▎ 摘　　要

NOVELTY - A fuel cell stack comprises an end region (E1) having N1 fuel cell units (10), and which is connected to a reactant inlet (I1), and a reactant source (S1) which is a hydrogen source, and configured to provide a reactant (R1) to fuel cell stack, and at least one fuel cell unit (10) comprising a membrane electrode assembly (MEA) (22) with a catalyst material (M1) comprising a catalyst composition (C1) on anode (14) and/or cathode (16) of fuel cell unit (10), an end region (E2) having N2 fuel cell units, and which is connected to a reactant inlet (I2), and a reactant source (S2) which is an oxygen source, and configured to provide a reactant (R2) to fuel cell stack, and at least one of the number (N2) of fuel cell units which is a fuel cell unit (U2) comprising an MEA with a catalyst material (M2) comprising a catalyst composition (C2) on anode and/or cathode of fuel cell unit (10). USE - Fuel cell stack e.g. proton exchange membrane fuel cell stack used in power source for vehicle and transportation application. ADVANTAGE - The fuel cell stack optimizes catalytic activities of the fuel cell units due to variation of catalyst support materials for fuel cell units, and enhances performance. DETAILED DESCRIPTION - A fuel cell stack comprises an end region (E1) having N1 fuel cell units (10), and which is connected to a reactant inlet (I1), and a reactant source (S1) which is a hydrogen source, and configured to provide a reactant (R1) to fuel cell stack, and at least one of fuel cell units comprising a membrane electrode assembly (MEA) (22) with a catalyst material (M1) comprising a catalyst composition (C1) on anode (14) and/or cathode (16) of fuel cell unit (10), an end region (E2) having a number (N2) of fuel cell units, and which is connected to a reactant inlet (I2), and a reactant source (S2) which is an oxygen source, and configured to provide a reactant (R2) to the fuel cell stack, and at least one of the number (N2) of fuel cell units which is a fuel cell unit (U2) comprising an MEA with a catalyst material (M2) comprising a catalyst composition (C2) on anode and/or cathode of fuel cell unit (10), and a middle region having a number (N3) of fuel cell units, and situated between the end region (E1, E2), and at least one of the number (N3) of fuel cell units which is a fuel cell unit (U3) comprising an MEA with a catalyst material (M3) comprising catalyst composition (C3) on either or both an anode and a cathode of the fuel cell unit (10). At least one of the catalyst compositions (C1, C2, C3) are different. DESCRIPTION OF DRAWING(S) - The drawing shows a schematic side view of fuel cell unit. Fuel cell unit (10) Polymer electrolyte membrane (12) Anode (14) Cathode (16) Gas diffusion layers (18,20) Membrane electrode assembly (22) Sides (24,26) Flow field (28,30)