Nanodenitrification with Bimetallic Nanoparticles Confined in N-doped Mesoporous Carbon
Nitrate and phosphorous were the leading cause of eutrophication and deterioration of water quality worldwide, owing to increasing fossil fuel consumption and use of modern fertilizers. Herein, we introduced an N-doped ordered mesoporous carbon based skeleton with Cu-Pd nanocrystals (Cu-Pd@N-OMC) for electrocatalytic reduction of NO3− to dinitrogen (N2). Laboratory experiments demonstrated high NO3− removal (91%) and N2 selectivity (97%) for eutrophic water treatment. The nanocatalyst also remained highly active over 15 experimental cycles. Metal organic frameworks (MOFs) induced dispersion and embedment of small Cu-Pd nanocrystals (4~9 nm) in the carbon mesochannels. Moreover, the metal loading was as low as 5 wt.% with a Cu/Pd ratios at 4/1. Results suggested that the electrocatalytic reactivity could be fine-tuned by size and crystallinity of Cu-Pd nanoparticles through controlling the pyrolysis temperature. The high-density Cu-Pd nanocrystals promoted rapid hydrogen adsorption to cleave the N-O bond for high N2 selectivity. The incorporation of MOFs and OMC improved dispersion and stabilization of metallic nanoparticles for prolonged electrocatalytic activity and durability.