The Influence of the Ammonolysis Temperature on the Photocatalytic Activity of β-TaON

Table 2

Crystallite size, specific surface area (SSA), nitrogen content, band gap, and O₂ evolution rate for β-TaON powders synthesized at different nitridation temperatures.

Temperature; (°C)	Crystallite size^a (nm)	SSA; (m^2/g)	N/(N + O)^b ratio	Band gap^c (eV)	O2 evolution (𝜇mol·g^−1·h^−1)
800^d	58.73 (9)	6.6	0.400	2.6	220
850	55.36 (5)	7.5	0.396	2.5	200
900	55.81 (6)	6.2	0.406	2.5	130
950	72.08 (6)	4.2	0.420	2.5	50
1000	73.58 (7)	3.2	0.436	2.4	20

^aCalculated by Scherrer equation with the Rietveld refinement.
^bObtained by TGA.
^cEstimated by extrapolating the onset of absorption to the wavelength axis from UV-visible diffuse reflectance spectra.
^dNitridation for 68 h.