Interface Density Engineering on Heterogeneous Molybdenum Dichalcogenides Enabling Highly Efficient Hydrogen Evolution Catalysis and Sodium Ion Storage

Abstract Constructing active heterointerfaces is powerful to enhance the electrochemical performances of transition metal dichalcogenides, but the interface density regulation remains a huge challenge. Herein, MoO₂/MoS₂ heterogeneous nanorods are encapsulated in nitrogen and sulfur co‐doped carbon matrix (MoO₂/MoS₂@NSC) by controllable sulfidation. MoO₂ and MoS₂ are coupled intimately at atomic level, forming the MoO₂/MoS₂ heterointerfaces with different distribution density. Strong electronic interactions are triggered at these MoO₂/MoS₂ heterointerfaces for enhancing electron transfer. In alkaline media, the optimal material exhibits outstanding hydrogen evolution reaction (HER) performances that significantly surpass carbon‐covered MoS₂ nanorods counterpart (η₁₀: 156 mV vs 232 mV) and most of the MoS₂‐based heterostructures reported recently. First‐principles calculation deciphers that MoO₂/MoS₂ heterointerfaces greatly promote water dissociation and hydrogen atom adsorption via the O–Mo–S electronic bridges during HER process. Moreover, benefited from the high pseudocapacitance contribution, abundant “ion reservoir”‐like channels, and low Na⁺ diffusion barrier appended by high‐density MoO₂/MoS₂ heterointerfaces, the material delivers high specific capacity of 888 mAh g⁻¹, remarkable rate capability and cycling stability of 390 cycles at 0.1 A g⁻¹ as the anode of sodium ion battery. This work will undoubtedly light the way of interface density engineering for high‐performance electrochemical energy conversion and storage systems.