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DOE OSTI2020

Materials Data on PmNd by Materials Project

PmNd is Magnesium-derived structured and crystallizes in the hexagonal P-6m2 space group. The structure is three-dimensional. Pm is bonded to six equivalent Pm and six equivalent Nd atoms to form PmPm6Nd6 cuboctahedra that share corners with eighteen equivalent PmPm6Nd6 cuboctahedra, edges with six equivalent PmPm6Nd6 cuboctahedra, edges with twelve equivalent NdPm6Nd6 cuboctahedra, faces with eight equivalent PmPm6Nd6 cuboctahedra, and faces with twelve equivalent NdPm6Nd6 cuboctahedra. All Pm–Pm bond lengths are 3.67 Å. All Pm–Nd bond lengths are 3.69 Å. Nd is bonded to six equivalent Pm and six equivalent Nd atoms to form NdPm6Nd6 cuboctahedra that share corners with eighteen equivalent NdPm6Nd6 cuboctahedra, edges with six equivalent NdPm6Nd6 cuboctahedra, edges with twelve equivalent PmPm6Nd6 cuboctahedra, faces with eight equivalent NdPm6Nd6 cuboctahedra, and faces with twelve equivalent PmPm6Nd6 cuboctahedra. All Nd–Nd bond lengths are 3.67 Å.

36 MATERIALS SCIENCE↗

DOE OSTI2025

Cu-induced robust Ni 2+ /Ni 3+ transition on amorphous Ni hydroxide-based electrocatalysts for advancing electrochemical ammonia oxidation and hydrogen evolution

The electrochemical ammonia oxidation reaction (AOR) is a promising anodic reaction for hydrogen production, offering a lower theoretical potential compared to oxygen evolution reaction. Despite this thermodynamic advantage, AOR suffers from sluggish multi-electron transfer reaction kinetics and the regeneration of catalytically active Ni 3+ species, which limits both activity and durability. In this study, amorphous NiCu bimetallic catalysts were prepared via facile precipitating metal nitrate deposition (PMND) method. The addition of Cu induces a robust Ni 2+ /Ni 3+ transition, stabilizing catalytically active Ni 3+ species and modulating the electronic structure of Ni. It alters the oxidation and desorption behavior of nitrogen-containing intermediates and facilitating their conversions to NO x species, resulting in fast active site regeneration. Furthermore, amorphous structure provides abundant dangling bonds, which enhances the intrinsic reactivity and accessibility of active sites rather than increasing the number of active sites. As a result, these effects accelerate the overall reaction kinetics. The optimized NiCu 5:1 catalyst achieved an ammonia removal efficiency of ∼100 % and a hydrogen production rate of 2.45 mmol/(h∙cm 2 ) at 1.6 V RHE .

Amorphous electrocatalyst↗