MXene─A New Paradigm Toward Artificial Nitrogen Fixation for Sustainable Ammonia Generation: Synthesis, Properties, and Future Outlook

Kok, Steven Hao Wan; Lee, Jiale; Tan, Lling‐Lling; Ong, Wee‐Jun; Chai, Siang‐Piao

doi:10.1021/acsmaterialslett.1c00673

Cited by 33 publications

(9 citation statements)

References 224 publications

(525 reference statements)

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“…Therefore, surface functional groups and chemical compositions of MXenes, which influence their electrical properties, are capable to impact their optical properties. − The DFT calculations predicted that pristine MXenes, which are not having surface terminal groups, exhibit metallic behavior due to the overlapping of conduction and valence bands at the Fermi level . However, the outermost metal layers of MXene are inevitably terminated with surface terminal groups during their synthesis, and DFT calculations predicted that electronic structure of MXenes is sensitive to the type and orientation (relative to the MXene sheet) of surface terminations. ,,, G. R. Berdiyorov employed DFT calculations to divulge the role of surface terminations on optical properties of Ti 3 C 2 T 2 (T = −F, −O, −OH) MXene . The results concluded that all surface terminations result in higher absorption and reflectivity for Ti 3 C 2 T 2 MXene in the UV range as compared to pristine MXene .…”

Section: Optical Propertiesmentioning

confidence: 99%

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

et al. 2022

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Photocatalytic water splitting, CO2 reduction, and pollutant degradation have emerged as promising strategies to remedy the existing environmental and energy crises. However, grafting of expensive and less abundant noble-metal cocatalysts on photocatalyst materials is a mandatory practice to achieve enhanced photocatalytic performance owing to the ability of the cocatalysts to extract electrons efficiently from the photocatalyst and enable rapid/enhanced catalytic reaction. Hence, developing highly efficient, inexpensive, and noble-metal-free cocatalysts composed of earth-abundant elements is considered as a noteworthy step toward considering photocatalysis as a more economical strategy. Recently, MXenes (two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides) have shown huge potential as alternatives for noble-metal cocatalysts. MXenes have several excellent properties, including atomically thin 2D morphology, metallic electrical conductivity, hydrophilic surface, and high specific surface area. In addition, they exhibit Gibbs free energy of intermediate H atom adsorption as close to zero and less than that of a commercial Pt-based cocatalyst, a Fermi level position above the H2 generation potential, and an excellent ability to capture and activate CO2 molecules. Therefore, there is a growing interest in MXene-based photocatalyst materials for various photocatalytic events. In this review, we focus on the recent advances in the synthesis of MXenes with 2D and 0D morphologies, the stability of MXenes, and MXene-based photocatalysts for H2 evolution, CO2 reduction, and pollutant degradation. The existing challenges and the possible future directions to enhance the photocatalytic performance of MXene-based photocatalysts are also discussed.

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Section: Optical Propertiesmentioning

confidence: 99%

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

et al. 2022

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“…(a) Different elements that can be used to build MXenes as shown by different colors . (b) Schematic illustration of various types of MXenes . (c) Atomic arrangement and chemical composition of various MXenes reported in the literature …”

Section: Fundamentals Characteristics and Advances In Ti3c2 Mxenesmentioning

confidence: 99%

Titanium Carbide MXenes Cocatalyst with Graphitic Carbon Nitride for Photocatalytic H₂ Production, CO₂ Reduction, and Reforming Applications: A Review on Fundamentals and Recent Advances

et al. 2023

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Two-dimensional (2D) titanium carbide (Ti3C2) MXenes have gained increasing attention in photocatalytic applications due to their prominent electrical conductivity, optical properties, and abundant surface functional groups. The unique layered microstructure characteristics of Ti3C2 provide a large surface area, interlayer spacing, and hydrophilic surface functional groups, contributing to their high photocatalytic efficiency. Graphitic carbon nitride is very promising among the semiconductors due to its layered structure and higher reduction potential. The present study discusses the recent advances in various Ti3C2 structures coupled with g-C3N4 for hydrogen evolution reactions (HER), photocatalytic CO2 reduction reactions (CO2 RR), and CO2 reforming of methane (CO2 RM). Initially, we provide an overview of the fundamental properties of Ti3C2-based composites and recent synthesis approaches, including structure development, of functional group formation, and various etching agents. We further explore using Ti3C2 in different structures coupled with g-C3N4 as a binary and ternary composite with the involvement of other semiconductors and sensitizers. The performance of various composites for water splitting to produce hydrogen and reforming systems, including CO2 conversion with H2O, CO2 methanation, dry reforming of CH4 (DRM), and bireforming of CH4 (BRM), is discussed in detail. The hydrophilic surface functional groups and efficient electron transport pathways of Ti3C2 MXenes make them excellent candidates for catalysts with high yield rates and selectivity. Finally, this review provides valuable insights into the potential applications of Ti3C2-based composites, and future research directions in this field are proposed.

