The photo is sourced from Energy World
The objective was to improve the water electrolysis efficiency (water splitting into hydrogen and oxygen) by the action of sun light. Japanese scientists back in 1970s used semiconductors-based catalysts based on titanium dioxides for that purpose, and later they switched to more efficient catalysts based on dichalcogenides of transition metals, i.e., thin monolayer semiconductors with one metal layer between two layers of chalcogen atoms. Chalcogens include the elements from Group 16 of the Periodic Table, i.e., oxygen (O), sulfur (S), selenium (brittle non-metal of grey colour) and tellurium (a slightly toxic semi-metal of silver-white colour).
The monolayers of Janus nanostructure named in such way due to upper and lower layers of atoms consisting of different elements became of especially high demand. This feature of Janus monolayers allows for using them to facilitate the reaction of water decomposition by the action of light.
Physicists from the Emanuel Institute of Biochemical Physics performed a computer simulation to identify the degree of water electrolysis efficiency when using the compounds based on molybdenum, sulfur, selenium and tellurium in the presence of monolayer crystalline semiconductors with Janus structure. The material based on SMoTe compound (where S is sulfur, Mo is molybdenum, and Te is tellurium): the estimated efficiency of hydrogen recovery from water made from 54% to 67% (depending on the type of medium – neutral or acidic), while the common recovery level in the electrolysis units does not exceed 18%. The estimated efficiency of other compounds – SMoSe, SMoO, SeMoO and SeMoT (where O is oxygen) also exceeded 18% during the simulation.
“Water splitting by the action of sun light is of great practical interest, because using hydrogen recovered by this method will help to decrease the GHG emissions, to satisfy the growing global demand for energy, as well as to resolve the problems of sustainable energy supplies across the entire world. During our research we demonstrated: the catalysts family that we had studied contains new dynamically stable structures with very useful features for practical applications”, the Russian Scientific Foundation quotes Zakhar Popov, the head of the project, Candidate of Physical and Mathematical Sciences, senior research fellow of the Institute of Biochemical Physics.