Polyurethane foam: A novel support for metal oxide packing used in the non-thermal plasma decomposition of CO2

Electrochemical Nitrate-to-Ammonia Conversion Enabled by Carbon-Decoration of Ni─GaOOH Synthesized via Plasma-Assisted CO2 Reduction

The release of nitrates into the environment leads to contaminated soil and water that poses a health risk to humans and animals. Due to the transition to renewable energy-based technologies, an electrochemical approach is an emerging option that can selectively produce valuable ammonia from nitrate sources. However, traditional metal-based electrocatalysts often suffer from low nitrate adsorption that reduces NH3  production rates. Here, a Ni-GaOOH-C/Ga electrocatalyst for electrochemical nitrate conversion into NH3 is synthesized via a low energy atmospheric-pressure plasma process that reduces CO2  into highly dispersed activated carbon on dispersed Ni─GaOOH particles produced from a liquid metal Ga─Ni alloy precursor. Nitrate conversion rates of up to 26.3 µg h-1  mg-1 cat  are achieved with good stability of up to 20 h. Critically, the presence of carbon centers is central to improved performance where both Ni─C and NiO─C interfaces act as NO3-  adsorption and reduction centers during the reaction. Density functional theory (DFT) calculations indicate that the NiO─C and Ni─C reaction sites reduce the Gibbs free energy required for NO3-  reduction to NH3  compared to NiO and Ni. Importantly, catalysts without carbon centers do not produce NH3 , emphasizing the unique effects of incorporating carbon nanoparticles into the electrocatalyst.

Recent advances in energy efficiency optimization methods for plasma CO2 conversion

Efforts to develop efficient methods for converting carbon dioxide (CO2) have drawn mounting interest due to incremental concerns over carbon emissions. Non-thermal plasma (NTP) technology has shown promise in this regard by producing numerous reactive substances at relatively low temperatures. However, an analysis of relevant literature reveals an underwhelming level of overall energy efficiency for this technology and an insufficient level of attention being paid to it. It is crucial to put forward more effective energy-saving schemes based on a comprehensive analysis of past research results to promote sustained development. This review highlights the latest advances in pertinent energy efficiency optimization studies and outlines state-of-the-art methods. In terms of energy efficiency optimization for plasma CO2 conversion, a comparison is made among different research results in four aspects as follows. Specifically, this study analyzes reactor structure optimization in terms of discharge characteristic, flow field, and plasma contact area; discusses pathways of heat transfer optimization to suppress the competing reaction; and explores catalyst optimization in terms of active sites, calcination temperature, and product selectivity; examines the potential of utilizing solar energy for clean energy applications. The analysis of energy efficiency data indicates an overall improvement when the aforementioned optimization measures are applied, which is essential to validate the effectiveness of each method. Finally, this paper discusses the potential difficulties and future research areas of NTP technology. Urgent further research is imperative on energy efficiency optimization methods for potential large-scale industrial applications in the future.

Cu/ACF adsorbent modified by non-thermal plasma for simultaneous adsorption-oxidation of H2S and PH3

Non-thermal plasma (NTP) surface modification technology is a new method to control the surface properties of materials, which has been widely used in the field of environmental protection because of its short action time, simple process and no pollution. In this study, Cu/ACF (activated carbon fiber loaded with copper) adsorbent was modified with NTP to remove H₂S and PH₃ simultaneously under low temperature and micro-oxygen condition. Meanwhile, the effects of different modified atmosphere (air, N₂ and NH₃), specific energy input (0-13 J/mL) and modification time (0-30 min) on the removal of H₂S and PH₃ were investigated. Performance test results indicated that under the same reaction conditions, the adsorbent modified by NH₃ plasma with 5 J/mL for 10 min had the best removal effect on H₂S and PH₃. CO₂ temperature-programmed desorption and X-ray photoelectron spectroscopy (XPS) analyzes showed that NH₃ plasma modification could introduce amino functional groups on the surface of the adsorbent, and increase the types and number of alkaline sites on the surface. Brunauer-Emmett-Teller and scanning electron microscopy showed that NH₃ plasma modification did not significantly change the pore size structure of the adsorbent, but more active components were evenly exposed to the surface, thus improving the adsorption performance. In addition, X-ray diffraction and XPS analysis indicated that the consumption of active components (Cu and Cu₂O) and the accumulation of sulfate and phosphate on the surface and inner pores of the adsorbent are the main reasons for the deactivation of the adsorbent.

Metal Oxides as Catalyst/Supporter for CO2 Capture and Conversion, Review

Various carbon dioxide (CO2) capture materials and processes have been developed in recent years. The absorption-based capturing process is the most significant among other processes, which is widely recognized because of its effectiveness. CO2 can be used as a feedstock for the production of valuable chemicals, which will assist in alleviating the issues caused by excessive CO2 levels in the atmosphere. However, the interaction of carbon dioxide with other substances is laborious because carbon dioxide is dynamically relatively stable. Therefore, there is a need to develop types of catalysts that can break the bond in CO2 and thus be used as feedstock to produce materials of economic value. Metal oxide-based processes that convert carbon dioxide into other compounds have recently attracted attention. Metal oxides play a pivotal role in CO2 hydrogenation, as they provide additional advantages, such as selectivity and energy efficiency. This review provides an overview of the types of metal oxides and their use for carbon dioxide adsorption and conversion applications, allowing researchers to take advantage of this information in order to develop new catalysts or methods for preparing catalysts to obtain materials of economic value.

Global opportunities and challenges on net-zero CO2 emissions towards a sustainable future

Artistic representation of CO2 emissions from various sources into the atmosphere, and its consequence on the global climatic conditions.