Targeted Construction of Amorphous MoSx with an Inherent Chain Molecular Structure for Improved Pseudocapacitive Lithium-Ion Response

Owing to low ion/electron conductivity and large volume change, transitional metal dichalcogenides (TMDs) suffer from inferior cycle stability and rate capability when used as the anode of lithium-ion batteries (LIBs). To overcome these disadvantages, amorphous molybdenum sulfide (MoS_x) nanospheres were prepared and coated with an ultrathin carbon layer through a simple one-pot reaction. Combining X-ray photoelectron spectroscopy (XPS) with theoretical calculations, MoS_x was confirmed as having a special chain molecular structure with two forms of S bonding (S²⁻ and S₂²⁻), the optimal adsorption sites of Li⁺ were located at S₂²⁻. As a result, the MoS_x electrode exhibits superior cycle and rate capacities compared with crystalline 2H-MoS₂ (e.g., delivering a high capacity of 612.4 mAh g⁻¹ after 500 cycles at 1 A g⁻¹). This is mainly attributed to more exposed active S₂²⁻ sites for Li storage, more Li⁺ transfer pathways for improved ion conductivity, and suppressed electrode structure pulverization of MoS_x derived from the inherent chain-like molecular structure. Quantitative charge storage analysis further demonstrates the improved pseudocapacitive contribution of amorphous MoS_x induced by fast reaction kinetics. Moreover, the morphology contrast after cycling demonstrates the dispersion of active materials is more uniform for MoS_x than 2H-MoS₂, suggesting the MoS_x can well accommodate the volume stress of the electrode during discharging. Through regulating the molecular structure, this work provides an effective targeted strategy to overcome the intrinsic issues of TMDs for high-performance LIBs.     

Embedding Amorphous Molybdenum Sulfide within a Porous Poly(3,4‐ethylenedioxythiophene) Matrix to Enhance its H2‐evolving Catalytic Activity and Robustness

Amorphous molybdenum sulfide (MoS_x) is a promising alternative to Pt catalyst for the H₂ evolution in water. However, it is suffered of an electrochemical corrosion. In this report, we present a strategy to tack this issue by embedding the MoS_x catalyst within a porous poly(3,4‐ethylenedioxythiophene) (PEDOT) matrix. The PEDOT host is firstly grown onto a fluorine‐doped tin oxide (FTO) electrode by electrochemical polymerization of EDOT monomer in an acetonitrile solution to perform a porous structure. The MoS_x catalyst is subsequently deposited onto the PEDOT by an electrochemical oxidation of [MoS₄]^2? monomer. In a 0.5 M H₂SO₄ electrolyte solution, the MoS_x/PEDOT shows higher H₂‐evolving catalytic activities (current density of 34.2 mA/cm² at ?0.4 V vs RHE) in comparison to a pristine MoS_x grown on a planar FTO electrode having similar catalyst loading (24.2 mA/cm²). The PEDOT matrix contributes to enhance the stability of MoS_x catalyst by a significant manner. As such, the MoS_x/PEDOT retains 81 % of its best catalytic activity after 1000 potential scans from 0 to ?0.4 V vs. RHE, whereas a planar MoS_x catalyst is completely degraded after about 240 potential scans, due to its complete corrosion.     

In2O3修饰三维纳米花MoSx构建S型异质结用于高效光催化产氢

形貌控制和异质结构建是提升光催化剂性能的有效策略。本文采用In₂O₃修饰三维纳米花MoS_x并构建S型异质结,为电子的传输提供了特殊的转移途径。通过合理调控In₂O₃的负载量,MoS_x/In₂O₃的最佳产氢速率能够达到6704.2 μmol∙g⁻¹∙h⁻¹,是纯MoS_x的1.8倍。采用荧光光谱和电化学测试证实复合材料中内部电子和空穴对的分离效率得到了有效的提升,并利用紫外漫反射测试和羟基自由基实验推测了析氢机理。