A study of Co3−xNixO4 (O≤x≤1) system

Insights into the Performance of CoxNi1–xTiO3 Solid Solutions as Photocatalysts for Sun-Driven Water Oxidation

“…The donor character of Ni atoms in other NiTiO 3 has been previously observed, and relatively high donor densities have been estimated for this material . Interestingly, these results agree with those obtained by other authors for Co 3– x Ni x O 4 spinels, which presented drastic decreases in the resistivity and Seebeck coefficient at room temperature up to x values of 0.5 . This electrical conductivity improvement has been ascribed to a transition from semiconductor to semimetallic nature and ferromagnetic features at x ≥ 5.…”

Valence Engineering via Selective Atomic Substitution on Tetrahedral Sites in Spinel Oxide for Highly Enhanced Oxygen Evolution Catalysis

“…From the results of XAFS and XPS, it is reasonable to conclude that Fe incorporation into NiCo oxides is responsible for increased ratio of Ni 3+ /Ni 2+ and decreased ratio of Co 3+ /Co 2+ in the octahedral occupation (as active sites), , respectively. On the basis of Yang’s principles and Xu’ reports , developed from the former, Ni 2+ ( t 2g 6 e g 2 ), Co 2+ ( t 2g 5 e g 2 ), and Fe 3+ ( t 2g 3 e g 2 ) with high-spin state have the same e g occupancy, while Ni 3+ ( t 2g 6 e g 1 ) and Co 3+ ( t 2g 6 e g 0 ) belong to low-spin state . Since the content of Fe in active octahedral sites on the catalyst surface is below 0.2% (the surface of NiCoFeO contains only 2% of Fe ions (from XPS data), among which 9.7% of them are in the octahedral sites), the Fe contribution on e g occupancy can be neglected.…”

Facile synthesis of NiCo2O4 nanorod arrays on Cu conductive substrates as superior anode materials for high-rate Li-ion batteries

“…[26][27][28][29][30][31][32] While compared with binary Co 3 O 4 electrode materials, the ternary NiCo 2 O 4 anode has a much higher electrical conductivity, e.g., the Nidoping improved the electrical conductivity from 3.1 6 10 25 S cm 21 for Co 3 O 4 to 0.1-0.3 S cm 21 for Ni x Co 32x O 4 . [33][34][35][36][37] Such a huge increase of the electrical conductivity of the Co 3 O 4 electrode should greatly enhance its lithium storage performances, especially for its high rate capability. Herein, we reported a mild and cost-effective solution method to directly grow Ni-substituted Co 3 O 4 (NiCo 2 O 4 ) nanorod arrays on Cu conductive substrates.…”