Abstract Mo2C@NC@MoSx porous nanospheres with sandwich shell have been synthesized for efficient hydrogen evolution in both acidic and alkaline media. Firstly, porous MoO2-Mo2C@NC nanospheres have been obtained with ultrafine Mo2C nanocrystallines as core and ultrathin N-doped carbon (NC) as shell through the carbonization of MoO42--/aniline-pyrrole (MoO42--Polymer) as precursor. Secondly, Mo2C@NC@MoSx porous nanospheres with sandwich shell have been synthesized by hydrothermal sulfurization, which can be confirmed by XPS and HRTEM. The sandwich shell is composed of ultrathin MoSx, NC layer and Mo2C nanocrystallines, which may reduce the strong Mo H bonding energy of pure Mo2C and lead to the suitable ΔGH* for HER. In addition, the ultrathin NC can prevent the aggregation of active sites and improve charge transfer rate due to rich N-doping. Mo2C@NC@MoSx exhibits enhanced performance and long-time durability in both acidic and alkaline solution. It requires a low onsetpotential of 119 mV, Tafel slope of 56 mV dec−1 in acidic solution and onsetpotential of 86 mV, Tafel slope of 90 mV dec−1 in alkaline solution. Therefore, designing sandwich nanostructure with better conductivity and optimized Mo H bonding energy may be a promising strategy for excellent Mo-based HER electrocatalysts.

中文翻译：

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基于 MoO 4 2- 聚合物前驱体的具有夹心壳的 Mo 2 C@NC@MoS x 多孔纳米球可在酸性和碱性介质中高效析氢

摘要 Mo2C@NC@MoSx 具有夹心壳的多孔纳米球已被合成用于在酸性和碱性介质中有效析氢。首先，通过MoO42--/苯胺-吡咯（MoO42--Polymer）作为前驱体的碳化，获得了以超细Mo2C纳米晶为核，超薄掺氮碳（NC）为壳的多孔MoO2-Mo2C@NC纳米球。其次，通过水热硫化合成了具有夹心壳的 Mo2C@NC@MoSx 多孔纳米球，这可以通过 XPS 和 HRTEM 证实。夹心壳由超薄 MoSx、NC 层和 Mo2C 纳米晶组成，这可能会降低纯 Mo2C 的强 Mo H 键能并导致适合 HER 的 ΔGH*。此外，由于富含 N 掺杂，超薄 NC 可以防止活性位点的聚集并提高电荷转移率。Mo2C@NC@MoSx 在酸性和碱性溶液中均表现出增强的性能和长期耐久性。它需要 119 mV 的低起始电位、酸性溶液中 56 mV dec-1 的 Tafel 斜率和 86 mV 的起始电位、碱性溶液中 90 mV dec-1 的 Tafel 斜率。因此，设计具有更好导电性和优化 Mo H 键能的夹心纳米结构可能是优秀的 Mo 基 HER 电催化剂的有前途的策略。