Pd single-atom-site stabilized by supported phosphomolybdic acid: design, characterizations and tandem Suzuki–Miyaura cross coupling/nitro hydrogenation reaction

Abstract

Herein, a single-metal (Pd) site with high surface energy was stabilized and dispersed on a support (zirconia) via a stabilizing agent (phosphomolybdic acid) using a wet chemistry method. HRTEM and HAADF-STEM showed a highly uniform dispersion of Pd SASc on PMA/ZrO₂. The Pd SASc showed superior catalytic activity (>99% conversion) for the Suzuki–Miyaura cross-coupling reaction, which was further feasible for catalyzing mechanistically different nitro hydrogenation reactions in tandem fusion under mild reaction conditions. This catalyst showed outstanding activity (100% conversion and 99% selectivity) with a substrate/catalyst ratio of 927 and TON of 918 using a very low amount of Pd (0.94 × 10⁻³ mmol) for the tandem Suzuki–Miyaura cross-coupling/nitro hydrogenation reaction. It also exhibited superior stability and reusability for up to three cycles without any change in its activity.