Perovskite LaNiO3/Ag3PO4 heterojunction photocatalyst for the degradation of dyes
Shahzad Ameen, Maida Murtaza, Muhammad Arshad, Aiyeshah Alhodaib, Amir Waseem
Abstract
Pristine lanthanum nickelate (LaNiO 3 ), silver phosphate (Ag 3 PO 4 ) and perovskite lanthanum nickelate silver phosphate composites (LaNiO 3 /Ag 3 PO 4 ) were prepared using the facile hydrothermal method. Three composites were synthesized by varying the percentage of LaNiO 3 in Ag 3 PO 4 . The physical properties of as-prepared samples were studied by powder X-ray diffraction (pXRD), Fourier-transform infrared (FT-IR), Scanning electron microscopy (SEM) and Energy-dispersive X-ray (EDX). Among all synthesized photocatalysts, 5%LaNiO 3 /Ag 3 PO 4 composite has been proved to be an excellent visible light photocatalyst for the degradation of dyes i.e., rhodamine B (RhB) and methyl orange (MO). The photocatalytic activity and stability of Ag 3 PO 4 were also enhanced by introducing LaNiO 3 in Ag 3 PO 4 heterojunction formation. Complete photodegradation of 50 mg/L of RhB and MO solutions using 25 mg of 5%LaNiO 3 /Ag 3 PO 4 photocatalyst was observed in just 20 min. Photodegradation of RhB and MO using 5%LaNiO 3 /Ag 3 PO 4 catalyst follows first-order kinetics with rate constants of 0.213 and 0.1804 min −1 , respectively. Perovskite LaNiO 3 /Ag 3 PO 4 photocatalyst showed the highest stability up to five cycles. The photodegradation mechanism suggests that the holes ( h + ) and superoxide anion radicals <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" id="m1"><mml:mrow><mml:mfenced open="" close=")" separators="|"><mml:mrow><mml:msubsup><mml:mrow><mml:mfenced open="(" close="" separators="|"><mml:mrow><mml:mi mathvariant="bold-italic">O</mml:mi></mml:mrow></mml:mfenced></mml:mrow><mml:mn mathvariant="bold">2</mml:mn><mml:mrow><mml:mtext> </mml:mtext><mml:mo>•</mml:mo><mml:mo>−</mml:mo></mml:mrow></mml:msubsup></mml:mrow></mml:mfenced></mml:mrow></mml:math> plays a main role in the dye degradation of RhB and MO.