Cross-linked g-C3 N4 /rGO nanocomposites with tunable band structure and enhanced visible light photocatalytic activity

Recent advances in ternary Z-scheme photocatalysis on graphitic carbon nitride based photocatalysts

Due to its excellent photocatalytic performance over the last few years, graphitic-like carbon nitride (g-C3N4) has garnered considerable notice as a photocatalyst. Nevertheless, several limitations, including small surface area, the rates at which photo-generated electrons and holes recombine are swift, and the inefficient separation and transport of photoexcited carriers continue to impede its solar energy utilization. To overcome those limitations in single-component g-C3N4, constructing a heterogeneous photocatalytic system has emerged as an effective way. Among the various studies involving the incorporation of hetero composite materials to design heterojunctions, among the most promising approaches is to assemble a Z-scheme photocatalytic configuration. The Z-scheme configuration is essential because it facilitates efficient photocarrier separation and exhibits superior redox ability in separated electrons and holes. Moreover, ternary composites have demonstrated enhanced photocatalytic activities and reinforced photostability. Ternary Z-scheme heterostructures constructed with g-C3N4 possess all the above-mentioned merits and provide a pioneering strategy for implementing photocatalytic systems for environmental and energy sustainability. A summary of the latest technological advancements toward design and fabrication in ternary all-solid-state Z-scheme (ASSZ) and direct Z-scheme (DZ) photocatalysts built on g-C3N4 is presented in this review. Furthermore, the review also discusses the application of ternary Z-scheme photocatalytic architecture established on g-C3N4.

Benzene-Linked Polymeric Carbon Nitride for Enhanced Photocatalytic Hydrogen Production

Cross-linking with functional molecular species in polymeric carbon nitride (PCN) could offer a positive strategy that tunes its molecular structure with excellent conductivity to improve photocatalytic activity. Herein, the benzene ring-cross-linked photocatalyst is obtained via the polymerization of urea, melamine, and trimesic acid. Benzene ring-cross-linked PCN narrows the band gap and augments the push-pull effect of carriers, thus enhancing visible light harvesting and transfer easiness of photogenerated electron/hole pairs. Notably, the amount of trimesic acid was optimized during the benzene ring-cross-linked photocatalyst preparation (marked as 01T/A-CN, 02T/A-CN, and 03T/A-CN). Among them, 02T/A-CN photocatalyst achieved an excellent hydrogen production rate of 1931 μmol/h·g, which is higher than that of CN under visible light and beyond most reported. Theoretical calculations further confirmed that the introduction of benzene ring significantly reduces the band gap of PCN, bringing the delocalized electron, a longer intramolecular electron transition distance, and molecular bending. All those factors made benzene ring-cross-linked PCN with improved photocatalytic hydrogen production under visible light irradiation.

Enhanced photocatalytic performance of the N-rGO/g-C3N4 nanocomposite for efficient solar-driven water remediation

This paper describes the synthesis and analysis of a photocatalyst made from a combination of reduced graphene oxide (rGO) and graphitic carbon nitride (g-C3N4) through a simple hydrothermal process. The effectiveness of the N-rGO/g-C3N4 heterostructure in photocatalysis was examined by studying the breakdown of different types of organic pollutants, such as cationic and anionic dyes, as well as antibiotics, under simulated solar light irradiation. Due to the presence of Schottky junctions formed between rGO and g-C3N4, the electron transfer process is significantly enhanced, leading to a reduction in the recombination of photogenerated electrons and holes. As a result, the photocatalytic activity of the rGO/g-C3N4 photocatalyst is significantly higher compared to that of g-C3N4 alone. The photocatalytic performance was further augmented through the nitrogen doping of rGO, which led to an increase in conductivity due to electron doping and an enhancement in the charge separation process. The heterojunction of rGO/g-C3N4 with an optimum concentration of 60% rGO attained a degradation efficiency of 98.7% for rhodamine B (RhB) dye after 50 minutes of light irradiation. In comparison, the nitrogen-doped photocatalyst (N-rGO/g-C3N4) achieved a photodegradation efficiency of 99.99% within 30 minutes. The reaction rate constant of the N-rGO/g-C3N4 nanocomposite was found to be 0.11 min-1 using pseudo first-order rate kinetics. This value is about 16 times more than that of pure g-C3N4 (0.007 min-1) for the degradation of rhodamine B. Additionally, N-rGO/g-C3N4 effectively degraded various contaminants, such as methylene blue, methyl orange, and tetracycline hydrochloride. The paper also addresses the photocatalytic mechanism, which entails the facilitated movement of electrons and holes produced by light, owing to the alignment of energy bands at the interface of the N-rGO/g-C3N4 heterojunction. These findings contribute to the advancement of a metal-free and porous photocatalyst that is highly interconnected and can be used for waste water treatment and environmental remediation.

Building a Charge Transfer Bridge between g-C3N4 and Perovskite with Molecular Engineering to Achieve Efficient Perovskite Solar Cells

Effective defect passivation and efficient charge transfer within polycrystalline perovskite grains and corresponding boundaries are necessary to achieve highly efficient perovskite solar cells (PSCs). Herein, focusing on the boundary location of g-C3N4 during the crystallization modulation on perovskite, molecular engineering of 4-carboxyl-3-fluorophenylboronic acid (BF) on g-C3N4 was designed to obtain a novel additive named BFCN. With the help of the strong bonding ability of BF with both g-C3N4 and perovskite and favorable intramolecular charge transfer within BFCN, not only has the crystal quality of perovskite films been improved due to the effective defects passivation, but the charge transfer has also been greatly accelerated due to the formation of additional charge transfer channels on the grain boundaries. As a result, the champion BFCN-based PSCs achieve the highest photoelectric conversion efficiency (PCE) of 23.71% with good stability.

