Boosting the Methanol Oxidation Reaction Activity of Pt-Ru Clusters via Resonance Energy Transfer

The sluggish kinetics of the methanol oxidation reaction (MOR) with PtRu electrocatalyst severely hinder the commercialization of direct methanol fuel cells (DMFCs). The electronic structure of Pt is of significant importance for its catalytic activity. Herein, it is reported that low-cost fluorescent carbon dots (CDs) can regulate the behavior of the D-band center of Pt in PtRu clusters through resonance energy transfer (RET), resulting in a significant increase in the catalytic activity of the catalyst participating in methanol electrooxidation. For the first time, the bifunction of RET is used to provide unique strategy for fabrication of PtRu electrocatalysts, not only tunes the electronic structure of metals, but also provides an important role in anchoring metal clusters. Density functional theory calculations further prove that charge transfer between CDs and Pt promotes the dehydrogenation of methanol on PtRu catalysts and reduces the free energy barrier of the reaction associated with the oxidation of CO* to CO2 . This helps to improve the catalytic activity of the systems participating in MOR. The performance of the best sample is 2.76 times higher than that of commercial PtRu/C (213.0 vs 76.99 mW cm - 2 mg Pt - 1 ${\rm{mW\ cm}}^{ - 2}{\rm{\ mg}}_{{\rm{Pt}}}^{ - 1}$ ). The fabricated system can be potentially used for the efficient fabrication of DMFCs.

Yttrium-based Double Perovskite Nanorods for Electrocatalysis

Herein, we investigate the effect of the chemical composition of double perovskite nanorods on their versatile electrocatalytic activity not only as supports for the oxidation of small organic molecules but also as catalysts for the oxygen evolution reaction. Specifically, Y₂CoMnO₆ and Y₂NiMnO₆ nanorods with average diameters of 300 nm were prepared by a two-step hydrothermal method, in which the individual effects of synthetic parameters, such as the pH, annealing temperature, and precursor ratios on both the composition and morphology, were systematically investigated. When used as supports for Pt nanoparticles, Y₂CoMnO₆/Pt catalysts exhibited an electrocatalytic activity for the methanol oxidation reaction, which is 2.1 and 1.3 times higher than that measured for commercial Pt/C and Y₂NiMnO₆/Pt, respectively. Similarly, the Co-based catalyst support material displayed an ethanol oxidation activity, which is 2.3 times higher than both Pt/C and Y₂NiMnO₆/Pt. This clear enhancement in the activity for Y₂CoMnO₆ can largely be attributed to strong metal-support interactions, as evidenced by a downshift in the binding energy of the Pt 4f bands, measured by X-ray photoelectron spectroscopy (XPS), which is often correlated not only with a downshift in the d-band center but also to a decreased adsorption of poisoning adsorbates. Moreover, when used as catalysts for the oxygen evolution reaction, Y₂CoMnO₆ displayed a much greater activity as compared with Y₂NiMnO₆. This behavior can largely be attributed not only to a preponderance of comparatively more favorable oxidation states and electronic configurations but also to the formation of an active layer on the surface of the Y₂CoMnO₆ catalyst, which collectively gives rise to improved performance metrics and greater stability as compared with both IrO₂ and Y₂NiMnO₆. Overall, these results highlight the importance of both the chemical composition and the electronic structure of double perovskites, especially when utilized in multifunctional roles as either supports or catalysts.

Heterogeneous Trimetallic Nanoparticles as Catalysts

The development and application of trimetallic nanoparticles continues to accelerate rapidly as a result of advances in materials design, synthetic control, and reaction characterization. Following the technological successes of multicomponent materials in automotive exhausts and photovoltaics, synergistic effects are now accessible through the careful preparation of multielement particles, presenting exciting opportunities in the field of catalysis. In this review, we explore the methods currently used in the design, synthesis, analysis, and application of trimetallic nanoparticles across both the experimental and computational realms and provide a critical perspective on the emergent field of trimetallic nanocatalysts. Trimetallic nanoparticles are typically supported on high-surface-area metal oxides for catalytic applications, synthesized via preparative conditions that are comparable to those applied for mono- and bimetallic nanoparticles. However, controlled elemental segregation and subsequent characterization remain challenging because of the heterogeneous nature of the systems. The multielement composition exhibits beneficial synergy for important oxidation, dehydrogenation, and hydrogenation reactions; in some cases, this is realized through higher selectivity, while activity improvements are also observed. However, challenges related to identifying and harnessing influential characteristics for maximum productivity remain. Computation provides support for the experimental endeavors, for example in electrocatalysis, and a clear need is identified for the marriage of simulation, with respect to both combinatorial element screening and optimal reaction design, to experiment in order to maximize productivity from this nascent field. Clear challenges remain with respect to identifying, making, and applying trimetallic catalysts efficiently, but the foundations are now visible, and the outlook is strong for this exciting chemical field.

