Hydrogen and Oxygen Evolution in a Membrane Photoreactor Using Suspended Nanosized Au/TiO2 and Au/CeO2

Electrochemical Generation of Hydrogen and Methanol using ITO Sheet Decorated with Modified-Titania as Electrode

Current issues of global warming and environmental pollution due to extensive use of fossil fuels has been reached to an alarming position. Being CO2 as main byproduct of fossil fuel consumption and water as abundantly available on earth surface has great potential to replace fossil fuels as energy source. Herein, electrocatalytic CO2 reduction with water for methanol and hydrogen gas (H2) production over ITO sheet decorated with modified-Titanium nanorods (TiO2 NR), has been investigated. The performance comparison of electrocatalytic activity of hydrothermally modified-titania with commercial TiO2 microparticles (MP) were further investigated. Electrochemical reactor containing KHCO3 aqueous solution with CO2 as an electrolyte and modified TiO2 nanorods (NR) as working electrodes offer an eco-friendly system to produce clean and sustainable energy system. The typical rates of product, i.e. methanol and H2 generation from the ITO sheet decorated with modified TiO2 NR layer recorded higher than those for the ITO sheet with commercial TiO2 microparticle. At 2.0V applied potential vs Ag/AgCl as reference electrode, the modified TiO2 NR electrocatalyst yielded methanol at a rate of 3.32 µmol.cm−2.L−1 and H2 at a rate of 6 µmol.cm−2.L−1 which was higher than that of commercial TiO2 MP electrocatalyst (methanol = 1.5 µmol.cm−2.L−1 and H2 = 3.7 µmol.cm−2.L−1). The enhancement in product yields of methanol and H2 was mainly due to the notable improvements and modification in texture of TiO2 working electrode interface. Hence, it is concluded that the modified TiO2 NR can be considered as a competent candidate for sustainable energy conversion applications. Copyright © 2021 by Authors, Published by BCREC Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0). 

A Mechanistic Approach on Oxygen Vacancy-Engineered CeO2 Nanosheets Concocts over an Oyster Shell Manifesting Robust Photocatalytic Activity toward Water Oxidation

Lethargic kinetics is the foremost bottleneck of the photocatalytic water oxidation reaction. Hence, in this respect, the CeO₂ coral reef made up of nanosheets is studied focusing on the oxygen vacancy that affects the water oxidation reaction. First, CeO₂ was prepared in an oyster shell/crucible with the presence/absence of urea by a simple calcination technique to tune the oxygen vacancy. More oxygen vacancy was detected in CeO₂ prepared from urea and oyster shell, which is evidenced from Raman and PL analyses. Further, the oyster shell-treated sample was found to be of nanosheet type with numerous pores as observed via TEM analysis. The theoretical approach was adopted to expose the role of oxygen vacancies and the fate of scavenging agents in the water oxidation mechanism. It was observed that an oxygen vacancy plays a vital role in minimizing the activation energy hump and opposes the reverse reaction. The apparent conversion efficiency of 7.1% is calculated for the oxygen evolution reaction. Oxygen vacancy, quantum confinement effect, and charge separation efficiency are mainly responsible for the better photocatalyzed water oxidation reaction and hydroxyl radical production. This investigation will help in providing valuable information toward designing cost-effective oxygen vacancy-oriented nanosheet systems and the importance of vacancy in the water-splitting reaction.

Overview of Photocatalytic Membrane Reactors in Organic Synthesis, Energy Storage and Environmental Applications

This paper presents an overview of recent reports on photocatalytic membrane reactors (PMRs) in organic synthesis as well as water and wastewater treatment. A brief introduction to slurry PMRs and the systems equipped with photocatalytic membranes (PMs) is given. The methods of PM production are also presented. Moreover, the process parameters affecting the performance of PMRs are characterized. The applications of PMRs in organic synthesis are discussed, including photocatalytic conversion of CO2, synthesis of KA oil by photocatalytic oxidation, conversion of acetophenone to phenylethanol, synthesis of vanillin and phenol, as well as hydrogen production. Furthermore, the configurations and applications of PMRs for removal of organic contaminants from model solutions, natural water and municipal or industrial wastewater are described. It was concluded that PMRs represent a promising green technology; however, before the application in industry, additional studies are still required. These should be aimed at improvement of process efficiency, mainly by development and application of visible light active photocatalysts and novel membranes resistant to the harsh conditions prevailing in these systems.