Interfacial Electron Redistribution of Hydrangea‐like NiO@Ni₂P Heterogeneous Microspheres with Dual‐Phase Synergy for High‐Performance Lithium–Oxygen Battery

Abstract

ultimately increasing the charge transfer resistance. [8] During the OER process, the insulated Li 2 O 2 can only be decomposed at high overpotential, which can trigger severe parasitic reactions. [9][10][11] Therefore, exploring efficient bifunctional electrocatalysts and understanding the formation and decomposition mechanism of Li 2 O 2 is of great significance for effectively reducing ORR and OER overpotential and improving the electrochemical performance of LOBs.Currently, two types of mechanisms (solution-mediated pathway and surface adsorption pathway) were commonly recommended to explain the deposition process of Li 2 O 2 on the electrode surface during ORR. Different mechanisms lead to various structure (crystallinity or defect) and morphology (toroid or thin film) of Li 2 O 2 , eventually determining the battery performance. [12] For the solution-mediated pathway, disproportionation reaction of dissolved intermediate LiO 2 usually forms a large-size toroid-like Li 2 O 2 , resulting in a large discharge capacity but a high charge overpotential which is due to the limited contact between large-size discharge products and electrode surface. [3,12] For the surface adsorption pathway, electrode surface shows strong adsorption toward intermediate LiO 2 , finally leading to the deposition of thin film-like amorphous Li 2 O 2 on the oxygen electrode. The thin film-like Li 2 O 2 is in close contact with electrode, which is beneficial to reduce the charging overpotential. However, film-like discharge product will deliver a small discharge capacity because of the quickly passivated electrode surface. [13] As a result, designing porous oxygen electrodes with tuned adsorption capacity towards O-containing intermediates is essential for LOBs with both large discharge capacity and small charge overpotential. Generally, regulating the heterogeneous interfaces in the catalytic materials to realize the electronic modulation through interfacial coupling has proved to be an effective strategy for optimizing the chemical adsorption of the O-containing intermediates and accelerating the kinetics of oxygen electrode reactions. [14][15][16] Specifically, to achieve the thermodynamic equilibrium state, two regions of opposing charge distribution and a built-in electric field will be created at the interface of the heterostructure, where the strong charge region can modulate the adsorption of reactant, while the built-in Lithium-oxygen batteries (LOBs) with ultra-high theoretical energy density (≈3500 Wh kg −1 ) are considered as the most promising energy storage systems. However, the sluggish kinetics during the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) can induce large voltage hysteresis, inferior roundtrip efficiency and unsatisfactory cyclic stability. Herein, hydrangea-like NiO@Ni 2 P heterogeneous microspheres are elaborately designed as high-efficiency oxygen electrodes for LOBs. Benefitting from the interfacial electron redistribution on NiO@Ni 2 P heterostructure, the electronic structure can b...

Ni2P Nanoparticle-Inserted Porous Layered NiO Hetero-Structured Nanosheets as a Durable Catalyst for the Electro-Oxidation of Urea

“…Notably, the Ni 2p XPS of Ni 2 P@NiO/NiF deconvoluted into two doublets along with their shake-up satellites peaks located at 853.5 eV and 871.7 eV, originating at the Ni 2+ component and shifted to a binding energy range by 0.38 eV and 0.48 eV that related to the NiO/NiF catalyst ( Figure 4 D). The above observed shift was mainly ascribed to the binding of the O, P, and Ni elements on Ni 2 P@NiO, which clearly confirmed the insertion of the Ni 2 P nanoparticles on the NiO nanosheet structure [ 51 , 52 ]. The O 1 s XPS of the Ni 2 P@NiO/NiF-40 and NiO/NiF samples are displayed in Figure 4 D. The O 1 s deconvoluted into three components at 528.9, 530.7, and 531.5 eV, corresponding to the lattice oxygen, the hydroxyl component, and the structurally adsorbed water, respectively.…”

Realizing fast polysulfides conversion within yolk-shelled NiO@HCSs nanoreactor as cathode host for high-performance lithium-sulfur batteries

“…2e). Furthermore, for Ni species, four peaks from the Ni 2p spectrum locating at binding energies of 857.88, 863.44, 875.34 and 881.4 eV corresponded to Ni 2p 3/2 regions, satellite peak, Ni 2p 1/2 region and satellite peak, respectively 45 (Fig. 2f).…”

Bucket effect on high-performance Li–O2 batteries based on P-doped 3D NiO microspheres with conformal growth of discharge products

“…Under such conditions, the poor contact between the cathode and Li 2 O 2 made the electrocatalytic performance unsatisfactory, leading to residual discharge products and poor electrochemical performance. [79][80][81] Electron localization function (ELF) calculations were performed for different catalysts to investigate the P doping effect on electron distribution properties, and color scales and corresponding ELF values are listed on the right, as shown in the dashed boxes. It can be clearly observed that the introduction of P atoms resulted in charge redistribution to form a highly reactive electron-like gas region with high reactivity, which contributed to the rapid transport of carriers and efficient adsorption of adsorbates for the OER and ORR.…”