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

Abstract

The catalytic performance of a catalyst is mainly determined by its surface structure, and superior catalytic activities have been observed on low-coordination surface sites. However, poor stability of low-coordination sites was observed during catalysis due to easier oxidation of these sites. By far, fabricating the catalysts with abundant low-coordination sites and stabilizing them still faces a significant challenge. Herein, we show the synthesis of an emerging type of PdPt alloy nanoframe wherein the ridges are composed of rugged surfaces with high-density, low-coordination sites. The synthesis of nanoframes mainly consists of two steps: preparation of PdPt alloy concave nanocubes and subsequent site-selective chemical etching. The nanoframe structure would endow low-coordination sites with excellent catalytic stability, preventing dissolution, migration, and aggregation of these active sites during catalysis. Electrochemical studies on the oxygen reduction reaction (ORR) catalysis show that it can deliver superior mass activities tens of times higher than that of commercial Pt/C catalysts in a broad pH range (from 1 to 13), with negligible activity decay after 40 000 cycles. In addition, as-prepared nanoframes can also exhibit excellent catalytic activity and stability toward methanol and ethanol oxidation reactions, 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/C catalysts. Theoretical calculations reveal that the coexistence of PdPt alloy components and high-density, low-coordination sites both is important for enhanced catalytic activities. This new strategy to stabilize the low-coordination sites on Pt-based electrocatalysts by constructing frame structures would shed new light on the rational design and synthesis of highly efficient electrocatalysts.

Ni2P Aerogels with Pt Single-Atom Doping Tune Competitive Adsorption for Boosted Methanol Electrooxidation

“…Metal aerogels (MAs), consisting of an assembly of individual building blocks to three-dimensional (3D) and self-supported network structures, have drawn tremendous attention in electrocatalysis and sensing, because of facile synthetic methods, tunable composition, and the perfect inheritance of aerogels. − Large surface areas endow MAs with abundant active sites and high porosity with interconnected backbones that can accelerate electron/mass transport. − Recently, single-atom doping has offered an effective opportunity for diverse catalytic reactions featuring modulated electronic structures of active sites. − Pt-based nanomaterials are usually employed to catalyze alcohol and they have excellent adsorption on organic molecules, therefore, it is possible to tune the adsorption ability of active sites and boost the reaction process. , In this regard, designing Ni-based MAs with single-atom Pt-doped building blocks is highly desirable for boosting the MOR performance and clarifying the competitive adsorption behavior between OH – and CH 3 OH, which, however, remains a major challenge.…”