Defect Rich Structure Activated 3D Palladium Catalyst for Methanol Oxidation Reaction

Mesoporous High-Entropy Alloy Films

High-entropy alloys (HEAs) are promising materials for electrochemical energy applications due to their excellent catalytic performance and durability. However, the controlled synthesis of HEAs with a well-defined structure and a uniform composition distribution remains a challenge. Herein, a soft template-assisted electrodeposition technique is used to fabricate a mesoporous HEA (m-HEA) film with a uniform composition distribution of Pt, Pd, Rh, Ru, and Cu, providing a suitable platform for investigating structure-performance relationships. Electrochemical deposition enables the uniform nucleation and grain growth of m-HEA, which can be deposited onto many conductive substrates. The m-HEA film exhibits an enhanced mass activity of 4.2 A mgPt-1 toward methanol oxidation reaction (MOR), which is 7.2-fold and 35-fold higher than a mesoporous Pt film and commercial Pt black, respectively. Experimental characterization indicates that structural defects and a low work function of the m-HEA film offer sufficient active sites and fast electron-transfer kinetics. Furthermore, theoretical calculations demonstrate that the variety of favorable adsorption sites on multimetallic elements of HEA reduces the barriers for dehydration pathways and *CO species removal, ensuring optimal performance for complex MOR reactions. This work provides an effective approach to designing a variety of HEA catalysts with well-controlled porous structures for targeted electrocatalytic applications.

Halogen Tailoring of Platinum Electrocatalyst with High CO Tolerance for Methanol Oxidation Reaction

The catalytic activity of platinum for CO oxidation depends on the interaction of electron donation and back-donation at the platinum center. Here we demonstrate that the platinum bromine nanoparticles with electron-rich properties on bromine bonded with sp-C in graphdiyne (PtBr NPs/Br-GDY), which is formed by bromine ligand and constitutes an electrocatalyst with a high CO-resistant for methanol oxidation reaction (MOR). The catalyst showed peak mass activity for MOR as high as 10.4 A mgPt -1, which is 20.8 times higher than the 20 % Pt/C. The catalyst also showed robust long-term stability with slight current density decay after 100 hours at 35 mA cm-2. Structural characterization, experimental, and theoretical studies show that the electron donation from bromine makes the surface of platinum catalysts highly electron-rich, and can strengthen the adsorption of CO as well as enhance π back-donation of Pt to weaken the C-O bond to facilitate CO electrooxidation and enhance catalytic performance during MOR. The results highlight the importance of electron-rich structure among active sites in Pt-halogen catalysts and provide detailed insights into the new mechanism of CO electrooxidation to overcome CO poisoning at the Pt center on an orbital level.

Modification Strategies for Development of 2D Material-Based Electrocatalysts for Alcohol Oxidation Reaction

2D materials, such as graphene, MXenes (metal carbides and nitrides), graphdiyne (GDY), layered double hydroxides, and black phosphorus, are widely used as electrocatalyst supports for alcohol oxidation reactions (AORs) owing to their large surface area and unique 2D charge transport channels. Furthermore, the development of highly efficient electrocatalysts for AORs via tuning the structure of 2D support materials has recently become a hot area. This article provides a critical review on modification strategies to develop 2D material-based electrocatalysts for AOR. First, the principles and influencing factors of electrocatalytic oxidation of alcohols (such as methanol and ethanol) are introduced. Second, surface molecular functionalization, heteroatom doping, and composite hybridization are deeply discussed as the modification strategies to improve 2D material catalyst supports for AORs. Finally, the challenges and perspectives of 2D material-based electrocatalysts for AORs are outlined. This review will promote further efforts in the development of electrocatalysts for AORs.

Bifunctional PdMoPt trimetallene boosts alcohol-water electrolysis

Substituting oxygen evolution with alcohol oxidation is crucial for enhancing the cathodic hydrogen evolution reaction (HER) at low voltages. However, the development of high-performance bifunctional catalysts remains a challenge. In this study, an ultrathin and porous PdMoPt trimetallene is developed using a wet-chemical strategy. The synergetic effect between alloying metals regulates the adsorption energy of reaction intermediates, resulting in exceptional activity and stability for the electrooxidation of various alcohols. Specifically, the mass activity of PdMoPt trimetallene toward the electrooxidation of methanol, ethylene glycol, and glycerol reaches 6.13, 5.5, and 4.37 A mgPd+Pt -1, respectively. Moreover, the catalyst demonstrates outstanding HER activity, requiring only a 39 mV overpotential to achieve 10 mA cm-2. By employing PdMoPt trimetallene as both the anode and cathode catalyst, we established an alcohol-water hybrid electrolysis system, significantly reducing the voltage requirements for hydrogen production. This work presents a promising avenue for the development of bifunctional catalysts for energy-efficient hydrogen production.

