PdPt Alloy Nanoframes with Rugged Surfaces: Efficient Bifunctional Fuel Cell Catalysts in a Broad pH Range

The catalytic performance of a catalyst is mainly determinedbyits surface structure, and superior catalytic activities have beenobserved on low-coordination surface sites. However, poor stabilityof low-coordination sites was observed during catalysis due to easieroxidation of these sites. By far, fabricating the catalysts with abundantlow-coordination sites and stabilizing them still faces a significantchallenge. Herein, we show the synthesis of an emerging type of PdPtalloy nanoframe wherein the ridges are composed of rugged surfaceswith high-density, low-coordination sites. The synthesis of nanoframesmainly consists of two steps: preparation of PdPt alloy concave nanocubesand subsequent site-selective chemical etching. The nanoframe structurewould endow low-coordination sites with excellent catalytic stability,preventing dissolution, migration, and aggregation of these activesites during catalysis. Electrochemical studies on the oxygen reductionreaction (ORR) catalysis show that it can deliver superior mass activitiestens of times higher than that of commercial Pt/C catalysts in a broadpH range (from 1 to 13), with negligible activity decay after 40 000cycles. In addition, as-prepared nanoframes can also exhibit excellentcatalytic activity and stability toward methanol and ethanol oxidationreactions, with mass activities up to 19.55 and 28.96 A/mg(Pd+Pt), respectively, which are 19 and 47 times that of commercial Pt/Ccatalysts. Theoretical calculations reveal that the coexistence ofPdPt alloy components and high-density, low-coordination sites bothis important for enhanced catalytic activities. This new strategyto stabilize the low-coordination sites on Pt-based electrocatalystsby constructing frame structures would shed new light on the rationaldesign and synthesis of highly efficient electrocatalysts.

Automated summary

A new synthesis method for PdPt alloy nanoframe catalysts with ridges composed of rugged surfaces with high-density, low-coordination sites is reported. The nanoframe structure endows the low-coordination sites with excellent catalytic stability, preventing dissolution, migration, and aggregation during catalysis. The nanoframes exhibit superior catalytic activity and stability in the oxygen reduction reaction, methanol oxidation reaction, and ethanol oxidation reaction.