Cobalt doped graphitic carbon nitride as an effective catalyst for peracetic acid to degrade sulfamethoxazole

In this study, cobalt doped graphitic carbon nitride (Co–CN) was prepared and applied as a catalyst to activate peracetic acid (PAA) for sulfamethoxazole (SMX) degradation at neutral pH. PAA could be efficiently activated by Co–CN resulting in the efficient degradation of SMX. Characterization results of fresh and used Co–CN suggested that cobalt was successfully doped in graphitic carbon nitride (g-C₃N₄) through chemical bonding (Co–N bond) and the surface cobalt species in Co–CN (i.e., Co(ii) and Co(iii)) were the main activators for PAA. Organic radicals (i.e., CH₃C(O)O˙ and CH₃C(O)OO˙) were proved to be the dominant reactive species for SMX removal in the Co–CN/PAA system by radical scavenging experiments. The increase of cobalt doping content, PAA dosage or Co–CN dosage could accelerate SMX degradation and the neutral condition was highly favorable to SMX removal in Co–CN/PAA system. Co–CN exhibited a good stability and reusability for PAA activation in degrading SMX. Four possible degradation pathways of SMX (i.e., hydroxylation, nitration, bond cleavage and coupling reaction) were proposed in the Co–CN/PAA system according to eight identified transformation products.

An efficient advanced oxidation process (AOP) for sulfamethoxazole (SMX) removal: peracetic acid activated with cobalt doped graphitic carbon nitride.     

Confining the polymerization degree of graphitic carbon nitride in porous zeolite-Y and its luminescence

Graphitic carbon nitride (g-C₃N₄) has aroused broad interest in the field of photocatalysis and luminescence as a kind of metal-free semiconductor with a suitable band gap of ∼2.7 eV. The properties largely depend on the polymerization degree of g-C₃N₄. This research exploits the nanocages of zeolite-Y to confine the polymerization of the melamine monomer to form g-C₃N₄. The composites are achieved via a facile two-step method, i.e., melamine–Na⁺ ion exchange reaction in the cage of the zeolite and subsequent calcination. BET measurement and transmission electron microscopy (TEM) confirm that the g-C₃N₄ is encapsulated in zeolite-Y, and the polymerization degree can be controlled by the melamine contents exchanged with Na⁺ in the cages of zeolite-Y. Photoluminescence and vibration spectroscopy also show the features of g-C₃N₄ with different polymerization degrees in the zeolite-Y composites. This research gives a perspective of fabricating subnanoscale g-C₃N₄ in porous zeolite, which may find potential applications in photocatalysis and optoelectronics.

The composites of porous zeolite-Y and graphitic carbon nitride can be synthesized via a facile two-step method, and the polymerization degree of the latter can be confined by the former.     

Scalable nanohybrids of graphitic carbon nitride and layered NiCo hydroxide for high supercapacitive performance

The limited number of edge nitrogen atoms and low intrinsic electrical conductivity hinder the supercapacitive energy storage applications of the nitrogen-rich graphitic carbon nitride (g-C₃N₄). In this study, a novel graphitic carbon nitride/NiCo-layered double hydroxide (CNLDH), a two-dimensional nanohybrid, is prepared by a simple hydrothermal synthesis. The homogeneous interpolation of g-C₃N₄ nanosheets into NiCo LDH stacked nanosheets effectively increases the overall performances of the g-C₃N₄/NiCo LDH nanohybrid. The improved morphology of the nanohybrid electrode upon the addition of g-C₃N₄ to the NiCo LDH yields a specific capacity of 183.43 mA h g⁻¹ in 6 M KOH at 1 A g⁻¹, higher than those of bare g-C₃N₄ (20.89 mA h g⁻¹) and NiCo LDH (95.92 mA h g⁻¹) electrodes. The excellent supercapacitive performance of the CNLDH nanohybrid is complemented by its low internal resistance, excellent rate capability, and large cycling lifetime. Furthermore, the hybrid supercapacitor is assembled using CNLDH 0.1 as a positive electrode and activated carbon (AC) as a negative electrode. The hybrid supercapacitor device of CNLDH 0.1//AC shows the maximum specific capacity of 37.44 mA h g⁻¹ at 1 A g⁻¹ with remarkable energy density, power density and good cycling performance. This confirms that the CNLDH 0.1 nanohybrid is an excellent electrode material for supercapacitor applications.