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“…[ 185,186 ] The commercial production of NH 3 is dominated by the Haber‐Bosch process, but it involves high temperature (400–500 °C) and pressure (200–250 bar), leading to high production cost and safety hazard. [ 187 ] Photocatalytic nitrogen reduction is the more attractive option for ammonia production compared to the Haber–Bosch process, because the photocatalytic reduction of N 2 into NH 3 is achieved at room temperature and pressure. [ 188–190 ] The key factor of photocatalytic nitrogen reduction is to reduce the recombination of photoinduced electrons and holes, producing more photoinduced electrons to participate in nitrogen reduction.…”

Section: Applications Of Metal Carbide Cocatalystsmentioning

confidence: 99%

Metal Carbide‐Based Cocatalysts for Photocatalytic Solar‐to‐Fuel Conversion

Campbell

Huang

et al. 2022

Small Structures

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Semiconductor‐based photocatalytic solar‐to‐fuel conversion has proven an appealing strategy for achieving carbon‐neutral and green‐hydrogen production. However, almost all semiconductors exhibit unsatisfactory photocatalytic performance due to insufficient surface‐active sites, weak selectivity, and fast charge‐carrier recombination. For these reasons, cocatalyst loading has become an encouraging strategy for improving photocatalytic activity and selectivity. Owing to the scarcity, and cost of noble metal‐based cocatalysts, utilization of low‐cost noble‐metal‐free cocatalysts, such as metal carbide‐based cocatalysts, has aroused tremendous attention. This review highlights some recent crucial advances in active metal carbide‐based cocatalysts for photocatalytic solar‐to‐fuel conversion. First, the fundamentals of metal carbide‐based cocatalysts are presented, including the photocatalytic mechanism, advantages, drawbacks, and design rules. Second, three synthesis approaches of high‐active metal carbide‐based cocatalysts, namely constructing metal carbide nanostructures, epitaxial synthesis of metal carbides on nanostructured carbon, and crystal imperfection construction on metal carbides, are thoroughly addressed. Subsequently, applications of metal carbide‐based cocatalysts in photocatalytic hydrogen production, CO2 reduction, and nitrogen reduction are further discussed. Finally, the crucial challenges and important directions of metal carbide‐based cocatalysts for photocatalytic solar‐to‐fuel conversion are proposed. This review demonstrates some new options for rationally designing and developing novel and efficient metal carbide‐based cocatalysts for highly active and selective photocatalytic solar‐to‐fuel conversion.

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MXene─A New Paradigm Toward Artificial Nitrogen Fixation for Sustainable Ammonia Generation: Synthesis, Properties, and Future Outlook

Cited by 33 publications

References 224 publications

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

Titanium Carbide MXenes Cocatalyst with Graphitic Carbon Nitride for Photocatalytic H₂ Production, CO₂ Reduction, and Reforming Applications: A Review on Fundamentals and Recent Advances

Metal Carbide‐Based Cocatalysts for Photocatalytic Solar‐to‐Fuel Conversion

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MXene─A New Paradigm Toward Artificial Nitrogen Fixation for Sustainable Ammonia Generation: Synthesis, Properties, and Future Outlook

Cited by 33 publications

References 224 publications

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

A Review on MXene Synthesis, Stability, and Photocatalytic Applications

Titanium Carbide MXenes Cocatalyst with Graphitic Carbon Nitride for Photocatalytic H2 Production, CO2 Reduction, and Reforming Applications: A Review on Fundamentals and Recent Advances

Metal Carbide‐Based Cocatalysts for Photocatalytic Solar‐to‐Fuel Conversion

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Titanium Carbide MXenes Cocatalyst with Graphitic Carbon Nitride for Photocatalytic H₂ Production, CO₂ Reduction, and Reforming Applications: A Review on Fundamentals and Recent Advances