Size‐Controllable Synthesis of Trimetallic RhPdPt Island‐Shaped Nanoalloys with Enhanced Electrocatalytic Performance for Ethanol Oxidation in Alkaline Medium

Size‐controllable, high‐yield, island‐shaped RhPdPt trimetallic nanocrystals with sub‐2.0 nm islands have been successfully synthesized through a facile aqueous solution approach. The results of X‐ray diffraction (XRD), energy‐dispersive X‐ray (EDX) line scanning and elemental mapping analysis showed the as‐synthesized RhPdPt nanocrystals are alloy structures. These island‐shaped RhPdPt trimetallic nanoalloys showed a composition‐dependent electrocatalytic performance for ethanol oxidation in alkaline medium. Due to the special structure and intermetallic synergies, the Rh₁₀Pd₄₀Pt₅₀ nanoalloys exhibited an enhanced catalytic activity and durability relative to island‐shaped Pd₅₀Pt₅₀ bimetallic nanoalloys and commercial Pt black. The peak current density for Rh₁₀Pd₄₀Pt₅₀ nanoalloys was 1.81 and 1.38 times that for commercial Pt black and Pd₅₀Pt₅₀ nanoalloys, respectively. In addition, the peak potential on Rh₁₀Pd₄₀Pt₅₀ nanoalloys decreased 42 mV relative to commercial Pt black and Pd₅₀Pt₅₀ nanoalloys.     

Carbon black supported PtCu nanoparticles derived from mix-phased Cu precursor for high-performanced oxygen reduction reaction in acid medium

Alloying high-cost Pt with transition metals has been considered as an effective route to synthesize the electrocatalysts with low Pt loading and excellent activity towards oxygen reduction reaction (ORR) under acid solution. The galvanic replacement method, as featured with efficiency and simplicity, is widely reported to produce Pt-based bimetallic alloys and thereby declare the significance of reductive transition metal precursor on the enhancement of ORR performance. Herein, mix-phased Cu−Cu₂O precursor was applied to prepare carbon black supported highly dispersed PtCu alloy nanoparticles (PtCu/C). The proper Cu−Cu₂O ratios can exactly facilitate the generation of small sized PtCu alloy nanoparticles with regulated bimetallic content. Meanwhile, the Cu₂O phase is revealed to benefit the electron transfer from Pt to Cu and thus improve the intrinsic activity of Pt active sites. And the metallic Cu can favor the promotion of electrochemical active surface area. Consequently, the as-prepared PtCu/C behaves impressive ORR activity with half-wave potential of 0.88 V (vs. RHE) and mass activity of 0.49 A cm⁻² mg_Pt⁻¹ at 0.8 V, which is 9.8 times of commercial Pt/C catalysts. Our work will offer helpful advices for the development and regulation of novel Pt-based alloy materials towards diverse electrocatalysis.     

凹形树突状PtCu纳米催化剂的合成及对甲醇的电催化

以邻苯二胺为表面活性剂,通过水热釜法一步制备凹形树突状PtCu双金属纳米催化剂(PtCu NCDs)。PtCu NCDs在电催化甲醇氧化(MOR)的应用中表现出非常高的活性和很强的抗有毒中间体作用。PtCu NCDs对于甲醇氧化的质量活性为(0.53 A·mg^-1 Pt)是商业Pt/C(0.26 A·mg^-1 Pt)的2.04倍。从比活性的CV曲线图对比发现PtCu NCDs(1.07 mA·cm^-2)是商业Pt/C(0.55 mA·cm^-2)的1.95倍。而且,PtCu NCDs(2.76)比商业Pt/C催化剂(1.02)表现出更高的I_f/I_b比值。这些优异的电催化活性可能归功于PtCu NCDs特殊的凹形树突状形貌。     

凹形树突状PtCu纳米催化剂的合成及对甲醇电催化的研究

以邻苯二胺为表面活性剂,通过水热釜法一步制备凹形树突状PtCu双金属纳米催化剂(PtCu NCDs)。PtCu NCDs在电催化甲醇氧化(MOR)的应用中表现出非常高的活性和很强的抗有毒中间体作用。PtCu NCDs对于甲醇氧化的质量活性为(0.53 A·mg^-1 Pt)是商业Pt/C(0.26 A·mg^-1 Pt)的2.04倍。从比活性的CV曲线图对比发现PtCu NCDs(1.07 mA·cm^-2)是商业Pt/C(0.55 mA·cm^-2)的1.95倍。而且,PtCu NCDs(2.76)比商业Pt/C催化剂(1.02)表现出更高的I_f/I_b比值。这些优异的电催化活性可能归功于PtCu NCDs特殊的凹形树突状形貌。     

