Reducing the Activation Energy by Introduction of Pb Atoms to Boost Oxygen Reduction Reaction Performance

The kinetic parameters of the catalytic reaction, such as the activation energy, are important indicators to evaluate the performance of catalysts but are often ignored in the oxygen reduction reaction. The half-wave potential and onset potential are often used to evaluate the performance of the ORR catalysts. In this work, we prepared Pt10Pb/C possessing kinetic currents of over 18 mA/cm(2) at 0.90 VRHE, which is 5.6 times that of Pt/C and 2.6 times of Pt10Ni/C by virtue of a lower activation energy resulting from the introduction of Pb atoms despite a lower onset potential (0.973 V) in comparison to Pt/C (0.984 V) and Pt10Ni/ C (0.999 V). DFT calculations show that the higher oxygen adsorption energy of Pt10Pb caused by tensile stress decreases the thermodynamic-limiting potential and instead facilitates the rate determining step, that is, O-OH bond breaking, thereby boosting the catalytic performance. The kinetic characterization suggests a lowest activation energy of only 29.89 kJ/mol when Pt10Pb/C was used as a catalyst, which verifies the above conclusion. Our work reveals that the enhancement of oxygen adsorption energy using the tensile effect can significantly reduce the apparent activation energy and enhance the ORR reactivity, which provided a new kinetic feasibility for the design and synthesis of ORR catalysts.