Engineering e_g Orbital Occupancy of Pt with Au Alloying Enables Reversible Li−O₂ Batteries

Abstract

Constructing well-designed catalysts to accelerate OER catalytic activity and alleviate the charge overpotential is prevailing for achieving sophisticated LiÀ O 2 batteries. Herein, we report a concept for engineering the e g occupancy of Pt with M alloying (M = Au, Ru) to tune the charge overpotentials for achieving high-performance LiÀ O 2 batteries. The X-ray photoelectron spectroscopy results coupled with density functional theory (DFT) calculations reveal that the highly electronegative Au can capture more e g electrons from Pt, leading to less e g electrons of Pt in PtAu than that in PtRu. The lower e g occupancy of Pt atoms in PtAu alloys entails the upward shift of the Pt d band, which causes a strong binding strength towards the intermediates (LiO 2 ), thereby decreasing the OER energy barrier. As a consequence, the LiÀ O 2 battery with a PtAu cathode delivers a low charge overpotential of 0.36 V and superior cycle life of 220 cycles at a cutoff capacity of 1000 mAh g À 1 , which is among the best in the reported noble metal-based cathodes.

Modulating Tit2gOrbital Occupancy in a Cu/TiO2Composite for Selective Photocatalytic CO2Reduction to CO

“…After the establishment of Cu 13 /TiO 2 , the d‐band center of Ti 3d moves towards a lower energy level (from 0.79 eV in the pristine TiO 2 to −1.13 eV in Cu 13 /TiO 2 ,), which is consistent with the phenomenon observed in XANES (Figure 2c). Meanwhile, the d‐band center of Cu 3d shifted to a higher level (from −2.36 eV in bulk Cu in Figure 5b to −2.23 eV in Cu 13 /TiO 2 ), suggesting a strong interaction between Ti and Cu in Cu 13 /TiO 2 [53, 54] . In 2 layers‐Cu/TiO 2 shown in Figure S21, the d‐band center of Cu 3d underwent a minor shift (from −2.36 eV in bulk Cu in Figure 5b to −2.31 eV), indicating that the excess of Cu loading leads to a weaker interaction in the composite.…”

“…Meanwhile, the d-band center of Cu 3d shifted to a higher level (from À 2.36 eV in bulk Cu in Figure 5b to À 2.23 eV in Cu 13 /TiO 2 ), suggesting a strong interaction between Ti and Cu in Cu 13 /TiO 2 . [53,54] In 2 layers-Cu/TiO 2 shown in Figure S21, the d-band center of Cu 3d underwent a minor shift (from À 2.36 eV in bulk Cu in Figure 5b to À 2.31 eV), indicating that the excess of Cu loading leads to a weaker interaction in the composite. Besides, in Figure 5c, the appearance of a spin-down state around the center of the forbidden band lowers the band gap from the 1.6 eV (Figure S22) to � 0.75 eV, i.e., improving the light absorption.…”

Regulating electron configuration of single Cu sites via unsaturated N,O-coordination for selective oxidation of benzene

“…As revealed, the conduction band of Cu 1 -N 1 O 2 site is muchcloser to the Fermi level than that of Cu 1 -N 3 site, further demonstrating the better charge transfer capability of Cu 1 -N 1 O 2 site 57 . Moreover, owing to the enhanced charge transfer capability and greater electrophilicity of O atom, the Cu 1 -N 1 O 2 site featuring less Cu-3 d electron, meaning more 3 d orbitals were unoccupied, which is beneficial to the adsorption of reactant 58 , 59 .

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A theoretical roadmap for the best oxygen reduction activity in two-dimensional transition metal tellurides

“…For the Pt atom (Figure 2a), the coexistence of unoccupied and occupied d orbitals can facilitate O2 adsorption and activation through a two-way charge transfer, where the unoccupied eg orbital accepts lone-pair electrons from O2, and the occupied t2g orbital donates electrons back to O2 antibonding orbitals. 44,45 This donation and back-donation concept is standard in molecular chemistry (Blyholder model) and has been successfully employed to describe the interaction between small molecules (e.g., N2, C2H4, CO) and transition metal and boron-based catalysts. [46][47][48][49][50][51][52][53] Interestingly, the Te atom possesses an orbital configuration analogous to that of Pt and B atoms in the transition metal stuffed boron nitride nanotube.…”