Tuning the metal valence state of Pd nanoparticles via codoping of B–N for chlorophenol hydrodechlorination

Abstract

Catalytic hydrodechlorination (HDC) is considered as one of the most promising strategies for the treatment of chlorinated environmental pollutants. Here we proposed a strategy for rapid complete dechlorination by exploiting a B–N co-doped hierarchically porous carbon material (BNC) to immobilize Pd NPs, which makes use of not only the micro/meso porous structure to accelerate the mass transport and to provide enormous active sites, but also the synergistic effect for codoping of B–N to enhance the interaction between Pd NPs and support and thus to stabilize and disperse the small size of the Pd particle. Ascribed to these combined advantages, Pd/BNC exhibited more distinctive catalytic dehalogenation activity (k = −0.14 min⁻¹) and better stability (about 90.0% activity retention after 5 cycles) than Pd/C (k = −0.0070 min⁻¹). Additionally, density functional theory (DFT) calculation indicates that the incorporation of N and B atoms in the carbon skeleton will reduce the adsorption energy of Cl⁻ and thus Pd/BNC exhibits more remarkable stability than Pd/C during long-term HDC reactions. As a result, ultrafine Pd particles and high Pd²⁺/(Pd²⁺ + Pd⁰) ratios were found in Pd/BNC.