Dual‐Function HKUST‐1: Templating and Catalyzing Formation of Graphitic Carbon Nitride Quantum Dots Under Mild Conditions

Abstract

Graphitic carbon nitride quantum dots (g‐CNQDs) are highly promising photoresponsive materials. However, synthesis of monodispersed g‐CNQDs remains challenging. Here we report the dual function of MOF [Cu3BTC2] (HKUST‐1) as a catalyst and template simultaneously to prepare g‐CNQDs under mild conditions. Cyanamide (CA), a graphitic carbon nitride precursor, catalytically dimerized inside the larger MOF cavities at 90 °C and condensed into g‐CNQDs at 120 °C in a controlled fashion. The HKUST‐1 template was stable under the reaction conditions, leading to uniform g‐CNQDs with a particle size of 2.22±0.68 nm. The as prepared g‐CNQDs showed photoluminescence emission with a quantum yield of 3.1 %. This concept (MOF dual functionality) for catalyzing CA polycondensation (open metal sites (OMSs) effect) and controlling the produced particle size (pore‐templating effect), together with the tunable MOF porosity, is expected to produce unique g‐CNQDs with controllable size, morphology, and surface functionality.

Triazine-Based Graphitic Carbon Nitride Thin Film as a Homogeneous Interphase for Lithium Storage

“…In the thermal vapor deposition process, the semiclosed synthesis environment involves a higher partial pressure of the intermediates, such as cyanamide, and byproducts, such as ammonia, in the crucible. The Cu foil does not only serve as a substrate, but during the reaction, the Cu atoms diffuse from the substrate through the material, stabilizing the t-CN structure and preventing formation of heptazine rings via the triazine ring-opening and -closing pathway . The computational model showed that the heptazine unit is more thermodynamically stable than triazine in the graphitic phase under ambient conditions.…”

Modulating In‐Plane Defective Density of Carbon Nanotubes by Graphitic Carbon Nitride Quantum Dots for Enhanced Triiodide Reduction

“…Highresolution TEM images of CNQDs/MWCNTs-4 (Figure 1f) display clear lattice fringes with spacings of 0.34 and 0.21 nm, which correspond to the interlayer distance in MWCNTs and the (100) plane of CNQDs, respectively. [38,39] The chemical composition of different catalysts was investigated via XRD and X-ray photoelectron spectroscopy (XPS). The XRD patterns of MWCNTs and CNQDs/MWCNTs-x (Figure S7, Supporting Information) display two typical diffraction peaks at 26 o and 43 o , which match well with the (002) and (100) crystal planes of MWCNTs.…”

Emerging Trends of Carbon‐Based Quantum Dots: Nanoarchitectonics and Applications

“…In 2020, Albolkany et al reported the first example of using MOF as both template and catalyst to synthesize g-CNQDs. [105] First, the cyanamide precursor was filled in the pores of HKUST-1; then, the filled precursor was heated at a temperature of 120 °C for 15 h to achieve a high degree of catalytic polycondensation. In the end, the template was removed by etching the framework with 1 m HCl, followed by a cleanup procedure using liquid-liquid extraction and dialysis techniques.…”

“…Mild conditions, tailorable sizes and properties Need to remove template after synthesis [103] Paraffin oil and carbon disulphide (CS 2 )@carbon powder S-GQDs [104] Cyanamide@MOF [Cu 3 BTC 2 ] (HKUST-1) g-CNQDs [105] Pyrolysis Citric acid powder CQDs Easy operations, low-cost, solvent-free, and large-scale production Nonuniform size distribution [106] Citric acid GQDs [107] Hexa-peri-hexabenzocoronene GQDs [108] Solid-phase method Urea and sodium citrate g-CNQDs High quantum Yield, high yield with tunable PL characteristics Purification treatment is complicated and time-consuming [109] Melamine and EDTA g-CNQDs [110] Freeze-dried urea and CQDs precursor Tubular CQDimplanted g-C 3 N 4 heterostructures [111] Table 1 Hydrolysis is another interesting approach for the preparation of carbon-based QDs, as it can chemically cleave the carbon lattice under mild conditions with the help of a hydrolysis agent. For example, Zhou et al first adopted a chemical tailoring method to cleave the tri-s-triazine units of bulk g-C 3 N 4 via hydrolysis, as shown in Figure 4b.…”