Robust, magnetic, and effective Pd-based nanocatalyst for reduction of toxic hexavalent chromium and nitrophenols

Abstract

A serial of magnetic and robust nanocatalysts of Pd nanoparticles with a mean size of 4 nm evenly supported on N-doped porous carbon with Co wrapped (Co-NC) were fabricated by a facile route at room temperature. Among these, 18 %Pd/Co-NC has regular morphology and exhibits the highest activity towards reduction of Cr (VI) with HCOOH and nitrophenols with NaBH4 in aqueous solution. What is more, 18 %Pd/Co-NC has a higher catalytic activity than that of 20 % commercial Pd/C towards the reduction of Cr(VI). The excellent performance may be due to the Pd nanoparticles of small size, uniform dispersion on Co-NC, large BET surface area, abundant active sites, nitrogen doping, and synergetic effect between Pd and the support of Co-NC. The introduction of Co nanoparticles to the support not only provides magnetism but also may prevent the oxidation of Pd, thus facilitating the separation of the catalyst from the solution and providing more active Pd species to catalyze the reduction reaction. The catalyst can be separated easily by an external magnet and remain the activity without obvious decline after the recycling experiment, indicating the catalyst has a good stability in acidic or basic solution. What is more, K2Cr2O7 can be catalytically reduced by Pd/Co-NC in an industrial environment, confirming the catalyst has a potential application in the remediation of industrial wastewater.