Recently, iChEM researcher, Prof. Yi Xie’s group from USTC made important progress in the area of synthesis and application of atomically thin 2D structures. The result was published in Angew. Chem. Int. Ed. (DOI: 10.1002/anie.201505245).

Producing hydrogen from electrolysis can help to defuse energy crisis and environmental pollution. Nevertheless, the slowly kinetic progress of oxygen evolution reaction (OER) in electrolysis of water limited the efficiency of the electrolysis of water. A great deal of researches indicated that some of noble metal catalysts can sharply improve the activity of OER. However, the easy inactivation, high cost, low abundance of them prevent those catalysts from commercial exploitation. Although the chalcogenides of transition metal are cheap and highly stable, the poor electrical conductivity of them result in a too high potential of OER and a low catalytic activity.

Aimed at the challenges, Prof. Yi Xie’s group built a metallic non-metal ultrathin 2D structural model. Taken CoSe2 as an example, they obtained a single-unit-cell orthorhombic 2D structure of CoSe2 by synthesizing lamellar hybrid CoSe2-DETA (DETA = diethylenetriamine) intermediate. Both first principle calculation and variable temperature conductivity test demonstrated that orthorhombic ultrathin 2D CoSe2 possesses metallic conducting behavior. They collaborated with Prof. Shiqiang Wei from the National Synchrotron Radiation Laboratory (NSRL) in Hefei to utilize the synchrotron radiation X-ray absorption fine structure spectroscopy (XAFS) to reveal that the ligancy of Co atom on the surface of CoSe2 2D ultrathin structure decreased obviously relative to bulk materials, which is conducive to improve its intrinsic catalytic activity. Based on this, CoSe2 2D ultrathin structure show a higher current density, smaller Tafel slope (64 mV dec-1) and larger TOF (745 h-1) compared with lamellar hybrid Cose2-DETA intermediate and bulk materials.