2 Interdisciplinary Research Center for Biology
and Chemistry, Liaoning Normal University, Dalian, Liaoning 116029, P.
R. China
* Corresponding authors.
Email addresses:
zhouxin@dlu.edu.cn
Abstract: LaTaON2 is a promising
visible-light-responsive photocatalyst for water splitting because of
its broad visible light absorption and suitable band edge positions.
However, the high defect concentration hinders the charge transfer and
results in the poor photocatalytic performance of
LaTaON2. Loading proper cocatalysts is one of the most
efficient strategies for promoting charge separation/transfer and
achieving high reaction activity. In this work, we have used density
functional theory calculations to study the depositions of Pt, Ru and Ni
single atom cocatalysts on LaTaON2(010) surface. The
most stable adsorption configuration is the same site for all the
elements, namely the top of the N atom on the La-terminated surface and
the fourfold hollow site on the Ta-terminated surface. The adsorption of
metal single atom on Ta-termination is stronger than that on
La-termination due to the formation of more bonds. Upon the deposition,
no localized impurity states appear in the middle of the forbidden gap
since the nd states of metal adatoms are located within the
valence band and conduction band of LaTaON2. The
efficiency of the photocatalysts is probed by investigating their
ability to adsorb H atom in a thermodynamically manner. Our results
reveal that the energetically favorable sites of HER are the N atom on
the La-termination and the O and N atoms on the Ta-termination,
respectively. Compared with the clean surface, the surfaces with Pt, Ru
and Ni single adatoms exhibit higher performance for HER because loading
metal cocatalysts can further activate the surface nonmetal atoms and
reduce the Gibbs free energy of hydrogen adsorption. The work gives an
atom-level insight into the role of metal single atom cocatalysts in
LaTaON2 photocatalyst for hydrogen production.
Keywords : photocatalysis; LaTaON2, metal
cocatalysts; hydrogen evolution reaction; DFT calculations