Enhanced optical and electrochemical properties of FeBTC MOF modified TiO2 photoanode for DSSCs application.

In this work, iron based 1, 3, 5-tricarboxylic acid (FeBTC) was prepared via microwave-assisted method and incorporated into TiO2 via ultrasonic assisted method. The TiO2-FeBTC nanocomposites were characterized by XRD, FTIR, Raman, BET, FESEM, HRTEM, TGA, UV‒vis DRS and PL to understand their crystallographic, surface morphology, and optical characteristics. The Raman spectra showed a blue shift of Eg, A1g, and B1g peaks upon incorporation of FeBTC MOF onto TiO2. HRTEM and XRD analysis confirmed a mixture of TiO2 nanospheres and hexagonal FeBTC MOF morphologies with high crystallinity. The incorporation of FeBTC onto TiO2 improved the surface area as confirmed by BET results, which resulted in improved absorption in the visible region as a results of reduced bandgap energy from 3.2 to 2.84 eV. The PL results showed a reduced intensity for TiO2-FeBTC (6%) sample, indicating improved separation of electron hole pairs and reduced recombination rate. After fabrication of the TiO2-FeBTC MOF photoanode, the charge transfer kinetics were enhanced at TiO2-FeBTC MOF (6%) with Rp value of 966 Ω, as given by EIS studies. This led to high performance due to low charge resistance. Hence, high power conversion efficiency (PCE) value of 0.538% for TiO2-FeBTC (6%) was achieved, in comparison with other loadings. This was attributed to a relatively high surface area which allowed more charge shuttling and thus better electrical response. Conversely, upon increasing the FeBTC MOF loading to 8%, significant reduction in efficiency (0.478%) was obtained, which was attributed to sluggish charge transfer and fast electron-hole pair recombination rate. The TiO2-FeBTC (6%) may be a good candidate for use in DSSCs as a photoanode materials for improved efficiency.

Evaluation of Advanced Nanomaterials for Cancer Diagnosis and Treatment.

Cancer is a persistent global disease and a threat to the human species, with numerous cases reported every year. Over recent decades, a steady but slowly increasing mortality rate has been observed. While many attempts have been made using conventional methods alone as a theragnostic strategy, they have yielded very little success. Most of the shortcomings of such conventional methods can be attributed to the high demands of industrial growth and ever-increasing environmental pollution. This requires some high-tech biomedical interventions and other solutions. Thus, researchers have been compelled to explore alternative methods. This has brought much attention to nanotechnology applications, specifically magnetic nanomaterials, as the sole or conjugated theragnostic methods. The exponential growth of nanomaterials with overlapping applications in various fields is due to their potential properties, which depend on the type of synthesis route used. Either top-down or bottom-up strategies synthesize various types of NPs. The top-down only branches out to one method, i.e., physical, and the bottom-up has two methods, chemical and biological syntheses. This review highlights some synthesis techniques, the types of nanoparticle properties each technique produces, and their potential use in the biomedical field, more specifically for cancer. Despite the evident drawbacks, the success achieved in furthering nanoparticle applications to more complex cancer stages and locations is unmatched.

Exploring Copper Oxide and Copper Sulfide for Non-Enzymatic Glucose Sensors: Current Progress and Future Directions.

Millions of people worldwide are affected by diabetes, a chronic disease that continuously grows due to abnormal glucose concentration levels present in the blood. Monitoring blood glucose concentrations is therefore an essential diabetes indicator to aid in the management of the disease. Enzymatic electrochemical glucose sensors presently account for the bulk of glucose sensors on the market. However, their disadvantages are that they are expensive and dependent on environmental conditions, hence affecting their performance and sensitivity. To meet the increasing demand, non-enzymatic glucose sensors based on chemically modified electrodes for the direct electrocatalytic oxidation of glucose are a good alternative to the costly enzymatic-based sensors currently on the market, and the research thereof continues to grow. Nanotechnology-based biosensors have been explored for their electronic and mechanical properties, resulting in enhanced biological signaling through the direct oxidation of glucose. Copper oxide and copper sulfide exhibit attractive attributes for sensor applications, due to their non-toxic nature, abundance, and unique properties. Thus, in this review, copper oxide and copper sulfide-based materials are evaluated based on their chemical structure, morphology, and fast electron mobility as suitable electrode materials for non-enzymatic glucose sensors. The review highlights the present challenges of non-enzymatic glucose sensors that have limited their deployment into the market.

