Harbin Engineering University

About: Harbin Engineering University is a education organization based out in Harbin, Heilongjiang, China. It is known for research contribution in the topics: Control theory & Microstructure. The organization has 31149 authors who have published 27940 publications receiving 276787 citations. The organization is also known as: HEU.

Cross-linked Na2VTi(PO4)3@C hierarchical nanofibers as high-performance bi-functional electrodes for symmetric aqueous rechargeable sodium batteries

Abstract: Significant interest has been devoted to the design and fabrication of flexible electronic devices owing to their immense potential in modern society. Constructing freestanding electrodes with superior electrochemical performance and excellent mechanical durability is the key to the development of high-performance energy storage devices. In this study, we introduce a new cross-linked Na2VTi(PO4)3/porous carbon nanofiber, which is employed as a self-supported bi-functional electrode in aqueous sodium ion batteries. The sodium intercalation mechanism of the Na2VTi(PO4)3/C electrode in an aqueous electrolyte is investigated. The reversible phase transformations and the valence state change of Na2VTi(PO4)3 in both high- and low-potential ranges (i.e. 0–0.6 V vs. Ag/AgCl; −1–0 V vs. Ag/AgCl) demonstrate its reliability as both the anode and the cathode in the aqueous electrolyte. Favored by the highly porous architecture and aligned cross-linked arrangement, the Na2VTi(PO4)3/C nanofiber achieves fast kinetics and good mechanical characteristics. Both result in its superior high-rate properties, good cycling durability and high structural stability. Moreover, a symmetric aqueous rechargeable sodium battery is prepared by assembling two cross-arranged Na2VTi(PO4)3/C nanofiber electrodes. The cell exhibits a flat potential plateau of ∼1.2 V and is capable of high-rate long-term cycling. It retains 83% of the capacity after six hundred cycles at alternate 40 and 4C. Therefore, this work not only introduces a novel symmetric aqueous sodium ion system, but also provides a highly efficient architecture for flexible high-performance electrodes. More importantly, it provides a new clue to construct energy storage devices with a simple configuration, low-cost and superior properties.

Ni–Mn LDH-decorated 3D Fe-inserted and N-doped carbon framework composites for efficient uranium(VI) removal

Abstract: Extraction of uranium from seawater is of great interest because of its potential applications in the nuclear energy field. In this study, we prepared 3D Fe-inserted and N-doped carbon nanosheet frameworks by a polymer-blowing process, followed by decoration with nickel–manganese layered double hydroxide (Fe-NCNF-LDH). Employing SEM, FTIR, XPS, XRD, TEM, and BET techniques, we confirmed the existence of 3D structured porous materials with advantageous interconnectivity to provide a highly accessible freeway for uranium(VI) ionic diffusion. We investigated the removal of uranium(VI) from an aqueous solution (ppm level) and simulated seawater (ppb level) by the Fe-NCNF-LDH composites. The results showed that the adsorption process fitted well with a pseudo-second-order model and Langmuir isotherm model. Based on XRD and XPS, before and after the adsorption of uranium(VI), we proposed a possible sorption mechanism (anion exchange, chemical reduction, and surface complexation). In addition, the Fe-NCNF-LDH composites show good adsorption properties after five adsorption–desorption cycles, which augur well for potential application in the field of the adsorption of uranium from seawater.