The slow kinetics at the cathode of oxygen reduction reaction (ORR) seriously limits the efficiencies of fuel cells and metal-air batteries. Pt, the state-of-the-art ORR electrocatalyst, suffers from high cost, low earth abundance, and poor stability. Here a self-templated strategy based on metal-organic frameworks (MOFs) is proposed for the fabrication of hollow nitrogen-doped carbon spheres that are embedded with cobalt nanoparticles (Co/HNC). The Co/HNC manifests better ORR activities, methanol tolerance, and stability than commercial Pt/C. The high ORR performance of Co/NHC can be attributed to the hollow structure which provides enlarged electrochemically active surface area, the formation of more Co-N species, and the introduction of defects. This work highlights the significance of rational engineering of MOFs for enhanced ORR activity and stability and offers new routes to the design and synthesis of high-performance electrocatalysts.

High-quality Pt-based catalysts are highly desirable for ethanol oxidation reaction (EOR), which is of critical importance for the commercial applications of direct ethanol fuel cells (DEFCs). However, most of the Pt-based catalysts have suffered from high cost and low operation durability. Herein a two-step method has been developed to synthesize porous Pt nanoframes decorated with Bi(OH)₃, which show excellent catalytic activity and operation durability in both alkaline and acidic media. For example, the nanoframes show a mass activity of 6.87 A·mg_Pt^-1 in alkaline media, which is 13.5-fold higher than that of commercial Pt/C. More importantly, the catalyst can be reactivated simply, which shows negligible activity loss after running for 180,000 s. Further in situ attenuated total reflection-infrared (ATR-IR) absorption spectroscopy and CO-stripping experiments indicate that surface Bi(OH)₃ species can greatly facilitate the formation of adsorbed OH species and subsequently remove carbonaceous poison, resulting in a significantly enhanced stability towards EOR. This work may favor the tailoring of desired electrocatalysts with high activity and durability for future commercial application of DEFCs.

The development of Pt-based core/shell nanoparticles represents an emerging class of electrocatalysts for fuel cells, such as methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR). Here, we present a one-pot synthesis approach to prepare hexagonal PtBi/Pt core/shell nanostructure composed of an intermetallic Pt₁Bi₁ core and an ultrathin Pt shell with well-defined shape, size, and composition. The structure and the synergistic effect among different components enhanced their MOR and EOR performance. The optimized Pt₂Bi nanoplates exhibit excellent mass activities in both MOR (4, 820 mA·mg_Pt^–1) and EOR (5, 950 mA·mg_Pt^–1) conducted in alkaline media, which are 6.15 times and 8.63 times higher than those of commercial Pt/C, respectively. Pt₂Bi nanoplates also show superior operation durability to commercial Pt/C. This work may inspire the rational design and synthesis of Pt-based nanoparticles with improved performance for fuel cells and other applications.

We have carried out a comprehensive study on the formation mechanism of Au nanorods (AuNRs) in binary surfactant mixtures composed of quaternary ammonium halide and sodium oleate (NaOL). We identify the cetyltrimethyl ammonium (CTA)-Br-Ag⁺ complex as the key ingredient in directing the anisotropic growth of AuNRs. Based on the improved understanding of the cooperative interactions among CTA⁺, Br^– and Ag⁺, we further demonstrate that AgBr, which is readily solubilized by the cetyltrimethyl ammonium bromide (CTAB) or cetyltrimethyl ammonium chloride (CTAC) micelles, can be employed as the combined source of Ag⁺ and Br^– for the preparation of AuNRs. The growth of high-quality AuNRs can be completed within 15 min under extremely low bromide content (0.1 mM).