Detection of Perfluorooctanoic and Perfluorodecanoic Acids on a Graphene-Based Electrochemical Sensor Aided by Computational Simulations.

Perfluoroalkyl carboxylic acids (PFCAs) exhibit high chemical and thermal stability, rendering them versatile for various applications. However, their notable toxicity poses environmental and human health concerns. Detecting trace amounts of these chemicals is crucial to mitigate risks. Electrochemical sensors surpass traditional methods in sensitivity, selectivity, and cost-effectiveness. In this study, a graphene nanosheet-based sensor was developed for detecting perfluorooctanoic acid (PFOA) and perfluorodecanoic acid (PFDA). Using the Hummer method, graphene nanosheets were synthesized and characterized in terms of morphology, structural ordering, and surface topology. Ab initio molecular dynamics simulations determined the molecular interaction of per- and poly-fluoroalkyl substances (PFASs) with the sensor material. The sensor exhibited high sensitivity (50.75 µA·µM-1·cm-2 for PFOA and 29.58 µA·µM-1·cm-2 for PFDA) and low detection limits (10.4 nM for PFOA and 16.6 nM for PFDA) within the electrode dynamic linearity range of 0.05-500.0 µM (PFOA) and 0.08-500.0 µM (PFDA). Under optimal conditions, the sensor demonstrated excellent selectivity and recovery in testing for PFOA and PFDA in environmental samples, including spiked soil, water, spoiled vegetables, and fruit samples.

Biowaste to bioenergy nexus: Fostering sustainability and circular economy.

Existing fossil-based commercial products present a significant threat to the depletion of global natural resources and the conservation of the natural environment. Also, the ongoing generation of waste is giving rise to challenges in waste management. Conventional practices for the management of waste, for instance, incineration and landfilling, emit gases that contribute to global warming. Additionally, the need for energy is escalating rapidly due to the growing populace and industrialization. To address this escalating desire in a sustainable manner, access to clean and renewable sources of energy is imperative for long-term development of mankind. These interrelated challenges can be effectively tackled through the scientific application of biowaste-to-bioenergy technologies. The current article states an overview of the strategies and current status of these technologies, including anaerobic digestion, transesterification, photobiological hydrogen production, and alcoholic fermentation which are utilized to convert diverse biowastes such as agricultural and forest residues, animal waste, and municipal waste into bioenergy forms like bioelectricity, biodiesel, bio alcohol, and biogas. The successful implementation of these technologies requires the collaborative efforts of government, stakeholders, researchers, and scientists to enhance their practicability and widespread adoption.

Electro-sensing layer constructed of a WO3/CuO nanocomposite, for the electrochemical determination of 2-phenylphenol fungicide.

The abstract highlights the development of an electroanalytical sensor for the detection of 2-phenylphenol (2-PPL) as a contaminant. The novelty of the experiment lies in the utilization of a 1-D nanostructured WO3/CuO nanocomposite integrated with a carbon paste electrode (CPE). The hydrothermal method was used to synthesize the WO3 NPs, which were then characterized using Scanning electron microscopy (SEM) and Energy-dispersive X-ray spectroscopy (EDS) techniques. Tungsten oxides (WO3) have been the subject of extensive study because of their many desirable characteristics, including their ease of preparation, tunable stoichiometry, crystal structure, particle morphology, 2.6 eV bandgap, excellent photocatalytic oxidation capacity, non-toxic nature, and widespread availability. The narrow band gap in CuO makes it an ideal sensing material. Copper oxide has applications in many different industries because it is a semiconductor metal with a narrow band gap in the spectrum of 1.2-1.9 eV and unique optical, electrical, and magnetic properties. Techniques like cyclic voltammetry (CV), and square wave voltammetry (SWV) were used. Real sample analysis was carried out in real-world samples like different types of soil, vegetables, and water. The electroanalytical sensor showed outstanding catalytic behavior by enhancing the peak current of the 2-phenylphenol with the potential shift to the less positive side compared to the unmodified carbon paste electrode in the presence of pH 7.0 phosphate buffer solution (PB). Throughout the experimental study, double distilled was used. Various electro-kinetic parameters like pH, accumulation time study, scan rate, concentration variation, standard heterogeneous rate constant, and participation of electrons, accumulation time, and transfer coefficient have been studied at WO3/CuO/CPE. The limit of detection was quantified together with the limit of quantification. Possible electrochemical oxidation mechanism of the toxic molecule was depicted. Overall, this research contributes to the field of electroanalytical sensing and offers potential applications in environmental monitoring.

