P- and F-co-doped Carbon Nitride Nanocatalysts for Photocatalytic CO2 Reduction and Thermocatalytic Furanics Synthesis from Sugars

Highly crystalline carbon nitride induced by ultralow dosage of sodium fluoride with pinning-docking mechanism

In the typical ionothermal synthesis of crystalline carbon nitride (CCN), alkali metal halides are usually used in large amounts. Here, we report a new method for synthesizing poly (heptazine imide) (PHI) using only a trace amount of NaF, which is 20 times less than the amount of NaCl typically required to achieve the PHI structure. Different from the prevailing view that salts function primarily as templates and chelating agents during polymerization, our research revealed the unique role that NaF plays in the polymerization of PHI. We propose a new formation mechanism, termed the "pinning-docking mechanism," in which fluoride (F) atoms and bidentate nitrogen atoms (N) coordinated to sodium (Na) atoms build a strong triangle configuration that synergistically promotes the formation of PHI. Calculations indicate that the highly electronegative F atom generates an effective electron flow within the N-metal-F complex, causing local electron reorganization and accordingly activating the N sites for H2 evolution. The synergistic roles of Na and F atoms in NaF for synthesizing PHI cannot be replicated with either NaCl or NH4F salts under low dosage conditions. The synthesized PHI structure exhibits an exceptional hydrogen evolution rate of 10.2 mmol h-1 gcat-1, exceeding that of amorphous TCN(550) by 217 times. This work provides an economical method for CCN synthesis and explores the underlying role of NaF salt during polymerization, which can be valuable for designing highly crystalline carbon nitride materials.

Aminosulfonated Graphene as a Catalyst for Efficient Production of Biodiesel from Fatty Acids and Crude Vegetable Oils

Climate change and the depletion of fossil fuels increase the demand for sustainable energy. Biodiesel synthesized using heterogeneous acid catalysts is a promising clean-energy carrier that supports a circular carbon economy. Herein, the efficient synthesis of biodiesel is reported using a reusable solid acid graphene catalyst functionalized with a natural aminosulfonic acid. Experimental and theoretical studies reveal the key role of functionalities that simultaneously contain amino and sulfonate groups, which impart superior acidity. Excellent activity and selectivity for oleic acid conversion to oleic acid methyl esters (a sustainable biofuel) are obtained, offering a strategy for achieving improved catalytic performance compared to earlier or benchmark catalysts in the field. Notably, the catalyst also effectively converts common vegetable oils into biodiesel via transesterification and facilitates carbohydrate dehydration to value-added chemicals, demonstrating broad applicability. Two additional variants of aminosulfonic acid-functionalized graphene show similar activity, confirming the crucial role of these functionalities in achieving high acidity and catalytic performance. The development of such potent, recyclable catalysts is crucial because acid catalysis is highly versatile, underpinning many biological and synthetic transformations.

The effects of bandgap and porosity on catalysis and materials characteristics of layered carbon nitrides

In layered carbon nitrides, changing the C : N ratio and pore size can be a key to tuning their optical, adsorption, electronic and single-atom loading properties, as well as their band structures, bandgaps, and band edge levels. Such tuning can develop a favorable layered semiconductor, adsorbent, photo/electro-catalyst, or support material for loading catalytic species. Over the last few years, carbon nitride synthetic methods, monomers and modification methods (i.e., doping) have been vastly investigated. However, the effects of the pore size and C : N ratio on catalysis, as well as other photo/electric properties, are worth further research. Here, I discuss the different types of layered carbon nitrides with a focus on the role of pores and the C : N ratio and crystal structure, and eventually their effect on various features such as conductivity, charge carrier mobility, optical activity, and catalytic activity.

Recent advances in the design and preparation of graphitic carbon nitride for photocatalysis

Graphitic carbon nitride (g-C3N4) has recently gained tremendous attention as a promising photocatalyst for environmental and energy-related applications owing to its high thermal and physicochemical stability as well as its suitable band structure. However, bulk g-C3N4, typically synthesized by directly heating N-rich small molecules, often suffers from severe aggregation, a low specific surface area for light harvesting and rapid recombination of photogenerated electron-hole pairs. These factors significantly hinder its photocatalytic efficiency. Consequently, considerable efforts have been devoted to the rational design and synthesis of g-C3N4 with tailored morphologies and controllable electronic and band structures, utilizing both top-down and bottom-up approaches. Thus far, in addition to the conventional and commonly used methods for carbon nitride preparation, new techniques and precursor families are continuously being developed. This review discusses the latest advancements in synthetic approaches for g-C3N4-based materials and provides valuable insights into utilizing these methods to enhance their photocatalytic performance. Finally, the review concludes by presenting an outlook on the future directions and challenges in the development of CN materials for photocatalysis.

