Systematic Bandgap Engineering of Graphene Quantum Dots and Applications for Photocatalytic Water Splitting and CO₂ Reduction

Abstract

Graphene quantum dots (GQDs), which is the latest addition to the nanocarbon material family, promise a wide spectrum of applications. Herein, we demonstrate two different functionalization strategies to systematically tailor the bandgap structures of GQDs whereby making them snugly suitable for particular applications. Furthermore, the functionalized GQDs with a narrow bandgap and intramolecular Z-scheme structure are employed as the efficient photocatalysts for water splitting and carbon dioxide reduction under visible light. The underlying mechanisms of our observations are studied and discussed.

High photoresponse and fast carrier mobility: Two‐dimensional rGO‐AgBr/Ag composite based on Z‐scheme heterointerface with plasma for hydrogen evolution

“…Obviously, the smallest Tafel slope and η of rGAA-2 reflect the high-efficient catalytic hydrogen production, [79][80][81] which is matched with the HER results. 82,83 Based on aforementioned research, the VLD catalytic mechanism of rGAA-α catalyst was confirmed to be the model as Figure 9. Generally, in M-S plots, the positive and negative slope of the linear region represent the electron donor characteristic and electron acceptor characteristic.…”

Dual Quantum Dot‐Decorated Bismuth Vanadate Photoanodes for Highly Efficient Solar Water Oxidation

“…To investigate the charge separation and transfer in this hybrid homojunction‐based CB/BVO‐NF photoanode, free‐standing BQDs with a similar size were prepared to estimate the electronic band position of BQD at the photoanode (Figure S11 and Table S2) . It is seen that the band gap increases from 2.49 to 2.61 eV upon decreasing the size from bulk down to nanoscale owing to the quantum confinement effect . Based on all the above results and analyses, a reaction scheme is proposed in Figure to illustrate the charge separation and transfer in the CB/BVO‐NF photoanode.…”

“…The band gap is greatly dependent on the size owing to quantum confinement effects. Hence, decreasing the size down to nanoscale by nano‐engineering provides a feasibility to tune the band position (both conduction and valence bands) . Nanoparticles of this type are also called quantum dots (QDs).…”

“…Hence, decreasing the size down to nanoscale by nano-engineering provides af easibility to tune the band position (both conduction and valence bands). [18] Nanoparticles of this type are also called quantum dots (QDs). Furthermore, smaller sized QDs facilitatet he migration of photo-induced charge carriers to the surface owing to the short diffusion distance.…”

A Supramolecular Approach to the Preparation of Nanographene Adlayers Using Water‐Soluble Molecular Capsules

“…[13] Fore xample,f unctionalized graphene quantum dots that allow the control of band gaps indicate the structural dependence of photocatalysts in water splitting and carbon dioxide reduction under visible-light irradiation. [13] Indeed, to date,anumber of attractive PA Hs have been synthesized by the Müllen group. [1, 12,14] Thedesign and synthesis of structurally defined PA Hs are essential for the creation of functional graphenes based on elemental doping and periodical defects (or vacancies) as the building blocks.However,large PA Hs without peripheral substituents are insoluble in both water and organic solvents.T he formation of adlayers on electrode surfaces is challenging because PA Hs without peripheral substituents are used as 2D molecular templates, [15] have applications in conductance enhancement between nanographene and Au junctions, [16] and are used in organic field-effect transistors (OFETs).…”