Background: The present scenario of rapid industrial and population growth has become a
serious threat to environmental and energy concerns. Extremely noxious pollutants like dyes, heavy
metal ions, phenols, antibiotics and pesticides in water are the reason behind deprived water quality
leading to inadequate access to clean water. Photocatalysis is a prominent strategy for environmental
remediation as photocatalytic materials not only convert solar energy into usable energy expedient
but also shows potential application in pollutant mitigation. An effectual photocatalytic system must
possess wide visible absorption range, high physio-chemical firmness, and effective space-charge
separation along with strong redox ability. Polymeric graphitic carbon nitride a metal-free semiconductor
photocatalyst has outshined as a robust photocatalyst for various photocatalytic applications.
Methods: Hybridizing polymeric g-C3N4 with other semiconductor photocatalysts has not only conquer
the limitations related to pristine g-C3N4 but also displayed improved photoactivity. Different
photocatalytic systems involving g-C3N4 coupled metal-oxides, metal-free systems and complex heterojunction
systems are reviewed. Moreover, an all-embracing study based on g-C3N4 based nanocatalysts
is explored via heterojunction formation taking g-C3N4 as one component.
Results: Photocatalytic experiments involving photodegradation of pollutants, revealed the significance
of metal-free g-C3N4 in the heterojunction system which remarkably boost the photoactivity
through effective separation and migration of photocarriers. Moreover, from recyclability experiments,
exceptional photostability of g-C3N4 based photocatalysts was observed. Photocatalytic pollutant
degradation is a complex phenomenon which requires significant experimental techniques to
support the mechanism. With the help of photoelectrochemical analysis, the mechanisms behind photodegradation
can be evaluated and explored.
Conclusion: Metal-free polymeric g-C3N4 is a potential semiconductor photocatalyst which can be
optimally utilized for wastewater treatment. Coupling g-C3N4 with another semiconductor material
with an appropriate band edge can effectively enhance the photocatalytic efficacy. Herein, g-C3N4
derived metal-oxide, metal-free and complex heterojunction systems are explored and their photocatalytic
efficiency is evaluated for pollutant degradation. However, more effective research efforts
are needed for large-scale applications of g-C3N4 based photocatalysts.