The discharge of
synthetic dyes from different industrial sources
has become a global issue of concern. Enormous amounts are released
into wastewater each year, causing concerns due to the high toxic
consequences. Photocatalytic semiconductors appear as a green and
sustainable form of remediation. Among them, graphitic carbon nitride
(g-C
3
N
4
) has been widely studied due to its
low cost and ease of fabrication. In this work, the synthesis, characterization,
and photocatalytic study over methylene blue of undoped, B/S-doped,
and exfoliated heterojunctions of g-C
3
N
4
are
presented. The evaluation of the photocatalytic performance showed
that exfoliated undoped/S-doped heterojunctions with 25, 50, and 75
mass % of S-doped (g-C
3
N
4
) present enhanced
activity with an apparent reaction rate constant (
k
app
) of 1.92 × 10
–2
min
–1
for the 75% sample. These results are supported by photoluminescence
(PL) experiments showing that this heterojunction presents the less
probable electron–hole recombination. UV–vis diffuse
reflectance and valence band-X-ray photoelectron spectroscopy (VB-XPS)
allowed the calculation of the band-gap and the valence band positions,
suggesting a band structure diagram describing a type I heterojunction.
The photocatalytic activities calculated demonstrate that this property
is related to the surface area and porosity of the samples, the semiconductor
nature of the g-C
3
N
4
structure, and, in this
case, the heterojunction that modifies the band structure. These results
are of great importance considering that scarce reports are found
concerning exfoliated B/S-doped heterojunctions.