Polyaniline coated sulfonated TiO2 nanoparticles for effective application in proton conductive polymer membrane fuel cell

Highly Sensitive Enzymatic Biosensor Based on Polyaniline-Wrapped Titanium Dioxide Nanohybrid for Fish Freshness Detection

Herein, we envisage the fabrication of a highly sensitive enzymatic electrochemical biosensor for selective detection of xanthine (Xn) using xanthine oxidase (XOs) immobilized polyaniline-wrapped titanium dioxide (PANI@TiO₂) nanohybrid as a sensing platform. The PANI@TiO₂ nanohybrid was synthesized via chemical polymerization using ammonium per sulfate as an oxidant. Various microscopic, spectroscopic, and electrochemical techniques have been utilized to confirm the electrophoretic deposition of the PANI and PANI@TiO₂ nanohybrids on to indium tin oxide (ITO) coated glass substrate. The fabricated XOs/PANI@TiO₂/ITO electrode exhibits enhanced electron transfer kinetics with an electron transfer rate constant of 0.904 cm s^-1. The electrochemical results show that the fabricated biosensor can detect Xn in the concentration range 1-100 µM, with a limit of detection of 0.1 µM (S/N = 3) and a response time of 10 s. The validation of the biosensors has been conducted using real samples obtained from the rohu (Labeo rohita) fish. The proposed biosensor can be a reliable analytical tool for determining Xn concentration in commercial fish and meat samples.

Titanium dioxide based nanocomposites - Current trends and emerging strategies for the photocatalytic degradation of ruinous environmental pollutants

Many ruinous pollutants are omnipresent in the environment and among them; pesticides are xenobiotic and pose to be a bio-recalcitrance. Their detrimental ecological and environmental impacts attract attention of environmental excerpts and the surge of stringent regulations have endows the need of a technically feasible treatment. This critical review emphasizes about the occurrence, abundance and fate of structurally distinct pesticides in different environment. The practiced remedial strategies and in particular, the advanced oxidation processes (AOPs) those utilize the photo-catalytic properties of nano-composites for the degradation of pollutants are critically discussed. Photo-catalytic degradation utilizes many composite materials at nano-scale level, wherein synthesis of nano-composites with appropriate precursors and other adjoining functional moieties are of prime importance. Therefore, suitable starter materials along with the reaction conditions are prerequisite for effectively tailoring the nano-composites. The aforementioned aspects and their customized applications are critically discussed. The associated challenges, opportunities and process economics of degradation using photo-catalytic AOP techniques are highlighted and in addition, the review tries to explain how best the photo-degradation can be a stand-alone tool with a societal importance. Conclusively, the future prospects for undertaking new researches in photo-catalytic breakdown of pollutants that can be judiciously sustainable.

Evaluation of membrane tailored with biocompatible halloysite‒polyaniline nanomaterial for efficient removal of carcinogenic disinfection by‒products precursor from water

Humic acid (HA) is the main component of natural organic matter that generates carcinogenic by‒products during disinfection and its removal from water resources is challenging. Biocompatible halloysite (HNTs) nanomaterial decorated with polyaniline (HNTs‒PANI) was synthesized via polymerization technique. HNTs‒PANI was added to prepare polyethersulfone mixed matrix membranes (MMMs). The influence of HNTs‒PANI concentration on HA removal efficiency was studied by varying the HNTs‒PANI (0.5, 1 and 1.5 wt%). The characterization studies of MMMs revealed that the addition of HNTs‒PANI improved the morphology of the membranes, surface properties, chemical stability and thermal property. The amine and hydroxyl groups within the MMMs improved the membrane wettability. The addition of HNTs‒PANI within the MMMs had significantly enhanced the pure water flux and HA filtration. YHP2 MMM with 1 wt% of HNTs‒PANI demonstrated sieving coefficient of 0.10 and the highest HA removal efficiency of 91% greater than the neat PES membrane. Furthermore, the antifouling property of the MMMs was studied using HA as foulant. 1 wt% of HNTs‒PANI added MMM showed a high flux recovery ratio (94.9%) with low total fouling of 12% and low irreversible fouling of 5%, respectively. Thus, HNTs‒PANI was an efficient nanomaterial for enhancing the pure water flux, removal efficiency and antifouling property to treat water contaminated with HA.

Protonated state and synergistic role of Nd3+ doped barium cerate perovskite for the enhancement of ionic pathways in novel sulfonated polyethersulfone for H2/O2 fuel cells

In recent decades, there has been a need for novel advancement of sustainable non-fluorinated polymer electrolyte membranes for proton exchange membrane fuel cell (PEMFC) applications. The set forth strategy aims to ameliorate proton conduction of sulfonated polyethersulfone (SPES) polymer membranes with a distinct mixture of barium cerate (BCO) and neodymium-doped barium cerate (BCNO) perovskites developing cationic composite membranes (CCMs) prepared through a technique of solvent casting. The CCMs were subjected to analysis of their mechanical, structural, chemical compositional, thermal, morphological, oxidative, physicochemical, electrochemical and fuel cell polarization performance respectively. Acceptor doping of the trivalent neodymium group at the B site of BCO increases the number of oxygen vacancies and improves ionic conduction. The CCM of neodymium-doped barium cerate demonstrates a higher proton conductivity of 42.2 mS cm-1 with a lower activation energy of 6.80 kJ mol-1 at 80 °C. The maximum current density and power density with the OCV of 0.93 V for the neodymium-doped barium cerate membrane are 397 mA cm-2 and 117 mW cm-2, which is 1.8 times greater than that of the pure SPES membrane. On the basis of polarization performance, the SPES membrane with neodymium-doped barium cerate has great potential in highly-efficient PEMFC applications.

Composite Polymers Development and Application for Polymer Electrolyte Membrane Technologies-A Review

Nafion membranes are still the dominating material used in the polymer electrolyte membrane (PEM) technologies. They are widely used in several applications thanks to their excellent properties: high proton conductivity and high chemical stability in both oxidation and reduction environment. However, they have several technical challenges: reactants permeability, which results in reduced performance, dependence on water content to perform preventing the operation at higher temperatures or low humidity levels, and chemical degradation. This paper reviews novel composite membranes that have been developed for PEM applications, including direct methanol fuel cells (DMFCs), hydrogen PEM fuel cells (PEMFCs), and water electrolysers (PEMWEs), aiming at overcoming the drawbacks of the commercial Nafion membranes. It provides a broad overview of the Nafion-based membranes, with organic and inorganic fillers, and non-fluorinated membranes available in the literature for which various main properties (proton conductivity, crossover, maximum power density, and thermal stability) are reported. The studies on composite membranes demonstrate that they are suitable for PEM applications and can potentially compete with Nafion membranes in terms of performance and lifetime.