Pd–Co alloy as an efficient recyclable catalyst for the reduction of hazardous 4-nitrophenol

Abstract

Palladium–Cobalt (Pd–Co) alloys with different atomic ratios were synthesized successfully by borohydride-assisted chemical reduction method. Pd–Co alloys were characterized to study their physical and chemical properties. Further, the catalytic behavior of the synthesized alloys and effect of cobalt inclusion into alloy for the catalytic behavior was studied using reduction of 4-nitrophenol (4-NP). The reduction of 4-NP into 4-aminophenol by sodium borohydride is one of the eminent model reactions to study catalytic behavior as it enables assessing the catalyst from the kinetic parameters calculated from the real-time spectroscopic monitoring of an aqueous solution. Pd–Co alloys show good catalytic activity towards the reduction of 4-NP and their rate constants were calculated. The catalytic studies reveal that reduction reaction catalyzed by prepared Pd–Co alloys follow the pseudo-first-order kinetics. Among them, Pd26Co74 catalyzed the reduction reaction with the minimum time of 7 min having a rate constant of 6.65 ms−1. The turn over frequency (TOF) for the corresponding alloy was calculated and found to be 26 h−1.