Siglinda Perathoner

1. Introduction 2. Synthesis of Novel Nanostructured Carbon Materials 2.1. Carbon Nanotubes 2.2. Graphene 2.3. Ordered Mesoporous Carbon 2.4. Carbon Hierarchy 2.5. Macroscopic Shaping of Nanocarbon 3. Functionalization of Nanocarbon Materials 3.1. Liquid-Phase Functionalization of Nanocarbon 3.2. Gas-Phase Functionalization of Nanocarbon 4. Characterization and Modeling 4.1. Characterization of Carbon 4.1.1. Microcalorimetry 4.1.2. Temperature-Programmed and Ambient Pressure Photoelectron Spectroscopy 4.1.3. Advanced Electron Microscopy 4.2. Theoretical Modeling 5. Nanocarbons in Catalytic Reactions 5.1. Enhanced Characteristics as a Support for Catalytic Functionalities 5.2. Stabilization of Small Catalytic Particles with Enhanced Catalytic Behavior 5.3. Direct Catalytic Role of Nanocarbon Functional Groups 5.4. Nanoconfinement 5.5. Electron-Transfer Induced Changes in the Properties of Supported Nanoparticles 5.6. Defect-Related Catalytic Reactivity 5.7. Catalysis by Two-Dimensional Carbon Nanomaterials 6. Concluding Remarks and Perspectives

Replacement of part of the fossil fuel consumption by renewable energy, in particular in the chemical industry, is a central strategy for resource and energy efficiency. This perspective will show that CO2 is the key molecule to proceed effectively in this direction. The routes, opportunities and barriers in increasing the share of renewable energy by using CO2 reaction and their impact on the chemical and energy value chains are discussed after introducing the general aspects of this topic evidencing the tight integration between the CO2 use and renewable energy insertion in the value chain of the process industry. The focus of this perspective article is on the catalytic aspects of the chemistries involved, with an analysis of the state-of-the-art, perspectives and targets to be developed. The reactions discussed are the production of short-chain olefins (ethylene, propylene) from CO2, and the conversion of carbon dioxide to syngas, formic acid, methanol and dimethyl ether, hydrocarbons via Fischer–Tropsch synthesis and methane. The relevance of availability, cost and environmental footprints of H2 production routes using renewable energies is addressed. The final part discusses the possible scenario for CO2 as an intermediary for the incorporation of renewable energy in the process industry, with a concise roadmap for catalysis needs and barriers to reach this goal.

This Review introduces this special issue of ChemSusChem dedicated to CO(2) recycling. Its aim is to offer an up-to-date overview of CO(2) chemical utilization (inorganic mineralization, organic carboxylation, reduction reactions, and biochemical conversion), as a continuation and extension of earlier books and reviews on this topic, but with a specific focus on large-volume routes and projects/pilot plants that are currently emerging at (pre-)industrial level. The Review also highlights how some of these routes will offer a valuable opportunity to introduce renewable energy into the existing energy and chemical infrastructure (i.e., "drop-in" renewable energy) by synthesis of chemicals from CO(2) that are easy to transport and store. CO(2) conversion therefore has the potential to become a key pillar of the sustainable and resource-efficient production of chemicals and energy from renewables.

Abstract Ammonia is synthesized directly from water and N 2 at room temperature and atmospheric pressure in a flow electrochemical cell operating in gas phase (half‐cell for the NH 3 synthesis). Iron supported on carbon nanotubes (CNTs) was used as the electrocatalyst in this half‐cell. A rate of ammonia formation of 2.2×10 −3 g m −2 h −1 was obtained at room temperature and atmospheric pressure in a flow of N 2 , with stable behavior for at least 60 h of reaction, under an applied potential of −2.0 V. This value is higher than the rate of ammonia formation obtained using noble metals (Ru/C) under comparable reaction conditions. Furthermore, hydrogen gas with a total Faraday efficiency as high as 95.1 % was obtained. Data also indicate that the active sites in NH 3 electrocatalytic synthesis may be associated to specific carbon sites formed at the interface between iron particles and CNT and able to activate N 2 , making it more reactive towards hydrogenation.