Novel Flower-like PdAu(Cu) Anchoring on a 3D rGO-CNT Sandwich-stacked Framework for Highly Efficient Methanol and Ethanol Electro-oxidation

Tailored synthesis of ultra-stable Au@Pd nanoflowers with enhanced catalytic properties using cellulose nanocrystals

A green strategy for the synthesis of bimetallic core-shell Au@Pd nanoflowers (NFs) employing banana pseudo-stem-derived TEMPO-oxidized cellulose nanocrystals (TCNC) as both capping and shape-directing agent via seed-mediated method is presented. Flower-like nanostructures of Au@Pd bound to TEMPO-oxidized cellulose nanocrystals (TCNC-Au@Pd) were decorated on amino-functionalized graphene (NH₂-RGO) without losing their unique structure, allowing them to be deployed as an efficient, reusable and a green alternative heterogeneous catalyst. The decisive role of TCNC in the structural metamorphosis of nanoparticle morphology were inferred from the structural and morphology analyses. According to our study, the presence of -OH rich TCNC appears to play a pivotal role in the structured evolution of intricate nanostructure morphology. The feasibility of the bio-supported catalyst has been investigated in two concurrently prevalent model catalytic reactions, namely the oxygen reduction reaction (ORR) and the reduction of 4-nitrophenol, the best model reactions in fuel cell and industrial catalytic applications, respectively.

One-pot synthesis of porous Pd-polypyrrole/nitrogen-doped graphene nanocomposite as highly efficient catalyst for electrooxidation of alcohols

Herein, a ternary-nanocomposite Pd-polypyrrole/nitrogen-doped graphene (Pd-PPy/NGE) has been prepared facilely by the one-pot method. In simple terms, PPy was in-situ polymerized on the surface of NGE with PdCl₄^2- as the oxidant, and simultaneously Pd nanopaticles were loaded on the surface of PPy or embedded in PPy particles. The obtained Pd-PPy/NGE nanocomposite exhibits promising electrocatalytic properties toward the oxidation reaction of alcohols in alkaline medium. Especially, the optimized Pd-PPy/NGE (1:50) catalyst possesses mass activity of 2176.7, 1192.7 and 498.9 mA mg_Pd^-1 toward ethylene glycol, methanol and ethanol electrooxidation, respectively, which are 4.3, 6.7 and 2.9 times of those for commercial Pd/C catalyst. Moreover, the Pd-PPy/NGE (1:50) also shows higher anti-poisoning ability and operating stability than the Pd/C catalyst. The promising electrocatalytic performance of the Pd-PPy/NGE (1:50) for alcohols oxidation can be ascribed to the well dispersion of Pd nanoparticles, the porous and stable three dimentional structure of the composite, and the synergistic effect between different components. The structural randomness of the conducting polymer and the potential synergistic effect between the metal nanoparticles and various supports would provide broad development space for these composites as electrocatalysts in direct alcohol fuel cell.

Palladium hydride with high-index facets for enhanced methanol oxidation

Nobel metal catalysts with high-index facets feature a high density of steps and kink sites, which bring about high activity but could be unstable during the electrocatalytic process. Doping with interstitial hydrogen atoms is a unique and effective way to regulate the electronic structure of the host materials. The formation of hydride also helps to stabilize the active sites on the surface of catalysts. Herein, we demonstrate the conformal doping of H atoms into the Pd nanostructure with preferential exposure of {730} facets, forming concave nanocubes of palladium hydride. Compared to the palladium counterparts, the palladium hydride catalysts show enhanced activity and stability in electrocatalytic methanol oxidation, and the structural differences between the Pd and PdH catalysts are revealed by XRD and X-ray photoelectron spectroscopy. Our work presents a powerful strategy for designing durable catalysts with high performance by combining high-index facet with interstitial atom doping.

