Researchers Augment Catalytic Activity for Core Chemical Reaction in Fuel Cells

Now researchers from the U.S. Department of Energy’s Brookhaven National Laboratory, California State University and Northridge Soochow University, Shanghai Institute of Applied Physicists have introduced catalysts that can undergo 50,000 voltage cycles with a negligible decay in such catalytic activity and no apparent alterations in their structure and elemental composition. According to the study, the catalysts are nanoplates that comprise an atomically ordered lead and Pt core encompassed by a thick uniform shell of four Pt layers.

Till now, the most successful catalysts for enhancing the activity of oxygen reduction reaction or ORR are highly slow that significantly constraints fuel cell efficacy. After the research work, the scientists synthesized the nanoplates. Utilizing electron diffraction images and patterns from high – resolution scanning transmission electron microscopy or STEM, both of which disclose that the relative positions of atoms, he confirmed the core – shell structure and the sequence and composition of atoms.

With such information, the group distinguished how the nanoplates created with the individual Pb and Pt atoms. As a surprise, the surface planes were different and compressive strain in single direction and tensile strength in the other, discovering from the PtPb core.

In durability experiments simulating fuel cell voltage cycling, Su’s associates found that after 50,000 cycles there were almost no alterations in the volume of generated electronic current. In other terms, the nanoplates had small decay in catalytic activity. After multiple cycles, most catalysts showcase some loss of activity with some losing more than half of their primary activity.

Synchronization and microscopy characterization methods disclosed that the structure and elemental composition of the nanoplates did not alter following durability testing. “The electron microscopy work at the CFN was crucial in explaining why our nanoplates revealed such high catalytic activity and stability,” says Huang.

In comparison to the commercial Pt-on-carbon catalysts, the group’s PtPb and Ptnanoplates have one of the biggest ORR activities till date, considering the volume of Pt used into account and excellent durability. The group’s nanoplates also revealed high electrocatalytic activity and stability in oxidation reactions of ethanol and methanol.

“We believe that relatively thick and absolute Pt layers play a vital role in protecting the core,” says Su.

“Such study opens a novel way to introduce big tensile strain on the stable plane to accomplish extremely high activity for oxygen reduction catalysis. We consider that our method will inspire efforts to design novel nanostructured catalysts with big tensile strain for more effective catalysts,” says ShaojunGuo of Peking University and co-author of the study.