Nitrogen-Doped Graphene Quantum Dots for Remarkable Solar Hydrogen Production

Abstract

We synthesized nitrogen (N)-doped graphene quantum dots (N-GQDs) using a top-down hydrothermal cutting approach. The concentration of N dopants was readily controlled by adjusting the concentration of the N source of urea. When N dopants were incorporated into GQDs, visible absorption was induced by C–N bonds, which created another pathway for generating photoluminescence (PL). Time-resolved PL data revealed that the carrier lifetime of GQDs was increased upon doping with the optimized N concentration. The photoelectrochemical properties of N-GQDs toward water splitting were studied, and the results showed that 2N-GQDs prepared with 2 g of urea produced the highest photocurrent. The photocatalytic activity of 2N-GQDs powder photocatalyst for hydrogen production was also examined under AM 1.5G illumination, showing substantial enhancement over that of pristine GQDs. Electrochemical impedance spectroscopy data further revealed a significant improvement in charge dynamics and reaction kinetics and an increased carrier concentration as a result of N doping.

Cold‐Resistant Nitrogen/Sulfur Dual‐Doped Graphene Fiber Supercapacitors with Solar–Thermal Energy Conversion Effect

“…A comparative experiment is adopted to further explore the effect of the 1 sun irradiation on the NS‐GF 2 electrodes, and the supercapacitor is operated at an ambient temperature of 40 °C to eliminate the influence of temperature, showing a similar discharge time to that at room temperature (Figure 7 f). Therefore, the improvement in charge storage ability should come from the increased carrier lifetime owing to the photocatalytic effect of the heteroatoms [66] . The long‐lived charge carriers are more likely to participate in redox reactions or are stored as an electric double layer capacitor before they are recombined.…”

“…Therefore, the improvement in charge storage ability should come from the increased carrier lifetime owing to the photocatalytic effect of the heteroatoms. [66] The long-lived charge carriers are more likely to participate in redox reactions or are stored as an electric double layer capacitor before they are recombined. Solar-thermal conversion effect of PVA/H 2 SO 4 /GO electrolyte on electrochemical performance of the all-solid-state NS-GF 2 supercapacitor at freezing temperature…”

Yolk–shell nanostructures: synthesis, photocatalysis and interfacial charge dynamics

“…Till now, various composite nanostructures have been proposed as the photocatalyst paradigm to construct superior photocatalytic systems. Representative examples are doped/ alloyed nanocrystals, [11][12][13][14][15][16] particle-decorated nanostructures, heterodimers, 41 core-shell nanocrystals, [42][43][44][45][46][47] and yolk-shell nanostructures. 48,49 Here, yolk-shell nanostructures stand for a newly emerging photocatalyst platform, which are composed of a movable core surrounded by a permeable shell with void space.…”

Review on Colloidal Quantum Dots Luminescent Solar Concentrators

“…Much attention has been given to QDs as ideal luminophores for their wide absorption spectra, controllable emission spectra, and high stability [24–30] . In addition to applications in LSC technology, the controllable emissions spectra of QDs have enabled the development of QDs as a photocatalyst in hydrogen production [31–36] . The color conversion properties of QDs lead to their application in high‐efficiency LEDs [37–43] .…”