Advances on sonophotocatalysis as a water and wastewater treatment technique: efficiency, challenges and process optimisation.

Due to water shortage and increased water pollution, various methods are being explored to improve water quality by treating contaminants. Sonophotocatalysis is a combination of two individual water treatment processes i.e., photocatalysis and sonocatalysis. With advantages including shorter reaction times and enhanced activity, this technique shows possible futuristic applications as an efficient water treatment technology. Herein, background insight on sonophotocalysis as a water and wastewater treatment technique as well as the general mechanism of activity is explained. The commonly used catalysts for sonophotocatalytic applications as well as their synthesis pathways are also briefly discussed. Additionally, the utilisation of sonophotocatalysis for the disinfection of various microbial species as well as treatment of wastewater pollutants including organic (dyes, pharmaceuticals and pesticides) and inorganic species (heavy metals) is deliberated. This review also gives a critical analysis of the efficiency, enhancement strategies as well as challenges and outlooks in this field. It is thus intended to give insight to researchers in the context of facilitating future developments in the field of water treatment, and advancing sonophotocatalysis towards large-scale implementation and commercialization.

Thin Films (FTO/BaTiO3/AgNPs) for Enhanced Piezo-Photocatalytic Degradation of Methylene Blue and Ciprofloxacin in Wastewater.

In this study, we investigate the ability of barium titanate/silver nanoparticles (BaTiO3/AgNPs) composites deposited on a fluorine-doped tin oxide (FTO) glass using tape-casting method to produce piezoelectric thin film (FTO/BaTiO3/AgNPs) for piezocatalytic, photocatalytic, and piezo-photocatalytic degradation of methylene blue (MB) and ciprofloxacin (CIP) in wastewater. The prepared piezoelectric materials (BaTiO3 and BaTiO3/AgNPs) were characterized using XRD, SEM, TEM, EDS, UV-DRS, TGA, PL, BET, EIS, and chronoamperometry. The UV-DRS showed the surface plasmon resonance (SPR) of Ag nanoparticles on the surface of BaTiO3 at a wavelength of 505 nm. The TEM images revealed the average Ag nanoparticle size deposited on the surface of BaTiO3 to be in the range of 10-15 nm. The chronoamperometry showed that the photoreduction of silver nanoparticles (AgNPs) onto BaTiO3 (BTO) resulted in a piezo-electrochemical current enhancement from 0.24 to 0.38 mA. The composites (FTO/BaTiO3/AgNPs) achieved a higher degradation of MB and CIP when the photocatalysis and piezocatalysis processes were merged. Under both ultrasonic vibration and UV light exposure, FTO/BTO/AgNPs degraded about 72 and 98% of CIP and MB from wastewater, respectively. These piezoelectric thin films were shown to be efficient and reusable even after five cycles, suggesting that they are highly stable. Furthermore, the reactive oxygen species studies demonstrated that hydroxyl radicals (·OH) were the most effective species during degradation of MB, with minor superoxide radicals (·O2 -) and holes (h+). From this study, we were able to show that these materials can be used as multifunctional materials as they were able to degrade both the dye and pharmaceutical pollutants. Moreover, they were more efficient through the piezo-photocatalytic process.

Recent developments in nanotechnology-based printing electrode systems for electrochemical sensors.

