Lower Solution Temperature Research Articles

Promoting effect of oxygen vacancies in Co/CoAl2O4 catalyst steered with a straightforward method on hydrogenation of furfural to 2-methylfuran

The exploitation of base metal catalysts to upgrade biomass chemicals remains a daunting challenge and a sustainable strategy. Here, a series of Co-Al spinel catalysts are rapidly prepared by low-temperature solution combustion synthesis for hydrogenation of furfural (FF) to 2-methylfuran (2-MF), in which oxygen vacancies are easily manipulated by regulating the proportion of glycine in the ingredients. The screened Co/CoAl2O4 incorporating adequate oxygen vacancies yields 2-MF over 97 % at 150 ℃ for 5 h, rivalling the state-of-the-art catalysts to date. Characterizations and DFT calculations attribute the success to oxygen vacancies, which not only enhance the adsorption of FF by changing the adsorption geometry, but also facilitate the hydrogen spillover from Co to substrate by moving down the d-band center of CoAl2O4. This study provides a versatile methodology for the efficient and low-temperature preparation of spinel and the construction of defect engineering on catalysts, enlightening the design of phenomenal catalysts.

Effects of solution temperatures on microstructures and mechanical properties of B4C/7A04Al composites: A comparison study with 7A04Al alloys

To prepare particle-reinforced aluminum matrix composites with ultra-high strength, high-strength 7xxx Al alloys are commonly employed as matrices. Heat treatment plays a crucial role in enhancing the mechanical properties of the alloys and their composites, but the influence of solution temperatures on composites based on 7xxxAl alloys remains unexplored. In this study, the effects of solution temperatures on the microstructures and mechanical properties of B4C/7A04Al composites fabricated via powder metallurgy (PM) technology were investigated, as well as those of 7A04Al alloys for comparison. Before solution treatments, the prominent second phases in the composite were MgZn2 phases, while those in the 7A04Al alloy consisted of MgZn2 and Al2CuMg phases. At lower solution temperature (420 °C), MgZn2 phases dissolved completely, whereas Al2CuMg phases persisted. Al2CuMg phases dissolved at 450 °C, and thus the 7A04Al alloy obtained the optimum strength and elongation. Further elevating the solution temperature caused abnormal grain growth (AGG) in the 7A04Al alloy, leading to a deterioration of strength and plasticity. In contrast, at various solution temperatures, the composite exhibited stability in grain size, which could be attributed to the pinning effects of B4C particles and Mg(Al)B2 phases, the reaction products between the boron impurity and the Al matrix. However, at higher solution temperatures (510 °C and 600 °C), the segregation of Mg and O around B4C particles was aggravated, and thus the elongation of the composite deteriorated. Interestingly, the strength remained relatively unaffected due to the strengthening effects of Mg(Al)B2 phases. The results indicate that the composite exhibited a broad range of solution temperature with comparable strength and elongation across a temperature range of 420 °C–470 °C. But for the 7A04Al alloy, the optimal solution temperature is 450 °C.

Solution combustion synthesis of metal tungstates for chromium reduction and dye degradation for environmental remediation

Metal tungstates CuWO4 and ZnWO4 nanoparticles were synthesized by simple, efficient, low temperature solution combustion synthesis using metal nitrate and ammonium tungstate. The prepared samples were characterized by different physicochemical characterization techniques i. e.XRD, FTIR, SEM, EDAX, UV–vis DRS, PL and XPS techniques. The petal and flower like morphology of these samples were obtained by using SEM analysis. Based on this novelty, we have studied the photodegradation of methylene blue and rhodamine B dyes in visible light. Results of photocatalytic dye degradation reaction reveal that both the tungstate’s can be employed as photocatalyst under visible light irradiation. ZnWO4 nanoparticles show comparatively higher activity than that of CuWO4, it may due to structural property as well as completely filled d10 orbital of Zn. Both CuWO4 as well as ZnWO4 were also applied to reduce toxic Cr(VI) into harmless Cr(III). This work implemented for the betterment of environmental remediation to the society.

Wafer-scale organic-on-III-V monolithic heterogeneous integration for active-matrix micro-LED displays.

The organic thin-film transistor is advantageous for monolithic three-dimensional integration attributed to low temperature and facile solution processing. However, the electrical properties of solution deposited organic semiconductor channels are very sensitive to the substrate surface and processing conditions. An organic-last integration technology is developed for wafer-scale heterogeneous integration of a multi-layer organic material stack from solution onto the non-even substrate surface of a III-V micro light emitting diode plane. A via process is proposed to make the via interconnection after fabrication of the organic thin-film transistor. Low-defect uniform organic semiconductor and dielectric layers can then be formed on top to achieve high-quality interfaces. The resulting organic thin-film transistors exhibit superior performance for driving micro light emitting diode displays, in terms of milliampere driving current, and large ON/OFF current ratio approaching 1010 with excellent uniformity and reliability. Active-matrix micro light emitting diode displays are demonstrated with highest brightness of 150,000 nits and highest resolution of 254 pixels-per-inch.