A two dimensional CNLDH 0.1 nanohybrid supercapacitor electrode prepared by simple hydrothermal hybridization of g-C₃N₄ and NiCO LDH shows the maximum specific capacity of 183.43 mA h g⁻¹ with remarkable electrochemical performance.     

Electrostatic interaction mechanism of visible light absorption broadening in ion-doped graphitic carbon nitride

Broadening the light response of graphitic carbon nitride (CN) is helpful to improve its solar energy utilization efficiency in photocatalytic reaction. In this work, a facile synthesis method was developed via the treatment of potassium-doped CN (CN–K) with H₂O₂ in isopropanol solvent. Various characterizations indicate the basic structure of CN–K treated with H₂O₂ (CN–K–OOH) resembles that of CN–K, while it presents light absorption up to 650 nm. A series of control experiments and TGA-MS measurements suggest the weak electrostatic attraction between potassium ions and hydroperoxyl groups inside CN–K–OOH is responsible for its enhanced visible light absorption. As a consequence, compared to pristine CN, the photodegradation organic pollutant ability of CN–K–OOH is obviously improved under visible light irradiation (>470 nm). The current synthesis strategy might be universal and it could be applied to other cations.

H₂O₂ treated K-doped graphitic carbon nitride presents an enhanced visible light absorption, which is due to the electrostatic attraction between K ions and OOH ions inside graphitic carbon nitride.     

Basic ionic liquid as catalyst and surfactant: green synthesis of quinazolinone in aqueous media

Basic imidazolium-based ionic liquids not only possess the extraordinary physicochemical properties of ionic liquids, but also have excellent basicity and surfactivity. 1-Propyl-3-alkylimidazole hydroxide ionic liquids ([PRIm][OH]) were synthesized and their catalytic and surfactant behavior were studied in this work. [PRIm][OH] owned excellent surfactivity, and their alkyl chains and ion pairs benefit hydrophobicity and hydrophilicity respectively. The surfactivity of [PRIm][OH] increased with increasing alkyl chain length. [PRIm][OH] showed better catalytic performance than NaOH in the condensation of 2-aminobenzonitrile with cyclohexanone in aqueous medium, and the catalytic performance was well coincident with their surfactant behavior. [PRIm][OH] could decrease the interfacial tension of solvent effectively and form micelles in water. The formed micelles could solubilise more reactants into water and effectively increase the chance of contact between reactants and catalytic active sites. The catalyst dosage obviously affected catalytic performance. The catalytic system is a promising recyclable system.

[PRIm][OH] showed excellent catalytic properties in synthesis of quinazolinone in aqueous medium, owing to its excellent surfactivity and basicity.     

A comparison study of sodium ion- and potassium ion-modified graphitic carbon nitride for photocatalytic hydrogen evolution

It is well known that modifying graphitic carbon nitride (GCN) is an imperative strategy to improve its photocatalytic activity. In this study, Na-doped and K-doped graphitic carbon nitride (GCN-Na and GCN-K) were prepared via the simple thermal polymerization of a mixture of melamine and NaCl or KCl, respectively. The structure characterization showed that both Na⁺ and K⁺ intercalation could reduce the interlayer distance of GCN and introduce cyano defects in GCN, while K⁺ apparently had a stronger influence on the structure variation of GCN. The chemical composition data showed that both Na⁺ and K⁺ could easily interact with GCN, while K-doping caused a greater change in the C/N ratio than Na-doping. Moreover, compared to GCN-Na-5 (5 represents weight ratio of alkali halide to melamine), the conduction and valence bands of GCN-K-5 both shifted upward based on the electronic and optical measurements. Consequently, GCN-K-5 yielded an H₂ evolution rate around 4 times higher than that of GCN-Na-5 under visible light irradiation (>420 nm). The cation size effect on GCN was proposed to be mainly responsible for the variation in the structure, optical and electronic properties of ion-doped GCNs, and hence the enhanced photocatalytic H₂ evolution. The current work can provide new insight into optimizing photocatalysts for enhanced photocatalytic performances.

