Local Electric Field Induced by Atomic‐Level Donor–Acceptor Couple of O Vacancies and Mn Atoms Enables Efficient Hybrid Capacitive Deionization

Abstract

Transition metal oxides suffer from slow salt removal rate (SRR) due to inferior ions diffusion ability in hybrid capacitive deionization (HCDI). Local electric field (LEF) can efficiently improve the ions diffusion kinetics in thin electrodes for electrochemical energy storage. Nevertheless, it is still a challenge to facilitate the ions diffusion in bulk electrodes with high loading mass for HCDI. Herein, this work delicately constructs a LEF via engineering atomic‐level donor (O vacancies)–acceptor (Mn atoms) couples, which significantly facilitates the ions diffusion and then enables a high‐performance HCDI. The LEF boosts an extended accelerated ions diffusion channel at the particle surface and interparticle space, resulting in both remarkably enhanced SRR and salt removal capacity. Convincingly, the theoretical calculations demonstrate that electron‐enriched Mn atoms center coupled with an electron‐depleted O vacancies center is formed due to the electron back‐donation from O vacancies to adjacent Mn centers. The resulted LEF efficiently reduce the ions diffusion energy barrier. This work sheds light on the effect of atomic‐level LEF on improving ions diffusion kinetics at high loading mass application and paves the way for the design of transition metal oxides toward high‐performance HCDI applications.

Interfacial Hydrogen Spillover on Pd-TiO2 with Oxygen Vacancies Promotes Formate Electrooxidation

“…42 Furthermore, a decreased peak intensity at 520−555 eV was observed for Pd/O v -TiO 2 compared to Pd/TiO 2 in O K-edge spectra (Figure 2c), which can be assigned to the elevated concentration of oxygen vacancies in Pd/O v -TiO 2 . 43 To explore the relative concentration and types of oxygen vacancies in Pd/O v -TiO 2 and Pd/TiO 2 , positron annihilation spectroscopy was further employed (Figure S6a). 29,44,45 The positron lifetime spectra of both Pd/O v -TiO 2 and Pd/TiO 2 yielded three lifetime components (Table S1).…”

“…The band gaps of Pd/O v -TiO 2 and Pd/TiO 2 were determined to be 2.94 and 3.16 eV, respectively (Figure b), providing further evidence for the successful incorporation of oxygen vacancies into Pd/O v -TiO 2 . Furthermore, a decreased peak intensity at 520–555 eV was observed for Pd/O v -TiO 2 compared to Pd/TiO 2 in O K-edge spectra (Figure c), which can be assigned to the elevated concentration of oxygen vacancies in Pd/O v -TiO 2 . To explore the relative concentration and types of oxygen vacancies in Pd/O v -TiO 2 and Pd/TiO 2 , positron annihilation spectroscopy was further employed (Figure S6a).…”

Oxygen-Vacancy-Induced Built-In Electric Field across MoCo Dual-Atomic Site Catalyst for Promoting Hydrogen Spillover in Hydrocracking and Hydrodesulfurization

“…The reduction of the valence of Co was generated by facilitating charge transfer from the Co atom, resulting from the absence of the coordination O atom on the vacancy. The electron enrichment on the Co atom can be attributed to the effect of electron accumulation in the Co atom site adjacent to the O vacancy due to an electron depletion center formed on the O vacancy with the electron delocalization effect . This explains why the valence of Co was decreased in XANES (Figure S10B) and the binding energy of O 1s in XPS (Figure B) increased.…”

“…The electron enrichment on the Co atom can be attributed to the effect of electron accumulation in the Co atom site adjacent to the O vacancy due to an electron depletion center formed on the O vacancy with the electron delocalization effect. 42 This explains why the valence of Co was decreased in XANES (Figure S10B) and the binding energy of O 1s in XPS (Figure 5B) increased. Subsequently, a weak electric field was generated with the charge imbalance between the Mo atom and the Co atom; the migration of electrons leads to the elevation of Mo valence in XANES (Figure S10A), which was promoted by electric field.…”

Iron Active Center Coordination Reconstruction in Iron Carbide Modified on Porous Carbon for Superior Overall Water Splitting

“…On the contrary, the increased integral area of 83.59 on C represents the accumulation of electron. [ 29 ] As expected, the decreased binding energy of XPS is consistent with the theoretically calculated variations of charge density on Fe, C, and N. The above results can be summarized in the following two points: i) Fe 3 C/NC‐550 acquires the optimal Gibbs free energy (both ΔG H* for HER and ΔG for OER), in which the absolute value is much lower than those of Fe 3 C/NC and Fe 3 C/NC‐350, respectively, which ensures a faster adsorption/desorption reaction process. ii) The obtained results confirm that the d‐band center value of the Fe 3 C/NC‐550 gradually approaches 0 eV with the progress of the experimental steps, demonstrating that the theoretical catalytic activity of the electrocatalyst is gradually improved.…”