Emerging trends and advances in valorization of lignocellulosic biomass to biofuels.

Sustainable technologies pave the way to address future energy demand by converting lignocellulosic biomass into fuels, carbon-neutral materials, and chemicals which might replace fossil fuels. Thermochemical and biochemical technologies are conventional methods that convert biomass into value-added products. To enhance biofuel production, the existing technologies should be upgraded using advanced processes. In this regard, the present review explores the advanced technologies of thermochemical processes such as plasma technology, hydrothermal treatment, microwave-based processing, microbial-catalyzed electrochemical systems, etc. Advanced biochemical technologies such as synthetic metabolic engineering and genomic engineering have led to the development of an effective strategy to produce biofuels. The microwave-plasma-based technique increases the biofuel conversion efficiency by 97% and the genetic engineering strains increase the sugar production by 40%, inferring that the advanced technologies enhances the efficiency. So understanding these processes leads to low-carbon technologies which can solve the global issues on energy security, the greenhouse gases emission, and global warming.

Valorization of biowastes for clean energy production, environmental depollution and soil fertility.

The mother earth is a source of natural resources that, in conjunction with anthropogenic activities, generates a wide spectrum of different biowastes. These biomaterials can be used as low-cost raw feedstock to produce bioenergy, value-added products, and other commodities. However, the improper management and disposal of these biowastes can generate relevant environmental impacts. Consequently, it is imperative to explore alternative technologies for the valorization and exploitation of these wastes to obtain benefits for the society. This review covers different aspects related to valorization of biowastes and their applications in water pollution, soil fertility and green energy generation. The classification and characteristics of different biowastes (biosolids, animal wastes and effluents, plant biomass, wood and green wastes) including their main generation sources are discussed. Different technologies (e.g., pyrolysis, hydrothermal carbonization, anaerobic digestion, gasification, biodrying) for the transformation and valorization of these residues are also analyzed. The application of biowastes in soil fertility, environmental pollution and energy production are described and illustrative examples are provided. Finally, the challenges related to implement low-cost and sustainable biowaste management strategies are highlighted. It was concluded that reliable simulation studies are required to optimize all the logistic stages of management chain of these residues considering the constraints generated from the economic, environmental and social aspects of the biowaste generation sources and their locations. The recollection and sorting of biowastes are key parameters to minimize the costs associated to their management and valorization. Also, the concepts of Industry 4.0 can contribute to achieve a successful commercial production of the value-added products obtained from the biowaste valorization. Overall, this review provides a general outlook of biowaste management and its valorization in the current context of circular economy.

An amperometric sensor composed of carbon hybrid-structure for the degradation of aminotriazole herbicide.

The use of the herbicide aminotriazole (3-ATA) in agriculture poses rising concerns about global water-borne contamination. Due to its toxicity which is known to cause cancer and thyroid dysfunction, 3-ATA is considered an important analytical target. Environmental protection agencies worldwide have introduced several directives that set concentration limits for chemicals to combat water pollution. Hence, to evaluate the presence of 3-ATA in water and limit their impact on ecosystems and human health, the development of an efficient real-time monitoring device is the key. The as-synthesized copper oxide decorated multiwall carbon nanotubes at 400 °C (CuO-MWCNT@400) showed remarkable efficiency as modifiers. Under optimal conditions, we explored the direct oxidation of 3-ATA at CuO-MWCNT@400 modified carbon paste electrode (MCPE). With its distinguishing synergistic features like high levels of porosity, stability, and surface area, this structure favoured greater detection, selectivity, and sensitivity. The amperometric i-t curve technique was adopted for the first time for 3-ATA quantification. This technique rendered a good detection sensitivity of 1.65 × 10-8 mol L-1 and anti-interference characteristics for several interferent species, including fungicides, fertilizers, herbicides, inorganic ions, and carbohydrates. Finally, the proof-of-concept was yielded by selective and sensitive detection of 3-ATA from two different samples of spiked water. We believe this work will enhance awareness and garner appreciation of the electrochemical sensor's analytical performance in protecting our environment and water resources.

Nanostructured graphitic carbon nitride (g-C3N4)-CTAB modified electrode for the highly sensitive detection of amino-triazole and linuron herbicides.

