Graphene Oxide-Impregnated PVA–STA Composite Polymer Electrolyte Membrane Separator for Power Generation in a Single-Chambered Microbial Fuel Cell

The present study deals with the development and application of a proton-exchange polymer membrane separator consisting of graphene oxide (GO), poly­(vinyl alcohol) (PVA), and silicotungstic acid (STA) in a single-chambered microbial fuel cell (sMFC). GO and the prepared membranes were characterized by FT-IR spectroscopy, XRD, SEM, TEM, and AC impedance analysis. Higher power was achieved with a 0.5 wt % GO-incorporated PVA–STA–GO membrane compared to a Nafion 117 membrane. The effects of oxygen crossover and membrane-cathode-assembly (MCA) area were evaluated in terms of current density and Coulombic efficiency. The electrochemical behavior of the membrane in an MFC was improved by adding different amounts of GO to the membrane to reduce biofouling and also to enhance proton conductivity. A maximum power density of 1.9 W/m³ was obtained when acetate wastewater was treated in an sMFC equipped with a PVA–STA–GO-based MCA. Therefore, PVA–STA–GO could be utilized as an efficient and inexpensive separator for sMFCs

Bifunctional Manganese Ferrite/Polyaniline Hybrid as Electrode Material for Enhanced Energy Recovery in Microbial Fuel Cell

Microbial fuel cells (MFCs) are emerging as a sustainable technology for waste to energy conversion where electrode materials play a vital role on its performance. Platinum (Pt) is the most common material used as cathode catalyst in the MFCs. However, the high cost and low earth abundance associated with Pt prompt the researcher to explore inexpensive catalysts. The present study demonstrates a noble metal-free MFC using a manganese ferrite (MnFe₂O₄)/polyaniline (PANI)-based electrode material. The MnFe₂O₄ nanoparticles (NPs) and MnFe₂O₄ NPs/PANI hybrid composite not only exhibited superior oxygen reduction reaction (ORR) activity for the air cathode but also enhanced anode half-cell potential upon modifying carbon cloth anode in the single-chambered MFC. This is attributed to the improved extracellular electron transfer of exoelectrogens due to Fe³⁺ in MnFe₂O₄ and its capacitive nature. The present work demonstrates for the first time the dual property of MnFe₂O₄ NPs/PANI, i.e., as cathode catalyst and an anode modifier, thereby promising cost-effective MFCs for practical applications

One-Step Synthesis and Operando Electrochemical Impedance Spectroscopic Characterization of Heterostructured MoP–Mo₂N Electrocatalysts for Stable Hydrogen Evolution Reaction

This study presents a novel synthesis of self-standing MoP and Mo2N heterostructured electrocatalysts with enhanced stability and catalytic performance. Facilitated by the controlled phase and interfacial microstructure, the seamless structures of these catalysts minimize internal resistivity and prevent local corrosion, contributing to increased stability. The chemical synthesis proceeds with an etching step to activate the surface, followed by phosphor-nitriding in a chemical vapor deposition chamber to produce MoP–Mo2N@Mo heterostructured electrocatalysts. X-ray diffraction analyses confirmed the presence of MoP, Mo2N, and Mo phases in the electrocatalyst. Morphology studies using scanning electron microscopy characterize the hierarchical growth of structures, indicating successful formation of the heterostructure. X-ray photoelectron spectroscopy (XPS) analyses of the as-synthesized and postcatalytic activity samples reveal the chemical shift in terms of the binding energy (BE) of the Mo 3d XPS peak, especially after catalytic activity. The XPS BE shifts are attributed to changes in the oxidation state, electron transfer, and surface reconstruction during catalysis. Electrochemical evaluation of the catalysts indicates the superior performance of the MoP-Mo2N@Mo heterostructured catalyst in hydrogen evolution reactions (HER), with lower overpotentials and enhanced Tafel slopes. The stability tests reveal changes in double layer capacitance over time, suggesting surface reconstruction and an increased active surface area during catalysis. Operando electrochemical impedance spectroscopy (EIS) further elucidates the dynamic changes in resistance and charge transfer during HER. Overall, a comprehensive understanding of the synthesis, characterization, and electrochemical behavior of the developed MoP-Mo2N@Mo heterostructured electrocatalyst, as presented in this work, highlights its potential utilization in sustainable energy applications