Ethylene Glycol Electrooxidation Based on Pentangle‐Like PtCu Nanocatalysts

The research of active and stable electrocatalysts toward liquid‐fuel oxidation reaction is of great significance for the large‐scale commercialization of fuel cells. Although extensive efforts have been devoted to pursuing high‐performance nanocatalysts for fuel cells, both the high cost and sluggish reaction kinetics have been two major drawbacks that limited its commercial development. In this regard, we demonstrated a facile solvothermal method for the syntheses of an advanced class of PtCu nanocatalysts with a unique pentangle‐like shape. By combining the merits of a highly active surface area as well as the synergistic and electronic effects, the as‐prepared pentangle‐like Pt₃Cu nanocatalysts showed superior electrocatalytic activity towards ethylene glycol oxidation with a mass and specific activities of 5162.6 mA mg^?1 and 9.7 mA cm^?2, approximately 5.0 and 5.1 times higher than the commercial Pt/C, respectively. More significantly, the Pt₃Cu pentangle also showed excellent long‐term stability with less activity decay and negligible changes in structure after 500 cycles, indicating another class of anode catalysts for fuel cells and beyond.     

Implanting Atomic Dispersed Ru in PtNi Colloidal Nanocrystal Clusters for Efficient Catalytic Performance in Electro-oxidation of Liquid Fuels

Although PtRu alloy nanocatalysts have been certified to possess excellent electrocatalytic performance and CO-poisoning tolerance toward formic acid and methanol electro-oxidation, the unaffordable usages of ruthenium (Ru) and platinum (Pt) have greatly limited their widespread adoption. Here, a facile one-pot method is reported for implanting atomic dispersed Ru in PtNi colloidal nanocrystal clusters with different Ru/Pt/Ni molar ratios, greatly reducing the dosages of Pt and Ru, and further improving the catalytic performances for the electro-oxidation of formic acid and methanol. Through simple control of the amount of Ni(acac)₂ precursor, trimetallic Ru_0.3Pt_70.5Ni_29.2, Ru_0.6Pt_55.9Ni_43.5, Ru_0.2Pt_77.3Ni_22.5, and Ru_0.9Pt_27.3Ni_71.8 colloidal nanocrystal clusters (CNCs) are obtained. In particular, the Ru_0.3Pt_70.5Ni_29.2 CNCs exhibit excellent specific activities for formic acid and methanol electro-oxidation, that is, 14.2 and 15.3 times higher, respectively, than those of the Pt/C catalyst. Moreover, the Ru_0.3Pt_70.5Ni_29.2 CNCs also possess better anti-CO-poisoning properties and diffusion ability than the other RuPtNi CNCs. The excellent formic acid and methanol electro-oxidation activities of RuPtNi CNCs are ascribed to the optimal ligand effects derived from the Pt, Ni, and atomic dispersed Ru atoms, which can improve the OH adsorption ability and further the anti-CO-poisoning capability. This research opens a new door for increasing the electro-oxidation properties of liquid fuels by using lower dosages of noble metals in Pt-based catalysts.     

Mesoporous PtCu Alloy Nanoparticles with Tunable Compositions and Particles Sizes Using Diblock Copolymer Micelle Templates

A simple, scalable route for the generation of mesoporous Rh particles by chemical reduction on self-assembled block-copolymer micelle templates was reported recently (Nat. Commun. 2017 , 8, 15581). Here, this concept is extended to generate mesoporous PtCu alloy nanoparticles through the same approach. The PtCu alloy particles possess high-surface-area nanoporous architectures and good chemical stability for applications in catalysis. Both the composition and diameter of the bimetallic PtCu nanoparticles can be controlled by adjusting the amount of precursor in the reaction, which affects the electrochemical properties of the material. The combination of the mesoporous structure with the synergistic bimetallic electronic effects of PtCu gives rise to enhanced activity for the catalytic oxidation of methanol compared with commercial Pt black.     