The ion size effect on graphitic carbon nitride is responsible for variations in its structure, optical and electronic properties, and hence the enhancement in photocatalytic hydrogen evolution.     

Effect of calcination temperature,pH and catalyst loading on photodegradation efficiency of urea derived graphitic carbon nitride towards methylene blue dye solution

In this study, the photodegradation of methylene blue (MB) dye was performed using urea based graphitic carbon nitride (g-C₃N₄). Interestingly, it has been observed that the calcination temperature for the synthesis of g-C₃N₄ along with factors (pH and catalyst loading) influencing the photodegradation process, can make an impactful improvement in its photodegradation activity towards MB dye solution. The concept behind the comparatively improved photoactivity of g-C₃N₄ prepared at 550 °C was explored using various characterisation techniques like XRD, FTIR, SEM, BET and DRS. The FTIR and XRD patterns demonstrated that synthesis of g-C₃N₄ took place properly only when the calcination temperature was above 450 °C. The evolution of morphological and optical properties based on calcination temperature led to dramatically increased BET surface area and a decreased optical band gap value of g-C₃N₄ prepared at 550 °C. The effects of pH conditions and catalyst concentration on the MB dye degradation rate using optimally synthesised g-C₃N₄ are discussed. The value of the apparent rate constant was found to be 12 times more in the case of photodegradation of the MB dye using g-C₃N₄ prepared at 550 °C at optimum pH and catalyst loading conditions when compared with g-C₃N₄ prepared at 450 °C showing the lowest photoactivity potential. Further, high stability of the photocatalyst was observed for four cyclic runs of the photocatalytic reaction. Hence, g-C₃N₄ can be considered as a potential candidate for methylene blue photodegradation.

The appropriate synthesis temperature and optimized photodegradation reaction conditions result in an appreciable enhancement of the photocatalytic activity of urea derived innate g-C₃N₄ towards MB dye degradation.     

Recent advances in visible-light graphitic carbon nitride (g-C3N4) photocatalysts for chemical transformations

Graphitic carbon nitride (g-C₃N₄) has emerged as a new research hotspot, attracting broad interdisciplinary attention in the form of metal-free and visible-light-responsive photocatalysts in the field of solar energy conversion and environmental remediation. These photocatalysts have evolved as attractive candidates due to their non-toxicity, chemical stability, efficient light absorption capacity in the visible and near-infrared regions, and adaptability as a platform for the fabrication of hybrid materials. This review mainly describes the latest advances in g-C₃N₄ photocatalysts for chemical transformations. In addition, the typical applications of g-C₃N₄-based photocatalysts involving organic transformation reactions are discussed (synthesis of heterocycles, hydrosulfonylation, hydration, oxygenation, arylation, coupling reactions, etc.).

Graphitic carbon nitride (g-C₃N₄) has emerged as a new research hotspot, attracting broad interdisciplinary attention in the form of metal-free and visible-light-responsive photocatalysts.     

Construction of a non-enzymatic electrochemical sensor based on graphitic carbon nitride nanosheets for sensitive detection of procalcitonin

In this study, we established a label free and ultrasensitive electrochemical sensor based on graphitic nitride nanosheets (g-C₃N₄ NS) for procalcitonin (PCT) detection. Firstly, an easy-to-prepare and well-conducting g-C₃N₄ NS was synthesized. Next the g-C₃N₄ NS was immobilized on the electrode surface by π–π stacking, and further used to anchor the specific recognition peptide (PP). The surface morphology and structure after g-C₃N₄ NS and PP modification was characterized by X-ray photoelectron spectroscopy (XPS), atomic force microscopy (AFM) and electrochemistry. The sensing property of this sensor was evaluated by differential pulse voltammetry (DPV) and showed a detection sensitivity with a dynamic range from 0.15 to 11.7 fg mL⁻¹ with a low limit of detection (LOD) of 0.11 fg mL⁻¹. Besides, the electrochemical biosensor was successfully used to detect PCT in human serum samples, and the results suggest its potential use in clinical application.

