2D MXenes as Co-catalysts in Photocatalysis: Synthetic Methods

Abstract

• Two-dimensional transition metal carbides/nitrides (MXenes) as co-catalysts were summarized and classified according to the different synthesis methods used: mechanical mixing, self-assembly, in situ decoration, and oxidation. • The working mechanism for MXenes application in photocatalysis was discussed. The improved photocatalytic performance was attributed to enhancement of charge separation and suppression of charge recombination.

Enhancing Capacitance Performance of Ti3C2Tx MXene as Electrode Materials of Supercapacitor: From Controlled Preparation to Composite Structure Construction

“…In order to control those situations, many works have focused on the modification of Ti 3 C 2 T x [33][34][35]. Figure 1 shows the common methods of enhancing the capacitance of Ti 3 C 2 T x as electrode materials of supercapacitors [21,[36][37][38][39][40][41]. With the efforts of predecessors, many interesting ideas about enhancing capacitance have been put forward, such as modification of preparation process, surface modification, and composite methods.…”

Photocatalytic H2 Evolution on TiO2 Assembled with Ti3C2 MXene and Metallic 1T-WS2 as Co-catalysts

“…Therefore, seeking an inexpensive and highly active co-catalyst is of paramount significance for achieving photocatalytic H 2 production in the future [12]. MXenes, as new 2D materials, have aroused remarkable attention because of its excellent electrical conductivity [13,14]. For example, a 2D material with an accordion-like structure of layered Ti 3 C 2 MXene can be prepared by etching Al layers from Ti 3 AlC 2 , in HF solution [15][16][17].…”

Thin‐Layered Photocatalysts

“…MXenes have received great interest from academia since the appearance of Ti 3 C 2 in 2011, and been regarded as a promising class of thin‐layered photocatalyst, in which the M represents transition metal, including Ti, Zr, Ta, Mo, and so on, X stands for C or N elements. [ 60,61 ] The MXenes with ultrathin thickness are usually fabricated by selective etching of A layers, which is composed of IIIA or IVA group elements, from the raw M n +1 AX n phases through an in situ HF etching process. Benefitting from their large specific surface area, excellent conductivity and abundant surface reactive sites, some MXenes, such as Ti 2 CO 2 , V 2 CO 2 , Zr 2 CO 2 , and Hf 2 CO 2 , are considered as promising candidate for being applied in the field of photocatalysis, which can be predicted by some works about theoretical calculations.…”

“…3) The MXenes own abundant surface functional groups, such as F, OH, O groups, which provide excellent platform for the heterojunction constructions. [ 60 ] For example, Cao et al successfully fabricated a novel heterojunction photocatalytic system, which was composed of thin‐layered Bi 2 WO 6 and MXene Ti 3 C 2 . In this photocatalytic system, the Ti 3 C 2 display ultrathin thickness (1.2–1.6 nm) with abundant terminal groups, which can facilitate the construction of intimate contact between two thin‐layered materials, thus improving the charge transfer ability.…”