Harnessing photocatalytic activity of mesoporous graphitic carbon nitride decorated by copper single-atom catalysts for oxidative dehydrogenation of N-heterocycles

This work describes the application of Cu single-atom catalysts (SACs) for photocatalytic oxidative dehydrogenation of N-heterocyclic amines to the respective N-heteroaromatics through environmentally benign and sustainable pathways. The mesoporous graphitic carbon nitride (mpg-C3N4), prepared by the one-step pyrolysis method, possesses a lightweight material with a high surface area (95 m2 g-1) and an average pore diameter (3.6 nm). A simple microwave-assisted preparation method was employed to decorate Cu single-atom over mpg-C3N4 support. The Cu single-atom decorated on mpg-C3N4 support (Cu@mpg-C3N4) is characterized by various characterization techniques, including XRD, UV-visible spectrophotometry, HRTEM, HAADF-STEM with elemental mapping, AC-STEM, ICP-OES, XANES, EXAFS, and BET surface area. These characterization studies confirmed that the Cu@mpg-C3N4 catalyst exhibited high surface area, mesoporous nature, medium band gap, and low metal loading. The as-synthesized and well-characterized Cu@mpg-C3N4 single-atom photocatalyst is then evaluated for its efficacy in converting N-heterocycles into corresponding N-heteroaromatic compounds with excellent conversion and selectivity (>99 %). This transformation is achieved using water as a green solvent and a 30 W white light as a visible light source, demonstrating the catalyst's potential for sustainable and environmentally benign reactions.

Metal-Free Carbon Co-Catalysts for Up-Conversion Photo-Induced Catalytic Cancer Therapy

Near-infrared (NIR)-responsive metal-free carbon co-catalysts that convert glucose into H2O2 to generate reactive oxygen species (ROS) are developed from phosphorus-doped carbon nitride (P-C3N4) and graphene quantum dots (GQD) composites, for enhanced photocatalytic cancer therapy by light exposure in the targeted tumor microenvironment. Upon irradiation, the NIR light is converted by GQD with up-conversion function into visible light to excite P-C3N4 for photocatalytic conversion of glucose into H2O2, which subsequently decomposes into ROS. ROS thus generated exhibits an excellent anticancer efficacy for efficient cancer therapy with minimal side effects, as evidenced by both in vitro and in vivo studies. This study demonstrates, for the first time, a cancer therapeutic of GQD/P-C3N4 composite that utilizes a two-step cascade effect using initially NIR-triggered GQD nanoparticles to activate P-C3N4 to photocatalytically generate ROS for effective and targeted cancer therapy.

How can heteroatoms boost the performance of photoactive nanomaterials for wastewater purification?

Photocatalysis, as an alternative for treating persistent water pollutants, holds immense promise. However, limitations hinder sustained treatment and recycling under varying light conditions. This comprehensive review delves into the novel paradigm of metal and non-metal doping to overcome these challenges. It begins by discussing the fundamental principles of photocatalysis and its inherent limitations. Understanding these constraints is crucial for developing effective strategies. Band gap narrowing by metal and non-metal doping modifies the band gap, enabling visible-light absorption. Impurity energy levels and oxygen vacancies influenced the doping energy levels and surface defects. Interfacial electron transfer and charge carrier recombination are the most important factors that impact overall efficiency. The comparative analysis of nanomaterials are reviewed on various, including nanometal oxides, nanocarbon materials, and advanced two-dimensional structures. The synthesis process are narratively presented, emphasizing production yields, selectivity, and efficiency. The review has potential applications in the environment for efficient pollutant removal and water purification, economic cost-effective and scalable production and technological advancement catalyst design, in spite of its challenges in material stability, synthesis methods and optimizing band gaps. The novelty of the review paper is on the proposal of a new paradigm of heterojunctions of doped metal and non-metal photocatalysts to promise highly efficient water treatment. This review bridges the gap between fundamental research and practical applications, offering insights into tailored nano photocatalysts.

