Cold Plasma Synthesis and Testing of NiOX-Based Thin-Film Catalysts for CO2 Methanation

Abstract

An essential problem in managing CO2 and transforming it into methane as a useful fuel is the quest for adequately efficient and cheap catalysts. Another condition is imposed by the new designs of structured reactors, which require catalysts in the form of the thinnest possible films. The aim of this work was to produce Ni-based thin-film catalysts by the cold plasma deposition method (PECVD) from a volatile metal complex (Ni(CO)4) and to study their structure and catalytic properties in the CO2 methanation process. We tested three basic types of films: as-deposited, calcined in Ar, and calcined in air. The nanostructure and molecular structure of the films were investigated by electron microscopy (SEM), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). The catalytic activity was evaluated in the methanation process (CO2 + H2), which was performed in a tubular reactor operating in the temperature range of 300–400 °C. The films calcined in air showed the highest activity in this process but behaved unstably. However, their regeneration by recalcination in air restored the initial catalytic activity. An important conclusion emerged from the obtained results, namely that the active phase in the tested films is Ni3+ (most likely in the form of Ni2O3), contrary to the common opinion that this phase is metallic Ni0. In our case, Ni0 quenches the catalytic activity.

In situ formation of Ni(CO)4 contaminant during IR analyses using a metal-containing reaction cell

“…In spite of its toxicity, Ni(CO) 4 is routinely used in laboratories to prepare organometallic complexes 6 and thin films. 7 The description of the Mond process emphasizes that Ni(CO) 4 may form whenever Ni-based catalysts are reduced and exposed to CO at temperatures below 200 °C. In fact, Hadjiivanov and co-workers 8 showed that Ni(CO) 4 formed already at −188 °C when SiO 2 -supported Ni nanoparticles (about 4 nm in diameter) were exposed to 0.2 kPa of CO.…”

“…In spite of its toxicity, Ni(CO) 4 is routinely used in laboratories to prepare organometallic complexes 6 and thin films. 7…”

Cold atmospheric microwave plasma (CAMP) stimulates dermal papilla cell proliferation by inducing β-catenin signaling

“…Compared to other types of plasma, the CAMP has a higher electron temperature than plasma obtained by the indirect and high-frequency discharge. Due to the high temperature of the electrons, there is also a higher dissociation and ionization degree, which is reflected in a wide range of uses of this type of discharge, including wound healing 35 , surface decontamination of fruits 36 , or deposition of thin layers 37 . Our finding suggested that CAMP has a therapeutic effect on stimulating hair regrowth through Akt/β-catenin signaling, YAP/TAZ Hippo pathway, and USP47-associated β-catenin deubiquitination in hDPCs (Fig.…”

Perspective Applications of Plasma-Deposited Thin Film Nanocatalysts on Structured Supports: From CO2 Capture to Wastewater Treatment

“…The meshes were pre-calcined in air at 900 °C for 48 hours. The finer mesh, denoted as A, was employed in processes related to CO 2 conversion [45,48,50,51] while the looser one (B) was used in catalytic ozonation of wastewater [49]. Figure 3 provides an example of plasma-fabricated thin-film catalysts based on CoO x on the applied support.…”