Graphene quantum dot / graphene heterostructure Van der Waals Advances in water solutions junction photoelectrocatalysis

two-dimensional material assembly Van der Waals heterojunction constituted Because of efficient electronic coupling, electron hole pairs are separated, charge transfer, a low energy barrier, properties such as band gap adjustable recently aroused great interest in research. Northwestern Polytechnical University, Huang academician and the Nanyang Technological University Professor Chen Peng team rollout a new dimension 0/2 Weifan Edward heterojunction having excellent photoelectric properties of water solution, and easy to scale production . The heterojunction based on zero-dimensional quantum dots and graphene two-dimensional graphene sheets. Team Firstly, the structure of the simplest and most inexpensive PAHs (naphthalene) as graphene precursor quantum dots , to the water after the first thermally efficient synthesis of mono nitrated bottom-up elements or heteroaryl multi-element doped graphene quantum dots. Then use its amphiphilic characteristics graphene quantum dots as a surfactant and intercalation agent solution was sonicated by a graphite powder, quick release simple uniform monolayer graphene nanosheet. Graphene quantum dots by π-π interaction adsorbed on the surfaces of the graphite sheet to form an alkylene dimension 0/2 Weifan Edward heterojunction . DFT calculation synthesis mechanism disclosed in detail graphene quantum dots, and a zero-dimensional / 2 state density Weifan Edward heterojunction, Schottky barrier, charge density. Nitrogen sulfur doped graphene quantum dots with a narrow band gap can promote light absorption, low Schottky barrier and facilitate separation of the photogenerated charge transfer, a significant surface charge and the rearrangement of the surfactant-rich sites are conducive greatly improves catalytic performance of the photo-assisted water . Also, the total zero-dimensional carbon / 2 Weifan Edward heterojunction catalysts high stability , with the practical application. This new large van der Waals heterojunction can be prepared having a wide range of applications, such as new optoelectronic devices. Production cost graphene quantum dot, while achieving a heteroatom doped modification, this provides the possibility of practical application of the new zero-dimensional carbon material widely. Meanwhile, the work is easy and efficient production of a monolayer of pure graphene sheet provides a new method. Figure 1. Synthesis and Characterization of graphene quantum dots Analysis: naphthalene-based material and water to heat the nitration prepared graphene quantum dots, about the size of 5.62nm, the most basic 546nm in single and double thickness, optimal fluorescence emission. 2. Synthesis of the mechanism of FIG graphene quantum dots Analysis: The most simple and inexpensive PAHs (naphthalene) as a starting material, the hydrothermal synthesis after the first quantum graphene nitrated point mechanism is based on the molecular-dinitro naphthalene dehydrogenation denitration gradual integration. Characterization of nitrogen doped nitrogen doped sulfur, sulfur-doped graphene quantum dots Figure 3. Analysis: the sulfur-doped nitrogen doped nitrogen doped sulfur graphene quantum dot doping element due the electron donating effect, so that the fluorescent red-shifted, narrow-band-gap light absorption enhancement. 0 Dimension Figure 4. graphene quantum dots formed by ultrasonic peeling graphene / 2 Weifan Edward heterojunction photo-applied water Analysis: Graphene quantum dots as amphiphilic surfactant and the release agent layer interposed graphene 0 3D / Weifan Edward heterojunction formed has good light generated electron-hole pair separation action, wherein the nitrogen-doped quantum dots sulfur graphene / graphene catalyst the most superior light current, and photo-charge conduction properties of water. Figure 5. graphene different quantum dot / graphene heterojunction DFT calculation van der Waals state density, charge distribution and Schottky barrier Analysis: doped with nitrogen sulfur graphene quantum dot / graphene heterojunction having the lowest Van Der Waals Schottky barrier, most electronic coupling, and the most significant charge rearrangement. 6. The optical and electrical FIG synergistic promoting effect Analysis: a nitrogen-doped quantum dots sulfur graphene / graphene heterojunction van der Waals catalyst having enhanced photogenerated current is gradually promoted and electrically-generated current, discloses synergistic electrocatalytic and photocatalytic promoted. Northwestern Polytechnical University, Huang academician and the Nanyang Technological University Professor Chen Peng as a co-corresponding author. Huang academician is in the field of polymer materials and nano-photovoltaic leader. Nanyang Technological University Professor Chen Peng graphiteOutstanding researchers alkenyl material (including a graphene quantum dots) in the field of biomedical research and energy applications. This work with \”van der Waals Heterojunction between Bottom-Up Grown Doped Graphene Quantum Dot and Graphene for Photoelectrochemical Water Splitting\” was published in ACS Nano Journal article link: https://doi.org/10.1021/acsnano.9b09554