Highly efficient blackberry-like trimetallic PdAuCu nanoparticles with optimized Pd content for ethanol electrooxidation

The rational design of highly efficient catalysts for ethanol electrooxidation is extremely challenging for developing direct ethanol fuel cells (DEFCs). Herein, a facile one-pot method has been developed to prepare blackberry-like PdAuCu nanoparticles (NPs) with tunable composition and surface structures. Among PdAuCu NPs with different Pd contents (1.6-22 mass%), PdAuCu NPs-0.5 (contained Pd at 2.5 mass%) delivered one of the highest catalytic activities of Pd-based catalysts towards ethanol electrooxidation, exhibiting a mass activity of 23.0 A mg_Pd^-1. Kinetic analysis, electrochemical impedance spectroscopy and CO stripping test results suggested that the excellent electrocatalytic activity may originate from the optimized balance between Pd content and surface structure of PdAuCu NPs-0.5. The optimization of the balance between composition and surface structure would contribute to the further design of multimetallic nanoparticles for fuel cells and other applications.

Recent Progress of Ultrathin 2D Pd-Based Nanomaterials for Fuel Cell Electrocatalysis

Pd- and Pd-based catalysts have emerged as potential alternatives to Pt- and Pt-based catalysts for numerous electrocatalytic reactions, particularly fuel cell-related reactions, including the anodic fuel oxidation reaction (FOR) and cathodic oxygen reduction reaction (ORR). The creation of Pd- and Pd-based architectures with large surface areas, numerous low-coordinated atoms, and high density of defects and edges is the most promising strategy for improving the electrocatalytic performance of fuel cells. Recently, 2D Pd-based nanomaterials with single or few atom thickness have attracted increasing interest as potential candidates for both the ORR and FOR, owing to their remarkable advantages, including high intrinsic activity, high electron mobility, and straightforward surface functionalization. In this review, the recent advances in 2D Pd-based nanomaterials for the FOR and ORR are summarized. A fundamental understanding of the FOR and ORR is elaborated. Subsequently, the advantages and latest advances in 2D Pd-based nanomaterials for the FOR and ORR are scientifically and systematically summarized. A systematic discussion of the synthesis methods is also included which should guide researchers toward more efficient 2D Pd-based electrocatalysts. Lastly, the future outlook and trends in the development of 2D Pd-based nanomaterials toward fuel cell development are also presented.

One-step hydrothermal method for preparation of Ni/carbon thin film electrodes for efficient electroreduction of imidacloprid

A Ni/CTF was used as the cathode for electroreduction of imidacloprid, achieving a 92.1% removal efficiency for the electroreduction of imidacloprid.

Current Trends in MXene-Based Nanomaterials for Energy Storage and Conversion System: A Mini Review

MXene is deemed to be one of the best attentive materials in an extensive range of applications due to its stupendous optical, electronic, thermal, and mechanical properties. Several MXene-based nanomaterials with extraordinary characteristics have been proposed, prepared, and practiced as a catalyst due to its two-dimensional (2D) structure, large specific surface area, facile decoration, and high adsorption capacity. This review summarizes the synthesis and characterization studies, and the appropriate applications in the catalysis field, exclusively in the energy storage systems. Ultimately, we also discussed the encounters and prospects for the future growth of MXene-based nanomaterials as an efficient candidate in developing efficient energy storage systems. This review delivers crucial knowledge within the scientific community intending to design efficient energy storage systems.

Tunable long-chains of core@shell PdAg@Pd as high-performance catalysts for ethanol oxidation

High performance nanomaterial catalysts have attracted great attention on the application for the direct alcohol fuel cell. To improve the catalytic behavior, it is a challenge to modulate the surface structure and morphology of catalysts. We integrated properties of advanced networks nanostructure and core@shell structure to form a series of PdAg@Pd worm-like networks catalysts. Importantly, the composition-optimized Pd₇₆Ag₂₄ WNWs exhibited excellent catalytic performance towards ethanol oxidation reaction compared to that of commercial Pd/C catalysts in alkaline media. The mass activity of Pd₇₆Ag₂₄ WNWs is 3.55 times higher than that of commercial Pd/C catalysts for EOR. Moreover, the Pd₇₆Ag₂₄ WNWs also showed superior stability after 250 successive cycles and kept far higher residual activities than that of the other catalysts. The synthesis of PdAg@Pd worm-like networks catalysts provides a reference to well combine the advantages of core@shell and networks structure to form high performance catalysts application for DEFC.

