It is still challengeable to develop a nonprecious bifunctional electrocatalyst for both hydrogen and oxygen evolution reactions (HER and OER), with higher efficiency and superior durability over the benchmark noble-metal-based electrocatalysts. To address such issues, for the first time, we design and synthesize FeNi 3 −Fe 3 O 4 heterogeneous nanoparticles (NPs) homogenously anchored on a matrix of metal-organic framework (MOF) nanosheets and carbon nanotubes (FeNi 3 −Fe 3 O 4 NPs/MOF-CNT) by a facile hydrothermal reaction and subsequent partial decomposition of a low-cost and earth-abundant Ni/Fe/C precursor. Due to its unique porous nanoarchitecture constructed by ultrafine nanoparticles anchored on two-dimensional (2D) nanosheets/one-dimensional (1D) CNT matrix, it can be employed as a bifunctional electrocatalyst with superior electrocatalytic activity for water splitting: it delivers a small Tafel slope of 37 mV/dec for OER and requires only a very low overpotential of 234 mV to obtain 10 mA/cm 2 ; it has a very low overpotential of 108 mV for HER and also shows an ultralow overpotential of 360 mV to reach 10 mA/cm 2 for overall water splitting by outperforming the precious-metal-based electrocatalysts (Pt/C and RuO 2 ; 393 mV at η 10 ). Moreover, it exhibits excellent longterm stability. This work presents a rational nanoarchitecture design and facile fabrication strategy to obtain nonprecious metalbased electrocatalysts with high efficiency and excellent long-lasting abilities.

It is still challenging to develop sulfur electrodes for Li−S batteries with high electrical conductivity and fast kinetics, as well as efficient suppression of the shuttling effect of lithium polysulfides. To address such issues, herein, polar MoTe 2 with different phases (2H, 1T, and 1T′) were deeply investigated by density functional theory calculations, suggesting that the 1T′-MoTe 2 displays concentrated density of states (DOS) near the Fermi level with high conductivity. By optimization of the synthesis, 1T′-MoTe 2 quantum dots decorated threedimensional graphene (MTQ@3DG) was prepared to overcome these issues, and it accomplished exceptional performance in Li−S batteries. Owing to the chemisorption and high catalytic effect of 1T′-MoTe 2 quantum dots, MTQ@3DG/S exhibits highly reversible discharge capacity of 1310.1 mAh g −1 at 0.2 C with 0.026% capacity fade rate per cycle over 600 cycles. The adsorption calculation demonstrates that the conversion of Li 2 S 2 to Li 2 S is the rate-limiting step where the Gibbs free energies are 1.07 eV for graphene and 0.97 eV for 1T′-MoTe 2 , revealing the importance of 1T′-MoTe 2 . Furthermore, in situ Raman spectroscopy investigation proved the suppression of the shuttle effect of LiPSs in MTQ@3DG/S cells during the cycle.

The slow redox kinetics during cycling process and the serious shuttle effect caused by the solubility of lithium polysulfides (LiPSs) dramatically hinder the practical application of Li‐S batteries. Herein, a facile and scalable spray‐drying strategy is presented to construct conductive polar Mo2C quantum dots‐decorated carbon nanotube (CNT) networks (MCN) as an efficient absorbent and electrocatalyst for Li‐S batteries. The results reveal that the MCN/S electrode exhibits a high specific capacity of 1303.3 mAh g−1 at 0.2 C, and ultrastable cycling stability with decay of 0.019% per cycle even at 1 C. Theoretical simulation uncovers that Mo2C exhibits much stronger binding energies for S8 and Li2Sn. The energy barrier for the conversion between Li2S4 and Li2S2 decreases from 1.02 to 0.72 eV when hybriding with Mo2C. Furthermore, in situ discharge/charge‐dependent Raman spectroscopy shows that long‐chain Li2S8 configuration is generated via S8 ring opening near the first plateaus at ≈2.36 V versus Li/Li+ and the S62− configuration in CNT/S electrode is maintained below the potential of ≈2.30 V versus Li/Li+, indicating that the shuttle of soluble LiPSs happens during the whole discharge process. This work provides deep insights into the polar nanoarchitecture design and scalable fabrication for advanced Li‐S batteries.