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Rechargeable aqueous zinc ion batteries are particularly attractive for large-scale application due to their features including low cost, environmental friendliness, and safety. Herein, we report the use of defect engineering to generate oxygen vacancies in tunneled α-MnO 2 through surface gradient Ti doping for long-life Zn MnO 2 battery. Interestingly, the introduction of surface gradient Ti doping leads to shrinkage of the interlayer, but simultaneously generates oxygen vacancies as compensated by electron due to the decreased valence state of Mn. Moreover, Ti substitution as well as the created oxygen vacancies open the [MnO 6 ] octahedral walls and result in imbalanced charge distribution and local electric field in the crystal structure, accelerating ion/electron migration rates. Thus, diffusion coefficients of both Zn2+ and H+ ions in Ti MnO 2 nanowires are improved. Consequently, the Ti MnO 2 nanowires show improved both H+ and Zn2+ ions storage capacity in Zn/MnO 2 battery and achieved excellent high-rate capability and ultralong cycling stability with a low capacity decay rate of 0.005% per cycle at high rate of 1 A g−1. It is believed that the intentionally created vacancies in this work opens up approaches to enhance existing materials that may have applications in more efficient and durable multi-valent ion battery and other technologies. • Ti substitution in α-MnO 2 created oxygen vacancies. • Local electric field accelerates ion/electron migration rates. • Ion diffusion coefficients in Ti-MnO 2 nanowires are improved. • A low capacity decay rate of 0.005% per cycle at 1 A g-1 is achieved. [ABSTRACT FROM AUTHOR]

• With sodium ions insertion, MoS 2 will first experience layer expansion and then phase transformation and finally fragmentation after triggering conversion reaction. • With sodium ions insertion, the HER activity of MoS 2 will gradually increase at the intercalation stage and further increase at the early stage of conversion reaction and finally slightly decrease at the end of discharging. • The possible structure-performance relationship is established. Though enormous attention has been paid to MoS 2 in the field of electrocatalytic hydrogen evolution reaction (HER), the conventional 2H MoS 2 is hardly regarded as an alternative to noble Pt due to the limited number of active sites and semiconducting character. Herein, sodium ions were intentionally introduced into the MoS 2 to regulate its structure and thus HER activity. We found that the HER activity of MoS 2 would gradually increase at the intercalation stage and further increase at the early stage of conversion reaction. Based on various characterization techniques, the possible structure-performance relationship was established. The first increase in activity was ascribed to interlayer expansion and phase transformation, and the second increase in activity was mainly ascribed to increase of active sites due to the fragmentation of MoS 2 after triggering conversion reaction. Even though deep discharging MoS 2 to 0.01 V (vs. Na+/Na) would slightly impair HER activity, such an activity was still much better than that of pristine MoS 2 , which might be originated from the doping of S into molybdenum oxide according to the DFT calculation. Sodium ions were intentionally introduced into the MoS 2 to regulate its structure and HER performance. Image, graphical abstract [ABSTRACT FROM AUTHOR]

The exploration of earth-abundant electrode materials with superior low-temperature behavior and high areal capacity have become more and more urgent for the field of electric vehicles and portable electronic devices. Hollow hierarchical microstructure composed of nanoscaled subunits holds great potential in developing novel electrode materials with superior electrochemical performance. Herein, we demonstrate a bubble-templated method to synthesize Fe 2 (MoO 4) 3 hollow microspheres, and the formation mechanism is carefully investigated. When evaluated as the lithium-ion battery anode, they exhibit a high reversible capacity of 1205 mA h g−1 at 0.5 A g−1 after 200 cycles, good rate performance of 565 mA h g−1 at 10 A g−1, excellent low temperature capability of 281 mA h g−1 at 1 A g−1 at −20 °C, and high reversible areal discharge capacity of 5.2 mA h cm−2 with a high active material mass loading of 5 mg cm−2. Additionally, the full cell assembled with activated Fe 2 (MoO 4) 3 hollow microspheres negative electrode and LiFePO 4 positive electrode exhibits a high reversible capacity of 1115 mA h g−1 at 0.2 A g−1. Furthermore, in situ X-ray diffraction analysis is applied to clarify the electrochemical reaction mechanism during the discharge/charge process. A bubble-templated method is developed to synthesize Fe 2 (MoO 4) 3 hollow hierarchical microspheres with superior high-rate, low-temperature, and high-areal-capacity lithium storage properties. Image 1 [ABSTRACT FROM AUTHOR]

To realize energy-efficient and cost-effective production of hydrogen by electrochemical water splitting, central to the research endeavors is the exploration of highly active and earth-abundant electrocatalysts for oxygen evolution reaction (OER). Promising non-noble candidates for OER are often based on transition metal oxides, while carbon-based electrocatalysts typically receive little attention due to their relatively poor performance. In this work, we present a novel method to significantly activate carbon cloth for OER by creating oxygen-containing functional groups on its surface with the assistance of peroxovanadium complexes, which have been seldom used to oxidize carbon materials. Compared to pristine carbon cloth (P-CC), the activated carbon cloth (A-CC) exhibits higher specific surface area and faster electron transfer rate. Particularly, the overpotential of A-CC (310 mV) to afford a current density of 10 mA cm −2 is much lower than that of P-CC and even comparable to that of noble RuO 2 /C (280 mV), ranking A-CC among the best reported nonmetal catalysts for OER. Moreover, densely distributed VO 2 (B) nanoplates in the intermediate product of VO 2 (B)/CC can prevent the highly active A-CC from degrading in air for two months, which endows another excellent feature for this fabrication method. [ABSTRACT FROM AUTHOR]

Molybdenum oxide nanowires have been found to show promise in a diverse range of applications, ranging from electronics to energy storage and micromechanics. This review focuses on recent research on molybdenum oxide nanowires: from synthesis and device assembly to fundamental properties. The synthesis of molybdenum oxide nanowires will be reviewed, followed by a discussion of recent progress on molybdenum oxide nanowire based devices and an examination of their properties. Finally, we conclude by considering future developments. [ABSTRACT FROM AUTHOR]