Nanostructured Carbon Nitrides for CO₂ Capture and Conversion

Abstract

Carbon nitride (CN), a 2D material composed of only carbon (C) and nitrogen (N), which are linked by strong covalent bonds, has been used as a metal-devoid and visible-light-active photocatalyst owing to its magnificent optoelectronic and physicochemical properties including suitable bandgap, adjustable energy-band positions, tailor-made surface functionalities, low cost, metal-free nature, and high thermal, chemical, and mechanical stabilities. CN-based materials possess a lot of advantages over conventional metal-based inorganic photocatalysts including ease of synthesis and processing, versatile functionalization or doping, flexibility for surface engineering, low cost, sustainability, and recyclability without any leaching of toxic metals from photocorrosion. Carbon nitrides and their hybrid materials have emerged as attractive candidates for CO 2 capture and its reduction into clean and green low-carbon fuels and valuable chemical feedstock by using sustainable and intermittent renewable energy sources of sunlight and electricity through the heterogeneous photo(electro) catalysis. Here, the latest research results in this field are summarized, including implementation of novel functionalized nanostructured CNs and their hybrid heterostructures in meeting the stringent requirements to raise the efficiency of the CO 2 reduction process by using state-of-the-art photocatalysis, electrocatalysis, photoelectrocatalysis, and feedstock reactions. The research in this field is primarily focused on advancement in the synthesis of nanostructured and functionalized CN-based hybrid heterostructured materials. More importantly, the recent past has seen a surge in studies focusing significantly on exploring the mechanism of their application perspectives, which include the behavior of the materials for the absorption of light, charge separation, and pathways for the transport of CO 2 during the reduction process.

Kalium‐Polyheptazinimid: Ein übergangsmetallfreier Festkörper‐Triplett‐Sensibilisator in Kaskadenenergietransfer und [3+2]‐Cycloadditionen

“…[1][2][3] In ähnlicher Weise werden Kohlenstoffnitride traditionell mit Wasserspaltung und CO 2 -Umwandlung in Verbindung gebracht. [4][5][6] Tatsächlich beeinflusste die Erzeugung von Wasserstoff aus Wasser, mithilfe von polymerem Kohlenstoffnitrid, die Arbeit in verwandten Bereichen, wie photoelektrochemischen Zellen, [7] metallfreien Elektroden [8,9] und Elektrolumineszenzvorrichtungen. [10] Darüber hinausgehend sind es autonome Aktuatoren, [11] Photodetektoren, die auf photonengetriebenen Ionentransport in asymmetrischen Kohlenstoffnitridmembranen basieren, [12] und lichtgesteuerte Ionenpumpen.…”

Photocatalysts Based on Organic Semiconductors with Tunable Energy Levels for Solar Fuel Applications

“…CN-based composites have been reported for CO 2 photoreduction, in the pristine state and doped state. [166][167][168] Structural modifications of CNs have shown increased performances for photoreduction. [169,170] For example, an increase in performance due to the presence of N vacancies has been reported.…”

“…[166][167][168] Structural modifications of CNs have shown increased performances for photoreduction. [169,170] For example, an increase in performance due to the presence of N vacancies has been reported. At 41% humidity, CO 2 reduction to CO was demonstrated with an average production rate of 0.54 µmol h −1 and a selectivity of 78%, with the material tested in the gas phase with no sacrificial agent.…”

A geopolymer route to micro- and meso-porous carbon

“…As is well known, large-scale consumption of fossil fuels has become a worldwide problem due to severe global warming. 13,14 To overcome this global problem, porous carbon has been suggested as an ideal CO 2 adsorbent because of its high adsorption capacity and high specic surface area. In addition to this, porous carbon with micro-porosity has been strongly suggested for CO 2 adsorption.…”