Application of TiO2-Cu Composites in Photocatalytic Degradation Different Pollutants and Hydrogen Production

Abstract

In the present work, copper nanoparticles were deposited onto the surface of two different commercial titanias (Evonik Aeroxide P25 and Aldrich anatase). During the synthesis, the concentration of copper was systematically varied (0.5%, 1.0%, 1.5%, 5.0%, and 10 wt.%) to optimize the composite-composition. The photocatalytic activity was evaluated under UV-light, using methyl orange and Rhodamine B as model and ketoprofen as real pollutant. For the hydrogen production capacity, oxalic acid was used as the sacrificial agent. The morpho-structural properties were investigated by using XRD (X-ray diffraction), TEM (Transmission Electron Microscopy) DRS (Diffuse Reflectance Spectroscopy), XPS (X-ray Photoelectron Spectroscopy), and SEM-EDX methods (Scanning Electron Microscopy-Energy Dispersive X-ray Analysis). Increasing the copper concentration enhanced the photocatalytic activity for methyl orange degradation in the case of Aldrich anatase-based composites. When the P25-based composites were considered, there was no correlation between the Cu concentration and the activity; but, independently of the base photocatalyst, the composites containing 10% Cu were the best performing materials. Contrarily, for the ketoprofen degradation, increasing the copper concentration deteriorated the photoactivity. For both Aldrich anatase and P25, the best photocatalytic activity was shown by the composites containing 0.5% Cu. For the degradation of Rhodamine B solution, 1.5% of copper nanoparticles was the most suitable. When the hydrogen production capacity was evaluated, the P25-based composites showed higher performance (produced more hydrogen) than the Aldrich anatase-based ones. It was found that Cu was present in four different forms, including belloite (Cu(OH)Cl), metallic Cu, and presumably amorphous Cu(I)- and Cu(II)-based compounds, which were easily convertible among themselves during the photocatalytic processes.

A Mini Review on Bismuth-Based Z-Scheme Photocatalysts

“…As a powerful and inexhaustible renewable energy source, solar energy is considered as one of the best methods to mitigate these problems. It can be exploited and utilized for energy production (for example H 2 [ 3 , 4 , 5 , 6 ], hydrocarbon fuel [ 7 , 8 ] and electric energy [ 9 , 10 ] production) and removal of pollutants (such as CO 2 [ 11 , 12 , 13 , 14 , 15 ], organic contaminants in water [ 16 , 17 , 18 , 19 , 20 , 21 ] or air [ 22 , 23 , 24 , 25 , 26 ], emerging micropollutants [ 27 , 28 ]) by using photocatalytic, photovoltaic and other light-conversion technologies [ 29 , 30 ]. As one of the most promising light conversion technologies, photocatalytic technology only needs the appropriate semiconductor photocatalyst and solar energy as energy input.…”

Main Hydrogen Production Processes: An Overview

“…In the case of palladium [93], a "series-parallel" reaction network has been proposed for describing the water splitting reaction using the mesoporous Pd-TiO2 and ethanol as organic scavenger (Figure 5) [94]. The addition of earth-abundant metals has a positive effect, in particular in the case of Ni [95] and Cu [96,97]. A high activity in hydrogen evolution under visible light has been demonstrated also for solid solutions of cadmium and manganese sulfides, due to their valence and conduction band position tuning, and for composite photocatalysts, CdS-β-Mn3O4-MnOOH, due to the ternary heterojunction formation [98].…”

Doping of TiO2 Using Metal Waste (Door Key) to Improve Its Photocatalytic Efficiency in the Mineralization of an Emerging Contaminant in an Aqueous Environment

“…Other studies mention that the crystalline phase of anatase occurs when heat treatment varies between 200 and 500 • C. It was said that the amount and physicochemical properties (high ionic radii and electronic status) of the doping metal can influence the rate of transformation of anatase to the rutile phase [24,25]. Such is the case of a study conducted by Hampel et al [25]; they observed that TiO 2 doped with 5 wt.% Cu ions, calcined at 450 • C, contained an anatase phase and a rutile phase fraction, which increased with increasing Cu concentration from 5 to 10 wt.%. In our case, the dopant concentration does not influence the anatase-rutile transition because the maximum theoretical concentration of doping ions in TiO 2 is less than 1 wt.%.…”