Nano-spatially confined Pd–Cu bimetals in porous N-doped carbon as an electrocatalyst for selective denitrification

Abstract

Nanodenitrification is achieved by bimetallic Pd–Cu nanoparticles encapsulated in porous N-doped carbon as electrocatalysts, with reduced nitrate below drinking water standards and a N2 selectivity as high as 83% in a neutral electrolyte.

On-Demand Atomic Hydrogen Provision by Exposing Electron-Rich Cobalt Sites in an Open-Framework Structure toward Superior Electrocatalytic Nitrate Conversion to Dinitrogen

“…(a) Product distribution of nitrate electrocatalytic reduction by Co-PBAs at the respective electrocatalytic time, (b) nitrate reduction performance of the Co PBA mixture and Co-PBAs under different conditions, (c) Co-PBA stability and reusability, and (d) nitrate reduction performance of different electrocatalysts in chlorine-free systems (data collected from refs , , , − ).…”

“…To date, palladium- and copper-based catalysts have been widely studied for electrochemical nitrate reduction owing to their favorable H* provision. − Furthermore, element doping and defect engineering are applied to enhance H* generation and retainment on the catalyst surface. , However, as electrochemical nitrate reduction is a mass transfer-limited process on a conventional plate cathode, the insufficient utilization of short-lived H* leads to low current efficiency and reaction kinetics (Scheme a). , In addition, the overhydrogenation of *NO 3 – by high-density surface-adsorbed H* reduces N 2 selectivity and accumulates undesirable byproducts like ammonia. − , Although several three-dimensional porous cathodes have been fabricated to address the abovementioned problems, the mismatch between target contaminants (i.e., NO 3 – ) and active species (i.e., H*) will accumulate undesired byproducts such as nitrite (*NO 3 – + 2H* → *NO 2 – ) and ammonia (*NO 3 – + 8H* → *NH 3 ) (Scheme a). ,,, We, therefore, propose a well-manipulated cathode to enhance mass transfer and precisely match the H* generation rate to the nitrate consumption rate. We hypothesize that if nitrate is efficiently transferred to the active sites and H* evolves at a controlled rate (i.e., five times that of *NO 3 – ) simultaneously, nitrate could be reduced to N 2 efficiently and selectively (Scheme b).…”

Metal Sub‐nanoclusters Confined within Hierarchical Porous Carbons with High Oxidation Activity

“…No significant aggregations were observed even at high Cu loadings (up to 8.6 wt %, as determined by ICP‐OES). The valence state of the encapsulated Cu SNCs was identified by X‐ray photoelectron spectroscopy (XPS), which showed characteristic peaks of Cu 0 at 932.5 eV and 952.2 eV (Figure 1 f), indicating Cu nodes in Cu‐BDC were reduced to Cu 0 after pyrolysis [18] . In the XRD pattern of Cu@HPC (Figure 1 a), a broad peak centered at 25.2° was assigned to the (002) plane of graphic carbon species derived from the organic ligands of Cu‐BDC, implying the good graphitization degree of the HPC.…”

Confinement synthesis in porous molecule-based materials: a new opportunity for ultrafine nanostructures

“…Teng et al constructed Pd-Cu NPs wrapped with porous N-doped carbon via such a strategy (Pd-Cu/PNC). 138 A Cu-BTC (BTC ¼ 1,3,5benzenetricarboxylic acid) octahedral crystal with nano-scale cavities was selected as the host molecule. Palladium acetylacetone (Pd(acac) 2 ) was selected as the guest molecule, which could enter the Cu-BTC nanocavities through immersion and capillary force.…”