Interfacial Engineering and Coupling of MXene/Reduced Graphene Oxide/C3 N4 Aerogel with Optimized d-Band Center as a Free-Standing Sulfur Carrier for High-Performance Li-S Batteries

To overcome the shuttle effect and improve the energy density of Li-S batteries, developing free-standing sulfur carriers with high capture and catalytic effect towards polysulfides is an effective strategy. Herein, a MXene/reduced graphene oxide/C3 N4 aerogel (MG/C3 N4 ) with three-dimensional architecture prepared through low-temperature hydrothermal approach followed by thermal treatment is used as sulfur carrier for free-standing cathode of Li-S batteries. In the MG/C3 N4 , MXene and rGO construct a highly conductive framework, and the MXene nanosheets offer chemical capture and catalytic activity towards lithium polysulfides, in favor of good cycling stability. The introduction of g-C3 N4 further enhances the reactivity of C-Ti-N at the hetero-interface by engineering the electronic state of Ti atoms, leading to the optimized metal d-band for expediting the multistep conversion of sulfur electrochemistry. Therefore, the free-standing sulfur cathode with MG/C3 N4 carrier achieves excellent performance with a capacity of 1315.6 mAh g-1 at 0.2 C and a capacity retention of 97.5% after 100 cycles as well as superior rate capability with 1167.4 mAh g-1 at 2 C. Even at a high sulfur loading of 4.92 mg cm-2 , the cathode remains 940.3 mAh g-1 (4.62 mAh cm-2 ) after 200 cycles, indicating its promising potential for achieving high-performance Li-S batteries.

Recent Advances in LDH/g-C3N4 Heterojunction Photocatalysts for Organic Pollutant Removal

Environmental pollution has been decreased by using photocatalytic technology in conjunction with solar energy. An efficient method to obtain highly efficient photocatalysts is to build heterojunction photocatalysts by combining graphitic carbon nitride (g-C3N4) with layered double hydroxides (LDHs). In this review, recent developments in LDH/g-C3N4 heterojunctions and their applications for organic pollutant removal are systematically exhibited. The advantages of LDH/g-C3N4 heterojunction are first summarized to provide some overall understanding of them. Then, a variety of approaches to successfully assembling LDH and g-C3N4 are simply illustrated. Last but not least, certain unmet research needs for the LDH/g-C3N4 heterojunction are suggested. This review can provide some new insights for the development of high-performance LDH/g-C3N4 heterojunction photocatalysts. It is indisputable that the LDH/g-C3N4 heterojunctions can serve as high-performance photocatalysts to make new progress in organic pollutant removal.

Bandgap Engineering of Melon using Highly Reduced Graphene Oxide for Enhanced Photoelectrochemical Hydrogen Evolution

The uncondensed form of polymeric carbon nitrides (PCN), generally known as melon, is a stacked 2D structure of poly(aminoimino)heptazine. Melon is used as a photocatalyst in solar energy conversion applications, but suffers from poor photoconversion efficiency due to weak optical absorption in the visible spectrum, high activation energy, and inefficient separation of photoexcited charge carriers. Experimental and theoretical studies are reported to engineer the bandgap of melon with highly reduced graphene oxide (HRG). Three HRG@melon nanocomposites with different HRG:melon ratios (0.5%, 1%, and 2%) are prepared. The 1% HRG@melon nanocomposite shows higher photocurrent density (71 µA cm-2 ) than melon (24 µA cm-2 ) in alkaline conditions. The addition of a hole scavenger further increases the photocurrent density to 630 µA cm-2 relative to the reversible hydrogen electrode (RHE). These experimental results are validated by calculations using density functional theory (DFT), which revealed that HRG results in a significant charge redistribution and an improved photocatalytic hydrogen evolution reaction (HER).

Photosynthesis of Hydrogen Peroxide Based on g-C3 N4 : The Road of a Cost-Effective Clean Fuel Production

Emerging artificial photosynthesis promises to offer a competitive means for solar energy conversion and further solves the energy crisis facing the world. Hydrogen peroxide (H2 O2 ), which is considered as a benign oxidant and a prospective liquid fuel, has received worldwide attention in the field of artificial photosynthesis on account of the source materials are just oxygen, water, and sunlight. Graphitic carbon nitride (g-C3 N4 )-based photocatalysts for H2 O2 generation have attracted extensive research interest due to the intrinsic properties of g-C3 N4 . In this review, research processes for H2 O2 generation on the basis of g-C3 N4 , including development, fabrication, merits, and disadvantages, and the state-of-the-art methods to enhance the performance are summarized after a brief introduction and the mechanism analysis of an efficient catalytic system. Also, recent applications of g-C3 N4 -based photocatalysts for H2 O2 production are reviewed, and the significance of active sites and synthetic pathways are highlighted from the view of reducing barriers. Finally, this paper ends with some concluding remarks to reveal the issues and opportunities of g-C3 N4 -based photocatalysts for producing H2 O2 in a high yield.

Silica sand-supported nano zinc oxide-graphene oxide composite induced rapid photocatalytic decolorization of azo dyes under sunlight and improved antimicrobial activity

Here, silica sand-supported heterojunction composite of nano zinc oxide (nZnO) and graphene oxide nanosheet (nZnO-GO@SS) was prepared, and its potential as an efficient photocatalyst for the degradation of methylene blue (MB) and Rhodamine-B (Rh-B) under sunlight was demonstrated. Transmission electron microscopy confirmed the uniform distribution of spherically shaped nZnO of average size of approximately 8 nm over graphene oxide nanosheet (GO) in the composites. Photodegradation yields of 95.3% and 97.5% for 100 ppm of MB and Rh-B dye within 150 and 220 min, respectively, were achieved under sunlight by the prepared nanocatalyst (nZnO-GO), while sand microparticle-supported nanocatalyst (nZnO-GO@SS) demonstrated faster degradation of MB and Rh-B, i.e., within 120 and 160 min, respectively. Furthermore, when the recyclability of the photocatalyst was studied, the nZnO-GO exhibited more than 80% degradation efficiency after five cycles for both the dyes and nZnO-GO@SS demonstrated 10% higher (~90%) removal capability after five cycles of reuse. Furthermore, the antibacterial assay showed complete inactivation of Escherichia coli and Staphylococcus aureus bacterial strain by nZnO-GO@SS. Hence, our proposed strategy for the removal of toxic dyes from the aquatic environment under sunlight proved that sand microparticle-supported nanocatalyst (nZnO-GO@SS) might be a superior, cost-effective, and suitable photocatalytic system for industrial applications toward toxic dye removal and decontamination from industrial wastewater.

Environmentally sustainable implementations of two-dimensional nanomaterials

Rapid advancement in nanotechnology has led to the development of a myriad of useful nanomaterials that have novel characteristics resulting from their small size and engineered properties. In particular, two-dimensional (2D) materials have become a major focus in material science and chemistry research worldwide with substantial efforts centered on their synthesis, property characterization, and technological, and environmental applications. Environmental applications of these nanomaterials include but are not limited to adsorbents for wastewater and drinking water treatment, membranes for desalination, and coating materials for filtration. However, it is also important to address the environmental interactions and implications of these nanomaterials in order to develop strategies that minimize their environmental and public health risks. Towards this end, this review covers the most recent literature on the environmental implementations of emerging 2D nanomaterials, thereby providing insights into the future of this fast-evolving field including strategies for ensuring sustainable development of 2D nanomaterials.

