Rapid fabrication of support-free trimetallic Pt53Ru39Ni8 nanosponges with enhanced electrocatalytic activity for hydrogen evolution and hydrazine oxidation reactions

Ternary Rare Earth Alloy Pt3-xIrxSc Nanoparticles Modulate Negatively Charged Pt via Charge Transfer To Facilitate pH-Universal Hydrogen Evolution

Rare earth (RE) elements possess electronic configurations that can provide additional pathways for tailoring the electronic structures of active elements through alloying, making it an important area of exploration in electrocatalysis. However, the large negative redox potential between RE and Pt has hindered the development of RE nanoalloys. In this study, a solid-phase synthesis strategy was employed to synthesize ternary Pt3-xIrxSc nanoparticles (NPs). By leveraging the electronegativity difference between Pt (2.28), Ir (2.20), and Sc (1.36), a charge-balance strategy was implemented to stabilize and enhance the catalytic performance of the alloy. The electron transfer from Sc to Pt/Ir results in the latter being negatively charged, and the Ir modifies the electron density of Pt, enabling favorable adsorption of active H species during the hydrogen evolution reaction (HER). Pt2IrSc exhibits enhanced HER activity at all pH values, achieving low overpotentials at 10 mA cm-2 of only 13, 18, and 25 mV in 0.5 M H2SO4, 1 M PBS, and 1 M KOH, respectively. This electrocatalyst also exhibits robust electrocatalytic stability even after 20,000 cycles. This work represents an application of the charge balance strategy to RE nanoalloys, and it is expected to inspire the design and synthesis of highly reactive RE nanoalloys.

Fabrication of heterogeneous bimetallic nanochains through photochemical welding for promoting the electrocatalytic hydrogen evolution reaction

Heterogeneous bimetallic nanochains (NCs) have gained significant attention in the field of catalysis due to their abundant active sites, multi-component synergistic catalytic, and exotic electronic structures. Here, we present a novel approach to synthesize one-dimensional heterogeneous bimetallic nanochains using a local surface plasmon resonance (LSPR) based strategy of liquid-phase photochemical welding method containing self-assembly and subsequent welding processes. Initially, we introduce additives that facilitate the self-assembly and alignment of Au nanoparticles (NPs) into orderly lines. Subsequently, the LSPR effect of the Au NPs is stimulated by light, enabling the second metal precursor to overcome the energy barrier and undergo photodeposition in the gap between the arranged Au NPs, thereby connecting the nano-metal particles. This strategy can be extended to the photochemical welding of Au NPs-Ag and Au NRs. Using electrocatalytic hydrogen evolution reaction (HER) as a proof-of-concept application, the obtained one-dimensional structure of Au5Pt1 NCs exhibit promoted HER performances, where the mass activity of the Au5Pt1 nanochains is found to be 4.8 times higher than that of Au5Pt1 NPs and 10.4 times higher than that of commercial 20 wt% Pt/C catalysts. The promoted HER performance is benefited from the electron conduction ability and abundant active sites.

Synthesis and potential applications of trimetallic nanostructures

The present review highlights the synthetic strategies and potential applications of TMNs for organic reactions, environmental remediation, and health-related activities.

Enhanced electrocatalytic activity of PtRu/nitrogen and sulphur co-doped crumbled graphene in acid and alkaline media

The low mass activity and high price of pure platinum (Pt)-based catalysts predominantly limit their large-scale utilization in electrocatalysis. Therefore, the reduction of Pt amount while preserving the electrocatalytic efficiency represents a viable alternative. In this work, we prepared new PtRu₂ nanoparticles supported on sulphur and nitrogen co-doped crumbled graphene with trace amounts of iron (PtRu₂/PF) electrocatalysts. The PtRu₂/PF catalysts exhibited enhanced electrocatalytic performance and stability for the hydrogen evolution reaction (HER) at pH = 0. Moreover, the prepared PtRu₂/PF electrocatalyst displayed higher HER activity than commercial 20% Pt/C. The PtRu₂/PF catalyst achieved a current density of 10 mA cm^-2 at an overpotential value of only 22 mV for HER, performing better activity than many other Pt-based electrocatalysts. Besides, the PtRu₂/PF revealed a good performance for the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) in alkaline media. The PtRu₂/PF catalyst recorded a current density of 10 mA cm^-2 at an overpotential of only 270 mV for OER in KOH (1.0 M) solution and an onset potential of 0.96 V vs. RHE (at 1 mA cm^-2) for ORR in KOH (0.1 M) solution.

