A heterostructure of interlayer-expanded 1T phase MoS2 and spherical MoO2 for efficient and stable hydrogen evolution

The inferior hydrogen evolution reaction (HER) catalytic performance of MoS2 can be attributed to its small edge ratio, large inert substrate surface, and poor electrical conductivity, while the multiple strategies are expected to be employed simultaneously to modulate the electronic structure of MoS2 and yield catalysts with superior HER catalytic performance. Here, we report a MoS2 containing a 1 T phase with expanded layer spacing and construct it as a heterostructured material with MoO2 (MoO2 @E-MoS2). Specifically, the presence of the 1 T phase and expanded layer structure of MoS2 can enhance electrode conductivity, increase active site exposure, promote H2O adsorption, and optimize the Gibbs-free energy of hydrogen. The constructed heterostructure can modulate the electronic structure of the catalyst, enhance electron transfer at the interface, elevate water adsorption energy, and reduce the hydrogen reaction energy barrier. Moreover, density functional theory calculations indicate that the S site of MoS2 in this catalyst exhibits a higher affinity for H2O adsorption, while the Mo site demonstrates a greater capacity for H* adsorption/desorption. Ultimately, MoO2 @E-MoS2 shows low overpotentials of 93 and 99 mV at a current density of 10 mA cm-2, as well as exceptional long-term stabilities exceeding 70 and 130 h at current densities ranging from 10 to 30 mA cm-2 in acidic and alkaline media, respectively.