(a) f broad observed within a range of diffraction angle of 24.0°±4.0° and having a half width of 10°±5.0°: 78% or more and 95% or less;
(b) f middle observed within a range of diffraction angle of 26.3°±1.5° and having a half width of 3.5°±3.0°: 4.0% or more and 15% or less; and
(c) f narrow observed within a range of diffraction angle of 26.5° ±1.0° and having a half width of 1.0°±0.9°: 1.0% or more and 12% or less.
9. The carbon catalyst according to claim 1 , wherein the carbon catalyst comprises the carbon structure in which a carbon dioxide desorption amount at from 150° C. to 900° C. exhibits a maximum value within a range of from 200° C. to 320° C. in a temperature programmed desorption method including measuring a desorption amount of carbon dioxide at from 0° C. to 1,000° C.
10. The carbon catalyst according to claim 1 , wherein the carbon catalyst comprises the carbon structure that exhibits a carbon monoxide desorption amount at from 150° C. to 1,000° C. of 0.35 mmol/g or more and a carbon dioxide desorption amount at from 150° C. to 900° C. of 0.11 mmol/g or more in a temperature programmed desorption method including measuring desorption amounts of carbon monoxide and carbon dioxide at from 0° C. to 1,000° C.