Strong Pyrrolic-N-Pd Interactions Boost the Electrocatalytic Hydrodechlorination Reaction on Palladium Nanoparticles

We demonstrated the heteroatomic nitrogen (N) doping on graphene can significantly enhance the performance of the graphene-palladium nanoparticles composite catalyst (N/G-Pd) in electrocatalytic hydrodechlorination reaction (EHDC). Specifically at -0.80 V (vs. Ag/AgCl), the N/G-430-Pd (prepared at 430 oC, pyridinic/pyrrolic-N-rich) and N/G-900-Pd (prepared at 900 oC, pyridinic/graphitic-N-rich) with equivalent total N content delivered the apparent rate constant (kobs) of 0.28 and 0.20 min-1 molPd-1 in removing 2,4-dichlorophenol, much higher than 0.13 min-1 molPd-1 of the C-Pd. Additionally, we identified the determinant role of pyrrolic-N in boosting EHDC from the linear relationship between kobs-N and the pyrrolic-N content in catalyst. A combined experimental and DFT analyses revealed the positive effect of N doping originated from the strong N-Pd interactions, which modulated the Pd electronic structure and its interactions with the reactant and EHDC products (phenol and Cl-). Pyrrolic N-Pd bond was favored as it could balance the reactant adsorption and the product desorption.