Nickel single atom catalyst supported on the gallium nitride monolayer: first principles investigations on the decisive role of support in the electrocatalytic reduction of CO2

Abstract

Designing efficient and low cost electrocatalysts for the reduction of CO₂ to valuable chemicals is a sustainable way of mitigating and balancing its concentrations in the atmosphere which is essential for avoiding effects like climate change and global warming. Herein by means of systematic density functional theory simulations, we investigate the effect of support on the activity/selectivity of Ni based single atom catalyst (SAC) supported on GaN, MoS₂, Mo₂C, g-C₂N and graphyne monolayers towards CO₂ activation and reduction to different C₁ products. Our results reveal that the Ni SAC strongly binds on all the monolayer supports forming highly stable catalysts. The type of support plays a strong role in tuning the binding and activation of CO₂ with Ni SAC supported on GaN and MoS₂ monolayers showing the highest CO₂ binding energies. Rigorous and in-depth electronic structure analysis reveals that the CO₂ binding energy on these catalysts can be successfully rationalized in terms of electronic properties such as the d-band centre and integrated crystal orbital Hamilton populations. Moreover, the computed reaction pathways using the computational hydrogen electrode model indicate that the Ni SAC supported on the GaN monolayer can catalyse the CO₂ reduction to CH₃OH at a record low limiting potential of −0.28 V whereas the Ni SAC supported on the MoS₂ monolayer catalyses CO₂ reduction to HCOOH at a limiting potential of –0.42 V. Thus, our results show that the nature and type of support plays critical role in modulating the CO₂ reduction activity/selectivity on these catalysts and provide insightful guidance for effective catalyst design for CO₂ conversion to value added chemicals.