Sugars induced exfoliation of porous graphitic carbon nitride for efficient hydrogen evolution in photocatalytic water-splitting reaction

Photocatalytic hydrogen evolution holds great promise for addressing critical energy and environmental challenges, making it an important area in scientific research. One of the most popular photocatalysts is graphitic carbon nitride (gCN), which has emerged as a noteworthy candidate for hydrogen generation through water splitting. However, ongoing research aims to enhance its properties for practical applications. Herein, we introduce a green approach for the fabrication of porous few-layered gCN with surface modifications (such as oxygen doping, carbon deposition, nitrogen defects) with promoted performance in the hydrogen evolution reaction. The fabrication process involves a one-step solvothermal treatment of bulk graphitic carbon nitride (bulk-gCN) in the presence of different sugars (glucose, sucrose, and fructose). Interestingly, the conducted time-dependent process revealed that porous gCN exfoliated in the presence of fructose at 180 °C for 6 h (fructose_6h) exhibits a remarkable 13-fold promotion of photocatalytic hydrogen evolution compared to bulk-gCN. The studied materials were extensively characterized by microscopic and spectroscopic techniques, allowing us to propose a reaction mechanism for hydrogen evolution during water-splitting over fructose_6h. Furthermore, the study highlights the potential of employing a facile and environmentally friendly fructose-assisted solvothermal process to improve the efficiency and stability of catalysts based on graphitic carbon nitride.

Multifunctional carbon nitride nanoarchitectures for catalysis

Catalysis is at the heart of modern-day chemical and pharmaceutical industries, and there is an urgent demand to develop metal-free, high surface area, and efficient catalysts in a scalable, reproducible and economic manner. Amongst the ever-expanding two-dimensional materials family, carbon nitride (CN) has emerged as the most researched material for catalytic applications due to its unique molecular structure with tunable visible range band gap, surface defects, basic sites, and nitrogen functionalities. These properties also endow it with anchoring capability with a large number of catalytically active sites and provide opportunities for doping, hybridization, sensitization, etc. To make considerable progress in the use of CN as a highly effective catalyst for various applications, it is critical to have an in-depth understanding of its synthesis, structure and surface sites. The present review provides an overview of the recent advances in synthetic approaches of CN, its physicochemical properties, and band gap engineering, with a focus on its exclusive usage in a variety of catalytic reactions, including hydrogen evolution reactions, overall water splitting, water oxidation, CO2 reduction, nitrogen reduction reactions, pollutant degradation, and organocatalysis. While the structural design and band gap engineering of catalysts are elaborated, the surface chemistry is dealt with in detail to demonstrate efficient catalytic performances. Burning challenges in catalytic design and future outlook are elucidated.

Functionalization of Fluorine on the Surface of SnO2-Mg Nanocomposite as an Efficient Photocatalyst for Toxic Dye Degradation

This work reports on the photocatalytic activity of tin oxide (SnO2)-doped magnesium (Mg) and fluorine (F) nanoparticles for methyl orange and safranin dye degradation under sunlight irradiation. Nanocatalysis-induced dye degradation was examined using UV-visible spectroscopy and a pseudo-first-order kinetics model. The results indicate that the prepared nanoparticles exhibit superior photocatalytic activity, and the degradation of methyl orange (MO) dye is approximately 82%. In contrast, the degradation of safranin dye is 96% in the same time interval of 105 min. The calculated crystallite size of the SnO2-Mg-F nanocomposite is 29.5 nm, which respects the particle size found in the DLS analysis with a tetragonal structure and spherical morphology affirmed. The optical characteristics were assessed, and their respective bandgap energies were determined to be 3.6 eV. The influence of F in Mg and SnO2 is recognized with the XRD and FT-IR spectra of the prepared particles.

A Review of Phosphorus Structures as CO2 Reduction Photocatalysts

Effective photocatalytic carbon dioxide (CO₂ ) reduction into high-value-added chemicals is promising to mitigate current energy crisis and global warming issues. Finding effective photocatalysts is crucial for photocatalytic CO₂ reduction. Currently, metal-based semiconductors for photocatalytic CO₂ reduction have been well reviewed, while review of nonmetal-based semiconductors is almost limited to carbon nitrides. Phosphorus is a promising nonmetal photocatalysts with various allotropes and tunable band gaps, which has been demonstrated to be promising non-metallic photocatalysts. However, no systematic review about phosphorus structures for photocatalytic CO₂ reduction reactions has been reported. Herein, the progresses of phosphorus structures as photocatalysts for CO₂ reduction are reviewed. The fundamentals of photocatalytic CO₂ reduction, corresponding properties of phosphorus allotropes, photocatalysts with phosphorus doping or phosphorus-containing ligands, research progress of phosphorus allotropes as photocatalysts for CO₂ reduction have been reviewed in this paper. The future research and perspective of phosphorus structures for photocatalytic CO₂ reduction are also presented.