Effect of High-Anisotropic Co²⁺ Substitution for Ni²⁺ on the Structural, Magnetic, and Magnetostrictive Properties of NiFe₂O₄: Implications for Sensor Applications

This work reports on the effect of substituting a low-anisotropic and low-magnetic cation (Ni2+, 2μB) by a high-anisotropic and high-magnetic cation (Co2+, 3μB) on the crystal structure, phase, microstructure, magnetic properties, and magnetostrictive properties of NiFe2O4 (NFO). Co-substituted NFO (Ni1–xCoxFe2O4, NCFO, 0 ≤ x ≤ 1) nanomaterials were synthesized using glycine-nitrate autocombustion followed by postsynthesis annealing at 1200 °C. The X-ray diffraction measurements coupled with Rietveld refinement analyses indicate the significant effect of Co-substitution for Ni, where the lattice constant (a) exhibits a functional dependence on composition (x). The a-value increases from 8.3268 to 8.3751 Å (±0.0002 Å) with increasing the “x” value from 0 to 1 in NCFO. The a–x functional dependence is derived from the ionic-size difference between Co2+ and Ni2+, which also induces grain agglomeration, as evidenced in electron microscopy imaging. The chemical bonding of NCFO, as probed by Raman spectroscopy, reveals that Co(x)-substitution induced a red shift of the T2g(2) and A1g(1) modes, and it is attributed to the changes in the metal–oxygen bond length in the octahedral and tetrahedral sites in NCFO. X-ray photoelectron spectroscopy confirms the presence of Co2+, Ni2+, and Fe3+ chemical states in addition to the cation distribution upon Co-substitution in NFO. Chemical homogeneity and uniform distribution of Co, Ni, Fe, and O are confirmed by EDS. The magnetic parameters, saturation magnetization (MS), remnant magnetization (Mr), coercivity (HC), and anisotropy constant (K1) increased with increasing Co-content “x” in NCFO. The magnetostriction (λ) also follows a similar behavior and almost linearly varies from −33 ppm (x = 0) to −227 ppm (x = 1), which is primarily due to the high magnetocrystalline anisotropy contribution from Co2+ ions at the octahedral sites. The magnetic and magnetostriction measurements and analyses indicate the potential of NCFO for torque sensor applications. Efforts to optimize materials for sensor applications indicate that, among all of the NCFO materials, Co-substitution with x = 0.5 demonstrates high strain sensitivity (−2.3 × 10–9 m/A), which is nearly 2.5 times higher than that obtained for their intrinsic counterparts, namely, NiFe2O4 (x = 0) and CoFe2O4 (x = 1)

Relation of HPV -16 and HPV-18 with clinico-pathological characteristics.

<p>* Statistically Significant, OR = odds ratio; CI = confidence interval;</p><p>^† Reference group for OR calculation</p><p>Relation of HPV -16 and HPV-18 with clinico-pathological characteristics.</p

Relationship of betel nut, tobacco, smoking, and alcohol and status of hr-HPV in Oral cavity patients only.

<p>* Statistically Significant OR = odds ratio; CI = confidence interval;</p><p>^† Reference group for OR calculation</p><p>Relationship of betel nut, tobacco, smoking, and alcohol and status of hr-HPV in Oral cavity patients only.</p

Demographic profiles and association with hr- HPV Positivity-.

<p>* Statistically Significant; OR = odds ratio; CI = confidence interval;</p><p>^† Reference group for OR calculation. Since only one variable is significant that will be significant in multivariate analysis also</p><p>Demographic profiles and association with hr- HPV Positivity-.</p

Relationship between clinico-pathological characteristics and hr- HPV Positivity.

<p>* Statistically Significant OR = odds ratio; CI = confidence interval;</p><p>^† Reference group for OR calculation</p><p>Relationship between clinico-pathological characteristics and hr- HPV Positivity.</p