Hole and Electron Doping of the 4d Transition‐Metal Oxyhydride LaSr₃NiRuO₄H₄

Abstract

Hole or electron doping of phases prepared by topochemical reactions (e.g. anion deintercalation or anion‐exchange) is extremely challenging as these low‐temperature conversion reactions are typically very sensitive to the electron counts of precursor phases. Herein we report the successful hole and electron doping of the transition‐metal oxyhydride LaSr3NiRuO4H4 by first preparing precursors in the range LaxSr4−xNiRuO8 0.5<x<1.4 and then converting into the corresponding LaxSr4−xNiRuO4H4 phases. This is particularly noteworthy as the (Ni/Ru)H2 sheets in the LaxSr4−xNiRuO4H4 phases are structurally analogous to the CuO2 sheets in cuprate superconductors and hole doping (Ni1+/2+, Ru2+) or electron doping (Ni2+, Ru1+/2+) yields materials with partial occupancy in Ni/Ru 3normald/4normaldx2-y2 –H 1s bands which are analogous to the partially occupied Cu 3normaldnormalx2-normaly2 –O 2p bands present in the CuO2 sheets of doped superconducting cuprates.

Is La3Ni2O6.5 a Bulk Superconducting Nickelate?

“…The ZFC curve distinctively shows two transitionsat temperatures of about 10 and 50 K, with the latter being much broader than the former. The field-dependent data were collected from the reduced phase at both 5 and 300 K over the field range −9 T ≤ H ≤ 9 T. The 300 K magnetization isotherm exhibits a “kink” instead of being a straight line passing through the origin, indicating that a trace amount (∼0.43% per mole of La 1.5 NiO 3.225 , calculated by comparing the 300 K isotherm step heights in Figure b and Figure S2) of ferromagnetic impurity with ∼0.43% molar ratio when compared to that of elemental Ni exists in the reduced sample La 3 Ni 2 O 6.45 , which is a known situation for topochemically reduced Ni-containing oxides. − The subtly opened-up hysteresis loop in the 5 K isotherm further confirms the existence of ferromagnetic impurity in the system, which is equivalent to 0.43% by mole of elemental Ni (Figure b). Therefore, it is necessary to employ a ferro-subtraction technique, which can unveil the magnetic behavior of the bulk material by applying an external field greater than 2 T to saturate the magnetization of the ferromagnetic impurity.…”

Mesoporous Electrocatalysts with p–n Heterojunctions for Efficient Electroreduction of CO2 and N2 to Urea

“…The d-electron number and d-electron delocalization in transition-metal catalysts play an important regulatory role in electrocatalytic oxidation–reduction reactions . Therefore, the orbital electron occupation state of the transition metals in electrocatalysts can be adjusted to create empty orbitals to receive intermediate σ orbital electrons, thus promoting spontaneous coupling of C–N bonds. ,− Moreover, transition-metal oxide catalysts can increase their specific surface area through metal doping, thereby enhancing its gas adsorption ability and promoting the activation of reaction gases. , …”