In agro-areas, linuron (LNR) and amino-triazole (ATZ) are the widely used herbicides to protect crops, but their widespread use pollutes the environment, especially when these are mixed with water or soil. In efforts to address these environmental issues and to detect trace quantities of the herbicides, a graphitic carbon nitride (g-C3N4) with cetyltrimethylammonium bromide (CTAB) modified carbon paste electrode (g-C3N4-CTAB/CPE) was developed and used for the detection of LNR and ATZ. Materials were characterized by XRD, TEM and AFM techniques. The effect of pH on electro-oxidation (under optimized conditions) showed the maximum peak current at pH of 4.2 for AMT and pH 6.0 for LNR. The electro-kinetic and thermodynamic parameters of LNR and ATZ were determined. Additional experiments were performed for the trace level detection of ATZ and LNR using the square wave voltammetric technique. Concentrations were varied linearly in the range of 3.0 × 10-7 M to 4.5 × 10-5 M for ATZ with a detection limit of 6.41 × 10-8 M, and 1.2 × 10-7 M to 3.0 × 10-4 M for LNR with a detection limit of 2.47 × 10-8 M. The developed novel sensor was effective for trace level detection of LNR and ATZ in water and soil samples.

Electrochemical sensors for the detection of SARS-CoV-2 virus.

Coronavirus (COVID-19), a deadly pandemic has spread worldwide and created many global health issues. Though methods of its detection are being continuously developed for the early detection and monitoring of COVID-19, still there is need for more novel methods. The presently used methods include rapid antigen tests, serological surveys, reverse transcription-polymerase chain reaction (RT-PCR), artificial intelligence-based techniques, and assays based on sensors/biosensors. Of all these, RT-PCR test has high sensitivity and specificity though it requires more time for testing and need for skilled technicians. Recently, electrochemical sensors have been developed for rapid monitoring and detection of SARS-CoV-2 from the patient's biological fluid samples. This review covers the recently developed electrochemical sensors that are focused on the detection of viral nucleic acid, immunoglobulin, antigen, and the entire viral particles. In addition, we also compare and assess their detection limits, sensitivities and specificities for the identification and monitoring of COVID-19. Furthermore, this review will address the best practices for the development of electrochemical sensors such as electrode fouling, limit of detection/limit of quantification determination and verification.

Two-dimensional ultrathin metal-based nanosheets for photocatalytic CO2 conversion to solar fuels.

Artificially simulated photosynthesis has created substantial curiosity as the majority of efforts in this arena have been aimed to upsurge solar fuel efficiencies for commercialization. The layered inorganic 2D nanosheets offer considerably higher tunability of their chemical surface, physicochemical properties and catalytic activity. Despites the intrinsic advantages of such metal-based materials viz., metal oxides, transition metal dichalcogenides, metal oxyhalides, metal organic frameworks, layered double hydroxide, MXene's, boron nitride, black phosphorous and perovskites, studies on such systems are limited for applications in photocatalytic CO2 reduction. The role of metal-based layers for CO2 conversion and new strategies such as surface modifications, defect generation and heterojunctions to optimize their functionalities are discussed in this review. Research prospects and technical challenges for future developments of layered 2D metal-based nanomaterials are critically discussed.

Hydrogen production technologies - Membrane based separation, storage and challenges.

The production of hydrogen, its separation, and storage for use as a primary source of energy is an important component of the green energy economy of the world. Hydrogen is a potential non-carbon-based energy source, which is gradually replacing the dependency on fossil fuels. It is anticipated that as the alternative fuel since hydrogen can be produced from green and clean sources. The evolution of hydrogen from renewable and non-renewable sources by various technologies has now gained tremendous research and industrial interest. The most appropriate methods for hydrogen generation involve the direct conversion of solar energy, exploitation of solar and wind energy for the electrolysis of water, besides conversion of fuel and biomass. To produce cleaner hydrogen and its separation from the chemical impurities is crucial and several methods including photobiological, photoelectrochemical, electrochemical, photocatalytic, thermochemical, thermolysis, and steam gasification have been used. The diverse types of membranes along with the pressure gas swing adsorption technique is another technique used to separate hydrogen, but the storage of hydrogen in an inexpensive, safe, compact, and environmentally friendly manner is one of the major concerns contributing to the country's economy. Apart from the countless advantages, storage and handling of hydrogen is a serious concern. Owing to its high inflammability, enough safety measures should be adopted during its production and storage as a fuel. It is necessary to provide information regarding the production technologies, storage, and separation methods of hydrogen and the present review addresses these issues.

