To our best knowledge, few studies have been reported to comprehensively explore the bifunctional ORR/OER activity of transition metal and P co-doped graphene-based catalysts with the determined TM-P coordination numbers (TM-P4-C) to date. There is a large gray area exists in evaluating the feasibility and revealing the detailed catalytic mechanism of TM-P4-C on ORR or OER, the more appropriate TM atom for catalytic processes and the origin of the ORR/OER activities remain unclear.