Cold plasma treatment of catalytic materials: a review

Abstract

Catalytic materials play important roles in chemical, energy, and environmental fields. The exhaustion of fossil fuels and the resulting deteriorative environment have become worldwide problems to be solved urgently. Therefore, treatment of catalytic materials by a green process is required for a sustainable future, and the atom efficiency of the catalytic materials should be improved at the same time. Cold plasma is rich in high-energy electrons and active species, and the gas temperature can be close to room temperature. It has been proved to be a fast, facile, and environmentally friendly novel method for treating catalytic materials, and has aroused increasing research interests. First, plasma treatment can achieve the reduction, deposition, combination, and decomposition of active components during the preparation of catalytic materials. The fast, low-temperature plasma process with a strong electric field in it leads to different types of nucleation and crystal growth compared to conventional thermal methods. Correspondingly, the synthesized catalytic materials generally possess smaller particle sizes and controlled structure depending on the plasma processing parameters and the materials to be treated, which can enhance their activity and stability. Second, plasma treatment can achieve the modification, doping, etching, and exfoliation of the catalytic materials, which can tune the surface properties and electronic structures of the catalytic materials to expose more active sites. Third, plasma treatment can regenerate deactivated catalytic materials by removing the carbon deposits or other poisons, and reconstruction of the destroyed structure. This work reviews the current status of research on cold plasma treatment of catalytic materials. The focus is on physical and chemical processes during plasma processing, the processing mechanism of the catalytic materials, as well as the future challenges in this filed.

Structural effect of Ni/TiO2 on CO methanation: improved activity and enhanced stability

“…The same phenomenon has also been observed with the other plasma-prepared Ni catalysts, supported by ZrO 2 , 4 SiO 2 16,30,37 and others. 27,28 These two samples have clear lattice fringes of anatase (101), which is consistent with the XRD analyses.…”

Plasma modified and tailored defective electrocatalysts for water electrolysis and hydrogen fuel cells

“…In the fabrication of nanocatalysts, the plasma conditions are different from those in conventional ones because electrons move faster than ions and particles consequently creating a plasma sheath around the sample 77 . As a result, an equilibrium is created to control the dynamics of positive ions and electrons across the plasma sheath which can be regulated to produce the desirable modification effects 54,56,78,79 . For example, vertical transition metal dichalcogenide nanosheets and carbon nanotubes (CNT) can be prepared on different types of substrates to form electrocatalysts, supercapacitors, and batteries 80,81 .…”

“…For example, vertical transition metal dichalcogenide nanosheets and carbon nanotubes (CNT) can be prepared on different types of substrates to form electrocatalysts, supercapacitors, and batteries 80,81 . Some transition metal oxides, hydroxides, perovskites, phosphates, chalcogenides, and nitrides have been synthesized efficiently 54,56,57,76,78,79 . Plasma‐enhanced chemical vapor deposition (CVD), physical vapor deposition (PVD), and atomic layer deposition (ALD) are common methods for nano manufacturing, and compared to conventional thermal deposition, the conditions are milder due to the lower nucleation barrier rendered by the plasma 82,83 .…”

“…77 As a result, an equilibrium is created to control the dynamics of positive ions and electrons across the plasma sheath which can be regulated to produce the desirable modification effects. 54,56,78,79 For example, vertical transition metal dichalcogenide nanosheets and carbon nanotubes (CNT) can be prepared on different types of substrates to form electrocatalysts, supercapacitors, and batteries. 80,81 Some transition metal oxides, hydroxides, perovskites, phosphates, chalcogenides, and nitrides have been synthesized efficiently.…”

Reusable citric acid modified V/AC catalyst prepared by dielectric barrier discharge for hydroxylation of benzene to phenol

“…Dielectric barrier discharge (DBD) plasma has been widely applied in surface modification and the preparation of materials owing to its advantages in reducing energy consumption and enhancing the chemical and physical properties of the catalysts. 22–26 The surface modification only changes the outermost layer of the material, without altering the bulk. 27 DBD plasma is composed of a large number of active particles, such as electrons, atoms, ions, and free radicals.…”