Recently, a research team led by Prof. LI Yue from Institute of Solid State Physics, Hefei Institutes of Physical Science of Chinese Academy of Sciences, developed a new kind of biaxial strained MoS2 nanoshells with controllable layers to boost alkaline hydrogen evolution in collaboration with Prof. FAN HongJin at Nanyang Technological University, Singapore.
The findings were published online in Advanced Materials.
Strain in layered transition-metal dichalcogenides (TMDs) is a type of effective approach to enhance the catalytic performance by activating their inert basal plane. However, compared with the traditional uniaxial strain, the influence of biaxial one and TMDs layer number on local electronic configuration remains unexplored.
In this work, the team presented a new in situ self-vulcanization strategy. They realized biaxial strained MoS2 nanoshells in the form of single-crystalline Ni3S2@MoS2 core-shell heterostructure, where the MoS2 layer was precisely controlled between 1 to 5 layers.
The present of biaxial strain and controllability of layer number made this MoS2 nanoshells quite unique compared to conventional heterostructure electrocatalysts. Through a careful vulcanization treatment, Ni3S2 core@ MoS2 shell structures were developed, and the Ni3S2 nanoparticle core provided a template to thermodynamically drive the growth of fully curved MoS2 nanoshells.
The catalytic activity was found dependent on MoS2 layer number, degree of biaxial strain from curved surfaces and the associated S vacancies, according to both systematical electrochemical measurement and DFT calculations.
More specifically, the BL MoS2 nanoshells with specific Mo sites with 4 coordination number exhibited highly efficient theoretical catalytic activities.
Such fundamental findings paved a new and effective way for the fabrication of biaxial-strained TMDs electrodes with fine-tuned layer number for boosting the electrocatalytic performance.
This investigation was supported by the financial support from the National Science Fund for Distinguished Young Scholars (Grant No. 51825103) and the Natural Science Foundation of China (Grant Nos. 51771188, 51571189, 52001306).
Synthesis scheme, morphology, and structure characterizations of biaxial strained MoS2 nanoshells. (Image by ZHANG Tao)
DFT calculations (Image by ZHANG Tao)