The oxygen reduction reaction (ORR) represents a highly important cathodic process in proton-exchange membrane fuel cells (PEMFC) and it has caught more attention recently. ORR in PEMFC is a slow reaction with a high potential around 300 mV, so it needs catalyst to accelerate the reaction. Pt is used to catalysis this reaction due to its outstanding performance and high stability. It was acknowledged that the high-index facets in Pt is beneficial to its catalytic performance. While the cooperated research results obtained by Prof. Yu-Jie Xiong from USTC and Prof. David Lou from Nanyang Technological University revealed it is unnecessary for the highly performed catalyst to have higher ratio of high-index facets. This work provided a new point in electrocatalytic materials, and it was published in international key journal Angew. Chem. Int. Ed. (Angew. Chem. Int. Ed. 2015, 54, 5666)

Compared to other facets, high-index facets have more un-coordinated saturated atom and step faceting, which contribute to its higher catalytic performance in thermocatalytic system. While in electrocatalytic system, it remains an open question as to whether it is feasible to achieve high ORR performance on Pt nanocrystals having a large high-index facets surface coverage. To understand this problem, a series of nanocrystals with controllable different facets ratio is in demand.

Yu-jie Xiong’s group has already developed a method creating a set of Pt nanocrystals with tunable ratios of high-index to low-index facets (ACS Nano 2012, 6, 979). They conducted a series of experiments based on these materials, which turned out that, with high {100} facet coverage, the Pt multicubes exhibit impressive ORR activity in terms of half-wave potential and current density nearly to the level of the most active Pt-based catalysts, and the durability of catalysts is well retained. The results reveal that the excellent ORR performance of Pt multicubes is a combined result of active sites by high-index facets and low resistance by flat surface. It is anticipated that this work, in which structural details decide performance, will offer a new approach to facet-controlled synthesis and ORR catalysts design.The research was funded by National Natural Science Foundation of China (NSFC) and CAS Hundred Talent Program.