Asymmetric magnetic nanosnowman loaded with AgPd nanocage toward NIR-enhanced catalytic activity†

Abstract

Although bimetallic noble nanostructures often possess high activity in nanocatalysis, their controllable fabrication, tunable catalytic activity, and easy separation remain significant challenges. In this study, an Fe₃O₄@AgPd/Polydopamine (Fe₃O₄@AgPd/PDA) nanosnowman loaded with an AgPd nanocage was designed by a one-step template-disposition-redox polymerization method. The AgPd nanocage endowed the product with high catalytic activity for the reduction of organic pollutants (4-NP, MO, MB). Interestingly, under near-infrared (NIR) light, the catalytic kinetics of the Fe₃O₄@AgPd/PDA nanosnowman on catalytic reduction of organic pollutants increased by 2.6, 1.57, and 5.45 times, respectively. The asymmetric nanostructure facilitated the separation of electron–hole pairs, promoted electron transfer, and accelerated the catalytic activity. Density functional theory (DFT) analysis indicated that the electron transfer between the AgPd alloy and the Fe₃O₄ nanosphere played a critical role on the high catalytic activity. Moreover, Fe₃O₄@AgPd/PDA also demonstrated excellent catalytic activity in the Heck carbon–carbon coupling reaction with a >95% conversion rate and >99% selectivity. Owing to the well-encapsulated PDA shell and outstanding magnetic properties, the Fe₃O₄@AgPd/PDA nanosnowman exhibited good cyclic catalytic activity. With its multi-mode catalysis, NIR-enhanced catalytic activity, and easy separation, the Fe₃O₄@AgPd/PDA nanosnowman exhibits great application potential in nanocatalysis.