Monodispersed Pt3Ni Nanoparticles as a Highly Efficient Electrocatalyst for PEMFCs

A facile strategy is proposed to synthesize monodispersed Pt3Ni nanoparticles. Such a kind of electrocatalyst shows a larger electrochemical surface area (98.9 m2 gpt−1) and double the mass activity of the oxygen reduction reaction activity compared to commercial Pt/C catalyst. The results show that the suitable addition of Ni and triethylamine in the reduction process plays an important role in controlling the size and dispersion of Pt3Ni nanoparticles. A further membrane electrode assembly test proves that as-prepared Pt3Ni nanoparticles can greatly enhance the electrochemical performance of a proton exchange membrane fuel cell, which exhibits a great potential of application in fuel cells.

Synthesis and characterization of size controlled bimetallic nanosponges

Metallic and bimetallic nanosponges with well-defined size and form have attracted increasing attention due to their unique structural properties and their potential for many applications. In this chapter, the recently developed methods for the synthesis and preparation of metallic and bimetallic nanosponges are presented. These methods can be mainly cataloged in two groups: dealloying-based methods and reduction reaction-based methods. Different topographical reconstruction methods for the investigation of their structural properties are then reviewed briefly. The optical properties of the metallic nanosponges are clearly different from those of the solid counterparts due to the tailored disordered structure. The recent advances in the exploration of the distinct linear and non-linear optical properties of the nanosponges are summarized.

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Facile Surfactant-Free Synthesis of Composition-Tunable Bimetallic PtCu Alloy Nanosponges for Direct Methanol Fuel Cell Applications

Sponge-like metal nanomaterials have been paid great attention due to their unique structure for wide applications in hydrogen storage, filtration, sensors, heterogeneous catalysis, and fuel cells. Here, we first use a facile, bottom-up method to successfully prepare composition-tunable PtCu alloy nanosponges constructed with sub-4.5 nm particle building blocks. Due to the porous structure, structure defects, and synergetic effect of Pt and Cu, the PtCu alloy nanosponges exhibit good electrocatalytic performances towards methanol oxidation. Compared with pure Pt nanosponges, the specific/mass activity on PtCu2 alloy nanosponges is 5.84/2.93 times that on pure Pt nanosponges. Furthermore, the stability and reactivation ability of PtCu alloy nanosponges are also superior to pure Pt nanosponges.

Fabrication of Pt nanoparticles on nitrogen-doped carbon/Ni nanofibers for improved hydrogen evolution activity

Among various methods for acquiring hydrogen fuel, electrocatalytic water splitting is considered to be as one of the most efficient and promising approaches. Pt is regarded as the best electrocatalyst for the hydrogen evolution reaction (HER) during water splitting process, however, the scarcity and costliness of Pt restrict the large-scale practical application. On the other hand, transition metal Ni is abundant in earth and exhibits favorable HER catalytic activity theoretically. In this work, we have demonstrated a facile electrospinning combined with calcination and chemical reduction processes to fabricate Pt nanoparticles loaded on nitrogen-doped carbon/Ni nanofibers (Ni-NCNFs-Pt) as efficient HER electrocatalysts. The as-prepared Ni-NCNFs-Pt not only reduced the usage of noble metal Pt but also revealed an excellent electrochemical activity at all values of pH, including the smaller overpotentials of 47, 22 and 84 mV (at j = 10 mA cm^-2) in 0.5 M H₂SO₄, 1 M KOH and 0.1 M phosphate buffer solution, respectively. In addition, Ni-NCNFs-Pt nanocatalyst displayed an extraordinary low Tafel slope and long durability over a wide range of pH. The remarkable HER performance could be ascribed to the increased electrochemical active surface area through the introduction of Ni nanoparticles, synergistic interactions between Ni and Pt nanoparticles and the introduction of the conductive nitrogen-doped carbon nanofibers (NCNFs) substrate which facilitated the fast electron transport. This investigation provides a potential route to construct efficient and low cost HER electrocatalysts with promising practical applications in renewable energy conversion and storage devices.