Insights into Photocatalytic Degradation Pathways and Mechanism of Tetracycline by an Efficient Z-Scheme NiFe-LDH/CTF-1 Heterojunction

Photocatalysis offers a sustainable approach for recalcitrant organic pollutants degradation, yet it is still challenging to seek robust photocatalysts for application purposes. Herein, a novel NiFe layered double hydroxide (LDH)/covalent triazine framework (CTF-1) Z-scheme heterojunction photocatalyst was rationally designed for antibiotics degradation under visible light irradiation. The NiFe-LDH/CTF-1 nanocomposites were readily obtained via in situ loading of NiFe-LDH on CTF-1 through covalent linking. The abundant coupling interfaces between two semiconductor counterparts lay the foundation for the formation of Z-scheme heterostructure, thereby effectively promoting the transfer of photogenerated electrons, inhibiting the recombination of carriers, as well as conferring the nanocomposites with stronger redox ability. Consequently, the optimal photocatalytic activity of the LDH/CTF heterojunction was significantly boosted for the degradation of a typical antibiotic, tetracycline (TC). Additionally, the photodegradation process and the mineralization of TC were further elucidated. These results envision that the LDH/CTF-1 can be a viable photocatalyst for long-term and sustainable wastewater treatment.

Carbon Nanodots from an In Silico Perspective

Carbon nanodots (CNDs) are the latest and most shining rising stars among photoluminescent (PL) nanomaterials. These carbon-based surface-passivated nanostructures compete with other related PL materials, including traditional semiconductor quantum dots and organic dyes, with a long list of benefits and emerging applications. Advantages of CNDs include tunable inherent optical properties and high photostability, rich possibilities for surface functionalization and doping, dispersibility, low toxicity, and viable synthesis (top-down and bottom-up) from organic materials. CNDs can be applied to biomedicine including imaging and sensing, drug-delivery, photodynamic therapy, photocatalysis but also to energy harvesting in solar cells and as LEDs. More applications are reported continuously, making this already a research field of its own. Understanding of the properties of CNDs requires one to go to the levels of electrons, atoms, molecules, and nanostructures at different scales using modern molecular modeling and to correlate it tightly with experiments. This review highlights different in silico techniques and studies, from quantum chemistry to the mesoscale, with particular reference to carbon nanodots, carbonaceous nanoparticles whose structural and photophysical properties are not fully elucidated. The role of experimental investigation is also presented. Hereby, we hope to encourage the reader to investigate CNDs and to apply virtual chemistry to obtain further insights needed to customize these amazing systems for novel prospective applications.

Photoassisted Charging of Li-Ion Oxygen Batteries Using g-C3N4/rGO Nanocomposite Photocatalysts

In this work, g-C₃N₄/rGO nanocomposites were synthesized to use them as photocatalysts in Li-ion oxygen batteries by aiming at the reduction of the charging potential efficiently under photoassisted conditions. Fourier transform infrared (FTIR) spectra showed that novel C═C bonds formed between g-C₃N₄ and rGO during the decomposition of melamine and that the formation of these bonds was assumed to cause a red shift in the optical absorption band edge. The competition between the narrowing in the optical band gaps of the nanocomposites as a result of the red shift due to the presence of rGO and the degradation in the visible light utilization as a result of favorably absorbed incident light by rGO instead of g-C₃N₄ pointed out that the g-C₃N₄/3% rGO nanocomposite has the optimum light absorbance efficiency. The photoassisted charging tests indicated that the g-C₃N₄/3% rGO nanocomposite reduced the charging potential effectively, especially at higher current densities, and improved the cyclic discharge-charge performance of the Li-ion oxygen batteries considerably.

Effectively compound the heterojunction formed by flower-like Bi2S3 and g-C3N4 to enhance photocatalytic activity

In this study, the flower-shaped Bi₂S₃/g-C₃N₄-2.6 heterojunction obtained by solvothermal method and its photocatalytic degradation efficiency of rhodamine B (RhB) and tetracycline (TC) in aqueous solution within 40 min is as high as 98.8% and 94.6%. For RhB degradation, the photocatalytic reaction rate constant (k) of Bi₂S₃/g-C₃N₄-2.6 is approximately 1.8 and 45.5 times that of Bi₂S₃ and g-C₃N₄. For TC, k is 3.1 and 2.4 times that of Bi₂S₃ and g-C₃N₄, respectively. The key to determining the high catalytic activity of Bi₂S₃/g-C₃N₄ lies in the formation of a good heterojunction between Bi₂S₃ and g-C₃N₄, which accelerates the electron transfer rate between the heterojunction interface and effectively avoids electron-hole recombination. The effects of catalyst dosage, different pH values, inorganic anions, and capture agents on the photodegradation performance of RhB were investigated. The results show that the catalyst dosage is 1.33 g/L, and the solution pH is in the range of 5-9, which has the best removal effect on pollutants, and the isolation of holes (h⁺) with strong oxidizing ability promotes the collapse of pollutant molecules. Combined with electrochemical tests, a possible degradation mechanism was advised.

Continuous g-C3N4 layer-coated porous TiO2 fibers with enhanced photocatalytic activity toward H2 evolution and dye degradation

TiO₂/g-C₃N₄ composite photocatalysts with various merits, including low-cost, non-toxic, and environment friendliness, have potential application for producing clean energy and removing organic pollutants to deal with the global energy shortage and environmental contamination. Coating a continuous g-C₃N₄ layer on TiO₂ fibers to form a core/shell structure that could improve the separation and transit efficiency of photo-induced carriers in photocatalytic reactions is still a challenge. In this work, porous TiO₂ (P-TiO₂)@g-C₃N₄ fibers were prepared by a hard template-assisted electrospinning method together with the g-C₃N₄ precursor in an immersing and calcination process. The continuous g-C₃N₄ layer was fully packed around the P-TiO₂ fibers tightly to form a TiO₂@g-C₃N₄ core/shell composite with a strong TiO₂/g-C₃N₄ heterojunction, which greatly enhanced the separation efficiency of photo-induced electrons and holes. Moreover, the great length–diameter ratio configuration of the fiber catalyst was favorable for the recycling of the catalyst. The P-TiO₂@g-C₃N₄ core/shell composite exhibited a significantly enhanced photocatalytic performance both in H₂ generation and dye degradation reactions under visible light irradiation, owing to the specific P-TiO₂@g-C₃N₄ core/shell structure and the high-quality TiO₂/g-C₃N₄ heterojunction in the photocatalyst. This work offers a promising strategy to produce photocatalysts with high efficiency in visible light through a rational structure design.