Leveraging the potential of silver nanoparticles-based materials towards sustainable water treatment.

Increasing demand of pure and accessible water and improper disposal of waste into the existing water resources are the major challenges for sustainable development. Nanoscale technology is an effective approach that is increasingly being applied to water remediation. Compared to conventional water treatment processes, silver nanotechnology has been demonstrated to have advantages due to its anti-microbial and oligodynamic (biocidal) properties. This review is focused on environmentally friendly green syntheses of silver nanoparticles (AgNPs) and their applications for the disinfection and microbial control of wastewater. A bibliometric keyword analysis is conducted to unveil important keywords and topics in the utilisation of AgNPs for water treatment applications. The effectiveness of AgNPs, as both free nanoparticles (NPs) or as supported NPs (nanocomposites), to deal with noxious pollutants like complex dyes, heavy metals as well as emerging pollutants of concern is also discussed. This knowledge dataset will be helpful for researchers to identify and utilise the distinctive features of AgNPs and will hopefully stimulate the development of novel solutions to improve wastewater treatment. This review will also help researchers to prepare effective water management strategies using nano silver-based systems manufactured using green chemistry.

Catalytic production and application of bio-renewable butyl butyrate as jet fuel blend- A review.

Butyl butyrate (BB) derived from bio-renewable resources is the most promising jet fuel blend. This review highlights essential properties of jet fuel, including calorific value, kinematic viscosity, freezing point, flash point, auto-ignition temperature, and density to compare with different bio-renewable chemicals, which are compatible to be blended with the jet fuel. A detailed discussion follows on the importance of intermediate formation, reaction mechanism, and catalyst properties that are critical towards the production of bio-renewable resource-derived BB. BB is primarily produced via the esterification of butyric acid (BA) in butanol (BuOH) with or without using a catalyst. The corresponding reactions are carried out in both homogeneous and heterogeneous phases, provided it has acidic properties. Thus, a wide range of acidic catalysts such as [HSO3-pmim] HSO4 ionic liquids, heteropolyacid, methanesulfonic acid, Dowex 50 Wx8-400 resins, and sulfonated char causes up to 98%, 97.9%, 93.2%, 95.3%, and 90% of BB yield, respectively are critically reviewed. Moreover, reaction mechanism, product, and by-product formation that primarily dictate the BB yield and selectivity have been comprehensively reviewed. In addition, catalytic and mechanistic insights on BB production from other bio-renewable resources such as butyric anhydride, butyraldehyde, dibutyl ether, and methanol have been discussed in this review.

In-vitro evaluation of antioxidant and anticholinesterase activities of novel pyridine, quinoxaline and s-triazine derivatives.

Cholinesterase enzymes such as acetylcholinesterase (AChE) and butyrylcholinesterase (BuChE) cause hydrolysis of acetylcholine (ACh), a neurotransmitter responsible for the cognitive functions of the brain such as acquiring knowledge and comprehension. Therefore, inhibition of these enzymes is an effective process to curb the progressive and fatal neurological Alzheimer's disease (AD). Herein, we explored the potential inhibitory activities of various pyridine, quinoxaline, and triazine derivatives (3a-k, 6a-j and 11a-h) against AChE and BuChE enzymes by following the modified Ellman's method. Further, anti-oxidant property of these libraries was monitored using DPPH (2,2'-diphenyl-1-picryl-hydrazylhydrate) radical scavenging analysis. From the studies, we identified that compounds 6e, 6f, 11b and 11f behaved as selective AChE inhibitors with IC50 values ranging from 7.23 to 10.35 µM. Further studies revealed good anti-oxidant activity by these compounds with IC50 values in the range of 14.80-27.22 µM. The kinetic studies of the active analogues demonstrated mixed-type of inhibition due to their interaction with both the catalytic active sites (CAS) and peripheral anionic sites (PAS) of the AChE. Additionally, molecular simulation in association with fluorescence and circular dichroism (CD) spectroscopic analyses explained strong affinities of inhibitors to bind with AChE enzyme at the physiological pH of 7.2. Binding constant values of 5.4 × 104, 4.3 × 104, 3.2 × 104 and 4.9 × 104 M-1 corresponding to free energy changes -5.593, -6.799, -6.605 and -8.104 KcalM-1 were obtained at 25 °C from fluorescence emission spectroscopic studies of 6e, 6f, 11b and 11f, respectively. Besides, CD spectroscopy deliberately explained the secondary structure of AChE partly unfolded upon binding with these dynamic molecules. Excellent in vitro profiles of distinct quinoxaline and triazine compounds highlighted them as the potential leads compared to pyridine derivatives, suggesting a path towards developing preventive or therapeutic targets to treat the Alzheimer's disease.

