Graphitic Carbon Nitride Nanorods for Photoelectrochemical Sensing of Trace Copper(II) Ions

Graphitic carbon nitride derived probes for the recognition of heavy metal pollutants of environmental concern in water bodies

Graphitic carbon nitride (g-CN) has a number of valuable features that have been recognized during the studies related to its photocatalytic activity enhancement derived by visible light. Because of these characteristics, g-CN can be used as a detecting signal transducer with different transmission modalities. The latest up-to-date detection capabilities of modified g-CN nanoarchitectures are covered in this study. The structural features and synthetic methodologies have been discussed in a number of reports. Herein, employment of the g-CN as a promising probing modality for the recognition of different toxic heavy metals is the promising feature of the present study.

Co3O4 Nanocrystals with an Oxygen Vacancy-Rich and Highly Reactive (222) Facet on Carbon Nitride Scaffolds for Efficient Photocatalytic Oxygen Evolution

Oxygen evolution reaction (OER) with sluggish kinetics is the rate-determining step of water splitting, which dominates the solar-to-hydrogen fuel conversion efficiency. Herein, we constructed an oxygen vacancy-rich and highly reactive (222) facet in Co₃O₄ nanocrystals anchored on carbon nitride nanofiber (CNF) by a solvothermal reduction method. The resulting Co₃O₄ nanocrystals/CNF (COCNF) demonstrated a dramatically enhanced OER with a rate of 24.9 μmol/h under visible light, which is 124 times higher than that of CNF. This excellent catalytic activity of COCNF is based on a synergistic effect between its binary components for charge separation, oxygen vacancies for enhanced conductivity, and facet (222) exposure of Co₃O₄ nanocrystals for improved heterogeneous kinetics. Density functional theory (DFT) calculations revealed the water oxidation mechanism at different facets and found that the formed oxygen vacancies lead to a reduction of the materials' bandgap. The correlation between Co₃O₄ crystal facets and the inherent OER catalytic activities under acidic solution was in the order of (222) > (220) > (311).

Emerging trends in sensors based on carbon nitride materials

A new class of functional materials, carbon nitrides, has recently attracted the attention of researchers.

Graphitic Carbon Nitride Doped with the s-Block Metals: Adsorbent for the Removal of Methyl Blue and Copper(II) Ions

The synthesis of graphitic carbon nitride (g-C₃N₄) doped with s-block metals is described. The materials were synthesized via thermal polycondensation of cyanamide and the appropriate metal chloride. The inclusion of the metal precursor strongly influenced the surface chemistry features as well as the textural, morphological, and structural properties of the g-C₃N₄. The doping of g-C₃N₄with s-block metals markedly enhanced its adsorption performance, which was studied during the removal of two model solutes (methyl blue and copper ions) from aqueous solutions. The maximum adsorption capacity for the organic dye was increased by 680 times after the doping process. The uptake of copper(II) increased ca. 30 times for the doped g-C₃N₄. The improvement of the adsorption performance is discussed in terms of the surface chemistry and textural features.

An Electrochemical Sensor of Poly(EDOT-pyridine-EDOT)/Graphitic Carbon Nitride Composite for Simultaneous Detection of Cd2+ and Pb2

In this study, poly(2,5-bis(3,4-ethylenedioxythienyl)pyridine)/graphitic carbon nitride composites (poly(BPE)/g-C₃N₄) were prepared by an in situ chemical polymerization method. Composites were characterized by using Fourier transform infrared spectroscopy (FT-IR), ultraviolet⁻visible absorption spectra (UV⁻vis), X-ray diffraction (XRD), energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), and transmission electron microscopy (TEM). Furthermore, electrochemical sensors were applied for the electrochemical determination of Cd²⁺ and Pb²⁺ using the differential pulse voltammetry (DPV) method. The results indicated that 10 wt % poly(BPE)/g-C₃N₄ composite-modified electrode exhibited linear detection ranging from 0.12 to 7.2 μM and 0.08 to 7.2 μM for Cd²⁺ and Pb²⁺, with detection limits (S/N = 3) of 0.018 μM and 0.00324 μM. Interference analysis suggested that the 10 wt % poly(BPE)/g-C₃N₄-modified electrode can be applied for the detection of the Cd²⁺ and Pb²⁺ in real samples.

Anion-exchange reactions: facile and general access to sensitive photoelectrochemical platforms for biomarker immunosensing

The combination of CdSe NCs with biocatalytic precipitation provides a highly sensitive immunosensing strategy.

Detection of Ag(+) using graphite carbon nitride nanosheets based on fluorescence quenching

The graphite carbon nitride (g-C3N4) nanosheets were synthesized and applied for the detection of Ag(+) ion in aqueous solutions. Transmission electron microscopy, Fourier infrared spectroscopy, x-ray diffraction, ultraviolet/visible and photoluminescence spectroscopy were used for characterization of g-C3N4 nanosheets. The fluorescence intensity of g-C3N4 nanosheets decreases with the increase in the concentration of Ag(+). The fluorescence probe can be applied for detection of Ag(+). The results show that it has high selectivity to Ag(+) and exhibits a good linearity over the concentration range 0.020-2.0μM with a detection limit of 27nM. Most cations do not have any interference on the detection of Ag(+). The quenching process is assessed and discussed. Finally, the g-C3N4 nanosheets have been successfully used for the detection of Ag(+) in real water samples. The recoveries of spiked water samples are >97%.

Graphitic Carbon Nitride Materials: Sensing, Imaging and Therapy

Graphitic carbon nitrides (g-C₃ N₄ ) are a class of 2D polymeric materials mainly composed of carbon and nitrogen atoms. g-C₃ N₄ are attracting dramatically increasing interest in the areas of sensing, imaging, and therapy, due to their unique optical and electronic properties. Here, the luminescent properties (mainly includes photoluminescence and electrochemiluminescence), and catalytic and photoelectronic properties related to sensing and therapy applications of g-C₃ N₄ materials are reviewed. Furthermore, the fabrication and advantages of sensing, imaging and therapy systems based on g-C₃ N₄ materials are summarized. Finally, the future perspectives for developing the sensing, imaging and therapy applications of the g-C₃ N₄ materials are discussed.

Photoelectrochemical detection of metal ions

Depending on the situation, metal ions may either play beneficial roles or be harmful to human health and ecosystems. Sensitive and accurate detection of metal ions is thus a critical issue in the field of analytical sciences and great efforts have been devoted to the development of various metal ion sensors. Photoelectrochemical (PEC) detection is an emerging technique for the bio/chemical detection of metal ions, and features a fast response, low cost and high sensitivity. Using representative examples, this review will first introduce the fundamentals and summarize recent progress in the PEC detection of metal ions. In addition, interesting strategies for the design of particular PEC metal ion sensors are discussed. Challenges and opportunities in this field are also presented.

An electrochemical sensor based on rhodamine B hydrazide-immobilized graphene oxide for highly sensitive and selective detection of Cu(ii)

A novel Cu²⁺ sensor based on rhodamine B hydrazide (RBH)-immobilized graphene oxide (GO) was fabricated and estimated to be a detection limit of 0.061 nM for Cu²⁺ detection.