Ultimate Corrosion to Pt-Cu Electrocatalysts for Enhancing Methanol Oxidation Activity and Stability in Acidic Media

Lanthanide-Induced Ligand Effect to Regulate the Electronic Structure of Platinum-Lanthanide Nanoalloys for Efficient Methanol Oxidation

The ligand effect in alloy catalysts is one of the decisive parameters of the catalytic performance. However, the strong interrelation between the ligand effect and the geometric effect of the active atom and its neighbors as well as the systematic alteration of the microenvironment of the active site makes the active mechanism unclear. Herein, Pt3Tm, Pt3Yb, and Pt3Lu with a cubic crystal system (Pm-3m) were selected. With the difference of Pt-Pt interatomic distance within 0.02 Å, we minimize the geometric effect to realize the disentanglement of the system. Through precise characterization, due to the low electronegativity of Ln (Ln = Tm, Yb, and Lu) and the ligand effect in the alloy, the electronic structure of Pt is continuously optimized, which improves the electrochemical methanol oxidation reaction (MOR) performance. The Ln electronegativity has a linear relationship with the MOR performance, and Pt3Yb/C achieves a high mass activity of up to 11.61 A mgPt-1, which is the highest value reported so far in Pt-based electrocatalysts. The results obtained in this study provide fundamental insights into the mechanism of ligand effects on the enhancement of electrochemical activity in rare-earth nanoalloys.

Bubbling resilient 3D free-standing nanoporous graphene with an encapsulated multicomponent nano-alloy for enhanced electrocatalysis

The design and synthesis of highly durable and active electrocatalysts are crucial for improving the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR) in proton exchange membrane fuel cells (PEMFCs). In this work, we present a novel dealloyed nanoporous PtCuNiCoMn multicomponent alloy with ligaments/pores ranging from 2-3 nm, which is in situ encapsulated in a three-dimensional, free-standing nanoporous nanotubular graphene network featuring a pore/tube diameter of ∼200 to 300 nm. This method allows precise control over the noble metal loading and alloy composition while preventing noble metal loss throughout the preparation process. The innovative bimodal nanoporous graphene/alloy structure, coupled with an open 3D spongy morphology, and optimized surface Pt electronic structure through multicomponent interaction, significantly enhances the activity for the HER/ORR, outperforming commercial Pt/C. Moreover, this design addresses the issues of Pt nanoparticle aggregation and detachment from carbon supports that typically exist in Pt/C-type catalysts, thereby substantially improving the catalytic durability, even under intense gas bubbling conditions.

Pt-C interactions in carbon-supported Pt-based electrocatalysts

Carbon-supported Pt-based materials are highly promising electrocatalysts. The carbon support plays an important role in the Pt-based catalysts by remarkably influencing the growth, particle size, morphology, dispersion, electronic structure, physiochemical property and function of Pt. This review summarizes recent progress made in the development of carbon-supported Pt-based catalysts, with special emphasis being given to how activity and stability enhancements are related to Pt-C interactions in various carbon supports, including porous carbon, heteroatom doped carbon, carbon-based binary support, and their corresponding electrocatalytic applications. Finally, the current challenges and future prospects in the development of carbon-supported Pt-based catalysts are discussed.

A RuCoBO Nanocomposite for Highly Efficient and Stable Electrocatalytic Seawater Splitting

Efficient and stable electrocatalysts are critically needed for the development of practical overall seawater splitting. The nanocomposite of RuCoBO has been rationally engineered to be an electrocatalyst that fits these criteria. The study has shown that a calcinated RuCoBO-based nanocomposite (Ru₂Co₁BO-350) exhibits an extremely high catalytic activity for H₂ and O₂ production in alkaline seawater (overpotentials of 14 mV for H₂ evolution and 219 mV for O₂ evolution) as well as a record low cell voltage (1.466 V@10 mA cm^-2) and long-term stability (230 h @50 mA cm^-2 and @100 mA cm^-2) for seawater splitting. The results show that surface reconstruction of Ru₂Co₁BO-350 occurs during hydrogen evolution reaction and oxygen evolution reaction, which leads to the high activity and stability of the catalyst. The reconstructed surface is highly resistant to Cl^- corrosion. The investigation suggests that a new strategy exists for the design of high-performance Ru-based electrocatalysts that resist anodic corrosion during seawater splitting.

