In-situ combination of CeO2-Au/SnO2 with g-C3N4 nanotubes as superior tubular catalysts for synergistically boosting the nitroaromatic reduction

Abstract

Integrating g-C₃N₄ nanotubes (CNTs) with nano-sized metal oxides to fabricate highly structured composites enables the innovative design of efficient Au-supported catalysts in environmental remediation applications. Here, we report a tubular core–shell catalyst, CNTs@CeO₂-Au/SnO₂, engineered through a Sn²⁺-mediated interfacial strategy enabling electrostatic adsorption and in-situ reduction of Au nanoparticles (NPs), followed by precise integration with CeO₂-decorated CNTs. The catalyst achieved exceptional performance in nitroaromatic pollutant reduction, exhibiting reaction rate constants of 2.286 min⁻¹ and 2.226 min⁻¹ with turnover frequencies (TOF) of 29.07 min⁻¹ and 69.43 min⁻¹ for 4-nitrophenol (4-NP) and 4-nitroaniline (4-NA) removals, respectively, surpassing control materials and prior counterparts. The catalyst’s practical versatility was demonstrated through its remarkable reduction of not only 4-NP and 4-NA isomers but also mixed nitroaromatics and dyes in complex wastewater. The catalyst proved excellent reusability, sustaining reliable catalytic activity and structural robustness across five consecutive cycles. Mechanistic insights revealed the critical role of metastable Au-H intermediates and a ternary electronic synergy between CeO₂, Au/SnO₂ and CNTs in lowering activation energy to drive otherwise non-spontaneous, endothermic reduction pathways. This work established a blueprint for multifunctional catalytic architectures leveraging interfacial engineering and electron-transfer modulation to address complex environmental matrices.