DFT calculations: A powerful tool for better understanding of electrocatalytic oxygen reduction reactions on Pt-based metallic catalysts

•The computational hydrogen electrode model as well as the ORR model were introduced.•The DFT assisting explanations of influences from alloying elements, concentration, facets, size and defects on catalytic performances for ORR were reviewed.•Examples of designing new Pt-based metallic catalysts for ORR by DFT calculations were summarized.•The developing tendency of DFT calculations in electrocatalysis field was prospected.