Exploring the electrocatalytic performance of silicene and single atom doped silicene for HER, OER and ORR activity using density functional theory

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The transition towards hydrogen energy is paramount due to its potential to mitigate environmental pollution caused by fossil fuels. The greener and cleaner way of producing and utilizing hydrogen is through water electrolysis and hydrogen fuel cell where the sluggish reaction kinetics bottlenecks the widescale implementation. Hence, in this study, density functional theory (DFT) is utilized to study the HER, OER and ORR performance of pristine and doped silicene sheets where the dopants (B, C, N, Al and P) are introduced as single atom. The thermodynamical stability for pristine and doped sheets are confirmed with ADMP study and the cohesive energy for all the sheets are found to be around -4.2 eV per atom which validates their stability. The hydrogen evolution reaction (HER) performance of all the sheets is studied and the N doped silicene exhibits better catalytic property with a lowest overpotential of 70 mV and the C doped silicene shown good HER performance with an overpotential of 180 mV. In case of oxygen evolution reaction (OER) and oxygen reduction reaction (ORR), the pristine silicene is found to behave better in the ORR performance while the C doped silicene has the lowest overpotential compared with the other sheets. The variation in the catalytic performance is studied with the reactivity parameters which implies that the nucleophilic nature of the material enhances the HER performance. Furthermore, the results suggest that C doped silicene can be utilized as a bifunctional catalyst for the HER and OER performance. This study suggests that the silicene in the pure form as well as with dopant can be a good electrocatalyst for the water splitting and fuel cell application.