Engineering S-scheme Ag2CO3/g-c3N4 heterojunctions sonochemically to eradicate Rhodamine B dye under solar irradiation

Abstract

The use of natural solar radiation is a low-cost significant technology for water pollution remediation and production of clean energy. In this work, S-scheme Ag2CO3/g-C3N4 heterojunctions were engineered for carefully eradicating Rhodamine B dye under natural sunlight irradiation. Solid thermal decomposition reactions generate g-C3N4 sheets by annealing urea at 520 °C. Ag2CO3 nanoparticles are directed and localized sonochemically to the active centers of g-C3N4 sheets. The physicochemical properties of the solid specimen were determined by PL, DRS, XRD, HRTEM, mapping, EDX, N2-adsorption-desorption isotherm and XPS analyses. As elucidated by HRTEM, PL and DRS analyses, 5 wt% of spherical Ag2CO3 nanoparticles deposited on the g-C3N4 sheet surface and nearly equidistant from each other elevate the electron-hole separation efficiency and broaden the absorption capacity of photocatalysts. Rhodamine B dye was degraded at a rate of 0.0141 min−1 by heterojunctions containing 5 wt% Ag2CO3 and 95 wt% g-C3N4, which is three-fold higher than that on pristine g-C3N4 nanosheets. Free radical scrubber experiments revealed the contribution of charge carriers and reactive oxygen species to the decomposition of RhB dye with a preferential role of positive holes and superoxide species. PL measurements of terephthalic acid and scrubber trapping experiments provide confirmatory evidence for charge diffusion via the S-scheme mechanism that accounts for the production of electron-hole pairs with strong redox power. This novel research work is contributory to manipulate the S-scheme heterojunction for efficient and low-cost wastewater treatment under natural solar irradiation.