高CO耐性的金属间PtBi纳米片用于甲醇电氧化

我们通过热注入的方法制备了一种高CO耐性的金属间PtBi纳米片。所制备的金属间PtBi纳米片在甲醇氧化反应(MOR)中展现出优异的催化性能和良好的稳定性能,最大的质量活性高达4.09 A·mg_Pt^-1,接近商业Pt/C的3.2倍。计时电流-时间(I-t)稳定性测试之后,活性仅仅衰减5.7%,远低于商业Pt/C。CO吸附-脱附(CO-Stripping)曲线和循环伏安演变(CV-Evolution)曲线证实了金属间PtBi纳米片高的CO耐受性。     

高CO耐性的金属间PtBi纳米片用于甲醇电氧化

我们通过热注入的方法制备了一种高CO耐性的金属间PtBi纳米片。所制备的金属间PtBi纳米片在甲醇氧化反应(MOR)中展现出优异的催化性能和良好的稳定性能，最大的质量活性高达4.09 A·mg_Pt^-1，接近商业Pt/C的3.2倍。计时电流-时间(I-t)稳定性测试之后，活性仅仅衰减5.7%，远低于商业Pt/C。CO吸附-脱附(CO-Stripping)曲线和循环伏安演变(CV-Evolution)曲线证实了金属间PtBi纳米片高的CO耐受性。     

Ultrasmall and uniform Pt3Au clusters strongly suppress Ostwald ripening for efficient ethanol oxidation

Clean and uniform Pt₃Au clusters decorated on graphene (Pt₃Au@PDDA-G) with an average size as small as 2.1 nm were successfully synthesized, offering higher catalytic activity and stability toward ethanol oxidation than that of Pt₃Au@G and commercial Pt/C, respectively. The catalytic enhancement mechanism of Pt₃Au@PDDA-G was proposed and discussed, and this work demonstrated that the uniformly distributed Pt₃Au clusters could strongly suppress Ostwald ripening to retain their original crystals size and morphology for highly catalytic properties.     

Highly Branched Metal Alloy Networks with Superior Activities for the Methanol Oxidation Reaction

Three‐dimensional (3D) interconnected metal alloy nanostructures possess superior catalytic performance owing to their advantageous characteristics, including improved catalytic activity, corrosion resistance, and stability. Hierarchically structured Ni‐Cu alloys composed of 3D network‐like microscopic branches with nanoscopic dendritic feelers on each branch were crafted by a facile and efficient hydrogen evolution‐assisted electrodeposition approach. They were subsequently exploited for methanol electrooxidation in alkaline media. Among three hierarchically structured Ni‐Cu alloys with different Ni/Cu ratios (Ni_0.25Cu_0.75, Ni_0.50Cu_0.50, and Ni_0.75Cu_0.25), the Ni_0.75Cu_0.25 electrode exhibited the fastest electrochemical response and highest electrocatalytic activity toward methanol oxidation. The markedly enhanced performance of Ni_0.75Cu_0.25 eletrocatalyst can be attributed to its alloyed structure with the proper Ni/Cu ratio and a large number of active sites on the surface of hierarchical structures.     

Methanol activation catalyzed by Pt7, Pt3Cu4, and Cu7 clusters: A density functional theory investigation

Metal clusters were considered as excellent catalysts for methanol dissociation. In this work, two main decomposition mechanisms of methanol on Pt₇, Pt₃Cu₄, and Cu₇ clusters were investigated by the density functional theory. One was methanol direct dehydrogenation, and the other was non‐CO‐involved oxidation. Stable adsorption configurations, elementary reaction barriers, the potential energy surface (PES), and the charge analysis were elucidated. The results showed that on Pt₇ cluster, methanol was favorable for direct decomposition. On Pt₃Cu₄ and Cu₇ clusters, methanol was inclined to the pathway of non‐CO‐involved oxidation. All the transition‐state energies and the final‐state energies were related in a linear, including those for the clusters. The results may be useful for computational design and catalysts optimization.     

