RESUMO
Fe2O3/TiO2 nanocomposites were fabricated via a facile impregnation/calcination technique employing different amounts iron (III) nitrate onto commercial TiO2 (P25 Aeroxide). The as-prepared Fe2O3/TiO2 nanocomposites were characterized by X-ray diffraction (XRD), Raman spectroscopy (RS), scanning electron microscopy/energy-dispersive spectroscopy (SEM/EDXS), X-ray photoelectron spectroscopy (XPS), Brunauer-Emmett-Teller analysis (BET), electron impedance spectroscopy (EIS), photoluminescence spectroscopy (PL), and diffuse reflectance spectroscopy (DRS). As a result, 5% (w/w) Fe2O3/TiO2 achieved the highest photocatalytic activity in the slurry system and was successfully immobilized on glass support. Photocatalytic activity under visible-light irradiation was assessed by treating pharmaceutical amoxicillin (AMX) in the presence and absence of additional oxidants: hydrogen peroxide (H2O2) and persulfate salts (PS). The influence of pH and PS concentration on AMX conversion rate was established by means of statistical planning and response surface modeling. Results revealed optimum conditions of [S2O82-] = 1.873 mM and pH = 4.808; these were also utilized in presence of H2O2 instead of PS in long-term tests. The fastest AMX conversion possessing a zero-order rate constant of 1.51 × 10-7 M·min-1 was achieved with the photocatalysis + PS system. The AMX conversion pathway was established, and the evolution/conversion of formed intermediates was correlated with the changes in toxicity toward Vibrio fischeri. Reactive oxygen species (ROS) scavenging was also utilized to investigate the AMX conversion mechanism, revealing the major contribution of photogenerated h+ in all processes.
RESUMO
Sustainable hydrogen production is one of the main challenges today in the transition to a green and sustainable economy. Photocatalytic hydrogen production is one of the most promising technologies, amongst which BiVO4-based processes are highly attractive due to their suitable band gap for solar-driven processes. However, the performance of BiVO4 alone in this role is often unsatisfactory. Herein we report the improvement of BiVO4 performance with reduced graphene oxide (rGO) as a co-catalyst for the photoelectrochemical water splitting (PEC-WS) in the presence of simple functionalized benzene derivatives (SFBDs), i.e., phenol (PH), benzoic acid (BA), salicylic acid (SA), and 5-aminosalicylic acid (5-ASA) as potential photogenerated hole scavengers from contaminated wastewaters. Linear sweep voltammetry and chronoamperometry, along with electrochemical impedance spectroscopy were utilized to elucidate PEC-WS performance under illumination. rGO has remarkably improved the performance of BiVO4 in this role by decreasing photogenerated charge recombination. In addition, 5-ASA greatly improved current densities. After 120 min under LED illumination, 0.53 µmol of H2 was produced. The type and concentration of SFBDs can have significant and at times opposite effects on the PEC-WS performance of both BiVO4 and rGO-BiVO4.
