High-density surface protuberances endow ternary PtFeSn nanowires with high catalytic performance for efficient alcohol electro-oxidation

Branch-Regulated Palladium-Antimony Nanoparticles Boost Ethanol Electro-oxidation to Acetate

Tuning the composition and morphology of bimetallic nanoparticles (NPs) offers an effective strategy to improve their electrocatalytic performance. In this work, we present a facile wet-chemistry procedure to engineer PdSb NPs with controlled morphology. Spherical or branched NPs are produced by tuning the heterogeneous nucleation of Sb on Pd seeds. Compared with pure Pd NPs, the incorporation of Sb not only decreases the amount of Pd used but also results in a significant increase of activity and stability for the electrocatalytic ethanol oxidation reaction (EOR). Best performances are obtained with highly branched PdSb NPs, which deliver a specific activity of 109 mA cm^-2 and a mass activity of up to 2.42 A mg_Pd^-1, well above that of a commercial Pd/C catalyst and branched Pd NPs. Moreover, PdSb displays significant stability enhancement of over 10 h for the EOR measurements. Density functional theory calculations reveal that the improved performance of PdSb NPs is related to the role played by Sb in reducing the energy barrier of the EOR rate-limiting step. Interestingly, as a side and value-added product of the EOR, acetate is obtained with 100% selectivity on PdSb catalysts.

PtM/Mx By (M=Ni, Co, Fe) Heterostructured Nanobundles as Advanced Electrocatalyst for Hydrogen Evolution Reaction

Optimizing the electronic and synergistic effect of hybrid electrocatalysts based on Pt and Pt-based nanocatalysts is of tremendous importance towards a superior hydrogen evolution performance under both acidic and alkaline conditions. However, developing an ideal Pt-based hydrogen evolution reaction (HER) electrocatalyst with moderated electronic structure as well as strong synergistic effect is still a challenge. Herein, we fabricated boron (B)-doped PtNi nanobundles by a two-step method using NaBH₄ as the boron source to obtain PtNi/Ni₄ B₃ heterostructures with well-defined nanointerfaces between PtNi and Ni₄ B₃ , achieving an enhanced catalytic HER performance. Especially, the PtNi/Ni₄ B₃ nanobundles (PtNi/Ni₄ B₃ NBs) can deliver a current density of 10 mA cm^-2 at the overpotential of 14.6 and 26.5 mV under alkaline and acidic media, respectively, as well as outstanding electrochemical stability over 40 h at the current density of 10 mA cm^-2 . Remarkably, this approach is also universal for the syntheses of PtCo/Co₃ B and PtFe/Fe₄₉ B with outstanding electrocatalytic HER performance.

A review of the role and mechanism of surfactants in the morphology control of metal nanoparticles

Although great progress has been made in the synthesis of metal nanoparticles, good repeatability and accurate predictability are still difficult to achieve. This difficulty can be attributed to the synthetic method based primarily on observation and subjective experience, and the role of many surfactants remains unclear. It should be noted that surfactants play an important role in the synthetic process. Understanding their function and mechanism in the synthetic process is a prerequisite for the rational design of nanocatalysts with ideal morphology and performance. In this review article, the function of surfactants is introduced first, and then the mechanism of action of surfactants in controlling the morphology of nanoparticles is discussed according to the types of surfactants, and the promoting and sealing effects of surfactants on the crystal surface is revealed. The relationship between surfactants and the morphology structure of nanoparticles is studied. The removal methods of surfactants are discussed, and the existing problems in the current development strategy are summarized. Finally, the application of surfactants in controlling the morphology of metal nanocrystals is prospected. It is hoped that the review can open up new avenues for the synthesis of nanocrystals.

A scalable synthesis of ternary nanocatalysts for a high-efficiency electrooxidation catalysis by microfluidics

Microfluidic synthesis has attracted extensive attention due to the ability for the multistep precise control of the synthesis parameters, continuous and reproducible preparation, and its ease of integration. However, its commercial application is still affected by its low production efficiency. In this case, we report a high-throughput continuous flow synthesis of highly dispersed PtFeCu/C nanocatalysts using a metal microchip setup with four parallel channels. The high flow rate and integrated channels enabled improving the throughput, whereby 1.33 g h^-1 of catalysts could be achieved with the flow rate of 1200 mL h^-1 under the experimental conditions. The as-prepared PtFeCu/C exhibited excellent performance, 1.94 times higher than Pt/C for methanol oxidation. More importantly, the yield of the PtFeCu/C nanocatalysts could be further increased through designing numerous parallel channels, which might provide a promising approach for large-scale commercialization of the catalysts. Such a high-throughput fabrication pathway is significant for the large-scale industrial production of nanomaterials.

Recent Achievements in Noble Metal Catalysts with Unique Nanostructures for Liquid Fuel Cells

In recent years, research efforts have been focused on the design and fabrication of highly efficient catalysts for liquid fuel cells, because the use of these cells is an important approach for alleviating environmental pollution and energy crises. However, the limitations of the catalytic performance of industrial Pt/C have strongly hindered the development of these fuel cells. The catalyst morphology has a strong impact on its performance; nanostructured catalysts are preferred as they offer large specific surface area and more exposed active centers. In view of this, many catalysts with unique structures have been synthesized in recent years, all of which show excellent catalytic performance characteristics. Despite these achievements, few efforts have been made to survey this field comprehensively. Herein, the recent advances in catalysts for liquid fuel cells are summarized, with a focus on noble metal catalysts with unique morphologies such as nanowires, nanosheets, and assembly structures. Their formation mechanisms are discussed critically. The relationship between the unique morphologies and excellent performance of these catalysts is also explored. This work may provide guidelines for the further development of liquid fuel cells.

A general carbon monoxide-assisted strategy for synthesizing one-nanometer-thick Pt-based nanowires as effective electrocatalysts

To balance the Pt utilization and the durability is the key issue for developing Pt-based oxygen reduction reaction (ORR) catalysts, and constructing ultrathin one-dimensional (1D) structure provides a practical solution. Here, a facile CO-assisted strategy has been proposed for synthesizing PtFe nanowires (NWs) with an ultrathin diameter of one-nanometer and high aspect ratio for the first time, which demonstrates great universality and can be extended to a ternary system. The NWs are found to grow following an oriented attachment mechanism facilitated by the preferential adsorption and reducibility of CO. Based on composition regulation, PtFe NWs and PtFeCo NWs exhibit superior catalytic performance, of which the electrochemical active surface areas are extremely high, achieving 1.5 folds of that of Pt/C catalyst. Benefiting from the synergistic effect endowed by alloying and the ultrathin anisotropic structure, PtFe NWs and PtFeCo NWs show remarkable mass activity of 0.57 and 0.58 A mg^-1_Pt, respectively, and the durability also meet the 2020 standard of DOE, holding great application potential.