Controlled morphological and structural
variations of LaTiO2N and CoO
x
nanoparticles loaded
as a cocatalyst increased the photocatalytic O2 evolution.
Four different LaTiO2N samples were prepared from two varied
La2Ti2O7 precursors by thermal ammonolysis
with and without flux. The most effective transformation from La2Ti2O7 into LaTiO2N in terms
of crystallinity and nitrogen contents was obtained in the following
two cases: flux-assisted ammonolysis of La2Ti2O7 characterized by a comparatively small particle size
and a large surface area and ammonolysis without flux of highly crystalline
La2Ti2O7. In both cases, high activity
for O2 evolution under visible-light illumination (λ
≥ 420 nm) (∼50 μmol h–1) was
obtained. Loading LaTiO2N with CoO
x
enhanced the photocatalytic activity for O2 evolution,
although the effect of CoO
x
depended on
the morphologies of LaTiO2N as a support. The promotional
effect was most pronounced for LaTiO2N with a skeletal
morphology, because such LaTiO2N contain most unsaturated
bonds that act as nucleation centers that in turn generate small and
highly dispersed CoO
x
nanoparticles.
Semiconductor powders are perfectly suited for the scalable fabrication of particle-based photoelectrodes, which can be used to split water using the sun as a renewable energy source. This systematic study is focused on variation of the electrode design using LaTiO2 N as a model system. We present the influence of particle morphology on charge separation and transport properties combined with post-treatment procedures, such as necking and size-dependent co-catalyst loading. Five rules are proposed to guide the design of high-performance particle-based photoanodes by adding or varying several process steps. We also specify how much efficiency improvement can be achieved using each of the steps. For example, implementation of a connectivity network and surface area enhancement leads to thirty times improvement in efficiency and co-catalyst loading achieves an improvement in efficiency by a factor of seven. Some of these guidelines can be adapted to non-particle-based photoelectrodes.
LaTiO(2)N photoanodes for solar water splitting were prepared by electrophoretic deposition and demonstrated the best photocurrents ever reported for this material. Further important enhancement of the performance was obtained by the use of a sputtered In(2)O(3) overlayer.
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