Concentration modulate engineering of cobalt-selenium-sulfide electrodes toward water splitting: A first principle study

Abstract Bifunctional catalysts for both hydrogen evolution reactions (HER) and oxygen evolution reactions (OER) with high catalytic performance and low cost are greatly significant for developing fuel cells. Recent research show that doping CoS2 with heteroatoms is an effective method to obtain high performance catalysts. However, the effects of doping concentration and their catalytic mechanism are still not clear, which is important for designing catalysts with high efficiency. Here, based on the first principle calculation, the HER and OER performance of Cobalt-Selenium-Sulfide with different composing proportion are analyzed. Results show that CoSe1.5S0.5 exhibits the lowest HER/OER overpotentials, which is key for the high HER/OER performance. Both HER and OER catalytic performances can be modulated due to the change of the d band center of Co and hybridized orbitals caused by different doping concentration. Our finding is highly beneficial for efficient overall water splitting.