A simple and ultra-sensitive electrochemical biosensor based on graphitic carbon nitride nanosheets (g-C₃N₄ NS) was developed for the detection of PCT. This sensor presented excellent sensing performance and demonstrates potential for clinical application.     

Synthesis of oxygen-doped graphitic carbon nitride and its application for the degradation of organic pollutants via dark Fenton-like reactions

Graphitic carbon nitride (g-C₃N₄) is a promising photocatalyst for environmental protection but its development is greatly limited for its application in dark Fenton-like reactions due to its extremely low specific surface area and lack of suitable active sites. Herein, for the first time, graphitic carbon nitride with large surface area and abundant defect sites was developed by tailoring oxygen via a simple and green method without any templates, namely, the calcination–hydrothermal–calcination successive treatment of melamine. The structure of the catalyst was characterized using several technologies, including XRD, SEM, TEM, N₂-physisorption, FT-IR, Raman spectroscopy and XPS. The results revealed that it possessed a large specific surface area (ca. 236 m² g⁻¹), while changes in its structural properties such as the formation of new defect sites and change in the content of nitrogen atoms were observed. These properties were beneficial for the in situ activation of H₂O₂ toward reactive oxygen species, as confirmed by the reactive oxygen species capturing experiments. Furthermore, various influencing factors were systemically investigated. The results clearly showed that the oxygen-doped g-C₃N₄ was light-independent and metal-free Fenton-like catalyst for the enhanced degradation of organic pollutants in wastewater. Compared to the pristine g-C₃N₄, the oxygen-doped g-C₃N₄ showed superior performance under various conditions such as broad pH range and excellent stability. Thus, this study provides a novel pathway for the treatment of organic pollutants in water.

Graphitic carbon nitride (g-C₃N₄) is a promising photocatalyst for environmental protection but its development is greatly limited for its application in dark Fenton-like reactions due to its extremely low specific surface area and lack of suitable active sites.     

An insight into the sodium-ion and lithium-ion storage properties of CuS/graphitic carbon nitride nanocomposite

Metal sulfides are gaining prominence as conversion anode materials for lithium/sodium ion batteries due to their higher specific capacities but suffers from low stability and reversibility issues. In this work, the electrochemical properties of CuS anode material has been successfully enhanced by its composite formation using graphitic carbon nitride (g-C₃N₄). The CuS nanoparticles are distributed evenly in the exfoliated g-C₃N₄ matrix rendering higher electronic conductivity and space for volume alterations during the repeated discharge/charge cycles. The 0.8CuS:0.2g-C₃N₄ composite when used as an anode for lithium ion coin cell exhibits a reversible capacity of 478.4 mA h g⁻¹ at a current rate of 2.0 A g⁻¹ after a run of 1000 cycles which is better than that reported for CuS composites with any other carbon-based matrix. The performance is equally impressive when 0.8CuS:0.2g-C₃N₄ composite is used as an anode in a sodium ion coin cell and a reversible capacity of 408 mA h g⁻¹ is obtained at a current rate of 2.0 A g⁻¹ after a run of 800 cycles. A sodium ion full cell with NVP cathode and 0.8CuS:0.2g-C₃N₄ composite anode has been fabricated and cycled for 100 runs at a current rate of 0.1 A g⁻¹. It can be inferred that the g-C₃N₄ matrix improves the ion transfer properties, alleviates the volume alteration happening in the anode during the discharge/charge process and also helps in preventing the leaching of polysulfides generated during the electrochemical process.

Metal sulfides are gaining prominence as conversion anode materials for lithium/sodium ion batteries due to their higher specific capacities but suffers from low stability and reversibility issues.     

