Effects of pyridine-like and pyrrolic-like nitrogen on the photoluminescence blue-shift of nitrogen-doped graphene oxide quantum dots

Highlights: • The PL of N-doped graphene oxide quantum dots (NGOQDs) exhibits a maximal blue-shift of 88 nm compared to that of the GOQDs. • Doping of pyridine-like and pyrrolic-like nitrogen can tune the band gap of GOQDs. • Density functional theory calculations support the above results. Materials with tunable photoluminescence (PL) are highly desirable. It can lead to important applications such as photodetectors, bio-imaging, and broadband modulators. In this work, nitrogen-doped graphene oxide quantum dots (NGOQDs) were synthesized by hydrothermal method. The microstructures as well as optical properties of NGOQDs were studied. The as-prepared NGOQDs present tunable PL and exhibit a maximal PL blue-shift of ca. 88 nm compared to that of the graphene oxide quantum dots (GOQDs). The observed PL blue-shift of the NGOQDs is attributed to the high content of pyridine-like and pyrrolic-like nitrogen atoms doping in the NGOQDs. Our proposed mechanism for the PL blue-shift of the NGOQDs is supported by density functional theory (DFT) calculations.