Synthesis of a functionalized carbon supported platinum–iridium nanoparticle catalyst by the rapid chemical reduction method for the anodic reaction of direct methanol fuel cells

Direct methanol fuel cells (DMFCs) stand out among the most common technologies in energy storage and are environmentally friendly energy converters that convert chemical energy into electrical energy.

Biomass-Derived Activated Carbon-Supported Copper Catalyst: An Efficient Heterogeneous Magnetic Catalyst for Base-Free Chan-Lam Coupling and Oxidations

Development of heterogeneous catalysts from biomass-derived activated carbon is a challenging task. Biomass-derived activated carbon possesses a large specific surface area, highly porous structure, and good thermal/chemical stability. Magnetic copper catalysts based on biomass-derived activated carbon exhibited good catalytic activity in base-free Chan-Lam coupling and oxidations. Herein, biomass-derived activated carbon was prepared by the carbonization of neem dead leaves (abundant waste biomass) followed by chemical activation with KOH. Such a porous carbon material was used as a low cost and highly efficient support material for the preparation of inexpensive and environmentally benign magnetic catalysts [Cu@KF-C/MFe2O4, M = Co, Cu, Ni, and Zn]. In addition, KF modification was done to impart basic character to the catalyst that can perform C-N coupling under base-free conditions. Initially, Brunauer-Emmett-Teller (BET) analysis of the synthesized catalysts was carried out, which indicated that Cu@KF-C/CoFe2O4 possess more surface area as well as pore volume, and so accounting for the highest activity among the other synthesized catalysts. Further, X-ray photoelectron spectroscopy (XPS) analysis was performed, which inferred that Cu@KF-C/CoFe2O4 contains most of the copper in reduced form, i.e., Cu(0), which is the active species responsible for better catalytic activity toward Chan-Lam coupling reactions as well as oxidation of alcohols and hydrocarbons. The physiochemical properties of the most active catalyst, Cu@KF-C/CoFe2O4, was examined by BET, XPS, Fourier transform infrared Spectroscopy (FTIR), thermogravimetric analysis (TGA), field emission gun scanning electron microscopy (FEG-SEM), high-resolution transmission electron microscopy (HR-TEM), energy dispersive X-ray (EDX) mapping, energy dispersive X-ray (EDX), inductively coupled plasma atomic emission spectroscopy (ICP-AES), powder X-ray diffraction (XRD), and vibrating sample magnetometry (VSM). Moreover, Cu@KF-C/CoFe2O4 shows excellent stability as well as reusability and could be easily separated with the help of an external magnet.

Pt-based nanoparticles decorated by phosphorus-doped CuWO4 to enhance methanol oxidation activity

DMFCs are promising power storage devices, while for methanol oxidation reaction, weak catalysis and carbon monoxide poisoning greatly limit their wide commercialization, so it's greatly necessary to exploit the anode catalysts with high performance.

Inter-regulated d-band centers of the Ni3B/Ni heterostructure for boosting hydrogen electrooxidation in alkaline media

Ni₃B/Ni heterostructures have been constructed, which exhibit exceptional catalytic performance toward the hydrogen oxidation reaction (HOR) under alkaline media, with the mass activity being about 10 times greater than that of Ni₃B and Ni, respectively, ranking among the most active platinum-group-metal-free electrocatalysts. Experimental results and theoretical calculations confirm electron transfer from Ni₃B to Ni at the Ni₃B/Ni interface, resulting in inter-regulated d-band centers of these two components. This inter-regulation gives rise to optimized binding energies of intermediates, which together contribute to enhanced alkaline HOR activity.