Highly efficient pollutant removal of graphitic carbon nitride by the synergistic effect of adsorption and photocatalytic degradation

Environmental remediation based on semiconducting materials offers a green solution for pollution control in water. Herein, we report a novel graphitic carbon nitride (g-C₃N₄) by one-step polycondensation of urea. The novel g-C₃N₄ material with a surface area of 114 m² g⁻¹ allowed the repetitive adsorption of the rhodamine B (RhB) dye and facilitated its complete photocatalytic degradation upon light irradiation in 20 min. This study provides new insights into the fabrication of g-C₃N₄-based materials and facilitates their potential application in the synergistic removal of harmful organic pollutants in the field of water purification.

A novel g-C₃N₄ with strong adsorption capability and efficient photocatalysis activity was prepared by heating urea through a facile method.     

Oxygen doped graphitic carbon nitride nanosheets for the degradation of organic pollutants by activating hydrogen peroxide in the presence of bicarbonate in the dark

The development of novel wastewater treatment processes that use heterogeneous catalysts to activate hydrogen peroxide (H₂O₂) with bicarbonate (HCO₃⁻) has been a subject of great interest in recent years; however, significant challenges remain, despite research into numerous metal-based catalysts. The work presented herein employed oxygen-doped graphitic carbon nitride (O/g-C₃N₄) as a non-metal catalyst for activating H₂O₂ in the presence of HCO₃⁻, and this method represented the first system capable of removing organic pollutants in the dark, to our knowledge. The catalysts were characterized using several microscopic imaging, spectroscopic, electrochemical, and crystallographic techniques, as well as N₂-physorption procedures. Analysis of the results revealed that the O/g-C₃N₄ catalyst possessed a high specific surface area and many defect sites. Various operational parameters, including the relative amounts of HCO₃⁻, H₂O₂, and O/g-C₃N₄, were systemically investigated. A clear performance enhancement was observed in the degradation of organic contaminants when subjected to the HCO₃⁻–H₂O₂–O/g-C₃N₄ system, and this result was ascribed to the synchronous adsorption and chemical oxidation processes. The novel system presented herein represented a new water treatment technology that was effective for removing organic contaminants.

Bicarbonate enhanced the degradation of organic pollutants over oxygen doped graphitic carbon nitride nanosheets in the presence of hydrogen peroxide. It occurred the both on the surface of the catalyst and the reaction solution.     

Hydrogen peroxide-assisted synthesis of oxygen-doped carbon nitride nanorods for enhanced photocatalytic hydrogen evolution

Polymer-derived carbon nitrides based photocatalysts are very promising for solar water splitting, CO₂ reduction and environmental remediation. However, these photocatalysts still suffer from low visible light utilization efficiency, rapid recombination of photogenerated charge carriers and slow transfer kinetics. Herein, we report a hydrogen peroxide-assisted hydrothermal strategy to synthesize one-dimensional oxygen-doped carbon nitrides (OCN) for photocatalytic hydrogen evolution. A possible self-assembly mechanism is discussed. Experimental results and theoretical calculations indicate that the as-synthesized one-dimensional OCN possess narrowed band gap energy and optimized band structure, which may allow more effective visible-light harvesting and facilitate photogenerated electron–hole pair separation and transfer. As a result, the photocatalytic hydrogen evolution rates improve from 10.4 μmol h⁻¹ to 74.0 μmol h⁻¹ under visible light (λ > 400 nm), which is among the best of the reported CN-based photocatalysts for visible-light-driven hydrogen evolution. This study provides a new avenue toward the development of highly efficient carbon nitrides based photocatalysts for photocatalytic applications.

One-dimensional oxygen-doped carbon nitride nanorods synthesized via a hydrogen peroxide-assisted process exhibit enhanced hydrogen evolution under visible light.     

Boosting charge separation and nitrogen vacancies in graphitic carbon nitride by implanted strontium vanadate for highly efficient photocatalytic reduction of hexavalent chromium

Strontium vanadate nanoparticles embedded graphitic carbon nitride (g-C₃N₄/Sr₂V₂O₇) was facilely prepared in situ via a hydrothermal method. It was shown that the Sr₂V₂O₇ nanoparticles implanted into g-carbon nitride had a small size and high distribution. Importantly, compared with some other photocatalysts, the as-prepared g-C₃N₄/Sr₂V₂O₇ nanohybrid showed excellent photocatalytic activity for reduction of Cr(vi), and as high as 99% efficiency for Cr(vi) reduction (100 mg L⁻¹) was reached within 8 min. Moreover, its activity was hardly changed after five cycles, demonstrating that the developed g-C₃N₄/Sr₂V₂O₇ nanohybrid was highly stable and promising an efficacious disposal of Cr(vi) in water. It was confirmed that the improved charge separation owing to more nitrogen vacancies in the hybrid was the main reason for the improved performance of the g-C₃N₄-Sr₂V₂O₇ nanohybrid.

