Effect of Growth Parameters on the Photocatalytic Performance of TiO<sub>2</sub> Films Prepared by MOCVD

Marcello, Bianca A.; Correa, Olandir V.; Bento, Rodrigo T.; Pillis, Marina F.

doi:10.21577/0103-5053.20200012

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Article • J. Braz. Chem. Soc. 31 (6) • June 2020 • https://doi.org/10.21577/0103-5053.20200012 copy

Effect of Growth Parameters on the Photocatalytic Performance of TiO₂ Films Prepared by MOCVD

Authorship SCIMAGO INSTITUTIONS RANKINGS

The present study evaluated the main factors that influence the photocatalytic activity of titanium dioxide (TiO₂) films grown by metalorganic chemical vapor deposition (MOCVD) at 400 and 500 °C, in different growth times. The photocatalytic behavior was analyzed by measuring the methyl orange dye degradation at different pH values. Structural and morphological characteristics, and the recyclability of the catalysts for several cycles were also investigated. Anatase phase was identified in all films. The higher photodegradation performances were obtained at acidic pH. The results demonstrated that the photocatalyst thickness is an important parameter in heterogenous photocatalysis. The best photocatalytic result occurred for the 395 nm-thick TiO₂ film grown at 400 °C, which presented 65.3% of the dye degradation under UV light. The recyclability experiments demonstrated that the TiO₂ films grown by MOCVD present a great stability after several photocatalytic cycles, which allows their practical application for water treatment with high efficiency.

Keywords:
titanium dioxide; MOCVD; dye degradation; heterogenous photocatalysis; recyclability

Growth temperature / °C	Growth time / min	Film thickness / nm	Mean grain size / nm
400	15	184	160
	30	395	216
	60	762	292
500	15	600	47
	30	1100	76
	60	2100	116

Growth temperature / °C	Growth time / min	Film thickness / nm	pH	k constant / min⁻¹	Dye degradation / %
400	15	184	2	1.35 × 10⁻³	34.4
			7	1.16 × 10⁻³	31.7
			10	8.45 × 10⁻⁴	24.8
	30	395	2	3.28 × 10⁻³	65.3
			7	2.69 × 10⁻³	59.2
			10	8.54 × 10⁻⁴	27.9
	60	762	2	1.02 × 10⁻³	27.3
			7	7.71 × 10⁻⁴	22.2
			10	3.56 × 10⁻⁴	12.4
500	15	600	2	1.04 × 10⁻³	30.2
			7	8.58 × 10⁻⁴	26.5
			10	8.21 × 10⁻⁴	22.9
	30	1100	2	8.76 × 10⁻⁴	24.4
			7	7.13 × 10⁻⁴	20.2
			10	3.68 × 10⁻⁴	10.7
	60	2100	2	4.42 × 10⁻⁴	12.2
			7	2.82 × 10⁻⁴	8.2
			10	2.58 × 10⁻⁴	7.4

Growth time / min	Film thickness / nm	k constant / min⁻¹	Dye degradation / %
15	184	1.35 × 10⁻³	34.4
20	260	1.71 × 10⁻³	44.3
30	395	3.28 × 10⁻³	65.3
40	520	1.00 × 10⁻³	31.1
60	762	1.02 × 10⁻³	27.3

Growth temperature / °C	Growth time / min	Film thickness / nm	k constant / min⁻¹	Dye degradation / %
400	30	395	3.28 × 10⁻³	65.3
500	11	407	1.48 × 10⁻³	39.2

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Growth time / min	11, 15, 20, 30, 40 and 60
Growth temperature / °C	400 and 500
Flow rate of the precursor / slm	0.5
Flow rate of the N₂ / slm	0.5
Chamber pressure / mbar	50

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Effect of Growth Parameters on the Photocatalytic Performance of TiO2 Films Prepared by MOCVD

Effect of Growth Parameters on the Photocatalytic Performance of TiO₂ Films Prepared by MOCVD