Design and regulation of defective electrocatalysts

Electrocatalysts are the key components of electrochemical energy storage and conversion devices. High performance electrocatalysts can effectively reduce the energy barrier of the chemical reactions, thereby improving the conversion efficiency of energy devices. The electrocatalytic reaction mainly experiences adsorption and desorption of molecules (reactants, intermediates and products) on a catalyst surface, accompanied by charge transfer processes. Therefore, surface control of electrocatalysts plays a pivotal role in catalyst design and optimization. In recent years, many studies have revealed that the rational design and regulation of a defect structure can result in rearrangement of the atomic structure on the catalyst surface, thereby efficaciously promoting the electrocatalytic performance. However, the relationship between defects and catalytic properties still remains to be understood. In this review, the types of defects, synthesis methods and characterization techniques are comprehensively summarized, and then the intrinsic relationship between defects and electrocatalytic performance is discussed. Moreover, the application and development of defects are reviewed in detail. Finally, the challenges existing in defective electrocatalysts are summarized and prospected, and the future research direction is also suggested. We hope that this review will provide some principal guidance and reference for researchers engaged in defect and catalysis research, better help researchers understand the research status and development trends in the field of defects and catalysis, and expand the application of high-performance defective electrocatalysts to the field of electrocatalytic engineering.

Mesoporous Hollow Carbon Sphere-Embedded MXene Architectures Decorated with Ultrafine Rh Nanocrystals toward Methanol Electrooxidation

The development of advanced Pt-alternative anode electrocatalysts with high activity and reliable stability is critical to overcoming the technical challenges of direct methanol fuel cells. Here, we propose a robust bottom-up strategy for the spatial construction of mesoporous hollow carbon sphere (HCS)-embedded MXene architectures decorated with ultrafine Rh nanocrystals (Rh/HCS-MX) via stereoscopic coassembly reactions. The rational intercalation of HCS effectively separates the MXene nanowalls to achieve a rapid mass-transfer efficiency, while the intimate coupling of the hybrid carrier with Rh nanocrystals enables their electronic structure optimization, thus contributing to strong synergistic catalytic effects. Accordingly, the resulting Rh/HCS-MX architectures exhibit outstanding methanol electrooxidation properties in terms of large electrochemical active surface areas, high mass/specific activities, and good long-term stability, all of which are significantly superior to the traditional Rh/carbon black, Rh/HCS, and Rh/MXene as well as commercial Pt/carbon balck and Pd/carbon balck electrocatalysts.

Improving the Electrochemical Glycerol-to-Glycerate Conversion at Pd Sites via the Interfacial Hydroxyl Immigrated from Ni Sites

The electrochemical conversion of glycerol into high-value chemicals through the selective glycerol oxidation reaction (GOR) holds importance in utilizing the surplus platform chemical component of glycerol. Nevertheless, it is still very limited in producing three-carbon chain (C3) chemicals, especially glyceric acid/glycerate, through the direct oxidation of its primary hydroxyl group. Herein, Pd microstructure electrodeposited on the Ni foam support (Pd/NF) is designed and fabricated to achieve a highly efficient GOR, exhibiting a superior current density of ca. 120 mA cm-2 at 0.8 V vs. reversible hydrogen electrode (RHE), and high selectivity of glycerate at ca. 70%. The Faradaic efficiency of C3 chemicals from GOR can still be maintained at ca. 80% after 20 continuous electrolysis runs, and the conversion rate of glycerol can reach 95% after 10-h electrolysis. It is also clarified that the dual-component interfaces constructed by the adjacent Pd and Ni sites are responsible for this highly efficient GOR. Specifically, Ni sites can effectively strengthen the generative capacity of the active adsorbed hydroxyl (OHad) species, which can steadily immigrate to the Pd sites, so that the surface adsorbed glycerol species are quickly oxidized into C3 chemicals, rather than breaking the C-C bond of glycerol; thus, neither form the C2/C1 species. This study may yield fresh perspectives on the electrocatalytic conversion of glycerol into high-value C3 chemicals, such as glyceric acid/glycerate.

The Accurate Synthesis of a Multiscale Metallic Interface on Graphdiyne

The accurate construction of composite material systems containing graphdiyne (GDY) and other metallic materials has promoted the formation of innovative structures and practical applications in the fields of energy, catalysis, optoelectronics, and biomedicine. To fulfill the practical requirements, the precise formation of multiscale interfaces over a wide range, from single atoms to nanostructures, plays an important role in the optimization of the structural design and properties. The intrinsic correlations between the structure, synthesis process, characteristic properties, and device performance are systematically investigated. This review outlines the current research achievements regarding the controlled formation of multiscale metallic interfaces on GDY. Synthetic strategies for interface regulation, as well as the correlation between the structure and performance, are presented. Furthermore, innovative research ideas for the design and synthesis of functional metal-based materials loaded onto GDY-based substances are also provided, demonstrating the promising application potential of GDY-based materials.