Highly uniform hierarchical Mo-polydopamine hollow spheres are synthesized for the first time through a liquid-phase reaction under ambient temperature. A self-assembly mechanism of the hollow structure of Mo-polydopamine precursor is discussed in detail, and a determined theory is proposed in a water-in-oil system. Via different annealing process, these precursors can be converted into hierarchical hollow MoO /C and Mo C/C composites without any distortion in shape. Owing to the well-organized structure and nanosize particle embedding, the as-prepared hollow spheres exhibit appealing performance both as the anode material for lithium-ion batteries and as the catalyst for hydrogen evolution reaction (HER). Accordingly, MoO /C delivers a high reversible capacity of 940 mAh g at 0.1 A g and 775 mAh g at 1 A g with good rate capability and long cycle performance. Moreover, Mo C/C also exhibits an enhanced electrocatalytic performance with a low overpotential for HER in both acidic and alkaline conditions, as well as remarkable stability.

Controllable synthesis of functional materials is of widespread interest for particle engineering. Such a method has not been widely promoted due to the lack of recognition of the fundamental principle, especially for organic-inorganic hybrid materials. Here, as an entrance, the controllable synthesis of Mo-polydopamine coordination flowers is realized through a facile foaming method, and a 2D nanopetal as the building monomer of the flower is synthesized. Depending on the morphology evolution of Mo-dopamine complex under different conditions, and the surface iterative topology growth of the Mo-polydopamine petal, the reasons of why the Mo-polydopamine complex self-assembles into a flower structure can be attributed to the synergistic effect of multicore symbiosis and structural self-protective growth behaviors. Benefiting from the strong structure stability of the Mo-polydopamine nanopetal, a hybrid structure of MoO quantum dot in situ anchoring in the N-doped 2D carbon framework is prepared by direct pyrolysis, which shows a highly reversible performance in application for lithium-ion secondary batteries (LIBs). This work enhances the possibility for the controllable synthesis of organic-inorganic hybrid materials by adjusting the multicore intergrowth and inhibiting the interfacial assembly.

With the aim of finding efficient non-noble metal catalysts for water splitting, hierarchical Ni-Mo-polydopamine microflowers (Ni-Mo C/C MF) were synthesized through a facile aqueous-phase reaction at room temperature. NiMoO nanowires were utilized as both Ni and Mo source; they can complex with dopamine to form a hierarchical structure and affect the scale of the final product. The energy dispersive spectroscopy (EDS) measurement of Ni-Mo C/C microflowers (MF) shows a high content of Mo C and Ni (>90 wt %). For the hydrogen evolution reaction (HER), the Ni-Mo C/C MF displays a low overpotential of 99 mV at a current density of -10 mA cm and a small Tafel slope of 73 mV dec in 1.0 m KOH. By comparison with Mo C/C microspheres (MS), the nanosized Ni-doped particles offer more active sites and enhance the kinetic performance. This facile synthesis strategy is also suitable for preparing other metal-Mo C/C composites that can be used in the fields of catalysis and energy conversion.

in Li stripping state influence the succeeding Li plating state; if stress relaxes randomly in Li stripping, inhomogeneous SEI films are broken and disordered Li pits occur. [6] Therefore, more efforts have been made to Li homogeneous nucleation and homoepitaxial growth, e.g., a SEI film originated from ideal nucleation toward free dendrites (see the details in the Supporting Information). [7] To the best of our knowledge, an ideal SEI film enables minimized breaking with releasing of the overwhelming stress during Li stripping, and an effective protection of major sheet SEI film was thereof achieved; back to Li plating, these modified regions enable being self-healing ascribed to lower nucleation barriers ( Figure S1, Supporting Information). [7b,8] Thus, inspired by such principle of zippers, we designed net-like SEI films acting as "zippers" to promote homogeneous Li ion flux. Nucleation barriers are synergistically governed for zipper-like SEI film toward effective controlling of stress. As a result, it leads ultimately to a remarkable enhancement of the stability of Li metal anode.The array pattern on Li surface can be prepared by using mechanical rolling for lower-polarization anode (Figure 1a). [9] In addition, a uniformly distributed rough surface of Li metal may be useful for the suppression of dendrites ( Figure S2, Supporting Information). [10] Therefore, we utilize a simple route to design zipper-like SEI films; the net-like morphology of Li surface was thereof obtained (Figure 1b). After Li metal contacts tightly with Cu/glass, a separation leads to the change of Li surface, correlated with the particular contacting areas due to possible different lithiophilic, thereof yielding various nucleation barrier regions ( Figures S3 and S4 (Supporting Information) and the details: the variation of roughness induces different potentials, and a higher roughness may tailor potential if the Li ion flux is homogeneous enough). [6a,11] In theory, surface patterns cannot remain after the reversible homogeneous growth/ dissolution. For Li metal anode, however, there is always one coating of SEI films on the Li metal surface. Alternatively, SEI films enable being utilized to stabilize the surface pattern. Thus, the reducing polarization in Li plating can be offered during charge/discharge cycling. That is, surface pattern on Li anode should target at controlling SEI film to maintain the stable cycling performance.The ORCID identification number(s) for the author(s) of this article can be found under https://doi.org/10.1002/aenm.201800650. Li Metal AnodesLi dendrite is responsible for a main failure of Li secondary anode, such as Li-S and Li-O 2 batteries with ultrahigh energy density. [1] Great attention has been paid to protect Li anode by suppressing breaking of ubiquitous solid electrolyte interphase (SEI) films (e.g., spontaneous SEI film contacting with the electrolyte, artificial film in Li metal via epitaxial growth, designed polymer electrolytes, some effective additives, and implanted SEI film). [1g,...