Photoreduction of a Pd-Doped Mesoporous TiO2 Photocatalyst for Hydrogen Production under Visible Light

Abstract

Photoreduction with visible light can enhance the photocatalytic activity of TiO2 for the production of hydrogen. In this article, we present a strategy to photoreduce a palladium-doped TiO2 photocatalyst by using near-UV light prior to its utilization. A sol-gel methodology was employed to prepare the photocatalysts with different metal loadings (0.25–5.00 wt% Pd). The structural and morphological characteristics of the synthesized Pd-TiO2 were analyzed by using X-ray Diffraction (XRD), BET Surface Area (SBET), TemperatureProgrammed Reduction (TPR), Chemisorption and X-ray Photoelectron Spectroscopy (XPS). Hydrogen was produced by water splitting under visible light irradiation using ethanol as an organic scavenger. Experiments were developed in the Photo-CREC Water-II (PCW-II) Reactor designed at the CREC-UWO (Chemical Reactor Engineering Centre). It was shown that the mesoporous 0.25 wt% Pd-TiO2 with 2.5 1eV band gap exhibits, under visible light, the best hydrogen production performance, with a 1.58% Quantum Yield being achieved.

Photocatalysis for Air Treatment Processes: Current Technologies and Future Applications for the Removal of Organic Pollutants and Viruses

“…However, by impregnating, doping, or co-doping TiO 2 with metals such as iron (Fe), silver (Ag), palladium (Pd) and platinum (Pt) or non-metals like nitrogen (N), one can improve (a) the reduction of the TiO 2 energy band gap (E BG < 3.2 eV), (b) the slowing of the (e − )/(h + ) recombination rate, and (c) the diminishing of the particle agglomeration [17,18]. Furthermore, through the use of a new photocatalyst synthesis utilizing a sol-gel method, larger TiO 2 surface areas (50 m 2 /g < S BET ≤ 150 m 2 /g), morphologies (high porosity) and crystal structures (anatase dominant crystalline phase) can be obtained [11,19]. All these advancements with TiO 2 photocatalysts are extremely important for the improvement of the process of photocatalysis and the extensive application of air treatment, both for VOCs conversion and airborne virus inactivation.…”

“…This allows numerical simulations for different reactor configurations and conditions relevant to industrial-scale applications [9,[35][36][37]. It can be anticipated that CFD will help to design, develop, and analyze novel photocatalytic reactors (bench or pilot-scale) for air [2,12,14,38] or water treatment applications [39][40][41] and water splitting for hydrogen production [18,19,42].…”

“…These tubular reactor configurations, as described in Figure 3a,b, show an improved photon absorption, with transmitted photons being transported through inner or outer TiO 2 deposition films [82]. These reactors provide symmetrical irradiation, facilitating the calculation of macroscopic irradiation energy balances [12,18,19,33,44].…”

“…Thus, the current circumstances of the SARS-CoV2 (COVID- 19) pandemic open new opportunities for the development of new photocatalytic air treatment units, adapted from a Photo-CREC-Air Reactor using lower energetic near-UV photons and a TiO 2 photocatalyst. These photocatalytic systems could inactivate the COVID-19 virus, as well as other viruses, while being much more operationally safe.…”

Peer Review #1 of "Characterization and evaluation of the photocatalytic activity of oxides based on TiO2 synthesized by hydrolysis controlled by the use of water/acetone mixtures (v0.1)"

“…Heterogeneous photocatalysis has proving to be a good alternative. Studies have shown its effectiveness in environmental remediation of contaminated waters (Machado et al, 2008;França et al, 2016;Hurtado, Sader & Delgado, 2019), as well as in hydrogen production (H 2 ), an important energy vector (Bahnemann & Schneider, 2013;Rusinque, Escobedo & Lasa, 2020;Galvão et al, 2019).…”