Gram-scale synthesis of ZnS/NiO core-shell hierarchical nanostructures and their enhanced H2 production in crude glycerol and sulphide wastewater.

Design and development of the efficient and durable photocatalyst that generates H2 fuel utilizing industrial wastewater under solar light irradiation is a sustainable process. Innumerable photocatalysts have been reported for efficient H2 production, but their large-scale production with the same efficiency of H2 production is a challenging task. In this study, a few gram-scale syntheses of ZnS wrapped with NiO hierarchical core-shell nanostructure via the surfactant-mediated process has been reported. Morphology and crystal structure analysis of ZnS/NiO showed spherical shaped hierarchical core-shell with cubic and face-centered cubic crystal structures. The surface examination confirmed the presence of Zn2+, S2-, Ni2+ and O2- ions in the nanocomposite. The photocurrent and photoluminescence studies of pristine and nanocomposites revealed that core-shell material is non-corrosive with a prolonged life-time of photo-excitons. Parametric studies on photocatalytic H2 generation in lab-scale photoreactor using crude glycerol in water recorded a high rate of H2 generation of 9.3 mmol h-1.g-1 of catalyst under the simulated solar light irradiation. Optimized reaction parameters are extended to a demonstrative photoreactor containing aqueous crude glycerol produced 18.5 mmol h-1 of H2 generation under the natural solar light irradiation. The same nanostructures were further tested with the simulated sulfide wastewater and the optimized catalyst showed H2 production of 350 mL h-1. The experimental results of time-on stream and catalytic stability demonstrated that ZnS/NiO hierarchical core-shell nanostructures can be recyclable and reusable for the continuous photocatalytic H2 generation.

Electrochemical investigations for COVID-19 detection-A comparison with other viral detection methods.

Virus-induced infection such as SARS-CoV-2 is a serious threat to human health and the economic setback of the world. Continued advances in the development of technologies are required before the viruses undergo mutation. The low concentration of viruses in environmental samples makes the detection extremely challenging; simple, accurate and rapid detection methods are in urgent need. Of all the analytical techniques, electrochemical methods have the established capabilities to address the issues. Particularly, the integration of nanotechnology would allow miniature devices to be made available at the point-of-care. This review outlines the capabilities of electrochemical methods in conjunction with nanotechnology for the detection of SARS-CoV-2. Future directions and challenges of the electrochemical biosensors for pathogen detection are covered including wearable and conformal biosensors, detection of plant pathogens, multiplexed detection, and reusable biosensors for on-site monitoring, thereby providing low-cost and disposable biosensors.

Microplastics in the environment: Occurrence, perils, and eradication.

Microplastics (MPs) with sizes < 5 mm are found in various compositions, shapes, morphologies, and textures that are the major sources of environmental pollution. The fraction of MPs in total weight of plastic accumulation around the world is predicted to be 13.2% by 2060. These micron-sized MPs are hazardous to marine species, birds, animals, soil creatures and humans due to their occurrence in air, water, soil, indoor dust and food items. The present review covers discussions on the damaging effects of MPs on the environment and their removal techniques including biodegradation, adsorption, catalytic, photocatalytic degradation, coagulation, filtration and electro-coagulation. The main techniques used to analyze the structural and surface changes such as cracks, holes and erosion post the degradation processes are FTIR and SEM analysis. In addition, reduction in plastic molecular weight by the microbes implies disintegration of MPs. Adsorptive removal by the magnetic adsorbent promises complete elimination while the biodegradable catalysts could remove 70-100% of MPs. Catalytic degradation via advanced oxidation assisted by S O 4 • - or O H • radicals generated by peroxymonosulfate or sodium sulfate are also adequately covered in addition to photocatalysis. The chemical methods such as sol-gel, agglomeration, and coagulation in conjunction with other physical methods are discussed concerning the drinking water/wastewater/sludge treatments. The efficacy, merits and demerits of the currently used removal approaches are reviewed that will be helpful in developing more sophisticated technologies for the complete mitigation of MPs from the environment.

