Introducing Covalent Metal-Phosphorus Bonds into Intermetallic Platinum-Based Catalysts for High-Performance Fuel Cells

The inadequate performance of oxygen reduction reaction(ORR)catalysts hampers the development of proton exchange membrane fuel cells(PEMFCs).Herein,we proposed an approach to tackle this problem by modulating the chemical bond type of intermetallic Pt-based catalysts,using phosphorus(P)doped L1_(0)-PtFeGa_(0.1)/C(P-L1_(0)-PtFeGa_(0.1)/C)as a proof of concept.X-ray absorption spectroscopy(XAS)demonstrated that the doped P transferred electrons to Pt,and thus,modified the electronic structure of Pt,weakening the adsorption strength with oxygen-containing species.Therefore P-L1_(0)-PtFeGa_(0.1)/C showed 13 times mass activity(MA)compared with commercial Pt/C,with a decay of only 28%after 100,000 potential cycles.When equipped in the membrane electrode assembly,the P-L1_(0)-PtFeGa_(0.1)/C catalyst also exhibited a remarkable activity(MA=0.84 A mgPt^(−1)at 0.9 V)and stability(MA retention=72%and voltage loss=9 mVat 0.8 A cm^(−2)after 30,000 cycles),making it one of the best performers among recorded Pt-based catalysts.Theoretical studies demonstrated that the doping of P optimized the adsorption energy between Pt and oxygen intermediates through sp-d orbital interactions and prevented metal dissolution by forming stronger Pt-P covalent bonds compared with Pt–Pt bonds.