  Facing with grave climate change and enormous energy demand, catalyzer gets
more and more important due to its significant effect on reducing fossil fuels
consumption. Hydrogen evolution reaction (HER) and oxygen evolution reaction
(OER) by water splitting are feasible ways to produce clean sustainable energy.
Here we systematically explored atomic structures and related STM images of Se
defects in PtSe2. The equilibrium fractions of vacancies under variable
conditions were detailly predicted. Besides, we found the vacancies are highly
kinetic stable, without recovering or aggregation. The Se vacancies in PtSe2
can dramatically enhance the HER performance, comparing with, even better than
Pt(111). Beyond, we firstly revealed that PtSe2 monolayer with Se vacancies is
also a good OER catalyst. The excellent bipolar catalysis of Se vacancies were
further confirmed by experimental measurements. We produced defective PtSe2 by
direct selenization of Pt foil at 773 K using a CVD process. Then we observed
the HER and OER performance of defective PtSe2 is much highly efficient than Pt
foils by a series of measurements. Our work with compelling theoretical and
experimental studies indicates PtSe2 with Se defects is an ideal bipolar
candidate for HER and OER.