TiO₂@g-C₃N₄ core/shell fibers with a continuous g-C₃N₄ layer packing around exhibit high photocatalytic efficiency toward H₂ production and RhB degradation due to the intimate core/shell structure with a high-quality TiO₂/g-C₃N₄ heterojunction.

Development and Mechanistic Studies of Ternary Nanocomposites for Hydrogen Production from Water Splitting to Yield Sustainable/Green Energy and Environmental Remediation

Photocatalysts lead vitally to water purifications and decarbonise environment each by wastewater treatment and hydrogen (H2) production as a renewable energy source from water-photolysis. This work deals with the photocatalytic degradation of ciprofloxacin (CIP) and H2 production by novel silver-nanoparticle (AgNPs) based ternary-nanocomposites of thiolated reduce-graphene oxide graphitic carbon nitride (AgNPs-S-rGO2%@g-C3N4) material. Herein, the optimised balanced ratio of thiolated reduce-graphene oxide in prepared ternary-nanocomposites played matchlessly to enhance activity by increasing the charge carriers’ movements via slowing down charge-recombination ratios. Reduced graphene oxide (rGO), >2 wt.% or <2 wt.%, rendered H2 production by light-shielding effect. As a result, CIP degradation was enhanced to 95.90% by AgNPs-S-rGO2%@g-C3N4 under the optimised pH(6) and catalyst dosage(25 mg/L) irradiating beneath visible-light (450 nm, 150 watts) for 70 min. The chemical and morphological analysis of AgNPs-S-rGO2%@g-C3N4 surface also supported the possible role of thiolation for this enhancement, assisted by surface plasmon resonance of AgNPs having size < 10 nm. Therefore, AgNPs-S-rGO2%@g-C3N4 has 3772.5 μmolg−1 h−1 H2 production, which is 6.43-fold higher than g-C3N4 having cyclic stability of 96% even after four consecutive cycles. The proposed mechanism for AgNPs-S-rGO2%@g-C3N4 revealed that the photo-excited electrons in the conduction-band of g-C3N4 react with the adhered water moieties to generate H2.

Visible-Light Driven Photocatalytic Degradation of 4-Chlorophenol Using Graphitic Carbon Nitride-Based Nanocomposites

4-chlorophenol (4-CP), a hydroxylated aromatic compound (HAC), is a recalcitrant and toxic organic pollutant found in industrial wastewater and various environmental media. In this paper, visible-light-activated photocatalysis using graphitic carbon nitride (GCN) was used to treat 4-CP in an aqueous media. Graphitic carbon nitride from different precursors (dicyanamide, urea, and melamine), as well as GCN/silver nanocomposites (AgBr, Ag3PO4, Ag2CrO4, and Ag), were successfully synthesized and characterized by BET, XRD, SEM, EDS, and UV-Vis DRS. The band gaps of the photocatalysts were estimated using the UV-Vis DRS characterization results and Tauc plots. The evaluation of the efficacy of the GCN-based catalysts in degrading 4-CP was conducted with different photoreactors such as a royal blue light-emitting diode (LED), a UV-A LED, LUZCHEM cool white lamps, and a solar simulator. The results showed that GCNs with royal blue LED can effectively degrade 4-CP from aqueous media. Among the different precursors, urea-derived GCN showed the best performance in degrading 4-CP due to its large surface area. GCN/0.3Ag2CrO4 nanocomposite showed a synergistic effect for the enhanced photocatalytic degradation of 4-CP. The degradation of 4-CP with a rate constant of 2.64 × 10−2 min−1 was achieved with a GCN/0.3Ag2CrO4 nanocomposite under royal blue LED irradiation.

Graphene Oxide-Assisted Covalent Triazine Framework for Boosting Photocatalytic H2 Evolution

Covalent triazine frameworks (CTFs) with two-dimensional structures have exhibited promising visible-light-induced H₂ evolution performance. However, it is still a challenge to improve their activity. Herein, we report π-conjugation-linked CTF-1/GO for boosting photocatalytic H₂ evolution. The CTF-1/GO hybrid material was obtained by a facile low-temperature condensation of 1,4-dicyanobenzene in the presence of GO. The results of photocatalytic H₂ evolution indicate that the optimum hybrid, CTF-1/GO-3.0, exhibited an H₂ evolution rate of 2262.4 μmol ⋅ g^-1  ⋅ h^-1 under visible light irradiation, which was 9 times that of pure CTF-1. The enhanced photocatalytic performance could be attributed to the fact that GO in CTF-1/GO hybrids not only acts as an electron collector and transporter like a "bridge" to facilitate the separation and transfer of photogenerated charges but also shortens the electron migration path due to its thin sheet layer uniformly distribution over CTF-1. This work could help future development of novel conjugated CTF-based composite materials as high-efficiency photocatalyst for photocatalysis.

Construction of Electrostatic Self-Assembled 2D/2D CdIn2S4/g-C3N4 Heterojunctions for Efficient Visible-Light-Responsive Molecular Oxygen Activation

Molecular oxygen activated by visible light to generate radicals with high oxidation ability exhibits great potential in environmental remediation The efficacy of molecular oxygen activation mainly depends on the separation and migration efficiency of the photoinduced charge carriers. In this work, 2D/2D CdIn₂S₄/g-C₃N₄ heterojunctions with different weight ratios were successfully fabricated by a simple electrostatic self-assembled route. The optimized sample with a weight ratio of 5:2 between CdIn₂S₄ and g-C₃N₄ showed the highest photocatalytic activity for tetracycline hydrochloride (TCH) degradation, which also displayed good photostability. The enhancement of the photocatalytic performance could be ascribed to the 2D/2D heterostructure; this unique 2D/2D structure could promote the separation and migration of the photoinduced charge carriers, which was beneficial for molecular oxygen activation, leading to an enhancement in photocatalytic activity. This work may possibly provide a scalable way for molecular oxygen activation in photocatalysis.

