2D molybdenum sulfide with unique physical and chemical properties, has been considered to possess application prospect in photocatalysis, electrocatalysis and heterogeneous catalysis, attracting extensive attention by catalysis researchers. The catalytic reaction usually involves multistep and complicated processes. For example, the electrocatalytic hydrogen evolution reaction (HER) of water splitting happening at the gas (H2), liquid (H2O) and solid (catalyst) three-phase interface, requires the 2D molybdenum sulfide catalyst to own not only excellent intrinsic activity, but also a suitable surface and interface structure. In order to catalyze this process with high efficiency, it needs multisale modulation and optimization of structural and electronic properties in 2D molybdenum sulfide, but still remains as a great challenge.
On the basis of previous studies towards surface and interface modulation of 2D catalytic materials, associate Prof. DENG Dehui and Prof. BAO Xinhe etc. from Dalian Institute of Chemical Physics have successfully achieved the multiscale structural and electronic control of 2D molybdenum sulfide atomic crystal. The optimized catalyst shows a superior catalytic activity and durability for electrocatalytic HER in acidic medium, and this work has been recently published in Nature Communications (Nat. Commun., 2017, 8, 14430; DOI: 10.1038/ncomms14430).
Multiscale structural and electronic control of molybdenum disulfide foam for highly efficient hydrogen production (Image by JIANG Xiumei and DENG Jiao)
The research group innovated the preparation strategy, and developed a “bottom-up” chemical method to synthesize the uniform mesoporous MoS2 foam assisted by the SiO2 nanospheres as hard template. Various analysis approaches indicated this structure can realize a triple-scale modulation: (1) the macro-scale: uniform mesopores facilitate the transport of reactant (H3O+) and product (H2), and increase the accessibility of active sites; (2) the nano-scale: oriented vertical growth of MoS2 nanosheets around the mesopores increase the number of edges as the active sites; (3) the atom-scale: on the basis of previous study by introducing single-atom into the MoS2 2D framework (Energy Environ. Sci., 2015, 8, 1594), further doping transition metal Co atoms into the 2D plane substitutinga part of Mo atoms can efficiently modify the electronic structure of surface S atoms, and thereby trigger their intrinsic catalytic activities. In addition, experiments combined with DFT calculations indicated MoS2 with moderate Co atoms doping content possesses the optimal activity. The 3D MoS2 catalyst with the multiscale modulation demonstrated a high electrocatalytic HER performance, showing a potential to replace the noble metal catalyst. The strategy through a multiscale structural and electronic control, introduced in the present work, opens a new opportunity for the rational design of MoS2 in the catalytic study and application, and the involved concept can be extended to other energy-related process or other 2D materials.
This work is supported by Ministry of Science and Technology of China, National Natural Science Foundation of China, Key Research Program of Frontier Sciences of the Chinese Academy of Sciences, Strategic Priority Research Program of the Chinese Academy of Sciences, and Collaborative Innovation Center of Chemistry for Energy Materials (2011-iChEM) . (Text and Image by JIANG Xiumei and DENG Jiao)
Dr. LU Xinyi
Dalian Institute of Chemical Physics, Chinese Academy of Sciences,
457 Zhongshan Road, Dalian, 116023, China,