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Teobaldi, Gilberto

Publications and source records attributed to Teobaldi, Gilberto.

Activating Bi p- orbitals in Dispersed Clusters of Amorphous BiO x for Electrocatalytic Nitrogen Reduction

Catalytic strategies based on main group metals are significantly less advanced than those of transition metal catalysis, leaving untapped areas of potentially fruitful research. Here, in this study, we demonstrate an effective approach for the modulation of Bi 6p energy levels during the construction of atomically dispersed clusters of amorphous BiO x . Bi oxidation state is proposed to strongly affects the nitrogen fixation activity, with the half-occupied p z orbitals of the Bi 2+ ions being highly efficient toward electron injection into the inert N 2 molecule. With sufficient catalytic sites to adsorb and activate N 2 , the bonding between N 2 and catalyst is able to be in situ identified. The catalyst shows an outstanding Faraday efficiency (≈30 %) and high yield (≈113 μg h -1 mg -1 cat ) in NH 3 production, outperforming most of the existing catalysts in aqueous solution. These results lay the basis for developing the potential of p-block elements for catalysis of multi-electron reactions.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗

Structure and Oxygen Evolution Activity of β-NiOOH: Where Are the Protons?

Ni oxides and oxyhydroxides (NiO x ) have been studied for a long time as cathode materials for alkaline batteries and electrocatalysts for the oxygen evolution reaction (OER). Yet, understanding of the connection between their atomic and electronic structures and electrochemical performance or stability is still incomplete. In this work, we use first-principles density functional theory (DFT) calculations to revisit the structure, electronic properties, and OER activity of β-NiOOH, the catalytically active phase of NiO x . Following extensive DFTbased screening, we identify a hitherto overlooked structure characterized by a uniform distribution of H atoms on the NiO 2 layers. All the Ni 3+ cations in this structure exhibit an identical t g 6 e g 1 electronic configuration with an occupied 3d z2 orbital. Comparison of the calculated bond lengths with extended X-ray absorption fine structure (EXAFS) data unequivocally supports this structure relative to all other low-energy configurations. Based on this structure, we uncover and detail defect-dominated OER mechanisms on the basal β-NiOOH (001) surface, with overpotentials as low as 0.39 V. The present results should provide a valuable contribution to ongoing efforts for understanding and developing enhanced transition-metal hydroxide catalysts for the OER.

37 INORGANIC, ORGANIC, PHYSICAL, AND ANALYTICAL CH↗