"Dual-Signal-On" Integrated-Type Biosensor for Portable Detection of miRNA: Cas12a-Induced Photoelectrochemistry and Fluorescence Strategy

The abnormal expression of microRNA (miRNA) can affect the RNA transcription and protein translation, leading to tumor progression and metastasis. Currently, the accurate detection of aberrant expression of miRNA, particularly using a portable detection system, remains a great challenge. Herein, a novel dual-mode biosensor with high sensitivity and robustness for miR-21 detection was developed based on the cis-cleavage and trans-cleavage activities of Cas12a. miRNA can be combined with hairpin DNA-horseradish peroxidase anchored on a CdS/g-C₃N₄/B-TiO₂ photoelectrode, thus the nonenzymatic amplification was triggered to form numerous HRP-modified double-stranded DNA (HRP-dsDNA). Then, HRP-dsDNA can be specifically recognized and efficiently cis-cleaved by Cas12a nucleases to detach HRP from the substrate, while the remaining HRP on HRP-dsDNA can catalyze 4-chloro-1-naphthol (4-CN) to form biocatalytic precipitation (BCP) on the surface of the photoelectrode, and thus the photocurrent can be changed. Meanwhile, the trans-cleavage ability of Cas12a was activated, and nonspecifically degrade the FQ-reporter and a significant fluorescence signal can be generated. Such two different kinds of signals with independent transmission paths can mutually support to improve the performance of the detection platform. Besides, a portable device was constructed for the point-of-care (POC) detection of miR-21. Moreover, the dual-mode detection platform can be easily expanded for the specific detection of other types of biomarkers by changing the sequence of hairpin DNA, thereby promoting the establishment of POC detection for early cancer diagnosis.

Spectroscopic Analyses of Changes in Photocatalytic and Catalytic Activities of Mn- and Ni-Ion Doped and Base-Treated Reduced Graphene Oxide

While reduced graphene oxide (rGO) is used widely as a catalyst, its catalytic activity can be improved significantly by modifying it with a metal. In this study, we compared the photocatalytic and catalytic properties of base-treated rGO particles and transition-metal-ion-doped rGO based on the oxidation reaction of thiophenol and the photocatalytic degradation of 4-chlorophenol. Since the two catalytic activities are related to the changes in the electronic structure of rGO, X-ray photoemission spectroscopy, X-ray absorption spectroscopy, and Raman spectroscopy were performed. When rGO was doped with Mn2+ ions, its catalytic properties improved with respect to both reactions. The changes in the electronic structure of rGO are attributed to the formation of defect structures on the rGO surface via a reaction between the doped Mn2+ ions and oxygen of the rGO surface. Thus, the results show that the doping of rGO with Mn ions in the +2-charge state (stable oxide form: MnO) enhances its catalytic and photocatalytic activities. Hence, this study provides new insights into the use of defect-controlled rGO as a novel catalyst.

Construction of Z-scheme NiO/NiC/g-C3N4 composites using NiC as novel cocatalysts for the efficient photocatalytic degradation

A novel composite consisting of NiO/NiC/g-C₃N₄ with excellent photocatalytic properties was successfully synthesized by the simple calcination of layered double metal hydroxide (LDH) and melamine. The color and chemical composition of the as-prepared composites could be tailored by changing the mass ratio of NiAl-LDH and g-C₃N₄. For the L4C composite at the ratio of 1 : 1, it showed the desired dark color due to the generated NiC. It also showed high photodegradation efficiency under visible light irradiation, reaching 97.5% toward Rhodamine B and 92.6% toward tetracycline. The high photodegradation efficiency could be mainly attributed to the unique formation of NiC cocatalysts coupled with g-C₃N₄ and NiO semiconductors, which constructed a Z-scheme system and facilitated the efficient separation of the photogenerated electron–hole pairs. The present findings provide a promising approach for fabricating the new types of composite photocatalysts for pollutant degradation.

A novel composite consisting of NiO/NiC/g-C₃N₄ with excellent photocatalytic properties was successfully synthesized by the simple calcination of layered double metal hydroxide (LDH) and melamine.

Synthesizing the High Surface Area g-C3N4 for Greatly Enhanced Hydrogen Production

Adjusting the structure of g-C3N4 to significantly enhance its photocatalytic activity has attracted considerable attention. Herein, a novel, sponge-like g-C3N4 with a porous structure is prepared from the annealing of protonated melamine under N2/H2 atmosphere (PH-CN). Compared to bulk g-C3N4 via calcination of melamine under ambient atmosphere (B-CN), PH-CN displays thinner nanosheets and a higher surface area (150.1 m2/g), which is a benefit for shortening the diffusion distance of photoinduced carriers, providing more active sites, and finally favoring the enhancement of the photocatalytic activity. Moreover, it can be clearly observed from the UV-vis spectrum that PH-CN displays better performance for harvesting light compared to B-CN. Additionally, the PH-CN is prepared with a larger band gap of 2.88 eV with the Fermi level and conduction band potential increased and valence band potential decreased, which could promote the water redox reaction. The application experiment results show that the hydrogen evolution rate on PH-CN was nearly 10 times higher than that of B-CN, which was roughly 4104 μmol h−1 g−1. The method shown in this work provides an effective approach to adjust the structure of g-C3N4 with considerable photocatalytic hydrogen evolution activity.

Facile Synthesis of g-C3N4/MoO3 Nanohybrid for Efficient Removal of Aqueous Diclofenac Sodium

Graphitic carbon nitride modified by molybdenum trioxide (g-C₃N_4/MoO₃) as a nanohybrid was synthesized by co-precipitation method. Here, g-C₃N₄/MoO₃ nanohybrid was used for the first time as an adsorbent for the pharmaceutical drug, diclofenac, (an aqueous micropollutant) from water to mitigate its possible environmental toxic effects. Compared to pristine components, the nanohybrid exhibited better adsorptive removal of diclofenac. Adsorption was enhanced with increment in MoO₃ content from 1 to 3 wt %; however further increment in MoO₃ content resulted in lower adsorption capacity due to agglomeration of MoO₃ particles over g-C₃N₄. 162 mg g⁻¹ adsorption capacity was achieved for 300 mg L⁻¹ diclofenac in solution with 1 g L⁻¹ adsorbent at pH = 6. Adsorption of diclofenac over g-C₃N₄ /MoO₃ followed pseudo 2nd order kinetics. Temkin, Langmuir, Dubinin Radushkevich and Freundlich isotherm models were applied on the experimental results concluding that diclofenac adsorption over g-C₃N₄/MoO₃ followed the Langmuir isotherm. The adsorption mechanism could be explained by the π–π interaction between aromatic rings of diclofenac and g-C₃N₄/MoO₃ (3%) nanohybrid, which is also evident by the FTIR results. This study presents the facile fabrication of a 2nd generation adsorbent for the treatment of diclofenac contaminated water that may as well help achieve the removal of other micropollutants form water.

