Facile preparation of three-dimensional porous Pd–Au films and their electrocatalytic activity for methanol oxidation

Research status of volatile organic compound (VOC) removal technology and prospect of new strategies: a review

As an important component of air pollution, the efficient removal of volatile organic compounds (VOCs) is one of the most important challenges in the world. VOCs are harmful to the environment and human health. This review systematically introduced the main VOC control technologies and research hotspots in recent years, and expanded the description of electrocatalytic oxidation technology and bimetallic catalytic removal technology. Based on a three-dimensional electrode reactor, the theoretical design of a VOC removal control technology using bimetallic three-dimensional particle electrode electrocatalytic oxidation was proposed for the first time. The future research focus of this method was analyzed, and the importance of in-depth exploration of the catalytic performance of particle electrodes and the system reaction mechanism was emphasized. This review provides a new idea for using clean and efficient methods to remove VOCs.

A study on the selective catalytic reduction of NO x by ammonia on sulphated iron-based catalysts

A series of sulphated iron-based catalysts was prepared via an impregnation method by changing the loading content of Fe³⁺ and SO₄²⁻ on ZrO₂, and their performance in the selective catalytic reduction (SCR) of NO_x by ammonia was investigated. The NO_x conversion exhibited large differences among the sulphated iron-based catalysts. To explore the synergistic mechanism of iron and sulphates, XRD, BET, H₂-TPR, XPS, TPD and in situ DRIFTS were used to characterize the catalysts, and it was found that among all the catalysts, the NO_x conversion by Fe₂SZr was greater than 90% at 350–450 °C. The results indicated that the interaction between Fe³⁺ and SO₄²⁻ can have an effect on the redox ability, acid sites, and adsorption of NO_x and NH₃. With an increase in the content of Fe³⁺, the redox activity of the catalyst and the adsorption of ammonia improved at medium and low temperatures. However, at higher temperatures, an increase in Fe³⁺ led to a decrease in the conversion of NO_x due to the enhanced oxidation of NH₃. At medium and low temperatures, an increase in the content of SO₄²⁻ decreased the concentration of Fe³⁺ on the surface of the catalyst and inhibited the adsorption of NO_x and NH₃. The addition of SO₄²⁻ reduced the redox activity of the catalyst and inhibited the oxidation reaction of NH₃, which follows the Eley–Rideal mechanism at high temperatures, further enhancing the SCR activity of the Fe_xS_yZr catalyst.

The roles of Fe³⁺ and SO₄²⁻ are different at low and high temperatures due to their interaction. It is the appropriate contents of Fe³⁺ and SO₄²⁻ that can result in high NH₃-SCR activity at varying temperatures.

Ethanol electrooxidation on high-performance mesoporous ZnFe2O4-supported palladium nanoparticles

As a catalyst for the electrooxidation of ethanol, a well-dispersed mesoporous ZnFe₂O₄ powder (ZnFe₂O₄MP) as a support for Pd nanoparticles (PdNPs) was fabricated using solution combustion synthesis, which is an easy and environmentally friendly method.

Some Aspects on the One-Pot Fabrication of Nanoporous Pd-Au Surface Films by Electrochemical Alloying/Dealloying of (Pd-Au)-Zn from a Chlorozincate Ionic Liquid

The high thermal stability of the Lewis acidic ZnCl₂-1-ethyl-3-methylimidazolium chloride ionic liquid enables the in situ fabrication of hierarchical nanostructured Pd-Au bimetallic surfaces via electrochemical alloying/dealloying of (PdAu)Zn on PdAu substrate in the ionic liquid. Nanostructured PdAu samples that consist of patterned cracks and ligaments are fabricated by using potential cycling method and constant-potential electrolysis method, respectively. The effects of working temperature and amounts of the deposited Zn on the morphology of the dealloyed (PdAu)Zn nanostructure are examined. The formation of the hierarchical nanostructure is a compromise between high-surface-diffusive Au and low-surface-diffusive Pd. Whereas Au in the alloy promotes the nanostructure formation, Pd in the PdAu nanostructure protects this material from coarsening. Compared with the plain PdAu, the nanostructured PdAu surface prepared at 150 °C exhibits a significantly higher active surface area and a high capability for the electro-oxidation of glucose.

Simple fabrication of pineapple root-like palladium-gold catalysts as the high-efficiency cathode in direct peroxide-peroxide fuel cells

Pd-Au/TiC electrodes with various three-dimensional structures are obtained by the pulsed potential electro-deposition in PdCl₂/HAuCl₄ electrolytes. The morphologies of Pd-Au/TiC composite catalysts are significantly dependent on the component of deposited solutions. The surface appearance of Pd-Au catalysts changes from rime-shaped structure, to feather-like construction, then to pineapple root-like structure and finally to flower-like configuration with the increase of PdCl₂ content in electrolytes. These particular three-dimensional structures may be very suitable for H₂O₂ electro-reduction, which assures a high utilization of Pd-Au catalysts and provides a large specific surface area. The electro-catalytic activities of H₂O₂ reduction on the Pd-Au/TiC electrodes improve as increasing the Pd content in Pd-Au alloy catalysts. The pineapple root-like Pd₅Au₁/TiC electrode reveals remarkably excellent electrochemical property and desirable stability for catalyzing H₂O₂ reduction in acid media. The direct peroxide-peroxide fuel cells with a 10 cm³ min^-1 flow rate display the open circuit voltage (OCV) of 0.85V and the peak power density of 56.5mWcm^-2 at 155mAcm^-2 with desirable cell stability, which is much higher than those previously reported.