Preface

The globally increasing concentration of carbon dioxide (CO₂) in the atmosphere is the main driving force of disruptive climate characteristics including extreme events. Thus, recent efforts have been heavily focused on finding sustainable pathways to reach net zero CO₂ emission. Recycling CO₂ into fuels and chemicals, which will help the environment, is a win–win scenario. This book 2D Nanomaterials for CO₂ Conversion into Chemicals and Fuels provides a glimpse into how this rapidly developing field is being approached, examines its motives, innovations, and different implications and viewpoints to offer an overview of the current situation, associated challenges, and future direction. It also delves into the technological roadblocks based on the potential and present methods of converting CO₂ into fuels and chemicals to accomplish important objectives in this area. Overall, this book takes an interdisciplinary approach to explaining and clarifying recent research developments in the field.

The sixteen chapters address different approaches of CO₂ capture to CO₂ utilization process. Chapter 1 deals with current trends in CO₂ utilization technologies covering the fundamental approach of CO₂ conversion to chemicals and fuels. This chapter explains the complexities of CO₂ conversion, various conversion processes, and intensification technologies for industrial applications. At the end of the chapter the scientific barriers preventing these processes from becoming industrially viable are examined, along with their prospects for the future.

The unique properties of two-dimensional (2D) nanomaterials and their hybrid nanocomposites have become a popular focus of research for developing catalytic CO₂ conversion processes into fuels and chemicals since the emergence of graphene in 2004. Chapter 2 compares two viable techniques for synthesizing 2D materials: the top-down and bottom-up strategies and their benefits and drawbacks. Various characterization techniques are examined in this chapter to analyze and assess the structural, morphological, chemical, and physical properties of produced 2D materials. Further, various synthesis methods, properties, current uses, present challenges, potential applications, and future possibilities are discussed in Chapter 3 for 2D hybrid nanomaterials utilized in CO₂ reduction to create value-added chemicals. As part of Chapter 4, several techniques for converting CO₂ into fuel are discussed, including harnessing solar energy by artificial photosynthesis to produce liquid solar fuels (e.g., methanol, ethanol) from CO₂ and water. The benefits and drawbacks of various approaches are also discussed.

Chapter 5 discusses the synthesis and characterization of 2D-metal oxides and the characterization and application of 2D-metal oxides as catalysts for CO₂ electrochemical reactions. The research gaps and difficulties discovered in utilizing 2D-metal oxides for CO₂ electrochemical at large-scale for industrial applications are highlighted. The focus of Chapter 6 is the creation of 2D hybrid nanostructured electrocatalysts for CO₂ electrochemical reduction. In particular, advances in reaction activity, primary product selectivity, and catalytic stability are emphasized and explored as insights into efficient and selective CO₂ electrochemical conversion to valuable compounds.

Next, Chapter 7 covers the basic characteristics of 2D nanostructured materials and their CO₂ electrochemical reduction performance in terms of product selectivity, catalytic activity, and reaction mechanism. Graphene, metal nanosheets, metal oxides, transition metal dichalcogenides (TMDC), metal–organic framework thin films, and hybrid compositions are emphasized as state-of-the-art catalysts for the CO₂ electrochemical conversion process. Numerous types of electrolyzers used to study CO₂ electrochemical conversion process are reviewed in terms of their configurations, working principles, and significant advantages/disadvantages.

Chapter 8 discusses the photoelectrocatalytic reduction of CO₂ in an aqueous medium using non-oxide 2D nanomaterials. In particular, 2D TMDC, nitrides, carbonitrides, metal–organic frameworks, and heterojunctions of these non-oxide two-dimensional as photocatalysts are reviewed. This chapter also discuss the guidelines for improving the material design by using the outstanding structural, optical, and electronic characteristics that influence catalyst selectivity, activity, and stability for effective CO₂ reduction applications. In a similar field, extended discussion concerning the application of several 2D-nanomaterials, and the essential elements of photocatalytic CO₂ reduction and the processes of photocatalytic CO₂ with water conversion on a conventional semiconductor photocatalyst are scrutinized in Chapter 9. Certain limitations and potential for enhancing the performance of 2D-nanomaterials and CO₂ photoreduction are provided to develop the field to satisfy dependable industrial applications. The fundamentals of photocatalytic CO₂ reduction are discussed first, followed by photocatalytic applications of 2D hybrid materials in Chapter 10. Photocatalysts based on graphene, graphitic carbon nitride, transition metal–oxides, and TMDC and their production are discussed. Furthermore, utilizing a photoelectrochemical method and different nanosized 2D hybrid materials, the photocatalytic reduction of CO₂ into fuel and chemicals is explored. In addition, using the density functional theory tool, insights into the CO₂ to fuel conversion process are elucidated, providing new opportunities to develop better photocatalysts for CO₂ conversion into fuels.

Chapter 11 summarizes recent successes through CO₂ utilization via thermal catalytic processes, including hydrogenation, methanation, and dry reforming. This chapter discusses the conversion of CO₂ to carbon compounds such as graphene or nanomaterials and polymers and modification techniques to increase CO₂ reduction catalytic activity. Additionally, bottlenecks, problems, and methods for design and application are discussed. The characteristics and performances of 2D materials are also evaluated for certain catalytic reactions in CO₂ reduction. As part of the review of ethylene dehydrogenation, Chapter 12 describes the significant progress in understanding the reactions, methods of reactions, and the nature of the active sites of catalysts. Various 2D nanomaterial catalysts have been primarily introduced, emphasizing the various additives and supports that increase the role of the catalysts, explaining which are more competitive for industrial applications. The chapter concludes with an assessment of future research prospects in catalysis science and ethane oxidative dehydrogenation.

Analyzing the effectiveness of electrochemical CO₂ conversion systems, Chapter 13 compares zero-dimensional (0D), one-dimensional (1D), and 2D nanocatalysts. An extensive review of various dimensional nanocomposite systems is presented, along with their electrical and mechanical characteristics and potential as electrochemical catalysts for CO₂ conversion to chemicals and fuels. The chapter also discusses the photoelectrochemical conversion of CO₂ into chemicals and fuels, and the use of 0D, 1D, and 2D nanostructured materials to boost the yield of high value-added CO₂ products. Essentially, this part is about a comparative study evaluating different methods for generating nano-dimensional metal–oxide photocatalysts for high-efficiency CO₂ reduction. Chapter 14 explores various methods for capturing and converting CO₂ into chemicals and fuels, including photoelectrochemical, photocatalytic, electrocatalytic, thermal catalysis, and biochemical approaches. The book then focuses on the use of 2D nanomaterials for CO₂ collection via catalysis and photocatalysis in Chapter 15, as well as conversion into clean fuels and value-added chemicals. Chapter 16 offers an overview of CO₂ electrochemical reduction fundamentals and the latest information on commercial CO₂ electrochemical conversion processes. It covers the secondary chemical function of 2D nanomaterials in electrochemical reduction processes and reverse microbial fuel cells.

In contrast to other books reporting on CO₂ conversion, this book is unique in its content; it features internationally known editors and authors, which will initially draw the attention of graduate students and researchers. With information on the many aspects and challenges of CO₂ conversion, the book provides the most current and authoritative information for chemists, process engineers, chemical engineers, and environmental officers. It provides pertinent guidelines and recommendations to government policymakers and analysts.

Kishor Kumar Sadasivuni

Karthik Kannan

Aboubakr M. Abdullah

Bijandra Kumar