Fabrication of a dual Z-scheme Ag3PO4/g-C3N4/Bi2MoO6 ternary nanocomposite for effective degradation of methylene blue dye

Abstract

Methylene blue is a recognized carcinogen with detrimental effects on both people and marine life. Henceforth, in this study, the photocatalytic activity of Ag₃PO₄/g-C₃N₄/Bi₂MoO₆ (AP/GCN/BMO) photocatalyst was investigated for the degradation of MB dye from an aqueous system. g-C₃N₄, BMO and AP photocatalysts bare photocatalysts were synthesized via thermal polycondensation, hydrothermal and co-precipitation methods, respectively. Similarly, binary (GCN/BMO) and ternary heterojunctions (AP/GCN/BMO) was constructed through in-situ hydrothermal and co-precipitation methods, respectively. Morphological and structural analysis validated close interaction amongst Ag₃PO₄, g-C₃N₄, and Bi₂MoO₆ photocatalysts_. Furthermore, density functional theory simulations were employed to explore the structural and electronic properties of the bare (Ag₃PO₄, g-C₃N₄, and Bi₂MoO₆) photocatalysts. The photocatalytic degradation experiments revealed that AP/GCN/BMO exhibited highest adsorption and photocatalytic degradation efficacy of methylene blue (MB) dye pollutant as compared to other photocatalysts. The achieved MB dye degradation efficiency of dual Z-scheme AP/GCN/BMO ternary photocatalyst was approx. ~94% within 60 min under visible light exposure which was much greater than pristine and binary photocatalysts. This higher efficiency was accredited to dual Z-scheme type of charge transfer route which boosted photocarriers charge separation and transferal rate. Furthermore, through scavenging experiment, the confirmed reactive species in this type of charge transfer route were ^•O₂⁻ and ^•OH radicals that efficiently degraded MB dye pollutant. Additionally, the ternary photocatalyst demonstrated good stability and recyclability for up to five successive catalytic cycles with 81% degradation efficiency. The current work extends our understanding of photocatalytic degradation by providing novel strategies for pollutant degradation that successfully degrade contaminants. Also, it promotes the development of more efficient, environmentally friendly waste treatment methods that uses solar/light energy.

Graphical Abstract