Intense Visible-Light Absorption in SrRuO3/C3N4 Heterostructures for the Highly Efficient Reduction of Hg(II)

Strontium ruthenium oxide (SrRuO₃) is recognized as a metallic itinerant ferromagnet and utilized as a conducting electrode in heterostructure oxides with unforeseen optical characteristics, including remarkably low-reflection and high-absorption visible-light spectrum compared to classical metals. By coupling mesoporous SrRuO₃ nanoparticles (NPs) with porous g-C₃N₄ nanosheets for the first time, we evidence remarkably promoted visible light absorption and superior photocatalytic performances for Hg(II) reduction under illumination with visible light. The photocatalytic performance of g-C₃N₄ increased upon boosting the SrRuO₃ percentage to 1.5%, and this (1.5% SrRuO₃/g-C₃N₄ heterostructure) is considered the optimum condition to obtain a high photocatalytic efficiency of about 100% within 50 min. It was promoted 3.68 and 5.75 times compared to SrRuO₃ and g-C₃N₄, respectively. Also, a Hg(II) reduction rate of 1.5% SrRuO₃/g-C₃N₄ was enhanced3.84- and 6.28-fold than those of pure SrRuO₃ NPs and g-C₃N₄, respectively. Such a high photocatalytic performance over SrRuO₃/g-C₃N₄ photocatalysts was explained by the characteristics of SrRuO₃ NPs incorporated on porous g-C₃N₄ layers, which demonstrate strong absorption of visible light with a narrow band gap, a large photocurrent density of ∼9.07 mA/cm², well-dispersed and small particle sizes, and cause facile diffusion of HCOOH and Hg(II) ions and electrons. The present work provides a dramatic novel approach to the challenge of constructing visible-light photosensitive photocatalysts for wastewater remediation.

Electrochemical immunosensor development based on core-shell high-crystalline graphitic carbon nitride@carbon dots and Cd0.5Zn0.5S/d-Ti3C2Tx MXene composite for heart-type fatty acid-binding protein detection

Acute myocardial infarction (AMI) is a significant health problem owing to its high mortality rate. Heart-type fatty acid-binding protein (h-FABP) is an important biomarker in the diagnosis of AMI. In this work, an electrochemical h-FABP immunosensor was developed based on Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene (MXene: Transition metal carbide or nitride) composite as signal amplificator and core-shell high-crystalline graphitic carbon nitride@carbon dots (hc-g-C₃N₄@CDs) as electrochemical sensor platform. Firstly, a facile calcination technique was applied to the preparation of hc-g-C₃N₄@CDs and immobilization of primary antibody was performed on hc-g-C₃N₄@CDs surface. Then, the conjugation of the second antibody to Cd_0.5Zn_0.5S/d-Ti₃C₂T_x MXene was carried out by strong π-π and electrostatic interactions. The prepared electrochemical h-FABP immunosensor was characterized by transmission electron microscopy (TEM), scanning electron microscopy (SEM), x-ray diffraction (XRD) method, Fourier-transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy (XPS), cyclic voltammetry (CV), and electrochemical impedance spectroscopy (EIS). The prepared electrochemical h-FABP immunosensor indicated a good sensitivity with detection limit (LOD) of 3.30 fg mL^-1 in the potential range +0.1 to +0.5 V. Lastly, low-cost, satisfactory stable, and environmentally friendly immunosensor was presented for the diagnosis of acute myocardial infarction.

An Overview of the Recent Progress in Polymeric Carbon Nitride Based Photocatalysis

Recently, polymeric carbon nitride (g-C₃ N₄ ) as a proficient photo-catalyst has been effectively employed in photocatalysis for energy conversion, storage, and pollutants degradation due to its low cost, robustness, and environmentally friendly nature. The critical review summarized the recent development, fundamentals, nanostructures design, advantages, and challenges of g-C₃ N₄ (CN), as potential future photoactive material. The review also discusses the latest information on the improvement of CN-based heterojunctions including Type-II, Z-scheme, metal/CN Schottky junctions, noble metal@CN, graphene@CN, carbon nanotubes (CNTs)@CN, metal-organic frameworks (MOFs)/CN, layered double hydroxides (LDH)/CN heterojunctions and CN-based heterostructures for H₂ production from H₂ O, CO₂ conversion and pollutants degradation in detail. The optical absorption, electronic behavior, charge separation and transfer, and bandgap alignment of CN-based heterojunctions are discussed elaborately. The correlations between CN-based heterostructures and photocatalytic activities are described excessively. Besides, the prospects of CN-based heterostructures for energy production, storage, and pollutants degradation are discussed.

Template-Free Synthesis of One-Dimensional g-C3N4 Chain Nanostructures for Efficient Photocatalytic Hydrogen Evolution

The development of graphite-carbon nitride (g-C3N4) photocatalyst is of great significance for various visible utilization applications. Control the nanostructures of g-C3N4 can tailor its photocatalytic performance. In this paper, one-dimensional chain-like g-C3N4 was successfully synthesized by heat-induced polymerization of melamine which was saturated in ethylene glycol. The photocatalytic hydrogen production rate (HER) of the prepared g-C3N4 chain enhanced about 3 times than that of bulk g-C3N4, increasing from 9.6 μmolh-1 to 28.7 μmolh-1. The improved photocatalytic activity of the g-C3N4 chain was attributed to the advantages of porosity and nanostructure. The extraordinary nanopores result in an enlarged specific surface area for adsorption and the production of abundantly available channels for charge transfer. The one-dimensional chain-like structure can facilitate the exposure of internal/external active sites as many as possible, and induce the directional migration of charge carriers.