The Effect of Carbon Content on Methanol Oxidation and Photo-Oxidation at Pt-TiO2-C Electrodes

The oxidation of methanol is studied at TiO2-supported Pt electrodes of varied high surface area carbon content (in the 30-5% w/w range) and C÷Ti atom ratio (in the 3.0-0.4 ratio). The Pt-TiO2 catalyst is prepared by a photo-deposition process and C nanoparticles (Vulcan XC72R) are added by simple ultrasonic mixing. The optimum C÷Ti atom ratio of the prepared catalyst for methanol electro-oxidation is found to be 1.5, resulting from the interplay of C properties (increased electronic conductivity and methanol adsorption), those of TiO2 (synergistic effect on Pt and photo-activity), as well as the catalyst film thickness. The intrinsic catalytic activity of the best Pt-TiO2/C catalyst is better than that of a commercial Pt/C catalyst and could be further improved by nearly 25% upon UV illumination, whose periodic application can also limit current deterioration.

Biomass-derived carbon-supported Ni catalyst: an effective heterogeneous non-noble metal catalyst for the hydrogenation of nitro compounds

The biomass-derived carbon material supported Ni catalysts (Ni/C) demonstrated a high catalytic activity for the hydrogenation of nitro compounds into primary amines at room temperature.

Nitrogen-Doped Carbon-Supported Nickel Nanoparticles: A Robust Catalyst to Bridge the Hydrogenation of Nitriles and the Reductive Amination of Carbonyl Compounds for the Synthesis of Primary Amines

An efficient method was developed for the synthesis of primary amines either from the hydrogenation of nitriles or reductive amination of carbonyl compounds. The reactions were catalyzed by nitrogen-doped mesoporous carbon (MC)-supported nickel nanoparticles (abbreviated as MC/Ni). The MC/Ni catalyst demonstrated high catalytic activity for the hydrogenation of nitriles into primary amines in high yields (81.9-99 %) under mild reaction conditions (80 °C and 2.5 bar H₂ ). The MC/Ni catalyst also promoted the reductive amination of carbonyl compounds for the synthesis of primary amines at 80 °C and 1 bar H₂ . The hydrogenation of nitriles and the reductive amination proceeded through the same intermediates for the generation of the primary amines. To the best of our knowledge, no other heterogeneous non-noble metal catalysts have been reported for the synthesis of primary amines under mild conditions, both from the hydrogenation of nitriles and reductive amination.

Trimetallic PtAuNi alloy nanoparticles as an efficient electrocatalyst for the methanol electrooxidation reaction

Platinum is an excellent electrocatalyst. However, the disadvantages of Pt as an electrocatalyst lie in its poor earth abundance, high cost, and poor stability due to surface poisoning. Thus it remains a challenge to find suitable alternative electrocatalysts and/or reduce the use of Pt. Herein, we report the solvothermal synthesis of bimetallic (PtAu and PtNi) and trimetallic (PtAuNi) alloy nanoparticles (NPs) with controlled percentages of individual metals. With an optimized Ni content, the trimetallic (Pt₆₆Au₁₁Ni₂₃) alloy NPs show superior electrocatalytic activity (in terms of lower onset oxidation potential and higher mass activity) not only to bimetallic alloy NPs (PtAu and PtNi) but also to commercial Pt/C (20% Pt loading) for methanol electrooxidation (MEO). This enhanced electrocatalytic activity is due to the synergistic role of different metals in MEO catalysis. In particular, the catalytic activity is found to be controlled by the balance between the adsorption of methanol species on Pt and the removal of carbonaceous species from the catalyst surface by Au and Ni, as demonstrated here. The multimetallic alloy of optimal individual content thereby not only reduces the Pt content in the catalyst but also exhibits higher electrocatalytic activity than Pt/C for MEO that is desirable for fuel cell applications.

Trimetallic PtPdCu nanowires as an electrocatalyst for methanol and formic acid oxidation

PtPdCu nanowires show enhanced electrocatalytic activity and stability compared to their bimetallic counterparts and commercial Pt/C.

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.