A well-dispersed strontium vanadate implanted into graphitic carbon nitride showed excellent photocatalytic activity for Cr(vi) reduction. The improved charge separation owing to more nitrogen vacancies was the main reason for its enhanced activity.     

The effect of metallic Fe(ii) and nonmetallic S codoping on the photocatalytic performance of graphitic carbon nitride

The metallic Fe(ii) ion and nonmetallic S codoped g-C₃N₄ photocatalyst was synthesized through the polymerization of melamine, ferrous chloride and trithiocyanuric acid (TCA) at elevated temperature. The performance of Fe(ii)–S codoped g-C₃N₄ compounds in RhB photocatalytic degradation was found to increase 5 times. This significant enhancement in catalytic activity is probably related to the enhanced visible light adsorption and the mobility of photoinduced electron/hole pairs, attributable to bandgap narrowing and also lowering in the surface electrostatic potential compared to that of the pure g-C₃N₄ nanosheets. XRD and XPS results indicate that the Fe species binds with N-atoms to form Fe–N bonds in the state of Fe(ii) ions. Fe(ii) doping increases the specific surface area, and enhances the photoinduced electron/hole pairs illustrated by PL, EIS spectra and transient photocurrent response measurements. The theoretical results show that divalent Fe(ii) ions coordinating in the pore centre among three triazine units form discrete dopant bands and S dopants substituting the N in triazine skeletons excite much stronger delocalized HOMO and LUMO states, facilitating the migration of photogenerated charge carriers, thus enhancing the visible-light driven photocatalytic performance.

The photoinduced electrons jump more easily to the conduction band of g-C₃N₄ for the Fe impurity band locates above the valence band acting a bridge for electron transfer.     

Enhanced performance of hydroxyl and cyano group functionalized graphitic carbon nitride for efficient removal of crystal violet and methylene blue from wastewater

This work reports the synthesis of an innovative multifunctional carbon nitride based adsorbent and its successful application for the removal of crystal violet (CV) and methylene blue (MB) from wastewater. The functionalized graphitic carbon nitride (f/g-CN) adsorbent was produced by the pyrolysis of melamine followed by thermal alkali treatment to introduce OH, NH_x, and CN groups onto the graphitic carbon nitride (g-CN) surface. Experimental data obtained from batch tests revealed that the maximum adsorption capacities of g-CN and f/g-CN were found to be 28.9 and 239.0 mg g⁻¹ for MB, and 163.0 and 532.0 mg g⁻¹ for CV, respectively, at pH 8, 25 °C and after 90 min. This increase in adsorption capacity of f/g-CN can be explained by the presence of multiple functional groups in its structure. f/g-CN showed 100% removal for MB and CV with concentrations lower than 100 ppm and the equilibrium time required for the 100% removal of 500 ppb dye is 60 seconds. Additionally, the experimental data fitted well with the Langmuir isotherm model (R² = 0.992) and pseudo second order kinetic model (R² = 0.999) suggesting that the mechanism of adsorption is based on π–π stacking and electrostatic interactions between the NH_x and OH groups of f/g-CN and dye molecules with monolayer formation. Moreover, a reusability test showed that the adsorption capacity remained at around 90% after 7 cycles. This work highlights the merits of the prepared adsorbent f/g-CN which is an eco-friendly, stable, efficient, and reusable adsorbent for removing cationic dyes from wastewater.

This work reports the synthesis of an innovative multifunctional carbon nitride based adsorbent and its successful application for the removal of crystal violet (CV) and methylene blue (MB) from wastewater.     

