Surface and Heterointerface Engineering of 2D MXenes and Their Nanocomposites: Insights into Electro- and Photocatalysis

Abstract

In 2011, a new and growing family of two-dimensional (2D) transition-metal carbides, nitrides, and carbonitrides (MXenes) was discovered. Benefitting from intriguing electronic and structural properties, MXenes have received increasing attention and emerged as next-generation nanomaterials for the exploration of environmentally friendly energy resources for catalysis in energy and environmental technologies. In this review, we systematically highlight the expeditious advances and achievements in design strategies, physico-chemical properties, and catalytic applications of 2D layered MXenes and their nanocomposites in environmental science and renewable energy. In addition, we unravel the structural, optical, and electronic properties of MXenes to elucidate their key roles of ameliorating the niche areas of photo(electro)catalytic hydrogen evolution reaction, oxygen evolution reaction, oxygen reduction reaction, carabon dioxide reduction reaction, nitrogen reduction reaction, and pollutant degradation. This review concludes with invigorating perspectives, outlooks, and formidable challenges in the future development of MXene-based materials for sustainable applications.

Metal–Organic Gel‐Derived Multimetal Oxides as Effective Electrocatalysts for the Oxygen Evolution Reaction

“…[2] Noble-metal-based catalysts RuO 2 and IrO 2 are recognized as the state-of-the-art OER electrocatalysts, but their widespread practical application is greatly limited by their scarcity and high cost. Non-noble-metal electrocatalysts, such as transition-metal-based carbides, [4] nitrides, [5] carbonitrides, [6] oxides, [7] fluorides, [8] sulfides, [9] phosphides, [10] metal-organic frameworks, [11] and carbon dots [12] are regarded as potential substitutes for preciousmetal catalysts. Non-noble-metal electrocatalysts, such as transition-metal-based carbides, [4] nitrides, [5] carbonitrides, [6] oxides, [7] fluorides, [8] sulfides, [9] phosphides, [10] metal-organic frameworks, [11] and carbon dots [12] are regarded as potential substitutes for preciousmetal catalysts.…”

Two‐Dimensional Electrocatalysts for Efficient Reduction of Carbon Dioxide

“…MXenes have been proposed theoretically to be a class of electrocatalysts for converting CO 2 into CH 4 . However, experimental results in the area of the eCO 2 RR have not been published so far, although MXenes are excellent electrocatalysts for the HER, oxygen reduction reaction, and oxygen evolution reaction . The advantages of this class of materials in the eCO 2 RR are yet to be established.…”

Two‐Dimensional Transition Metal Carbides and Nitrides (MXenes): Synthesis, Properties, and Electrochemical Energy Storage Applications

“…A summary of MXene properties is shown in Figure . In particular, Ti 3 C 2 T x MXene possesses a high specific capacitance due to the abundant pseudocapacitive sites .…”

“…By adjusting the functional termination groups, MXenes can demonstrate a narrow band‐gap semiconductor behavior. Except for Sc 2 C(OH) 2 which has a direct band gap, most MXenes have indirect band gaps . The electronic structure of the MXene surface, which can be influenced by the surface functionalization, plays a key role in their electronic properties .…”

“…To date, MXenes have triggered continuous breakthroughs in many areas, including MXene antennas, MXene pen, MXene membrane, supercapacitors, and rechargeable batteries, to name just a few. There are also several reviews covering chemical composition, synthesis routes, unique properties, electrochemical and photocatalysis, and various biomedical applications of MXene . Considering that the number of publications on MXenes grows enormously, we aim to summarize the most‐up‐to‐date progresses in the MXene field for energy storage applications, rather than attempting to include all aspects of other promising applications.…”