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Inverse ‘intra-lattice’ charge transfer in nickel–molybdenum dual electrocatalysts regulated by under-coordinating the molybdenum center

The prevalence of intermetallic charge transfer is a marvel for fine-tuning the electronic structure of active centers in electrocatalysts. Although Pauling electronegativity is the primary deciding factor for the direction of charge transfer, we report an unorthodox intra-lattice ‘inverse’ charge t...

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Detalles Bibliográficos
Autores principales: Parvin, Sahanaz, Bothra, Neha, Dutta, Supriti, Maji, Mamoni, Mura, Maglu, Kumar, Ashwani, Chaudhary, Dhirendra K., Rajput, Parasmani, Kumar, Manvendra, Pati, Swapan K., Bhattacharyya, Sayan
Formato: Online Artículo Texto
Lenguaje:English
Publicado: The Royal Society of Chemistry 2023
Materias:
Acceso en línea:https://www.ncbi.nlm.nih.gov/pmc/articles/PMC10016623/
https://www.ncbi.nlm.nih.gov/pubmed/36937581
http://dx.doi.org/10.1039/d2sc04617b
Descripción
Sumario:The prevalence of intermetallic charge transfer is a marvel for fine-tuning the electronic structure of active centers in electrocatalysts. Although Pauling electronegativity is the primary deciding factor for the direction of charge transfer, we report an unorthodox intra-lattice ‘inverse’ charge transfer from Mo to Ni in two systems, Ni(73)Mo alloy electrodeposited on Cu nanowires and NiMo-hydroxide (Ni : Mo = 5 : 1) on Ni foam. The inverse charge transfer deciphered by X-ray absorption fine structure studies and X-ray photoelectron spectroscopy has been understood by the Bader charge and projected density of state analyses. The undercoordinated Mo-center pushes the Mo 4d-orbitals close to the Fermi energy in the valence band region while Ni 3d-orbitals lie in the conduction band. Since electrons are donated from the electron-rich Mo-center to the electron-poor Ni-center, the inverse charge transfer effect navigates the Mo-center to become positively charged and vice versa. The reverse charge distribution in Ni(73)Mo accelerates the electrochemical hydrogen evolution reaction in alkaline and acidic media with 0.35 and 0.07 s(−1) turnover frequency at −33 ± 10 and −54 ± 8 mV versus the reversible hydrogen electrode, respectively. The corresponding mass activities are 10.5 ± 2 and 2.9 ± 0.3 A g(−1) at 100, and 54 mV overpotential, respectively. Anodic potential oxidizes the Ni-center of NiMo-hydroxide for alkaline water oxidation with 0.43 O(2) s(−1) turnover frequency at 290 mV overpotential. This extremely durable homologous couple achieves water and urea splitting with cell voltages of 1.48 ± 0.02 and 1.32 ± 0.02 V, respectively, at 10 mA cm(−2).