Highly dispersed Rh single atoms over graphitic carbon nitride as a robust catalyst for the hydroformylation reaction

Rhodium-catalysed hydroformylation, effective tool in bulk and fine-chemical synthesis, predominantly uses soluble metal complexes. For that reason, the metal leaching and the catalyst recycling are still the major drawbacks of this process. Single-atom catalysts have emerged as a powerful tool to combine the advantages of both homogeneous and heterogeneous catalysts. Since using an appropriate support material is key to create stable, finely dispersed, single-atom catalysts, here we show that Rh atoms anchored on graphitic carbon nitride are robust catalysts for the hydroformylation reaction of styrene.

Interface Engineering of SRu-mC3N4 Heterostructures for Enhanced Electrochemical Hydrazine Oxidation Reactions

Hydrazine oxidation in single-atom catalysts (SACs) could exploit the efficiency of metal atom utilization, which is a substitution for noble metal-based electrolysers that results in reduced overall cost. A well-established ruthenium single atom over mesoporous carbon nitride (SRu-mC3N4) catalyst is explored for the electro-oxidation of hydrazine as one of the model reactions for direct fuel cell reactions. The electrochemical activity observed with linear sweep voltammetry (LSV) confirmed that SRu-mC3N4 shows an ultra-low onset potential of 0.88 V vs. RHE, and with a current density of 10 mA/cm2 the observed potential was 1.19 V vs. RHE, compared with mesoporous carbon nitride (mC3N4) (1.77 V vs. RHE). Electrochemical impedance spectroscopy (EIS) and chronoamperometry (i-t) studies on SRu-mC3N4 show a smaller charge-transfer resistance (RCt) of 2950 Ω and long-term potential, as well as current stability of 50 h and 20 mA/cm2, respectively. Herein, an efficient and enhanced activity toward HzOR was demonstrated on SRu-mC3N4 from its synergistic platform over highly porous C3N4, possessing large and independent active sites, and improving the subsequent large-scale reaction.

Carbon-Based Nanocatalysts (CnCs) for Biomass Valorization and Hazardous Organics Remediation

The continuous increase of the demand in merchandise and fuels augments the need of modern approaches for the mass-production of renewable chemicals derived from abundant feedstocks, like biomass, as well as for the water and soil remediation pollution resulting from the anthropogenic discharge of organic compounds. Towards these directions and within the concept of circular (bio)economy, the development of efficient and sustainable catalytic processes is of paramount importance. Within this context, the design of novel catalysts play a key role, with carbon-based nanocatalysts (CnCs) representing one of the most promising class of materials. In this review, a wide range of CnCs utilized for biomass valorization towards valuable chemicals production, and for environmental remediation applications are summarized and discussed. Emphasis is given in particular on the catalytic production of 5-hydroxymethylfurfural (5-HMF) from cellulose or starch-rich food waste, the hydrogenolysis of lignin towards high bio-oil yields enriched predominately in alkyl and oxygenated phenolic monomers, the photocatalytic, sonocatalytic or sonophotocatalytic selective partial oxidation of 5-HMF to 2,5-diformylfuran (DFF) and the decomposition of organic pollutants in aqueous matrixes. The carbonaceous materials were utilized as stand-alone catalysts or as supports of (nano)metals are various types of activated micro/mesoporous carbons, graphene/graphite and the chemically modified counterparts like graphite oxide and reduced graphite oxide, carbon nanotubes, carbon quantum dots, graphitic carbon nitride, and fullerenes.

Selective Photocatalytic Reduction of CO2 to Syngas Over Tunable Metal-Perovskite Interface

The extensive emission of CO₂ results in critical environmental issues, such as global warming. Photocatalytic CO₂ conversion is a meaningful route to convert CO₂ into useful chemicals. However, the highly selective reduction of CO₂ with the avoidance of hydrogen evolution is still challenging. Herein, the photocatalytic reduction CO₂ to synthesis gas (syngas) was achieved on a metal Ag socketed perovskite LaFeO₃ (LFO) catalytic interface prepared by an in-situ exsolution method. The conduction band of Ag-exsolved LFO is more negative than LFO, benefiting efficient CO₂ reduction. By tuning the dopant Ag cation in the lattice to nanoparticles pinned on the surface, the CO formation rate was improved around five-fold from 0.51 to 2.41 μmol g^-1  h^-1 . Meanwhile, the H₂ /CO molar ratio also showed strong dependence on the modality of Ag at the metal-perovskite interface. The design offers a promising pathway for transforming CO₂ to valuable chemicals based on efficient photocatalysts design.