Toward Electrocatalytic Methanol Oxidation Reaction: Longstanding Debates and Emerging Catalysts

The study of direct methanol fuel cells (DMFCs) has lasted around 70 years, since the first investigation in the early 1950s. Though enormous effort has been devoted in this field, it is still far from commercialization. The methanol oxidation reaction (MOR), as a semi-reaction of DMFCs, is the bottleneck reaction that restricts the overall performance of DMFCs. To date, there has been intense debate on the complex six-electron reaction, but barely any reviews have systematically discussed this topic. To this end, the controversies and progress regarding the electrocatalytic mechanisms, performance evaluations as well as the design science toward MOR electrocatalysts are summarized. This review also provides a comprehensive introduction on the recent development of emerging MOR electrocatalysts with a focus on the innovation of the alloy, core-shell structure, heterostructure, and single-atom catalysts. Finally, perspectives on the future outlook toward study of the mechanisms and design of electrocatalysts are provided.

Superior Electrocatalysis Delivered by a Directional Electron Transfer Cascade in Hierarchical CoNi/Ru@C

Exploiting directional electron transfer cascades could lead to high-performance electrocatalysts for processes such as the hydrogen evolution reaction, but realising such systems is difficult. Herein, a hierarchical confined material (CoNi/Ru@C) is presented, which provides a suitable spatial junction to enable directional electron transfer, giving superior hydrogen evolution in alkaline water/seawater.

Stoichiometry design in hierarchical CoNiFe phosphide for highly efficient water oxidation

Rational composition design of trimetallic phosphide catalysts is of significant importance for enhanced surface reaction and efficient catalytic performance. Herein, hierarchical Co _x Ni _y Fe _z P with precise control of stoichiometric metallic elements (x:y:z = (1-10):(1-10):1) has been synthesized, and Co_1.3Ni_0.5Fe_0.2P, as the most optimal composition, exhibits remarkable catalytic activity (η = 320 mV at 10 mA cm^-2) and long-term stability (ignorable decrease after 10 h continuous test at the current density of 10 mA cm^-2) toward oxygen evolution reaction (OER). It is found that the surface P in Co_1.3Ni_0.5Fe_0.2P was replaced by O under the OER process. The density function theory calculations before and after long-term stability tests suggest the clear increasing of the density of states near the Fermi level of Co_1.3Ni_0.5Fe_0.2P/Co_1.3Ni_0.5Fe_0.2O, which could enhance the OH^- adsorption of our electrocatalysts and the corresponding OER performance.

ELECTRONIC SUPPLEMENTARY MATERIAL

Supplementary material is available in the online version of this article at 10.1007/s40843-022-2061-x.

Hierarchically Fractal PtPdCu Sponges and their Directed Mass- and Electron-Transfer Effects

Fractal Pt-based materials with hierarchical structures and high self-similarity have attracted more and more attention due to their bioinspiring maximum optimization of energy utilization and mass transfer. However, their high-efficiency design of the mass- and electron-transfer still remains to be a great challenge. Herein, fractal PtPdCu hollow sponges (denoted as PtPdCu-HS) facilitating both directed mass- and electron-transfer are presented. Such directed transfer effects greatly promote electrocatalytic activity, regarded as 3.9 times the mass activity, 7.3 times the specific activity, higher poison tolerance, and higher stability than commercial Pt/C for the methanol oxidation reaction (MOR). A new "directed mass- and electron-transfer" concept, characteristics, and mechanism are proposed at the micro/nanoscale to clarify the structural design and functional enhancement of fractal electrocatalyst. This work displays new possibilities for designing novel nanomaterials with high activity and superior stability toward electrocatalysis or other practical applications.