Generation of Hydrogen Gas Using CuCr2O4-g-C3N4 Nanocomposites under Illumination by Visible Light

In this research, nanocomposites made of CuCr₂O₄-g-C₃N₄ accommodating distinct contents of CuCr₂O₄ (1-4 wt %) nanoparticles (NPs) were endorsed for hydrogen gas production after illumination by visible light in the presence of aqueous glycerol solution. The ultrasonication-mixture method was applied to assure the homogeneous distribution of CuCr₂O₄ NPs over synthesized mesoporous g-C₃N₄. Such nanocomposites possess suppressed recombination between the photoinduced charges. High-resolution transmission electron microscopy and X-ray photoelectron spectroscopy examinations affirmed the formation of CuCr₂O₄-g-C₃N₄ heterojunctions. The separation between the induced charges and the photocatalytic performance with the CuCr₂O₄ NP amount were investigated. The CuCr₂O₄-g-C₃N₄ heterojunction of 3 wt % CuCr₂O₄ content was documented as the optimal heterojunction. Upgraded hydrogen gas generation was attained over the optimal heterojunction with the extent of ten and thirty times as those registered for pure CuCr₂O₄ and g-C₃N₄ specimens, respectively, under illumination by visible light. The photocatalytic performance acquired by the diverse synthesized specimens was assessed not only by their effectiveness to absorb light in the visible region but also by their potential to separate the photoinduced charges.

Novel siligraphene/g-C3N4 composites with enhanced visible light photocatalytic degradations of dyes and drugs

In this research, a novel graphene-like SiC (siligraphene) was synthesized using a natural precursor and used to improve the photocatalytic activity of g-C₃N₄. The synthesized siligraphene has shown an excellent photocatalytic property due to its low band-gap and graphene-like structure which increases the electron transfer and reduces the electron-hole recombination rate and can improve the photocatalytic activity. Also, the positive charged Si atoms in siligraphene structure can adsorb oxygen to produce radicals that can promote the oxidation reaction. However, commercial β-SiC has exhibited very poor photocatalytic properties. As we know, g-C₃N₄ is a potential material for photocatalytic applications. Here, the novel siligraphene/g-C₃N₄ composites were successfully synthesized to enhance the photocatalytic properties of g-C₃N₄ in the degradation of model dyes (Congo red, Methyl red, and Methyl orange) and model drugs (Acetaminophen and Tetracycline) under visible light irradiation. Results show that siligraphene/g-C₃N₄ composite exhibits much better photocatalytic properties than pure g-C₃N_4. This enhanced photocatalytic properties can be justified by the enlarged surface area, suitable band gap, excellent electron properties, appropriate surface charge, and efficient migration of electron in siligraphene/g-C₃N₄ composite.

Carbon-Graphitic Carbon Nitride Hybrids for Heterogeneous Photocatalysis

Polymeric graphitic carbon nitride (g-C₃ N₄ ) and various carbon materials have experienced a renaissance as viable alternates in photocatalysis due to their captivating metal-free features, favorable photoelectric properties, and economic adaptabilities. Although numerous efforts have focused on the integration of both materials with optimized photocatalytic performance in recent years, the direct parameters for this emerging enhancement are not fully summarized yet. Fully understanding the synergistic effects between g-C₃ N₄ and carbon materials on photocatalytic action is vital to further development of metal-free semiconductors in future studies. Here, recent advances of carbon/g-C₃ N₄ hybrids on various photocatalytic applications are reviewed. The dominant governing factors by inducing carbon into g-C₃ N₄ photocatalysts with involving photocatalytic mechanism are highlighted. Five typical carbon-induced enhancement effects are mainly discussed here, i.e., local electric modification, band structure tailoring, multiple charge carrier activation, chemical group functionalization, and abundant surface-modified engineering. Photocatalytic performance of carbon-induced g-C₃ N₄ photocatalysts for addressing directly both the renewable energy storage and environmental remediation is also summarized. Finally, perspectives and ongoing challenges encountered in the development of metal-free carbon-induced g-C₃ N₄ photocatalysts are presented.

A Colorimetric Assay for the Detection of Glucose and H2O2 Based on Cu-Ag/g-C3N4/ZIF Hybrids with Superior Peroxidase Mimetic Activity

In this work, we report the synthesis of Cu-Ag bimetallic nanopartiles and g-C3N4 nanosheets decorated on zeolitic imidazolate framework-8 (ZIF-8) to form a Cu-Ag/g-C3N4/ZIF hybrid. The hybrid was synthesized and characterized by Transmission electron microscopy (TEM), Fourier transformed infrared (FTIR), the X-ray diffraction (XRD) and X-ray photoelectron spectroscopy (XPS). The Cu-Ag/g-C3N4/ZIF hybrid has intrinsic peroxidaselike catalytic activity towards the oxidation of TMB in the presence of H2O2. The situ synthesis of Cu-Ag bimetallic nanopartiles on 2D support such as g-C3N4 nanosheets would significantly enhance the peroxidaselike catalytic properties of individual Cu-Ag bimetallic nanopartiles and the g-C3N4 nanosheets. After loading of Cu-Ag bimetallic nanopartiles and g-C3N4 nanosheets on the ZIF-8, the hybrids exhibited superior peroxidaselike catalytic activity and good recyclability. Then, this method was applied for detecting glucose in human serum, owing the significant potential for detection of metabolites with H2O2-generation reactions.

Facile Fabrication of a Novel Au/Phosphorus-Doped g-C3N4 Photocatalyst with Excellent Visible Light Photocatalytic Activity

The intrinsic disadvantages of pristine graphitic carbon nitride (g-C3N4) significantly restrict its applications in photocatalysis field. Hence, we have demonstrated facile thermal copolymerization and in situ photodeposition methods to fabricate a novel Au/phosphorus-doped g-C3N4 (Au/P-g-C3N4) photocatalyst. The results showed that phosphorus was doped into the structure of g-C3N4 and that the surface deposition of gold was successfully accomplished. The H2 generation rate of the optimal Au/P-g-C3N4 is 8.4 times compared with the pristine g-C3N4 under visible light irradiation. The enhancement of photocatalytic activity is due to the synergic effect between gold induced surface plasmon resonance and the modified structural and electronic properties of the g-C3N4 induced by the phosphorus dopant.