Identification and removal of micro- and nano-plastics: Efficient and cost-effective methods.

Microplastics (MPs) and nanoplastics (NPs) have gained much attention in recent years because of their ubiquitous presence, which is the widely acknowledged threat to the environment. MPs can be <5 mm size, while NPs are <100 nm, and both can be detected in various forms and shapes in the environment to alleviate their harmful effects on aquatic species, soil organisms, birds, and humans. In efforts to address these issues, the present review discusses about sampling methods for water, sediments, and biota along with their merits and demerits. Various identification techniques such as FTIR, Raman, ToF-SIMS, MALDI TOF MS, and ICP-MS are critically discussed. The detrimental effects caused by MPs and NPs are discussed critically along with the efficient and cost-effective treatment processes including membrane technologies in order to remove plastics particles from various sources to mitigate their environmental pollution and risk assessment.

Point of care detection of COVID-19: Advancement in biosensing and diagnostic methods.

The recent outbreak of COVID-19 has created much inconvenience and fear that the virus can seriously affect humans, causing health hazards and death. This pandemic has created much worry and as per the report by World Health Organization (WHO), more than 43 million individuals in 215 countries and territories were affected. People around the world are still struggling to overcome the problems associated with this pandemic. Of all the available methods, reverse-transcriptase polymerase chain reaction (RT-PCR) has been widely practiced for the pandemic detection even though several diagnostic tools are available having varying accuracy and sensitivity. The method offers many advantages making it a life-saving tool, but the method has the limitation of transporting to the nearest pathology lab, thus limiting its application in resource limited settings. This has a risen a crucial need for point-of-care devices for on-site detection. In this venture, biosensors have been used, since they can be applied immediately at the point-of-care. This review will discuss about the available diagnostic methods and biosensors for COVID-19 detection.

A novel sensor based on WO3·0.33H2O nanorods modified electrode for the detection and degradation of herbicide, carbendazim.

In the present-day scenario, it is necessary to establish more flexible, effective and selective analytical methods that are easy to operate and less expensive. Cyclic voltammetry (CV) can be a useful technique to assess minute quantity of pollutants and in this work, an effort has been made to detect the trace quantification from the environmental samples. Herein, electrochemical sensor was fabricated using tungsten oxide nanorod (WO3·0.33H2O) for sensitive detection of fungicide, carbendazim (CBZ). Under optimal conditions, while studying the effect of pH on peak current, the highest peak current was observed at pH 4.2. The degradation of CBZ followed the mixed diffusion-adsorption controlled and quasi-reversible processess at the WO3·0.33H2O/GC electrode surface. Using WO3·0.33H2O/GCE sensor in SWV provided the lowest limit of detection (LOD) and limit of quantification (LOQ) values of 2.21 × 10-8 M and 7.37 × 10-8 M, respectively over the concentration ranges of 1.0 × 10-7 M to 2.5 × 10-4 M. The proposed method demonstrates potential applicability of the fabricated sensor for soil and water samples analysis in the management of creating a benign environment.

Photocatalytic hydrogen production by ternary heterojunction composites of silver nanoparticles doped FCNT-TiO2.

Silver nanoparticles doped with FCNT-TiO2 heterogeneous catalyst was prepared via one-step chemical reduction process and their efficacy was tested for hydrogen production under solar simulator. Crystallinity, purity, optical properties, and morphologies of the catalysts were examined by X-Ray diffraction, Raman spectroscopy, UV-Visible diffuse reflectance spectra, and Transmission Electron Microscopy. The chemical states and interface interactions were studied by X-ray photoelectron spectroscopy and Fourier transform infrared spectroscopy. The optimized catalyst showed 19.2 mmol g-1 h-1 of hydrogen production, which is 28.5 and 7 times higher than the pristine TiO2 nanoparticles and FCNT-TiO2 nanocomposite, respectively. The optimized catalyst showed stability up to 50 h under the solar simulator irradiation. The natural solar light irradiated catalyst showed ~2.2 times higher hydrogen production rate than the solar simulator irradiation. A plausible reaction mechanism of Ag NPs/FCNT-TiO2 photocatalyst was elucidated by investigating the beneficial co-catalytic role of Ag NPs and FCNTs for enhanced hydrogen production.