Role of Hydrogen-Related Defects in Photocatalytic Activity of ZnO Films Grown by Atomic Layer Deposition

Abstract

The photocatalytic activity of ZnO films, grown by atomic layer deposition on sapphire, was investigated for different amounts of residual hydrogen incorporated unintentionally into the matrix during the crystal growth. A close correlation was found between the level of incorporated hydrogen and the rate of photocatalytic degradation of methylene blue on ZnO films. The rate of degradation is consistent with predominantly zero-order reaction kinetics. An enhanced photocatalytic activity, observed for films of predominantly (001)-oriented grains and low concentration of residual hydrogen, is explained by the reduced number of hydrogen-related defects responsible for recombination of charge carriers in combination with the preferential adsorption of water on polar (001) surfaces of ZnO grains.

Hydrogen and Deuterium Incorporation in ZnO Films Grown by Atomic Layer Deposition

“…Due to the scattering effects, the amount of Zn in the film was slightly underestimated [42]. However, oxygen rich ZnO films deposited with ALD, especially at low deposition temperatures, have been reported previously [10,27,[43][44][45]. The high oxygen concentration in the ZnO films was attributed to the zinc vacancies [44] in the crystal as well as to the oxygen interstitials [43].…”

“…The high oxygen concentration in the ZnO films was attributed to the zinc vacancies [44] in the crystal as well as to the oxygen interstitials [43]. In addition, hydrogen impurities were proposed to occupy the Zn-sites in the crystal [27].…”

“…As a result, significant amounts of precursor-derived impurities, such as carbon and hydrogen, are incorporated in the film due to incomplete reactions. While hydrogen incorporation is sometimes even desired [26], more often, high-purity films are required, and hydrogen impurities can have a negative effect on the film properties [27]. The hydrogen concentration of ALD ZnO films has also been found to be related to the conductivity of the films [28,29].…”

Preparation of Degradable Superhydrophobic Mg/P/Z/F/H Composite Materials and Their Anticorrosion

“…[25,[32][33][34][35][36] ZnO powders are used in electronic and optoelectronic devices, solar cells and pharmaceuti-cal engineering because of the high safety, low price, extraodinary opto-electronic property and lacking of polluting effects as a newer type of promising candidate. [35,37,38] In this study, degradable and superhydrophobic M/P/Z/F/H composite materials were prepared through one-step method to solve the poor corrosion resistance of magnesium. As a widely applied and simple surface treatment technology, dip-coating can produce a relatively adherent, stable and uniform films on the surface of materials.…”

Preparation and Properties of Floral CaO/ZnO Nanocomposite From Achatina Fulica Snail Shell

“…Metal oxide Semiconductors are the primary choice of photocatalysts. ZnO has high visible light response, high e ciency and low cost, which is suitable for industrial applications (Peter et al 2020).…”