Enhanced methanol electro-oxidation and oxygen reduction reaction performance of ultrafine nanoporous platinum-copper alloy: Experiment and density functional theory calculation

Novel ultrafine nanoporous Pt-Cu alloy with a Pt:Cu stoichiometric ratio of 3:1 (np-Pt₃Cu) has been prepared by mechanical alloying and subsequent two-step chemical dealloying. The obtained np-Pt₃Cu has uniform and bicontinuous ligament(metal)-channel(void) structure with the ligament size of 3.3 ± 0.7 nm. To explore its potential application in energy conversion reactions, the np-Pt₃Cu alloy has been examined as electrocatalyst for the operating reactions in direct methanol fuel cells (DMFCs). Compared with the commercial JM Pt/C, a benchmark catalyst extensively used in fuel cell research, the np-Pt₃Cu alloy demonstrates better performance in both the methanol electro-oxidation and oxygen reduction reactions in acidic medium. Theoretical calculations reveal that the electronic structure of Pt has been modified with the shift of Pt d-band center due to alloying with Cu, which can decrease CO poisoning and enhance the methanol oxidation and oxygen reduction reaction activities.