Water splitting is considered as a promising sustainable technology to produce hydrogen thereby reducing dependence on fossil fuels.1,2 Oxygen evolution reaction (OER) is half reaction of water splitting which is hampered by slow kinetics due to multiple proton-coupled electron transfer. Consequently, it is critical to develop high performance electrocatalysts for enhancing OER kinetics to promote this technology. At present, noble metal oxides (RuO2 and IrO2) are the best OER electrocatalysts, but their scarcity and high cost have impeded the widespread application. It is thus highly required to develop cheap and efficient OER catalysts. Recently, transition metal sulfides (T-M-X, where M = Co, Ni, Fe etc. and X = S, Se, or Te), due to their high conductivity and facial fabrication process, have been emerging as promising OER electrocatalysts. However, the T-M-X based OER electrocatalysts developed so far still generally underperform the noble metal oxides. Achieving high performance T-M-X based OER electrocatalyst with comparable activities to the noble metal oxides are still challenging. CoS2 is one of the typical T-M-X which have been reported as a potential alkaline OER catalysts due to its good activities. Metallic doping (For example Fe) has been reported an efficient method to enhance the catalytic performance of electrocatalysts for hydrogen evolution reactions (HER) by virtue of optimization the hydrogen adsorption energy and enhancing electronic conductivity. Motivated by the previous success of Fe-doped transition for catalyst, in this work, we use a combined experiment and computation study to investigate the possibility of enhancing the activity of CoS2 as OER electrocatalysts by Fe-doping. Ternary cobalt iron disulfides were successfully obtained. The OER activity of the as obtained compound have been studied. The experimental measurements and electronic structure calculations both have shown the significant enhancement in OER actives. Using density functional theory calculations, we identified the active phase during the relevant OER potentials to be a thin layer of oxide. This oxide phase supported on sulfide leads to the enhanced catalytic activity in Fe-doped CoS2.

Fe doped CoS2 ternary disulfide as a robust electrocatalyst for water oxidation

ACS Spring Meeting 2021

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