2D Early Transition Metal Carbides (MXenes) for Catalysis

Abstract

MXenes, a bourgeoning class of 2D transition metal carbides, are of considerable interest in catalysis due to their rich surface chemistry, tunable electronic structures, and thermal stability. Here, recent conceptual advances in applying MXenes and their nanocomposites in (photo)electrocatalysis and conventional heterogeneous catalysis are highlighted. In addition, the nature of active sites in the MXene‐based catalysts are discussed and the significance and challenges in the future development of catalysts using MXenes as the platforms are summarized.

A Hybrid Assembly of MXene with NH2−Si Nanoparticles Boosting Lithium Storage Performance

“…[8][9][10][11] Excitingly, MXene, superior to graphene, features an exceptional combination of rich compositions and surface chemistry, surface hydrophilicity, and energy storage functionalities, offering unique advantages for energy-related applications. [12] Among the MXene family, titanium carbide (Ti 3 C 2 T x ) is the most intensively studied and can be used as the host material for LIBs due to its considerable theoretical capacity (320 mAh g À 1 ), lower Li diffusion barrier (0.07 eV), large potential range from ca. 0 to 2 V vs. Li + /Li and beyond, [13,14] and even higher capacitance than carbon materials in O-terminated Ti 3 C 2 T x with extra Li layers.…”

Positioning MXenes in the Photocatalysis Landscape: Competitiveness, Challenges, and Future Perspectives

“…The 2D structure and high electronic conductivity of MXenes make people naturally recall the star 2D material, graphene. [64] Thus far, the progress on applying MXenes for photocatalysis is mainly concentrated on using MXenes as electron acceptors to promote the separation of charge carriers in semiconductors, [16,24,25,[45][46][47][48] as graphene has done over the past decade. [65][66][67] As such, we spontaneously encounter the questions: what are the unique properties of MXenes and what can MXenes bring to us for photocatalytic applications?…”

“…These surface species have proven to serve as active sites for electrocatalytic applications, such as hydrogen evolution reaction. [1,16,25] In recent years, researchers have moved to utilizing MXenes with specific surface properties as active sites for photocatalytic reactions. [70,[133][134][135] DFT calculations have been performed to explore the potential of Ti 3 C 2 T x as a hydrogen evolution cocatalyst.…”

“…Thus far, various semiconductors/ MXenes composites have been constructed and utilized for a broad spectrum of photocatalytic applications, such as environmental remediation, water splitting for hydrogen evolution, CO 2 reduction, and nitrogen photofixation ( Figure 2). [16,[24][25][45][46][47][48] There have been some reviews recapping recent advances in using MXenes-based composites for photocatalytic applications. [16,20,24,25,[45][46][47][48][49] From these previous reviews, we can acknowledge that MXenes have been quickly becoming a research hotspot for constructing composites for photocatalysis.…”

“…[16,[24][25][45][46][47][48] There have been some reviews recapping recent advances in using MXenes-based composites for photocatalytic applications. [16,20,24,25,[45][46][47][48][49] From these previous reviews, we can acknowledge that MXenes have been quickly becoming a research hotspot for constructing composites for photocatalysis. In addition to the valuable information provided in these reviews, it is highly desirable that some key issues of MXenes-based photocatalysis should be reasonably justified, especially the competitiveness and challenges of MXenes as a functional component for photocatalysis, which is the essential goal of the present review.…”