Two-Dimensional Co₂S₂ As Electrocatalysts For Water Splitting

Climate change is one of the most pressing problems in the 21^st century. Mastering this challenge will require an energy transition from fossil fuels to renewable fuels. An active area of research is the conversion of H₂O into O₂ and H₂ fuel, a reaction that requires a (electro)catalyst electrocatalyst, especially for improving the efficiency of the sluggish oxygen-evolution-reaction (OER). In the present study, we investigate the OER performance of 2-dimensional Co₂S₂ monolayers using density-functional-theory (DFT). Our study suggests that defect free monolayers are inferior to RuO₂ and IrO₂ which are currently the industrial standard for OER and electrocatalytic water splitting. In contrast, our preliminary results show that defects in Co₂S₂ significantly improve OER activity. Our computations predict an overpotential η_OER = 0.41 V for a single anion dopant form comparison, RuO₂: η_OER = 0.42 V and for IrO₂: η_OER = 0.56 V, at least 60% higher as predicted for monolayer Co₂S₂. In summary, we find that defect engineering, for example in Co₂S₂, has a significant beneficial effect on catalytic performance, in support of the energy transition toward renewable fuels.