Solar active ZnO–Eu2O3 for energy and environmental applications

Abstract

ZnO–Eu<inf>2</inf>O<inf>3</inf> nanocomposite was fabricated by a simple hydrothermal route. This material forms a potential class of photocatalysts in which the increased absorption behaviour in ZnO–Eu<inf>2</inf>O<inf>3</inf> is expected to couple with the existing characteristics of Eu<inf>2</inf>O<inf>3</inf> and ZnO materials. ZnO–Eu<inf>2</inf>O<inf>3</inf> was characterized using surface analytical (SEM, EDS, HR-TEM, AFM, XRD) and spectroscopic techniques (XPS, DRS,PL). From the XRD patterns, formation of well-crystallized cubic Eu<inf>2</inf>O<inf>3</inf> and hexagonal wurtzite phase of ZnO were inferred. Presence of nanoflake like structure with hexagonal ZnO and cubical Eu<inf>2</inf>O<inf>3</inf> is shown by SEM pictures. ZnO–Eu<inf>2</inf>O<inf>3</inf> possesses higher UV and visible absorption than Eu<inf>2</inf>O<inf>3</inf> and ZnO. ZnO–Eu<inf>2</inf>O<inf>3</inf> produces larger methanol oxidation current indicating its anodic catalytic efficiency in direct methanol fuel cells (DMFCs). This reveals higher electrocatalytic activity of ZnO–Eu<inf>2</inf>O<inf>3</inf> than ZnO. It is observed that at ?1.6 V, cathodic current density (i<inf>pc</inf>) of ZnO–Eu<inf>2</inf>O<inf>3</inf> (?103.17 mA cm?2) for Hydrogen evolution reaction (HER) is more than five times of ZnO (?18.19 mA cm?2) and the hydrogen evolved with ZnO–Eu<inf>2</inf>O<inf>3</inf>is 15.6 mL, which is higher than that of ZnO (6.8 mL). This indicates the superior catalytic property of ZnO–Eu<inf>2</inf>O<inf>3</inf> in water splitting. This catalyst exhibited higher catalytic activity of 99.2% in the photodegradation of Rhodamine B (Rh-B) with natural sunlight in 75 min under neutral pH, whereas Eu<inf>2</inf>O<inf>3</inf> and ZnO produced 60 and 82% degradations in the same time. Degradation quantum efficiency by ZnO–Eu<inf>2</inf>O<inf>3</inf> is larger than ZnO and Eu<inf>2</inf>O<inf>3</inf>. ZnO–Eu<inf>2</inf>O<inf>3</inf> was stable and reusable. The multifunctionality of this catalyst makes it suitable for energy and environmental applications. © 2020 Elsevier B.V.