In
this work, different alkaline earth metals intercalated into
g-C3N4 (MCN, M = Ca, Sr, Ba) were prepared through
the calcination of alkaline earth metal chlorides (MCl2, M = Ca, Sr, Ba) and melamine. The crystallite sizes of Bulk CN,
BaCN, SrCN, and CaCN are 4.6, 4.8, 1.9, and 1.5 nm, respectively.
In order to efficiently transfer charges among the g-C3N4 layers, the alkaline earth metal ions were designed
as a “bridge”, which could chemically bond with the
atoms of two adjacent layers while connecting the upper and lower
layer. It is found that the cyano groups appearing on the MCN skeleton
have a strong electron-attracting effect, which has a good guiding
effect on promoting the separation of electrons and holes. The results
of density functional theory further confirmed that BaCN had the strongest
adsorption energy for peroxymonosulfate. Experiment results showed
that the BaCN photocatalyst exhibited an excellent bisphenol A (BPA)
degradation activity in the presence of peroxymonosulfate. The results
showed that the performance of the BaCN photocatalyst to degrade BPA
under visible light was 12 times that of CN. Meanwhile, the BaCN photocatalyst
still had a 95% efficiency of BPA removal after four cycles of the
experiment. The possible reaction mechanism in the degradation process
was analyzed through electron spin resonance and capture experiments.
This paper provides an idea for the comodification of g-C3N4 with alkali earth metals and cyanide groups to activate
peroxymonosulfate.