r-GO coated magnetic high entropy alloy/oxide nanocomposites as highly efficient Fenton and photo-Fenton catalysts

Abstract

To utilize the synergistic effect of high entropy alloy, high entropy oxide and r-GO (reduced graphene oxide), we prepared r-GO coated nanocomposites comprising bcc high entropy alloy/spinel high entropy oxide (H730) and bcc high entropy alloy/hexagonal high entropy oxide (H725), encompassing elemental constituents such as Aluminum (Al), Chromium (Cr), Manganese (Mn), Iron (Fe), and Cobalt (Co). The samples were meticulously synthesized using the sol-gel technique followed by subsequent calcination at a temperature of 700 °C under nitrogen or air atmospheres. The assessment through X-ray diffraction and electron diffraction methodologies conclusively confirmed the successful formation of nanocomposite structures. The electron microscopy and Raman spectroscopy confirmed the r-GO coating over both the composites. The saturation magnetization values of 32 and 10 emu/g were noticed at 30 kOe for H730 and H725 samples, respectively. In-depth analysis using X-ray photoelectron spectroscopy revealed the coexistence of diverse oxidation states within the constituent elements of the samples. Notably, the H730 nanocomposite exhibited superior catalytic efficacy in comparison to its H725 counterpart for the degradation of p-nitrophenol (PNP) under both Fenton and photo-Fenton reaction conditions. Impressively, complete degradation of PNP was achieved within a remarkably short span of 18 min. Furthermore, the H730 nanocomposite alongwith stronger magnetic attributes, demonstrated a notable 86 % degradation efficiency even after undergoing five consecutive cycles. © 2024 Elsevier Ltd and Techna Group S.r.l.