Formation of Mo–Polydopamine Hollow Spheres and Their Conversions to MoO₂/C and Mo₂C/C for Efficient Electrochemical Energy Storage and Catalyst

Abstract

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.

Metal–Organic Coordination Strategy for Obtaining Metal‐Decorated Mo‐Based Complexes: Multi‐dimensional Structural Evolution and High‐Rate Lithium‐Ion Battery Applications

“…Structural characterization:T he morphology of MDA is preserved after annealing to obtain the final metal oxide products (e.g.,N i-MoO 2 /N-C), demonstrating good structurals tability and the feasibility of our strategy (Figure 4a-m). The redox couples at 1.25/1.4 Vand 1.6/1.7 V, corresponding to the (de)lithiationo fM oO 2 , [20,31,37] weref ound to be well overlapped after the 1st cycle (Figure 6c). Lattice spacings of 0.242, 0.34, and0 .2 nm correspond to the (À211) and (À111)p lanes of MoO 2 and the (111)p lane of Ni, respectively ( Figure 4m).…”

“…[30] Here, we have studied the coordination behavior of Mo-polydopamine upon varying the amount of surfactant. [20,32] Thes urfactant-dependent chelation process was confirmed to be the reason for the varied structures. [20,32] Thes urfactant-dependent chelation process was confirmed to be the reason for the varied structures.…”

Recent Progress on Molybdenum Oxides for Rechargeable Batteries

“…[70] If the dosageo fd opamine-HClr eaches 300 mg, hollow pores can be achieved. Wang et al first synthesized uniform Mo-polydopamine hollow spheres througha liquid-phase reaction.…”

“…a) SEM and b) TEM images,and c) rate performance of the as-fabricated MoO 2 /C hybrid hollow spheres [70]. Copyright 2017Wiley.ChemSusChem 2019, 12,755 -771 www.chemsuschem.org…”

Transition Metal Carbide Complex Architectures for Energy‐Related Applications

“…One notable example is hierarchical Mo 2 C/C hollow spheres, used as high‐performance HER catalysts, that were prepared by a self‐polymerization method . In detail, uniform hierarchical Mo‐polydopamine hollow spheres were first synthesized in a water/oil (H 2 O/ethanol) solution by polymerization of dopamine‐HCl, and the water‐in‐oil system, along with the molar ratio of the dopamine‐HCl, is proposed as a decisive factor to form the hollow architecture.…”