Recent Advances of Photocatalytic Hydrogenation of CO2 to Methanol

Constantly increasing hydrocarbon fuel combustion along with high levels of carbon dioxide emissions has given rise to a global energy crisis and environmental alterations. Photocatalysis is an effective technique for addressing this energy and environmental crisis. Clean and renewable solar energy is a very favourable path for photocatalytic CO2 reduction to value-added products to tackle problems of energy and the environment. The synthesis of various products such as CH4, CH3OH, CO, EtOH, etc., has been expanded through the photocatalytic reduction of CO2. Among these products, methanol is one of the most important and highly versatile chemicals widely used in industry and in day-to-day life. This review emphasizes the recent progress of photocatalytic CO2 hydrogenation to CH3OH. In particular, Metal organic frameworks (MOFs), mixed-metal oxide, carbon, TiO2 and plasmonic-based nanomaterials are discussed for the photocatalytic reduction of CO2 to methanol. Finally, a summary and perspectives on this emerging field are provided.

Single-Step Hydrothermal Synthesis of Biochar from H3PO4-Activated Lettuce Waste for Efficient Adsorption of Cd(II) in Aqueous Solution

Developing an ideal and cheap adsorbent for adsorbing heavy metals from aqueous solution has been urgently need. In this study, a novel, effective and low-cost method was developed to prepare the biochar from lettuce waste with H3PO4 as an acidic activation agent at a low-temperature (circa 200 °C) hydrothermal carbonization process. A batch adsorption experiment demonstrated that the biochar reaches the adsorption equilibrium within 30 min, and the optimal adsorption capacity of Cd(II) is 195.8 mg∙g-1 at solution pH 6.0, which is significantly improved from circa 20.5 mg∙g-1 of the original biochar without activator. The fitting results of the prepared biochar adsorption data conform to the pseudo-second-order kinetic model (PSO) and the Sips isotherm model, and the Cd(II) adsorption is a spontaneous and exothermic process. The hypothetical adsorption mechanism is mainly composed of ion exchange, electrostatic attraction, and surface complexation. This work offers a novel and low-temperature strategy to produce cheap and promising carbon-based adsorbents from organic vegetation wastes for removing heavy metals in aquatic environment efficiently.

Light-assisted coupling of phenols with CO2 to 2-hydroxybenzaldehydes catalyzed by a g-C3N4/NH2-MIL-101(Fe) composite

The present work described a novel photocatalytic approach for the synthesis of 2-hydroxybenzaldehydes from the coupling of phenols and CO2 in the presence of a base using a graphitic carbon nitride/NH2-MIL-101(Fe) composite under mild conditions.

Recent Advances and Challenges in Photoreforming of Biomass-Derived Feedstocks into Hydrogen, Biofuels, or Chemicals by Using Functional Carbon Nitride Photocatalysts

Photoreforming of biomass into hydrogen, biofuels, and chemicals is highly desired, yet this field of research is still in its infancy. Developing an efficient, novel, and environmentally friendly photocatalyst is key to achieving these goals. To date, the nonmetallic and eco-friendly material carbon nitride has found many uses in reactions such as water splitting, CO₂ reduction, N₂ fixation, and biorefinery, owing to its outstanding photocatalytic activity. However, a narrow light absorption range and fast charge recombination are often encountered in the pristine carbon nitride photocatalytic system, which resulted in unsatisfying photocatalytic activity. To improve the photocatalytic performance of pure carbon nitride in biomass reforming, modification is needed. In this Review, the design and preparation of functional carbon nitride, as well as its photocatalytic properties for the synthesis of hydrogen, biofuels, and chemicals through biomass reforming, are discussed alongside potential avenues for its future development.

