A DFT study on PtMo resistance to SO2 poisoning

Pt is a catalyst in proton exchange membrane fuel cell (PEMFC), and its activity will be degraded in the air due to the existence of SO _x impurities. On strategy is introducing of Mo into the Pt catalyst because it can improve the SO _x -tolerance capacity. Based on the aforementioned phenomenon, a density function theory (DFT) study on SO _x adsorbed on Pt(111) and PtMo(111) was performed to enhance Pt catalytic activity. The adsorption energy of adsorbed species, the net change, partial density of state (PDOS), and d-band center were calculated and analyzed comparatively. The results show that the presence of Mo-atom weakens the S-Pt bond strength and reduces the adsorption energies for SO₂, S and SO₃ on PtMo(111). Moreover, the Mo atom weakens the effects of SO₂ on the PtMo(111) electronic structure and makes the catalyst maintains its original electronic structure after SO₂ adsorption as compared with Pt(111).