Adjusting the Coordination Environment of Mn Enhances Supercapacitor Performance of MnO₂

Abstract

delivers a low volumetric capacitance due to its insufficient active sites, as well as the existence of "dead volumes" without capacitance contribution. Especially, both the low conductivity and the poor ion transport ability of MnO 2 significantly hinder the charge transfer rate. [3] Therefore, it is highly desirable to improve the intrinsically electrical conductivity and ion diffusion ability aiming to achieve high performance of MnO 2 for supercapacitor applications.As known, electronic structure, as an important physical and chemical feature, significantly impacts the properties of metal oxide electrode materials. Consequently, optimized electronic structure of metal oxides has drawn dramatically attention in order to solve the problems of low electrical conductivity and poor ion diffusion ability. Specifically, the local coordination environment of metal atoms, including the oxidation state, the coordination number (CN), the coordination structure and so on, usually plays a significant role in electrical structure and charge diffusion dynamics of metal oxides. [4] Recently, several studies have been devoted to adjusting the coordination environment of metal atoms to regulate the performances of metal oxides based catalysis for oxygen evolution reaction, [4] hydrogen evolution reaction, [5] CO 2 reduction, [6] and organic oxidation. [7] However, the effect on the coordination environment of metal atoms on the capacitive performance of metal oxides, as far as we know, remains elusive. In particular, no effort has been made to tailoring electrochemical properties of MnO 2 as supercapacitor electrode material in considering adjusting the coordination environment of Mn atoms. Therefore, it is scientifically meaningful to optimize the coordination environment of Mn atoms, thus endowing MnO 2 electrode material with promising supercapacitor performances.Herein, MnO 2 -TEA nanosheets (NSs) were successfully prepared through a solution-based chemical deposition process using Triethanolamine (TEA) as a typical complex agent. Scanning transmission electron microscopy (STEM), X-ray photoelectron spectroscopy (XPS), and X-ray absorption spectroscopy (XAS) confirm that the coordination environment of Mn atoms in MnO 2 -TEA has been sufficiently adjusted by forming oxygen deficiency and more Mn-Mn2 (corner-shared Mn-Mn shell). As a result, the electrochemical performance of MnO 2 -TEA isThe electrochemical properties of transition metal oxides strongly depend on the coordination environment of metal atoms. Nevertheless, the relationship between the coordination environment of metal atoms and electrochemical performance of metal oxides is unclear, while the strategy of adjusting the coordination environment of metal atoms is rare. Herein, the engineering of the coordination environment of Mn atoms in manganese dioxides (MnO 2 ) by using a triethanolamine (TEA) complex-induced method is reported. The detailed experimental characterizations and density functional theory calculations show that the optimized Mn coordination e...

Mineral Hydrogel from Inorganic Salts: Biocompatible Synthesis, All‐in‐One Charge Storage, and Possible Implications in the Origin of Life

“…The EIS plot of the mineral gel from 0.1 to 10 5 Hz (Figure 6e) was recorded: in the low-frequency region, the high slope indicated an ideal capacitive behavior with excellent ion transfer capability; [54] in the high-frequency regime, the equivalent series resistance (R ESR ), as directly read from the intercept with the real axis, was very low (1 Ω), indicating an excellent ionic conductivity of the electrolyte, while the interfacial charge-transfer resistance (R ct ) measured from the diameter of the semicircle was small (3 Ω), revealing an efficient charge/ion transport at the interface between the electrode material and the electrolyte. [55] This efficient charge/ion transport is attributed to the one-piece holistic design, which perfectly solves the common problem of poor interfacial wettability between electrode and electrolyte.…”

The synergistically enhanced activity and stability of layered manganese oxide via the engineering of defects and K+ ions for oxygen electrocatalysis

“…To be specific, the spin energy difference of 4.93 eV for the MnO 2 sample corresponds to a typical layered manganese dioxide structure with an AOS of 3.40. 44 Due to the conditions supplied due to the amorphous nature and the partial substitution of NH 4 + with K + /Na + , poorly crystalline K-DMO and DMO both display relatively lower AOS values of 3.29 and 3.28, respectively, compared with K-MnO 2 (3.52) and MnO 2 (3.40), suggesting the presence of abundant defects combined with sufficient electroactive Mn 3+ sites. 45 Different surface oxygen species, which can be sorted into three types, engage in the electrochemical processes.…”

Oxygen‐Deficient Metal Oxides for Supercapacitive Energy Storage: From Theoretical Calculation to Structural Regulation and Utilization

“…Zhang et al [ 141 ] synthesized oxygen‐deficient MnO 2 via a triethanolamine (TEA) complex‐induced method (denoted as MnO 2 ‐TEA) shown in Figure a; they then tuned the Mn coordination environment by forming OVs. HAADF‐STEM characterization shows that the Mn columns distribution changes in MnO 2 ‐TEA (Figure 11b–d), which should result from the change in the Mn atom coordination environment.…”