Promoting Photodegradation Efficiency via a Heterojunction Photocatalyst Combining with Oxygen Direct and Fast Diffusion from the Gas Phase to Active Catalytic Sites

The low solubility of oxygen in solution is the main obstacle for the biodegradation of organic pollutants in wastewater. To address this problem, inspired by the degradation mechanism of aerobic bacteria toward organic pollutants, a novel photodegradation system was presented and operated by a heterojunction photocatalyst combining with a hydrophobic triphase interface, allowing oxygen to directly diffuse from the gas phase to active catalytic sites submersed in polluted solutions. Especially, the heterojunction photocatalyst was fabricated by graphitic carbon nitride nanosheets (C₃N₄ NS) sensitized with 5,10,15,20-tetrakis(4-carboxylphenyl)porphyrin (TCPP). The resulting photocatalyst was coated on a certain part of the commercial superhydrophobic carbon paper (CP) and submersed in the polluted wastewater, while the other part of hydrophobic CP (without coating with C₃N₄-TCPP nanocomposite) was exposed to air to form a gas-liquid-solid tri-phase photodegradation system. With this system, the photodegradation rate was 10-fold higher than that of a conventional liquid/solid diphase system in oxygen-saturated solutions. This was, on one hand, due to the abundant oxygen on the surface of a photocatalyst coming from the fast and direct diffusion from the gas phase through the superhydrophobic nanoporous part of CP. On the other hand, the hybrid C₃N₄-TCPP nanocomposite enhanced the light absorption efficiency under simulated sunlight irradiation and restrained the recombination of photogenerated electron-hole. Moreover, the triphase photodegradation system was stable in aqueous solutions for a long time and can be reused almost without attenuation for five cycles, which provided a great potential to be utilized for practical wastewater treatment.

Carbon-Intercalated 0D/2D Hybrid of Hematite Quantum Dots/Graphitic Carbon Nitride Nanosheets as Superior Catalyst for Advanced Oxidation

Efficient charge separation and sufficiently exposed active sites are important for light-driving Fenton catalysts. 0D/2D hybrids, especially quantum dots (QDs)/nanosheets (NSs), offer a better opportunity for improving photo-Fenton activity due to their high charge mobility and more catalytic sites, which is highly desirable but remains a great challenge. Herein, a 0D hematite quantum dots/2D ultrathin g-C₃ N₄ nanosheets hybrid (Fe₂ O₃ QDs/g-C₃ N₄ NS) is developed via a facile chemical reaction and subsequent low-temperature calcination. As expected, the specially designed 0D/2D structure shows remarkable catalytic performance toward the removal of p-nitrophenol. By virtue of large surface area, adequate active sites, and strong interfacial coupling, the 0D Fe₂ O₃ QDs/2D g-C₃ N₄ nanosheets establish efficient charge transport paths by local in-plane carbon species, expediting the separation and transfer of electron/hole pairs. Simultaneously, highly efficient charge mobility can lead to continuous and fast Fe(III)/Fe(II) conversion, promoting a cooperative effect between the photocatalysis and chemical activation of H₂ O₂ . The developed carbon-intercalated 0D/2D hybrid provides a new insight in developing heterogeneous catalysis for a large variety of photoelectronic applications, not limited in photo-Fenton catalysis.

Carbon Nitride Co-catalyst Activation Using N-Doped Carbon with Enhanced Photocatalytic H2 Evolution

Photocatalytic water splitting holds huge potential to meet the current challenges of energy and environments. Among them, polymeric carbon nitride (CN) has drawn much attention as a promising metal-free photocatalyst. As it is known, a number of promising co-catalysts have been developed to improve catalytic reactions, Pt nanoparticles is still among the best co-catalysts for CN in photocatalytic H₂ evolution, due to the suitable Fermi level to transfer excited electrons and the low overpotential for H₂ reduction. Herein, we report the interface engineering of urea-derived bulk CN and Pt co-catalyst by using a small portion of N-doped carbon (N-C) as a transition layer with a boosted photocatalytic activity up to 7 times. It was revealed that the activation energy of the Pt co-catalyst for water reduction was lowered in the presence of N-C, and the intimate interaction between CN and N-C, ascribing to the similar elemental composition and crystal structure, promoted the efficient separation and migration of charge carriers. This study may open a new avenue to develop CN-based photocatalysts for solar fuel conversion with even higher activity by photocatalyst/co-catalyst interface engineering.

Oxygen-Functionalized and Ni+x (x=2, 3)-Coordinated Graphitic Carbon Nitride Nanosheets with Long-Life Deep-Trap States and their Direct Solar-Light-Driven Hydrogen Evolution Activity

Graphitic carbon nitride, a 2 D layered photocatalyst coupled with transition metal oxides often shows promising photocatalytic hydrogen evolution activity. However, low surface area and poor charge separation greatly hinder its photocatalytic efficiency. A Ni^+x (x=2, 3)/O-g-C₃ N₄ photocatalyst with a very high specific surface area (199 m²  g^-1 ) has been prepared by thermal condensation and wet-impregnation methods. The oxygen-functionalized and Ni^+x (x=2, 3)-coordinated g-C₃ N₄ produced 1664 μmol g^-1 of hydrogen evolution from water under direct solar light irradiation in 4 h, which is 23 times higher than that over O-g-C₃ N₄ . This significant enhancement results from the combined effects of large surface area, the formation of long-life deep-trap states, effective charge carrier separation, and extended visible light absorption. The separation and transport behavior of the charge carriers are investigated by photoluminescence, time-resolved photoluminescence, photocurrent and Mott-Schottky measurements. Additionally, the interaction between Ni^+x (x=2, 3) and O-g-C₃ N₄ is studied by X-ray photoelectron spectroscopy, X-ray diffraction, and FTIR spectroscopy. The Ni^+x (x=2, 3)/O-g-C₃ N₄ photocatalyst shows remarkable reusability over a period of two months (six cycles). This study may provide a pathway to simultaneously overcome the challenges of low surface area and poor charge separation in g-C₃ N₄ -based photocatalysts.

Voltammetric determination of adefovir dipivoxil by using a nanocomposite prepared from molecularly imprinted poly(o-phenylenediamine), multi-walled carbon nanotubes and carbon nitride

An electrochemical sensor for adefovir dipivoxil (ADV) detection was prepared by electropolymerization of o-phenylenediamine in the presence of ADV on a glassy carbon electrode modified with multi-walled carbon nanotubes and carbon nitride. The electrode was characterized by field emission scanning electron microscopy and differential pulse voltammetry. The performance was optimized by response surface methodology. The changes in differential pulse voltammetric peak currents of the redox probe, ferricyanide, were linear to ADV concentrations in the range from 0.1 to 9.9 μmol L^-1, with the detection limit of 0.05 μmol L^-1 (S/N = 3). The sensor was applied to the determination of ADV in drug formulations, human serum and urine samples. It is selective due to the use of an imprinted material, well reproducible, long-term stable, and regenerable. Graphical abstract By merging the unique properties of carbon nitride with intrinsic properties of MWCNTs, and molecularly imprinted polymers, a novel electrochemical sensor with selective binding sites was prepared for determination of adefovir dipivoxil in pharmaceutical and biological samples.