Pt–Cu alloy with high density of surface Pt defects for efficient catalysis of breaking C–C bond in ethanol

Ultrafast synthesis of efficient TS-PtCoCu/CNTs composite with high feed-to-product conversion rate by Joule heating for electrocatalytic oxidation of ethanol

Due to the challenges involved in achieving high metal load, uniform metal dispersion and nanosized metal particles simultaneously, it is difficult to develop a simple protocol for the rapid and efficient synthesis of Pt-based composites for electrocatalytic ethanol oxidation reaction (EOR). In this study, a facile ultrafast thermal shock strategy via Joule heating was applied to fabricate a series of PtCoCu ternary nanoalloys decorated carbon nanotube composites (TS-PtCoCu/CNTs), without the need for a reducing agent or surfactant. The TS-PtCoCu/CNTs with optimal Pt content (∼15 %) exhibited excellent EOR activity, with mass and specific activity of 3.58 A mgPt-1 and 5.79 mA cm-2, respectively, which are 3.8 and 13.5 times higher than those of Pt/C. Compared with the control prepared through the traditional furnace annealing, the catalyst also showed excellent activity and stability. DFT calculations revealed that the TS-PtCoCu/CNTs possesses a downshifted d-band center, weakened CO adsorption and higher OH affinity compared with monometallic Pt, all of which lead to the preferred C1 pathway for EOR. This study demonstrates an ultrafast construction of a highly efficient Pt-Co-Cu ternary catalyst for EOR. Additionally, it provides insights into the reaction mechanism based on structural characterization, electrochemical characterization, and theoretical calculations.

Study on ethanol electro-oxidation over a carbon-supported Pt-Cu alloy catalyst by pinhole on-line electrochemical mass spectrometry

A carbon supported Pt-Cu electrocatalyst was synthesized by the microwave-polyol method following acid-treatment and physically characterized by different techniques including X-ray diffraction (XRD) and transmission electron microscopy (TEM). Both potentiodynamic and potentiostatic measurements with pinhole on-line electrochemical mass spectrometry were carried out to study the electrocatalytic activity and reaction intermediates of Pt/C and Pt-Cu/C electrocatalysts during the ethanol oxidation reaction. The results of potentiodynamic and potentiostatic measurements showed that the Pt-Cu/C electrocatalyst has higher ethanol oxidation efficiency and incomplete ethanol oxidation to acetaldehyde and acetic acid prevails under the given conditions. After calibration of the m/z = 44 mass signal, the CO₂ current efficiencies on Pt/C and PtCu-3/C were ∼7% and ∼12%, respectively, which reveal that the presence of copper enhances the complete ethanol oxidation to CO₂.

One-Pot Synthesis of Pt High Index Facets Catalysts for Electrocatalytic Oxidation of Ethanol

Direct ethanol fuel cell (DEFC) has attracted wide attention due to its wide range of fuel sources, cleanliness, and high efficiency. However, the problems of low catalytic efficiency and poor catalyst stability still exist in DEFC catalysts, which restrict its rapid development. With chloroplatinic acid (H₂PtCl₆·6H₂O) as the precursor, Polyvinylpyrrolidone (PVP) plays the role of surfactant, stabilizer, and reducing agent in the experiment. Glycine is the surface control agent and co-reducing agent. Pt high-index facets nanocatalyst was prepared with the one-pot hydrothermal method by adjusting the amount of PVP and glycine. X-Ray Diffraction (XRD), transmission electron microscope (TEM), and scanning electron microscope (SEM) were used to characterize the micro-structure of the nanocatalyst, and the influence of PVP and glycine on the synthesis of high-index facets catalyst was studied. The electrocatalytic performance of the catalyst was tested with an electrochemical workstation, and it was found that the performance of the prepared catalyst was better than that of the commercial catalyst. When the mass ratio of PVP and Pt was 50:1 and the molar ratio of glycine and Pt was 24:1, Pt nanocatalysts with {310}, {520} and {830} high exponential facets were prepared. The electrochemical test results showed that the peak current density of ethanol oxidation was 2.194 m²/g, and the steady-state current density was 0.241 mA/cm², which was 5.7 times higher than that of commercial catalyst. The results of this paper show that due to the defects such as steps and kinks on the surface of the high-index facets, the active sites are increased, thus showing excellent electrocatalytic performance. This study provides a theoretical basis for the development and commercial application of high index facets nanocatalysts.