General synthesis of Pd-pm (pm = Ga, In, Sn, Pb, Bi) alloy nanosheet assemblies for advanced electrocatalysis

Owing to the synergistic compositional and structural advantages, ultrathin bimetallic nanosheet assembly nanostructures are widely recognized as advanced catalysts for alcohol electrooxidation reaction. Although numerous efforts have been made, the fabrication of well-defined ultrathin bimetallic nanosheet assemblies (NSAs) at large scale is still a tough challenge. Herein, a universal synthetic approach has been proposed to produce a series of well-defined Pd-pm (pm = Ga, In, Sn, Pb, Bi) alloy NSAs. Due to multiple merits of their unique 3D flower-like nanostructure and alloyed crystalline features, the self-supported Pd-pm NSAs show excellent electrocatalytic performance for the methanol oxidation reaction (MOR) and glycerol oxidation reaction (GOR). Given the eco-friendly synthetic concept, facile universality, and outstanding electrocatalytic properties of the generated bimetallic Pd-pm NSAs, we believe that this method could be employed for building more advanced nanocatalysts toward efficient electrocatalytic applications.

Electrocatalytic Oxidation of Ethanol on the Surface of Graphene Based Nanocomposites: An Introduction and Review to it in Recent Studies

This review gives an overview of the electrochemical investigations about the properties of various types of graphene composites in the ethanol oxidation. Various routes to provide appropriate graphene-based materials required electrochemical techniques for investigation of different types of the materials as well as their performance and efficacy in ethanol oxidation are discussed in detail. Furthermore, it is demonstrated that the incorporation of suitable materials, e. g. noble metals (graphene-supported binary and ternary metal nanoparticles), metal oxides, conductive polymer, etc, with graphene results in excellent electrocatalytic activity, superb durability and selectivity in ethanol oxidation. Immobilization of electrocatalytically active NPs on graphene supports using physical approaches is considered as an effective route to prepare direct ethanol fuel cell (DEFC) anode catalysts.

Superior Ethanol Oxidation Electrocatalysis Enabled by Ternary Pd-Rh-Te Nanotubes

Designing and elaborating cost-efficient Pd-based electrocatalysts for direct ethanol fuel cells is thought to be a significant approach to obliterating the challenge of large-scale practical application of fuel cells. Herein, our group creates a novel class of one-dimensional (1D) PdRhTe nanotubes (NTs) by using H₂PdCl₄ and RhCl₃ as metal precursors and Te nanowires (NWs) as the reductant and sacrificial template. Strikingly, the as-obtained PdRhTe ternary nanomaterials with a unique 1D nanotube structure display a high specific activity of 6.53 mA cm^-2 and a mass activity of 2039.2 mA mg^-1 for the ethanol oxidation reaction (EOR) in alkaline media, which are 1.25 (1.6) and 1.77 (8.0) times those of PdTe/C and (Pd/C), respectively. More significantly, further electrochemical measurements such as CA and successive CV confirm that the optimized PdRhTe NTs display desirable durability and negligible activity decay. Taking advantage of physicochemical characterizations and electrochemical measurements, we reasonably reveal that the outstanding electrocatalytic performances are derived from the unique geometric structure and synergistic effect. The introduction of Rh facilitates the cleavage of C-C bonds, increasing the self-stability of PdRhTe NTs. In general terms, this work should provide new orientations to synthesize cost-efficient electrocatalysts by a sacrificial template method.

Recent progress in Pt and Pd-based hybrid nanocatalysts for methanol electrooxidation

Hybrid nanomaterials can combine merits of different components and modulate electronic states of Pt and Pd based nanocrystals simultaneously.

One-pot fabrication of Nitrogen-doped graphene supported binary palladium-sliver nanocapsules enable efficient ethylene glycol electrocatalysis

Fuel cells hold great potential of replacing traditional fossil fuel to alleviate the energy crisis and increasing environmental concerns. Although great progresses have been achieved over decades, the sluggish reaction kinetics and poor durability of electrocatalysts in fuel cells have been the decisive bottleneck that limited their practical applications. Herein, we focus on the design and development of cost-efficient anode electrocatalysts for fuel cells and report the successful creation of an advanced class of N-doped graphene (NG) supported binary PdAg nanocapsules (PdAg NCPs). The well-defined nanocatalysts with highly open structure exhibit greatly improved electrocatalytic performances for ethylene glycol oxidation reaction (EGOR). In particular, the optimized PdAg NCPs/NG show the mass and specific activities of 6118.3 mA mg^-1 and 13.8 mA cm^-2, which are 5.8 and 6.9 times larger than those of the commercial Pd/C catalysts, respectively. More importantly, such PdAg NCPs/NG can also maintain at least 500 potential cycles with limited catalytic activity attenuation, showing an advanced class of electrocatalysts for fuel cells.

