Enhanced Photocatalytic and Antimicrobial Performance of Cuprous Oxide/Titania: The Effect of Titania Matrix

Abstract

A simple, low-cost method was applied to prepare hybrid photocatalysts of copper (I) oxide/titania. Five different TiO2 powders were used to perform the study of the effect of titania matrix on the photocatalytic and antimicrobial properties of prepared nanocomposites. The photocatalytic efficiency of such a dual heterojunction system was tested in three reaction systems: ultraviolet-visible (UV-Vis)-induced methanol dehydrogenation and oxidation of acetic acid, and 2-propanol oxidation under visible light irradiation. In all the reaction systems considered, the crucial enhancement of photocatalytic activity in relation to corresponding bare titania was observed. The reaction mechanism for a specific reaction and the influence of titania matrix were discussed. Furthermore, antimicrobial (bactericidal and fungicidal) properties of Cu2O/TiO2 materials were analyzed. The antimicrobial activity was found under UV, visible and solar irradiation, and even for dark conditions. The origin of antimicrobial properties with emphasis on the role of titania matrix was also discussed.

Visible-Light Active Titanium Dioxide Nanomaterials with Bactericidal Properties

“…Titania can be coupled with metal oxides (e.g., Cu 2 O, Fe 2 O 3 , WO 3 ) and chalcogenides (e.g., CdS, MoS 2 and WS 2 ) to form a heterojunction for the charge separation in enhanced visible light absorption. Those coupled semiconductors acting as sensitizers should be nontoxic, and exhibit visible light photocatalytic activity, with a bandgap smaller than that of titania [177][178][179][180][181][182][183]. In this respect, photoexcited electrons in the CB and holes in the VB of a sensitizer semiconductor can be transferred to the CB and VB of TiO 2 NPs [180].…”

“…Cadmium sulfide is toxic and carcinogenic, so it is unfavorable to form CdS/TiO 2 heterojunction for practical applications. Nontoxic molybdenum disulfide (MoS 2 ) with a direct band-gap of 1.9 eV can be coupled with titania to form MoS 2 /TiO 2 nanocomposites, having excellent visible photocatalytic activity [181] [177,179,182,183]. Inexpensive and nontoxic Cu 2 O, with its efficient electron injection to the conduction band of TiO 2 , is particularly suitable for forming heterojunction photocatalysts [182,183].…”

“…Limited studies are available in the literature on the visible-light photocatalytic bactericidal activity of oxide semiconductor heterojunctions [177,179]. Recently, Janczarek et al studied the antibacterial performance of cuprous oxide/titania nanocomposites prepared by mechanically mixing Cu 2 O with TiO 2 powders of different structures including pure anatase TiO 2 (8 nm), pure rutile TiO 2 (16 nm) and Aeroxide ® TiO 2 P25 in an agate mortar [177]. (Figure 29a).…”

“…Error bars in Cu2O: standard deviation determined from two or three independent measurements. Reproduced with permission from[177]. Copyright MDPI, 2018.…”

Photocatalytic and Antimicrobial Properties of Ag2O/TiO2 Heterojunction

“…Two-times improvement was reached for anatase-predominant samples (ST01 and ST41). It is proposed that through similarity to another heterojunction system Cu 2 O/TiO 2 [58], two kinds of mechanisms could be proposed, i.e., Z-scheme and p-n heterojunction (II type), as shown in Figure 8. The first mechanism (recombination between e − (TiO 2 ) and h + (Ag 2 O)) is preferential for high photocatalytic activity, due to the high oxidation (h + in titania) and reduction (e − in argentous oxide) potential of the obtained composites.…”