The Dependence of Bi2MoO6 Photocatalytic Water Oxidation Capability on Crystal Facet Engineering

Crystal facet engineering of semiconductor photocatalysts is

regarded as an emerging strategy to tune their physicochemical

properties and optimize the photoreactivity of the materials. In

this work, two plate-like Bi2MoO6 samples were prepared,

dominant in either the distinctly different {100} or {010} facets.

As a consequence of the electronic structure effects induced by

the facets, the {100}-dominant Bi2MoO6 (100-BMO) possessed a

smaller band gap and delivered a much higher photocatalytic

water oxidation activity than {010}-dominant Bi2MoO6 (010-

BMO). A greater charge carrier density in 100-BMO was found

to promote electron accumulation on the {100} surfaces,

leading to the narrower band gap, as supported by Mott-

Schottky measurements. Efficient intrinsic electron-hole separation

and longer charge carrier lifetimes in 100-BMO were also

observed. Further, a higher photocurrent density and smaller

Nyquist plot arc radius presented by 100-BMO imply a higher

charge transfer capacity. EPR analysis indicated that the 100-

BMO boasted a higher oxygen vacancy density, whereby the

vacancies could serve as shallow donors to trap electrons and

suppress photogenerated electron-hole pair recombination.

Overall, the {100} facet in Bi2MoO6 delivered a mix of distinctly

advantageous characteristics relative to the {010} facet with the

findings clearly illustrating the value of crystal facet engineering

in boosting photocatalytic performance.