3D-2D heterostructure of PdRu/NiZn oxyphosphides with improved durability for electrocatalytic methanol and ethanol oxidation

The rational design and engineering of bimetallic Pd-based nanocatalysts with both high activity and durability are of paramount significance for the practical applications of fuel cells. Herein, a new class of well-defined 2D NiZn oxyphosphide nanosheets (NiZnP NSs) have been successfully engineered to support unique 3D PdRu nanoflowers (PdRu NFs) via a facile strategy. Such nanohybrids with abundant surface active areas and modified electronic structure exhibit a great enhancement in electrocatalytic activity for the methanol oxidation reaction (MOR) and ethanol oxidation reaction (EOR), whose mass/specific activities are 1739.5 mA mg-1/4.5 mA cm-2 and 4719.8 mA mg-1/12.3 mA cm-2, which are 8.3/9.0 and 8.3/9.5 times higher than those of commercial Pd/C catalysts, respectively. More interestingly, with the remarkable promotional effect of NiZnP NSs, such 3D-2D PdRu/NiZn oxyphosphide nanohybrids can even retain 72.4% and 70.1% of initial catalytic activity toward MOR and EOR for 1000 potential cycles with negligible morphological or compositional variations. The successful construction of this new class of electrocatalysts opens up a new way for designing 3D-2D nanohybrids with high performance for electrochemical reactions and beyond.

Synthesis and characterization of core–shell structured M@Pd/SnO2–graphene [M = Co, Ni or Cu] electrocatalysts for ethanol oxidation in alkaline solution

Core–shell structured M@Pd/SnO₂–graphene (Gr), [M = Co, Ni or Cu] electrocatalysts were synthesized using ethylene glycol as a reducing agent with the aid of microwave irradiation in a two-step process.

Ionic-exchange immobilization of ultra-low loading palladium on a rGO electro-catalyst for high activity formic acid oxidation

A formic acid oxidation electro-catalyst with ultra-low palladium (Pd) loading was prepared via an ionic exchange method by utilizing the acidic functional groups on graphene oxide (GO). After simultaneous reduction of exchanged Pd²⁺ and residual functional groups on the GO surface, an ionic exchange reduced Pd catalyst supported on reduced GO (IE-Pd/rGO) was obtained. Three times improved formic acid oxidation mass activity compared with that of the conventional synthesized Pd/C catalyst was exhibited for the IE-Pd/rGO catalyst. More importantly, formic acid oxidation stability on the IE-Pd/rGO catalyst was remarkably improved due to synergistic effect of the strong immobilization of Pd nanoparticles and the effect of in situ doped N on the rGO support.

A formic acid oxidation electro-catalyst with ultra-low palladium (Pd) loading was prepared via an ionic exchange method by utilizing the acidic functional groups on graphene oxide (GO).

Synthesis of europium oxide-promoted Pd catalyst by an improved impregnation method as a high performance catalyst for the ethanol oxidation reaction

Simple and new strategy for the preparation of the Pd/Eu₂O₃ catalyst with the lowest palladium loading using Zn/HCl reduction system.

Enhanced and durable electrocatalytic performance of thin layer PtRu bimetallic alloys on Pd-nanocubes for methanol oxidation reactions

Enhanced and durable electrocatalytic performance of thin layer PtRu bimetallic alloys on Pd-nanocubes for methanol oxidation reactions.

Porous SnO2 hexagonal prism-attached Pd/rGO with enhanced electrocatalytic activity for methanol oxidation

Herein, we chose porous SnO₂ hexagonal prisms as a new promoter for Pd/rGO electrocatalyst. The as-prepared catalyst exhibited excellent electrochemical catalytic activities and enhanced durability for the oxidation of methanol.