Electrochemical reduction of CO2: a review of cobalt based catalysts for carbon dioxide conversion to fuels

Electrochemical CO2 reduction reaction (CO2RR) provides a promising approach to curbing harmful emissions contributing to global warming. However, several challenges hinder the commercialization of this technology, including high overpotentials, electrode instability, and low Faradic efficiencies of desirable products. Several materials have been developed to overcome these challenges. This mini-review discusses the recent performance of various cobalt (Co) electrocatalysts, including Co-single atom, Co-multi metals, Co-complexes, Co-based metal–organic frameworks (MOFs), Co-based covalent organic frameworks (COFs), Co-nitrides, and Co-oxides. These materials are reviewed with respect to their stability of facilitating CO2 conversion to valuable products, and a summary of the current literature is highlighted, along with future perspectives for the development of efficient CO2RR

Capture and Electrochemical Reduction of Carbon Dioxide to Value-added Material

The atmospheric concentration of anthropogenic greenhouse gases (GHGs) has increased substantially in the past 50 years, particularly in recent years. In response, interest in CO2 capture technologies and methodologies to reduce it to valuable synthetic building blocks, such as carbon monoxide (CO), methanol (CH3OH) and methane (CH4), has increased. Although proposing to tackle the climate issue with current carbon capture and storage (CCS) technologies is unrealistic, chemical utilization of CO2 has great potential. Controlled and selective electrochemical CO2 reduction to fuel from renewable energy, such as electricity, is a promising approach to remove and utilize CO2 from air. Electrochemical CO2 reduction reactions (CO2RRs) are among the most promising techniques for this purpose due to their simple operation and environmental economy. To achieve a system viable for industrial implementation, thoughtful design of the electrochemical cell and the molecular catalysts are both important. This body of work demonstrates a wide range of potential applications for CO2 capture and utilization. Strategies involving CO2 capture and its reduction are described and systematically evaluated in different electrolyzer setups, and a series of new catalysts sporting tunable features fit for both homogeneous and heterogeneous applications are reported herein. Successful reduction of CO2 to several gaseous products, including CO, CH4 and a CH3OH liquid product, were achieved using metallated and non-metallated porphyrin electrocatalysts as well as cost-effective and commercially available linear amines. In sum, electrochemical reduction of CO2 using homogeneous porphyrin catalysts in non-aqueous environment as well as heterogeneous immobilized porphyrin catalysts in an aqueous environment was investigated using H-Cell and Flow-Cell technologies for potential industrial applications. We have also introduced new and cost-effective primary amine catalysts for CO2RR, which is a unique approach for industrial applications. The work herein demonstrates the potential of facile porphyrin-based systems and reports on their remarkable performance as CO2 reductive electrocatalysts. Moreover, it serves as an example of an adaptive synthetic design that can demonstrate the value of reductive CO2 technology for industrial large-scale applications to fight climate change issues.Ph.D.2021-11-30 00:00:0

Synthesis of a Polyacrylamide Hydrogel using CO2 at Room Temperature

Carbon dioxide (CO2) is an environmentally harmful “greenhouse gas” that is present in abundant quantities in the earth’s atmosphere. Thus, the sequestration and conversion of CO2 to value-added organic chemicals is of environmental and economical importance. In this proof-of-concept study, amine groups of acrylamide compounds were found to react with CO2 under ambient conditions to form a polyacrylamide hydrogel. This composite was characterized using scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), transmission electron microscopy (TEM), Fourier-transform infrared spectroscopy (FTIR) and electrospray ionization mass spectrometry (ESI–MS), which confirmed successful synthesis and demonstrated all characteristics representative of a typical hydrogel material. Rheology analyses further proved the formation of the hydrogel, as well as its self-healing nature. The novel approach proposed in this work can potentially be used in the construction of versatile amine-based gel materials for efficient CO2 utilization applications.The accepted manuscript in pdf format is listed with the files at the bottom of this page. The presentation of the authors' names and (or) special characters in the title of the manuscript may differ slightly between what is listed on this page and what is listed in the pdf file of the accepted manuscript; that in the pdf file of the accepted manuscript is what was submitted by the author

Evaluation of vascular graft infection following Bentall surgery using 18F‐FDG PET/CT scan: A pediatric case report

Key Clinical Message After a Bentall surgery, there is a small chance of developing a serious complication called vascular graft infection. 18F‐FDG PET/CT, a new and accurate diagnostic tool, can help detect it early, especially if the symptoms are unusual. Abstract A 14‐year‐old boy who had undergone Bentall surgery 1 year prior presented with symptoms of fever, chills, loss of appetite, and weight loss over the course of a month. The initial Bentall surgery was performed due to an aneurysm of the thoracic aorta, along with severe aortic valve insufficiency and moderate aortic valve stenosis. The patient was referred to the PET/CT department for evaluation of possible endarteritis or infection of Dacron graft, which had been reported in trans‐esophageal echocardiography as suspicious findings. Despite normal blood tests, blood cultures, and other imaging modalities, the 18F‐FDG PET/CT confirmed the diagnosis of vascular graft infection. This diagnostic tool allowed for timely and appropriate treatment and prevention of possible complications

Higher-order thinking skills assessment in 3D virtual learning environments using motifs and expert data

The research reported in this paper addresses the problem of assessing higher-order thinking skills, such as reflective and creative thinking, within the context of virtual learning environments. Assessment of these skills requires process-based observations and evaluation, as the output-based methods have been found to be insufficient. Virtual learning environments offer a wealth of data on the process, which makes them good candidates for process-based evaluation, but the existing assessment methods in these environments have shortcomings, such as reliance on large data sets, inability to offer specific feedback on actions, and the lack of consideration for how actions are integrated into bigger tasks. Demonstrating and confirming the ability of three-dimensional virtual learning environments to work with process metrics for assessment, we propose and evaluate the use of motifs as an assessment tool. Motifs are short and meaningful combination of metrics. Combining time-ordered motifs with a similarity analysis between expert and learner data, our proposed approach can potentially offer feedback on specific actions that the learner takes, as opposed to single output-based feedback. It can do so without the use of large training datasets due to reliance on expert data and similarity analysis. Through a user study, we found out that such a motif-based approach can be effective in the assessment of higher-order thinking skills while addressing the identified shortcomings of previous work. We also address the limited research on similarity-based analysis methods, compare their effectiveness, and show that utilizing different similarity measures for different tasks may be a more effective approach. Our proposed method facilitates and encourages the involvement of instructors and course designers through the definition of motifs and expert problem-solving paths

Energy comparison of sequential and integrated CO2 capture and electrochemical conversion

Integrating carbon dioxide (CO2) electrolysis with CO2 capture provides exciting new opportunities for energy reductions by simultaneously removing the energy-demanding regeneration step in CO2 capture and avoiding critical issues faced by CO2 gas-fed electrolysers. However, understanding the potential energy advantages of an integrated process is not straightforward due to the interconnected processes which require knowledge of both capture and electrochemical conversion processes. Here, we identify the upper limits of the integrated process from an energy perspective by comparing the working principles and performance of integrated and sequential approaches. Our high-level energy analyses unveil that an integrated electrolyser must show similar performance to the gas-fed electrolyser to ensure an energy benefit of up to 44% versus the sequential route. However, such energy benefits diminish if future gas-fed electrolysers resolve the CO2 utilisation issue and if an integrated electrolyser shows lower conversion efficiencies than the gas-fed system