Nitrogen-doped Graphene-Supported Transition-metals Carbide Electrocatalysts for Oxygen Reduction Reaction

A novel and facile two-step strategy has been designed to prepare high performance bi-transition-metals (Fe- and Mo-) carbide supported on nitrogen-doped graphene (FeMo-NG) as electrocatalysts for oxygen reduction reactions (ORR). The as-synthesized FeMo carbide -NG catalysts exhibit excellent electrocatalytic activities for ORR in alkaline solution, with high onset potential (−0.09 V vs. saturated KCl Ag/AgCl), nearly four electron transfer number (nearly 4) and high kinetic-limiting current density (up to 3.5 mA cm⁻² at −0.8 V vs. Ag/AgCl). Furthermore, FeMo carbide -NG composites show good cycle stability and much better toxicity tolerance durability than the commercial Pt/C catalyst, paving their application in high-performance fuel cell and lithium-air batteries.

Ternary Pt-Ru-Ni catalytic layers for methanol electrooxidation prepared by electrodeposition and galvanic replacement

Ternary Pt-Ru-Ni deposits on glassy carbon substrates, Pt-Ru(Ni)/GC, have been formed by initial electrodeposition of Ni layers onto glassy carbon electrodes, followed by their partial exchange for Pt and Ru, upon their immersion into equimolar solutions containing complex ions of the precious metals. The overall morphology and composition of the deposits has been studied by SEM microscopy and EDS spectroscopy. Continuous but nodular films have been confirmed, with a Pt ÷ Ru ÷ Ni % bulk atomic composition ratio of 37 ÷ 12 ÷ 51 (and for binary Pt-Ni control systems of 47 ÷ 53). Fine topographical details as well as film thickness have been directly recorded using AFM microscopy. The composition of the outer layers as well as the interactions of the three metals present have been studied by XPS spectroscopy and a Pt ÷ Ru ÷ Ni % surface atomic composition ratio of 61 ÷ 12 ÷ 27 (and for binary Pt-Ni control systems of 85 ÷ 15) has been found, indicating the enrichment of the outer layers in Pt; a shift of the Pt binding energy peaks to higher values was only observed in the presence of Ru and points to an electronic effect of Ru on Pt. The surface electrochemistry of the thus prepared Pt-Ru(Ni)/GC and Pt(Ni)/GC electrodes in deaerated acid solutions (studied by cyclic voltammetry) proves the existence of a shell consisting exclusively of Pt-Ru or Pt. The activity of the Pt-Ru(Ni) deposits toward methanol oxidation (studied by slow potential sweep voltammetry) is higher from that of the Pt(Ni) deposit and of pure Pt; this enhancement is attributed both to the well-known Ru synergistic effect due to the presence of its oxides but also (based on the XPS findings) to a modification effect of Pt electronic properties.

Facile synthesis of PdPt nanoalloys with sub-2.0 nm islands as robust electrocatalysts for methanol oxidation

The high-yield, composition-tunable PdPt nanoalloys with sub-2.0 nm islands were first achieved through a facile aqueous approach.

PPyNT-Im-PtAu alloy nanoparticle hybrids with tunable electroactivity and enhanced durability for methanol electrooxidation and oxygen reduction reaction

Polypyrrole nanotubes (PPyNTs)/PtAu alloy nanoparticle (NP) hybrids were synthesized in gram-scale by using covalently attached imidazolium moieties as a linker. The approach involves the surface functionalization of PPyNTs with pendant imidazolium moieties (PPyNT-Im), anion-exchange with Pt and Au precursors, and followed by the reduction of metal ions to produce the PtAu alloy NPs on the surface of PPyNTs. X-ray diffraction (XRD), X-ray photoelectron spectroscopy (XPS), high-angle annular dark-field scanning transmission electron microscopy (HAADF-STEM), and elemental mapping showed that both Pt and Au were atomically distributed in the PtAu alloy NPs without phase segregation. The composition of the PtAu alloy NPs can be simply controlled by adjusting the feed ratio in the metal precursor solution. The electrocatalytic properties of prepared PPyNT-Im-PtxAuy (the suffixes x and y represent the relative molar ratio of Pt and Au in the feed, respectively) NP hybrids were determined by the composition of alloy NPs. The Pt-rich NP hybrids, PPyNT-Im-Pt8Au2, showed highly electrocatalytic activity and stability toward the methanol oxidation in both acidic and alkaline solutions, whereas the Au-rich NP hybrids, PPyNT-Im-Pt2Au8, showed an enhanced catalytic activity and durability upon oxygen reduction. The present study provided a simple and effective approach for the preparation of PtAu alloy catalysts with controllable composition for high-performance fuel cells and electrochemical sensors.