Oxidation of carbon monoxide and formic acid on bulk and nanosized Pt–Co alloys

Bulk Pt₃Co and nanosized Pt₃Co and PtCo alloys supported on high area carbon were investigated as the electrocatalysts for the CO_ads and HCOOH oxidation. Pt₃Co alloy with Co electrochemically leached from the surface (Pt skeleton) was employed to separate electronic from ensemble and bifunctional effects of Co. Cyclic voltammetry in 0.1 M HClO₄ showed reduced amount of adsorbed hydrogen on Pt sites on Pt₃Co alloy compared to pure Pt. However, no significant difference in hydrogen adsorption/desorption and Pt-oxide reduction features between Pt₃Co with Pt skeleton structure and bulk Pt was observed. The oxidation of CO_ads on Pt₃Co alloy commenced earlier than on Pt, but this effect on Pt₃Co with Pt skeleton structure was minor indicating that bifunctional mechanism is stronger than the electronic modification of Pt by Co. The HCOOH oxidation rate on Pt₃Co alloy was about seven times higher than on bulk Pt when the reaction rates were compared at 0.4 V, i.e., in the middle of the potential range for the HCOOH oxidation. Like in the case of CO_ads oxidation, Pt skeleton showed similar activity as bulk Pt indicating that the ensemble effect is responsible for the enhanced activity of Pt₃Co alloy toward HCOOH oxidation. The comparison of CO_ads and HCOOH oxidation on Pt₃Co/C and PtCo/C with the same reaction on Pt/C were qualitatively the same as on bulk materials.     

Bimetallic Cluster Provides a Higher Activity Electrocatalyst for Methanol Oxidation

The cluster complex Pt₂Ru₄(CO)₁₈ was used as a precursor to prepare a 60 wt% 1:2 Pt:Ru nanoparticles on carbon (PtRu/C) for use as an electrocatalyst for methanol oxidation. This bimetallic carbonyl cluster complex was found to provide smaller, more uniform bimetallic nanoparticle that exhibited higher electrocatalytic activity than a 60 wt% 1:1 Pt:Ru commercial catalyst from E-Tek. Using bimetallic cluster precursors simplifies the synthetic procedures by reducing the need for high temperature reduction and assures a more intimate mixing of the two different metals. Transmission electron microscopy (TEM) images of the catalyst obtained from the cluster precursor showed bimetallic nanoparticles having a narrow size range of 2–3 nm that were dispersed uniformly over the surface of the support. Images of the commercial catalyst showed particles 3–4 nm in diameter that tended to agglomerate near the edges of the carbon support particles. Cyclic voltammograms of methanol oxidation from the two catalysts showed significantly higher activity for the cluster-derived catalyst. The onset potential for methanol oxidation for the cluster-derived catalyst was approximately 170 mV lower than that of the commercial catalyst at 100 A/g Pt, and approximately 250 mV lower at 400 A/g Pt. ^* This report is dedicated to Prof. Günter Schmid on the occasion of his 70th birthday.     

Dealloying of Mesoporous PtCu Alloy Film for the Synthesis of Mesoporous Pt Films with High Electrocatalytic Activity

Mesoporous Pt film with highly electrocatalytic activity is successfully synthesized by dealloying of mesoporous PtCu alloy film prepared through electrochemical micelle assembly. The resulting mesoporous electrode exhibits high current density and superior stability toward the methanol oxidation reaction.     

2D Bi2WO6/MoS2 as a new photo-activated carrier for boosting electrocatalytic methanol oxidation with visible light illumination

In this paper, a new two-dimensional (2D)/2D composite of Bi₂WO₆/MoS₂ was facile synthesized, and then was used as supporting material for depositing Pt nanoparticles. The as-synthesized Pt-Bi₂WO₆/MoS₂ was extended into photo-assisted electrocatalytic oxidation of methanol, which is a model anode reaction for direct methanol fuel cell. Compare with traditional electrocatalytic process, Pt-Bi₂WO₆/MoS₂ displays 1.5 times enhanced electrocatalytic performance on methanol oxidation with assistance of visible light irradiation and 2.2 times for commercial Pt/C. Besides, from the results of chronoamperometric and chronopotentiometry experiments, the stability of Pt-Bi₂WO₆/MoS₂ electrode is clearly improved under visible light irradiation. The synergistic effects of photo- and electro-catalytic in the heterojunction of Pt-Bi₂WO₆/MoS₂ in favor of the above enhancement. This research gives more insights in the fields of photo-assisted traditional electrocatalytic application by constructing of semiconductor heterojunction carrier.     