Promoting the Electrocatalytic Ethanol Oxidation Activity of Pt by Alloying with Cu

The development and commercialization of direct ethanol fuel cells requires active and durable electro-catalysts towards the ethanol oxidation reactions (EOR). Rational composition and morphology control of Pt-based alloy nanocrystals can not only enhance their EOR reactivity but also reduce the consumption of precious Pt. Herein, PtCu nanocubes (NCs)/CB enclosed by well-defined (100) facets were prepared by solution synthesis, exhibiting much higher mass activity (4.96 A mgPt−1) than PtCu nanoparticles (NPs)/CB with irregular shapes (3.26 A mgPt−1) and commercial Pt/C (1.67 A mgPt−1). CO stripping and in situ Fourier transform infrared spectroscopy (FTIR) experiments indicate that the alloying of Cu enhanced the adsorption of ethanol, accelerated the subsequent oxidation of intermediate species, and increased the resistance to CO poisoning of PtCu NCs/CB, as compared with commercial Pt/C. Therefore, alloying Pt with earth-abundant Cu under rational composition and surface control can optimize its surface and electronic structures and represents a promising strategy to promote the performance of electro-catalysts while reduce the use of precious metals.

Defect-Rich, Highly Porous PtAg Nanoflowers with Superior Anti-Poisoning Ability for Efficient Methanol Oxidation Reaction

The design of efficient and sustainable Pt-based catalysts is the key to the development of direct methanol fuel cells. However, most Pt-based catalysts still exhibit disadvantages including unsatisfied catalytic activity and serious CO poisoning in the methanol oxidation reaction (MOR). Herein, highly porous PtAg nanoflowers (NFs) with rich defects are synthesized by using liquid reduction combining chemical etching. It is demonstrated that the proportion of precursors determines the inhomogeneity of alloy elements, and the strong corrosiveness of nitric acid to silver leads to the eventual porous flower-like structure. Impressively, the optimal etched Pt₁ Ag₂ NFs have the mixed defects of surface steps, dislocations, and bulk holes, and their mass activity (1136 mA mg_Pt^-1 ) is 2.6 times higher than that of commercial Pt/C catalysts, while the ratio of forward and backward peak current density (I_f /I_b ) can reach 3.2, exhibiting an excellent anti-poisoning ability. Density functional theory calculations further verify their high anti-poison properties from both an adsorption and an oxidation perspective of CO intermediate. The introduction of Ag makes it easier for CO to be oxidized and removed. This study provides a facile approach to prepare rich defects and porous alloy with excellent MOR performance and superior anti-poisoning ability.

Pt–Cu nanoalloy catalysts: compositional dependence and selectivity for direct electrochemical oxidation of formic acid

A PtCu3 nanoalloy catalyst showed much enhanced catalytic activity for the direct electrochemical oxidation of formic acid compared to a commercial platinum catalyst.

Pt Nanoparticles Densely Coated on SnO2-Covered Multiwalled Carbon Nanotubes with Excellent Electrocatalytic Activity and Stability for Methanol Oxidation

A new electrocatalyst exhibiting enhanced activity and stability is designed from SnO₂-covered multiwalled carbon nanotubes coated with 85 wt % ratio Pt nanoparticles (NPs). This catalyst showed a mass activity 6.2 times as active as that of the commercial Pt/C for methanol oxidation, owing to the unique one-dimensional structure. Moreover, the durability and antipoisoning ability were also improved greatly. The enhanced intrinsic performance was ascribed to the densely connected networks of Pt NPs on the SnO₂ NPs.