Perovskite-supported Pt single atoms for methane activation

ABO₃ perovskites are increasingly being explored as catalysts, but it is unclear how they behave as supports for single atoms and how the subsequent single-atom catalysts can be employed for important reactions such as methane activation. Here we examine the stability of Pt single atoms (Pt₁) on the commonly exposed (100) surfaces of SrBO₃ perovskites (B = 3d transition metals) and their methane-adsorption properties by first principles density functional theory. We find that the stability and charge state of Pt₁ on the SrBO₃(100) surfaces are termination-sensitive. Due to polar compensation, Pt₁ is negatively charged on the A termination but positively charged on the B termination. This charge state greatly impacts methane adsorption: negatively charged Pt₁ on the A-termination chemisorbs methane (in some cases, dissociatively), but positively charged Pt₁ on the B-termination adsorbs methane physically. Analysis of the density of states of the negatively charged Pt₁ reveals that its sp states are key to methane chemisorption and C-H activation. Our work shows that polar compensation on the perovskite surfaces can be used to tune the charge state of a single atom for methane chemisorption and C-H activation.