TiBALDH as a precursor for biomimetic TiO2 synthesis: stability aspects in aqueous media

Titanium(iv) bis(ammonium lactate)dihydroxide (TiBALDH) is a commercially available reagent frequently used to synthesize TiO₂. Particularly, for the biomimetic synthesis of TiO₂, TiBALDH is the preferred precursor because it can be mixed in aqueous solutions with no apparent hydrolysis or condensation reactions. Thus, proteins or other biomolecules can be used as a template in aqueous systems for the synthesis of TiO₂ from TiBALDH. Nevertheless, there is evidence that TiBALDH is in equilibrium with TiO₂, and even, the principal structure of the complex has been suggested as [Ti₄O₄(lactate)₈]⁸⁻. Since that chemical equilibrium depends on the polarity of the solvent, in this work we explored a diversity of media to test the chemical stability of TiBALDH and its equilibrium with TiO₂ at room temperature. TiBALDH (2.078 M) contains particles of 18.6 ± 7.3 nm in size, if it is diluted with deionized water, the particles reach a size of 5.2 ± 1.7 nm, which suggest that intermolecular interactions form polymers of titanium lactate complexes reversibly, reaching equilibrium after 10 hours. Typical buffer systems were tested; TiBALDH reacted rapidly only with phosphate groups, even if the source came from DNA. Therefore, phosphate buffer must be avoided in biomineralization TiO₂ synthesis. In solutions of TiBALDH at basic pH, condensation reactions are promoted to form a gel containing anatase nanoparticles, but if the solutions are acidic, monodisperse anatase nanoparticles of ∼5 nm were observed. The results show that the commercial reagent TiBALDH contains many species of titanium lactate complexes in equilibrium with TiO₂, and it is affected by the concentration, time, pH, and several ions. This peculiar behavior must be taken into account when this precursor is used and it could be useful to develop novel synthesis routes of macrostructures with biomolecules in aqueous systems.

Factors affecting TiO₂ biomineralization using TiBALDH as precursor.     

Monomer sequence design at two solvent interface enables the synthesis of highly photoactive carbon nitride

Structural modifications in carbon nitrides and related carbon-based materials have been achieved in recent years by organizing their monomers into versatile supramolecular structures that serve as reactants for the high temperature solid-state reaction. To date, the organization is usually carried out in one solvent where the building blocks must be dispersed. Here, we show the utilization of a molecule with both hydrogen bond donor and acceptor sites for constructing hydrogen bonded frameworks in interfacial systems. The chemical and electronic properties of the carbon nitride materials after calcination are strongly altered showing enhanced photocatalytic performance in different model reactions. This work shows a new large-scale pathway for the synthesis of highly photoactive carbon nitride with tailored properties and morphology by employing novel supramolecular assemblies prepared in the interface between two solvents, and furthermore opens new opportunities in the rational design of different carbon–nitrogen based materials utilizing supramolecular structures.

The design of a supramolecular assembly in a two solvent interface is used to tailor the morphology, chemical and electronic properties of carbon nitride. This approach opens many opportunities for the design of C–N based materials.     

Facile synthesis of carbon nitride quantum dots as a highly selective and sensitive fluorescent sensor for the tetracycline detection

Enhanced blue fluorescent carbon nitride quantum dots (g-C₃N₄QDs) were synthesized by a simple solvothermal “tailoring” process from bulk g-C₃N₄ and analyzed by various characterization methods. The as-obtained g-C₃N₄QDs were successfully applied in the determination of tetracycline (TC) with a good linear relationship in the range of 0.23–202.70 μM. The proposed fluorescent sensor shows excellent stability, good repeatability, high selectivity and outstanding sensitivity to TC with a low detection limit of 0.19 μM. The fluorescence quenching mechanism of g-C₃N₄QDs with TC was mainly governed by static quenching and the inner filter effect. The method was successfully applied to monitor TC in tap water and milk powder samples.

The g-C₃N₄QDs were synthesized by a simple solvothermal “tailoring” process from bulk g-C₃N₄ which have a “strong quenching” behaviour in the presence of TC. The proposed fluorescent sensor has been successfully applied to detect TC in actual samples.