In this review, the state-of-the-art of screen, inkjet, and three-dimensional (3D) printing electrode technologies of diverse types, manufacturing processes, and applications are critically reviewed for the first time. Emerging printing electrode-based technologies for advanced fabrication of printed electrode materials have given rise to the development of printed electrode devices and systems, thereby opening new avenues for several electrochemical applications. Additionally, their properties can be fine-tuned for specific electrochemical applications by embedding and/or immobilizing nano-structured materials. Nano-based printed or modified electrodes exhibit attractive features such as enhanced performance, cost-effectiveness, scalability, and high selectivity towards various targeted electroactive analytes. Furthermore, these nano-sized printed electrodes are flexible and portable, and thus are applicable for on-site measurements. However, their performance is affected by the type of printed electrode materials and fabrication methods employed. Hence, this review delves on the various electrode materials, printing methods and their applications for biosensors as well as for the detection of organic and inorganic compounds. The printed electrode materials that focus on properties such as selectivity, sensitivity and limit of detection available in the literature are highlighted in this review. Finally, future prospects, possibilities, and challenges of these advanced printing electrode technologies are deliberated.

PAMAM templated N,Pt co-doped TiO2 for visible light photodegradation of brilliant black.

This study examined the photocatalytic degradation of an azo dye brilliant black (BB) using non-metal/metal co-doped TiO2. N,Pt co-doped TiO2 photocatalysts were prepared by a modified sol-gel method using amine-terminated polyamidoamine dendrimer generation 0 (PG0) as a template and source of nitrogen. Structural, morphological, and textural properties were evaluated using scanning electron microscopy coupled to energy-dispersive X-ray spectroscopy (SEM/EDX), high-resolution transmission electron microscopy (HRTEM), X-ray diffraction spectroscopy (XRD), X-ray photoelectron spectroscopy (XPS), thermal gravimetric analysis (TGA), Fourier transform infrared (FTIR), Raman spectroscopy (RS), photoluminescence (PL) and ultra-violet/visible spectroscopy (UV-Vis). The synthesized photocatalysts exhibited lower band gap energies as compared to the Degussa P-25, revealing a red shift in band gap towards the visible light absorption region. Photocatalytic activity of N,Pt co-doped TiO2 was measured by the reaction of photocatalytic degradation of BB dye. Enhanced photodegradation efficiency of BB was achieved after 180-min reaction time with an initial concentration of 50 ppm. This was attributed to the rod-like shape of the materials, larger surface area, and enhanced absorption of visible light induced by N,Pt co-doping. The N,Pt co-doped TiO2 also exhibited pseudo-first-order kinetic behavior with half-life and rate constant of 0.37 and 0.01984 min-1, respectively. The mechanism of the photodegradation of BB under the visible light irradiation was proposed. The obtained results prove that co-doping of TiO2 with N and Pt contributed to the enhanced photocatalytic performances of TiO2 for visible light-induced photodegradation of organic contaminants for environmental remediation. Therefore, this work provides a new approach to the synthesis of PAMAM templated N,Pt co-doped TiO2 for visible light photodegradation of brilliant black.

The application of exfoliated graphite electrode in the electrochemical degradation of p-nitrophenol in water.

We report the application of exfoliated graphite (EG) as an electrode material in the electrochemical degradation of p-nitrophenol in water. Bulk electrolysis (degradation) of p-nitrophenol was carried out at a potential of 2.0 V (vs. Ag/AgCl) in the presence of 0.1 M Na2SO4 supporting electrolyte, while UV-Vis spectrophotometry was used to monitor the degradation efficiency. An initial p-nitrophenol load concentration of 0.2 mM for 3 h electrolysis time was studied under the optimized conditions of pH 7, and 10 mAcm(-2) current density. The electro-degradation reaction displayed a pseudo-first-order kinetic behavior with a rate constant (k(r)) of 11×10(-3) min(-1). The removal efficiency was found to be 91.5%. Chromatography coupled with time of flight mass spectrometry revealed p-benzoquinone as a major intermediate product. These results demonstrate the potential and viability of electrochemical technology as an alternative approach to water treatment using a low cost graphite electrode.