A Review on Hybrid Graphene Oxide and Graphene Quantum Dot Nanostructures for Sensing, Photocatalysis, and Nonlinear Optical Properties

ABSTRACT The two‐dimensional layered architecture of sp 2 ‐hybridized carbon atoms, also known as graphene, is the fundamental substructure of various carbon allotropes, including graphite, carbon nanotubes, and fullerenes. This super‐thin material exhibits remarkable properties, including exceptional mechanical strength, optical transparency, and excellent electronic and photonic conductance. Before the outstanding properties of few‐layered graphene sheets were discovered, graphene was considered thermodynamically unstable and were widely used in theoretical studies of 3D allotropes of carbon. Due to the exceptional properties and remarkably high application potential, research momentum in the graphene‐related area is exceptionally high. However, unlike the allotropes of carbon, graphene exhibits exceptionally high mechanical strength, conductance, and optical transparency. However, due to the tradeoff between yield and the cost of fabricating pristine graphene, most researchers are focused on the functional derivatives of graphene. Unfortunately, the properties of graphene derivatives are inferior to those of pristine graphene. The engineered hybrids of graphene derivatives can overcome limitations by incorporating the complementary properties of their constituents. This review critically addresses the functional applications of graphene oxide and graphene quantum dots and their engineered hybrids, highlighting the developments over the last 10 years for surface enhanced Raman spectroscopy, photocatalysis, photoluminescence sensing, and nonlinear optical applications.