| HF etching |
TiO2/Ti3C2
|
HF |
O, OH, F |
20 mL of 48% HF, 15 h etching
time |
multilayer MXene produced with lower photocatalytic
efficiency
compared to monolayer counterpart |
(138) |
| 2D/2D HCN/MXene |
HF |
|
39% HF, 24 h etching time |
high purity of MXene
was produced with well-defined multilayer
structure |
(139) |
| 39% HF, 48 h etching time |
the growth of anatase TiO2 on exfoliated multilayers
MXene |
| 39% HF, 96 h etching time |
the growth of anatase and rutile TiO2 was observed
on MXene layer; more exfoliated layer and increase in the growth of
TiO2 NP with increasing etching time |
| TiO2/Ti3C2
|
HF |
O, OH, F |
49% HF, 24 h etching
time (35
°C); ethyl alcohol as a washing agent; hydrothermally treated
at 450 °C |
the formation of TiO2/Ti3C2 safflower-like morphology with ∼1 μm safflower size and shorter nanorods
formation |
(140) |
| 49% HF, 24 h etching time (35
°C); ethyl alcohol as a washing agent; hydrothermally treated
at 550 °C |
average safflower size ∼2 μm upon heat increase heat treatment;
well-formed safflower morphology |
| 49% HF, 24 h etching time (35
°C); ethyl alcohol as a washing agent; hydrothermally treated
at 650 °C |
average safflower size ∼2 μm with lower spatial density of
TiO2/Ti3C2 nanorods compared to at
550 °C heat treatment; the safflower
morphology slightly deformed at higher temperature |
| BQ/TiC/UCN |
HF |
|
40% HF, 72 h etching
time, 20
mL DMSO, 24 h intercalation time |
ultrathin MXene sheet is produced, effectively function as
the electron mediator |
(141) |
| Ti3C2-QD/Ni-MOF |
HF |
|
20 mL HF, 24 h etching time,
DMF intercalating agent |
MXene QD constructed with enhance
charge transfer and higher
separation capabilities of the photocarriers |
(142) |
| 2D/2D g-C3N4/Ti3C2TA/R (CN/TCT)
MXene |
HF |
|
39% HF, 24 h etching time |
less distribution of TiO2 NPs
on the surface of
MXene |
(121) |
| 39% HF, 96 h etching time |
higher amount of TiO2 growth/conversion with more
of rutile phase compared to anatase |
| 49% HF, 24 h etching time |
higher distribution
of TiO2 on the MXene surface
when employing more concentrated etchants |
| 49% HF, 96 h etching time |
both TiO2 (rutile) and TiO2 (anatase)
having higher concentration due to more oxidation |
| acid-containing fluoride ions |
TiO2/Ti3C2
|
LiF + HCl |
O, OH, F |
LiF with 6 M HCl, 24 h etching time |
MXene flakes exhibit
excellent hydrophilicity and dispersity
with flakes size range of 10–100 nm |
(138) |
| ZnCdS/TiO2/Na-MXene |
LiF + HCl |
|
LiF with 9 M of
HCl, 24 h etching time (35 °C) |
the preintercalation of Na+ and attachment of ZnCdS
nanoparticles on the MXene flakes improve the oxidation stability
and slowing the oxidation to TiO2
|
(143) |
| 2D-Bi2MoO6@2D MXene |
LiF + HCl |
O, OH |
LiF with 9 M of 20 mL HCl, 24 h etching time (35
°C) |
2D MXene serves as effective platform for impeding
the agglomeration
and support the growth of Bi2MoO6 constructing
a hierarchical composite structure |
(144) |
| Ti3AlC2/Ti3C2Tx
|
LiF + HCl |
|
3.08 M LiF/HCl, 6 h etching time; 1, 3, 6, 24, and 36 h |
delaminated MXene with more conversion
to Ti3C2Tx than 1 h etched |
(145) |
| 3.08 M LiF/HCl, 24 h etching time |
delaminated MXene
are formed with residual of Ti3AlC2 was observed |
| 3.08 M LiF/HCl, 36 h etching time |
delaminated MXene
with residual of Ti3AlC2 was observed; partial
delamination occurs even at 36 h etched
time |
| Ti3C2Tx
|
LiF + HCl |
O, OH, F |
LiF with 9 M HCl, 24 h etching time (30 °C) |
c-lattice parameter of 25.75 Å |
(146) |
| LiF with 9 M HCl, 24 h etching time (35 °C), ethanol as washing
agent |
the highest c-lattice parameter of 30.99 Å obtained with ethanol as washing agent
with improved delamination
ratio |
| alkaline
etching |
Ti3C2Tx
|
KOH |
O, OH |
5 M KOH, 120 °C hydrothermal
treatment |
less developed of accordion-like structure
of MXene; more exposed
of Ti-OH sites with with alkali etching |
(147) |
| Ti3C2Tx
|
NaOH |
O, OH |
27.5 M NaOH treatment at 270
°C |
higher purity (92%) of multilayer MXene produced
with removal
of −F termination group |
(129) |
| 27.5 M NaOH
treatment at 250
°C |
Ti3C2Tx yield
decrease with reaction temperature |
| 5–10 M NaOH treatment
at 270 °C |
formation of Na/K–Ti–O
compounds (NTOs) due to
lower concentration of NaOH, increasing the water content and facilitate
oxidation |
| NaOH treatment at 100–220 °C |
no formation
of MXene as reation cannot happen at lower temperature
regardless of any concentration |
| electrochemical etching |
Ti3C2Tx
|
NH4Cl, TMAOH |
O, OH |
1 M NH4Cl, 0.2 M TMAOH |
higher yield of single or bilayer (>90%) with
larger average dimension |
(126) |
| Ti2C |
HCl |
–Cl, −O, −OH |
1 M HCl, 0.6 V, 1 day etching |
less
conversion of MXene sheets. |
(128) |
| 2 M HCl, 0.6 V, 5 days etching |
the formation of carbon-derived-carbide (CDC)
as the results of overetching |
| molten salt substitution |
Ti3C2Tx
|
CuCl2
|
–Cl, −O |
Ti3SiC2 in CuCl2 molten
salt (750 °C) |
delamination of the layer proceed
with the aid of SiCl4 gas molecules produced through etching
process |
(136) |
| Ti3C2Tx
|
ZnCl2
|
–Cl, −O |
Ti3ZnC2 + ZnCl2 (annealed time: 0.5 h, 1 h, 1.5 h, 3.0 h) |
the increasing
of the ratio of molten salt, ZnCl2 in the starting precursor,
a gradual conversion to Ti3C2Cl2 can
be observed |
(134) |
| Ti3C2Tx
|
NaCl2, KCl, CuCl2
|
–I, −Br, −Cl |
NaCl2, KCl, CuCl2 (mixed
ratio of 1:2:2:3), 10 h annealed time in Ar (700 °C) |
well-configured Lewis acidic etching route could tailored
the
surface chemistry of MXene |
(148) |
