A unique structural transformation of a lepidocrocite-type layered titanate, K0.8Ti1.73Li0.27O4, into a rutile-type TiO2 has recently been realized via dilute HCl treatment and subsequent drying at room temperature for producing rutile-nanoparticle-decorated protonated layered titanate exhibiting highly efficient photocatalytic activity. Herein, the authors report synthesis of a lepidocrocite-type layered cesium titanate with nominal compositions of
C
s
0.7
T
i
1.825
‐
x
/
2
N
i
x
□
0.175
‐
x
/
2
O
4
(
x
=
0
, 0.05, 0.1, and 0.35) through solid-state reactions of Cs2CO3, TiO2, and Ni(CH3COO)2·4H2O at different temperatures (600 or 800°C), followed by treatment with dilute HCl and subsequent drying to produce a Ni-doped protonated layered titanate/TiO2 composite.
C
s
0.7
T
i
1.825
‐
x
/
2
N
i
x
□
0.175
‐
x
/
2
O
4
with an optimized Ni content obtained at a lower temperature was converted into a Ni-doped protonated layered titanate/TiO2 composite to exhibit high photocatalytic activity for NO
x
decomposition reactions.