Remediation and mineralization processes for per- and polyfluoroalkyl substances (PFAS) in water: A review

Per- and polyfluoroalkyl substances (PFAS) are synthetic organic molecules used to manufacture various consumer and industrials products. In PFAS, the CF bond is stable, which renders these compounds chemically stable and prevents their breakdown. Several PFAS treatment processes such as adsorption, photolysis and photocatalysis, bioremediation, sonolysis, electrochemical oxidation, etc., have been explored and are being developed. The present review article has critically summarized degradative technologies and provides in-depth knowledge of photodegradation, electrochemical degradation, chemical oxidation, and reduction mineralization mechanism. Also, novel non-degradative technologies, including nano-adsorbents, natural and surface-modified clay minerals/zeolites, calixarene-based polymers, and molecularly imprinted polymers and adsorbents derived from biomaterials are discussed in detail. Of these novel approaches photocatalysis combined with membrane filtration or electrochemical oxidation via a treatment train approach shows promising results in removing PFAS in natural waters. The photocatalytic mineralization mechanism of PFOA is discussed, leading to recommendations for future research on novel remediation strategies for removing PFAS from water.

Phosphorus- and fluorine-co-doped carbon nitride: modulated visible light absorption, charge carrier kinetics and boosted photocatalytic hydrogen evolution

A phosphorus and fluorine co-doped carbon nitride (PF-CN) photocatalyst was synthesized to modulate the band gap structure, visible light response ability and photocatalytic H₂ evolution activity. Experimental results demonstrated that the electronic structure of g-C₃N₄ was regulated by phosphorus replacing the C site and fluorine substituting the N site in the g-C₃N₄ framework to form P-N species and C-F bonds, respectively. P- and F-co-doped carbon nitride gave rise to a more negative conduction band potential, larger surface area, efficient separation of photogenerated charge carriers and a faster charge transfer rate, contributing to an enhancement of photocatalytic H₂ production activity. PF-CN achieved an optimal H₂ evolution activity of 1690.56 μmol g^-1 which was 17.83 times higher with respect to that of pristine g-C₃N₄ (94.81 μmol g^-1). Meanwhile, PF-CN achieved the highest apparent quantum efficiency of 3.76% at 435 nm.

Silver nanomaterials: synthesis and (electro/photo) catalytic applications

In view of their unique characteristics and properties, silver nanomaterials (Ag NMs) have been used not only in the field of nanomedicine but also for diverse advanced catalytic technologies. In this comprehensive review, light is shed on general synthetic approaches encompassing chemical reduction, sonochemical, microwave, and thermal treatment among the preparative methods for the syntheses of Ag-based NMs and their catalytic applications. Additionally, some of the latest innovative approaches such as continuous flow integrated with MW and other benign approaches have been emphasized that ultimately pave the way for sustainability. Moreover, the potential applications of emerging Ag NMs, including sub nanomaterials and single atoms, in the field of liquid-phase catalysis, photocatalysis, and electrocatalysis as well as a positive role of Ag NMs in catalytic reactions are meticulously summarized. The scientific interest in the synthesis and applications of Ag NMs lies in the integrated benefits of their catalytic activity, selectivity, stability, and recovery. Therefore, the rise and journey of Ag NM-based catalysts will inspire a new generation of chemists to tailor and design robust catalysts that can effectively tackle major environmental challenges and help to replace noble metals in advanced catalytic applications. This overview concludes by providing future perspectives on the research into Ag NMs in the arena of electrocatalysis and photocatalysis.

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.

Carbon Nitride-Based Ruthenium Single Atom Photocatalyst for CO2 Reduction to Methanol

With increasing concerns for global warming, the solar-driven photocatalytic reduction of CO₂ into chemical fuels like methanol is a propitious route to enrich energy supplies, with concomitant reduction of the abundant CO₂  stockpiles. Herein, a novel single atom-confinement and a strategy are reported toward single ruthenium atoms dispersion over porous carbon nitride surface. Ruthenium single atom character is well confirmed by EXAFS absorption spectrometric analysis unveiling the cationic coordination environment for the single-atomic-site ruthenium center, that is formed by Ru-N/C intercalation in the first coordination shell, attaining synergism in N-Ru-N connection and interfacial carrier transfer. From time resolved fluorescence decay spectra, the average carrier lifetime of the RuSA-mC₃ N₄ system is found to be higher compared to m-C₃ N₄ ; the fact uncovering the crucial role of single Ru atoms in promoting photocatalytic reaction system. A high yield of methanol (1500 µmol g^-1 cat. after 6 h of the reaction) using water as an electron donor and the reusability of the developed catalyst without any significant change in the efficiency represent the superior aspects for its potential application in real industrial technologies.