Ultrafine PtRu Dilute Alloy Nanodendrites for Enhanced Electrocatalytic Methanol Oxidation

Dilute alloy nanostructures have been demonstrated to possess distinct catalytic properties. Noble-metal-induced reduction is one effective synthesis strategy to construct dilute alloys and modify the catalytic performance of the host metal. Herein, we report the synthesis of ultrafine PtRu dilute alloy nanodendrites (PtRu NDs, molar ratio Ru/Pt is 1:199) by the reduction of Ru^III ions induced by Pt metal. For the methanol oxidation reaction, PtRu NDs showed the highest forward peak current density (2.66 mA cm⁻², 1.14 A/mg_Pt) and the best stability compared to those of pure-Pt nanodendrites (pure-Pt NDs), commercial PtRu/C and commercial Pt/C catalysts.     

Combinatorial screening of ternary Pt–Ni–Cr catalysts for methanol electro-oxidation

Methanol electro-oxidation activity of ternary Pt–Ni–Cr system was studied by using a combinatorial screening method. A Pt–Ni–Cr thin-film library was prepared by sputtering and quickly characterized by a multichannel multielectrode analyzer. Among the 63 different composition thin-film catalysts, Pt₂₈Ni₃₆Cr₃₆ showed the highest methanol electro-oxidation activity and good stability. This new composition was also studied in its powder form by synthesizing and characterizing Pt₂₈Ni₃₆Cr₃₆/C catalyst. In chronoamperometry testing, the Pt₂₈Ni₃₆Cr₃₆/C catalyst exhibited “decay-free” behavior during 600 s operation by keeping its current density up to 97.1% of its peak current density, while the current densities of Pt/C and Pt₅₀Ru₅₀/C catalysts decreased to 14.0% and 60.3% of their peak current densities, respectively. At 600 s operation, current density of the Pt₂₈Ni₃₆Cr₃₆/C catalyst was 23.8 A g_{noble metal}⁻¹, while that of those of the Pt/C and Pt₅₀Ru₅₀/C catalysts were 2.74 and 18.8 A g_{noble metal}⁻¹, respectively.     

One-pot fabrication of single-crystalline octahedral Pd-Pt nanocrystals with enhanced electrocatalytic activity for methanol oxidation

This study reports the synthesis of octahedral Pd-Pt bimetallic alloy nanocrystals through a facile, one-pot, templateless, and seedless hydrothermal method in the presence of glucose and hexadecyl trimethyl ammonium bromide. The morphologies, compositions, and structures of the Pd-Pt nanocrystals were fully characterized by various physical techniques, thereby demonstrating their highly alloying octahedral nanostructures. The formation or growth mechanism of the Pd-Pt bimetallic alloy nanocrystals was explored and is discussed here based on the experimental observations. In addition, the synthesized Pd-Pt nanocrystals were applied to the methanol oxidation reaction (MOR) in alkaline media, which proved that the as-prepared catalysts exhibit enhanced electrocatalytic activity for MOR. Pd₁Pt₃ exhibited the best stability and durability, and its mass activity was 3.4 and 5.2 times greater than those of Pt black and Pd black catalysts, respectively. The facile synthetic process and excellent catalytic performance of the as-prepared catalysts demonstrate that they have the potential to be used in direct methanol fuel cell techniques.     

碳黑预处理对Pt/C催化剂对甲醇氧化电催化活性的影响

直接甲醇燃料电池(DMFC)由于具有较多的优点而受到广泛的关注. 但是碳载Pt (Pt/C)阳极催化剂电催化活性低是限制其应用的一个主要问题. 为了提高Pt/C催化剂对甲醇氧化的电催化性能, 分别用CO₂, 空气, H₂O₂或HNO₃对常用作为载体的Vulcan XC-72碳黑进行预处理. 结果表明, 在用CO₂, 空气, HNO₃, H₂O₂处理的及未处理的碳黑作载体制得的Pt/C催化剂电极上, 甲醇氧化峰的峰电流密度顺序为39, 33, 32, 20和18 mA•cm^－2, 表明用CO₂处理的碳载体制备的Pt/C催化剂对甲醇氧化有最好的电催化活性和稳定性. 其主要原因是用CO₂处理能减少碳黑表面的含氧基团和增加石墨化程度, 而使碳黑的电阻降低及Pt粒子在碳黑上的分散性变好.