Myristic acid-tetradecanol-capric acid ternary eutectic/SiO2/MIL-100(Fe) as phase change humidity control material for indoor temperature and humidity control

Building materials with the dual function of temperature and humidity regulation can improve people's living comfort and reduce energy consumption. In this work, a simple and convenient strategy for building a comfortable indoor temperature and humidity environment was proposed. The phase change humidity control material (PCHCM) was prepared by the mixing of form-stable composite phase change material (CPCM) as temperature-control component and hygroscopic MIL-100(Fe) as humidity-control component. In PCHCM, the CPCM was obtained by molten recombination of myristic acid, tetradecanol, and capric acid (MA-TD-CA) as phase change material and hydrophilic fumed silica (SiO2) as porous carrier, and MIL-100(Fe) was synthesized by low-temperature solution method. Thermal analysis indicated that, under the optimized mass ratio of 28.8%MA-61.2%TD-10%CA, the CPCM containing 30 % SiO2 could effectively prevent the leakage of ternary eutectic, with a suitable phase change temperature and enthalpy (21.74 °C, 96.70 J·g−1). The thermal and wet performance evaluation confirmed that the PCHCMs containing 40–50 % CPCM had human body comfortable phase change temperature (26.96–27.26 °C) and high saturation adsorption capacity (0.179–0.205 g/g) at 60 % RH as well as outstanding thermal and wet cycle reliability, indicating the novel MA-TD-CA/SiO2/MIL-100(Fe) PCHCM has broad application potential in room temperature and humidity control and building energy conservation.

Corrosion Inhibition Efficiency of Steel by Mango Peel Extract in Hydrochloric Acid at Different Temperature

Nowadays, researchers are interested in exploring the possibility of replacing harmful inorganic chemicals with green organic substances derived from natural sources. This study focuses on accessing the potential of a green corrosion inhibitor for mild steel, using plant extracts from local mango peel. The Harumanis mango peel leftover was extracted using solvent extraction techniques and the chemical compounds were characterized through Fourier Transform Infra-Red (FTIR) and UV-visible spectroscopy. The analysis showed that the crude extract of Harumanis mango peel (HMPE) contained active functional groups for corrosion inhibitory properties such as -OH, -COOH, -C=O and aromatic ring structure. The presence of mangiferin and other flavonols, likely acid gallic, was also detected. The efficiency of HMPE as a corrosion inhibitor for mild steel was investigated through a conventional corrosion test. The immersion test was carried out in different temperatures at 30, 40, 50 and 60 ⁰C with and without the addition of the 50 to 350 ppm HMPE inhibitor in 1 M hydrochloric acid, HCl. The result showed that the corrosion inhibition efficiency for mild steel in acidic medium increased as the concentration of the Harumanis mango peel increased. The maximum inhibition efficiency of 85 % was obtained at 30 ⁰C for 300 ppm. The adsorption of the Harumanis mango peel corrosion inhibitor obeys Langmuir isotherm model. The adsorption of HMPE on mild steel showed comprehensive (mixed) types as revealed by thermodynamic studies. Favourable adsorption was more dominant for 30 and 40 ºC inhibitors system, whereas at high temperatures the adsorption showed weak and unfavourable interaction between HMPE and the mild steel surface. Surface analysis showed the mild steel surface was free from pits and uniform corrosion as it was inhibited by the HMPE in low temperature solution.

Nanomolar detection of essential amino acid in dairy products using a novel electrochemical sensor based on zinc cobaltite nanoflowers embedded porous 3D reduced graphene oxide

L-tryptophan (L-Trp) is a vital amino acid that sways neuronal function, immunity, and gut homeostasis, and its accurate detection in food samples is crucial. The aim of this study is to integrate zinc cobaltite (ZCO) nanoparticles and 3D porous reduced graphene oxide (rGO) on a screen-printed carbon electrode (SPCE) surface for building a novel electrochemical sensor to sensitively detect L-Trp in food products. A low-temperature aqueous solution method was employed in ZCO nanoflower synthesis and a hydrothermal approach was utilized to prepare 3D rGO. SEM, elemental mapping, XRD, Raman spectroscopy, XPS, and EIS characterizations were performed on the prepared nanocomposite, ZCO/3DrGO. Electrochemical experiments conducted with the cyclic and differential pulse voltammetric techniques were used for effectively assessing the catalytic power of ZCO/3DrGO/SPCE. With a low detection limit of 3 nM, high sensitivity of 19.53 μAμM−1cm−2, and a broad linear range of 0.08–5.93; 5.93–87.18 μM, the sensor demonstrated promising electrocatalytic activity towards L-Trp. Further, the reliability of the sensor was proved by analyzing its stability, repeatability, reproducibility, and selectivity towards L-Trp. The successful detection of L-Trp in dairy products (yogurt, milk, and cottage cheese) using the proposed sensor evinced its practical feasibility with high recovery of 98.16%–101.16% and low RSD of 2.8%.

Strain Effects on Flexible Perovskite Solar Cells.

Flexible perovskite solar cells (f-PSCs) as a promising power source have grabbed surging attention from academia and industry specialists by integrating with different wearable and portable electronics. With the development of low-temperature solution preparation technology and the application of different engineering strategies, the power conversion efficiency of f-PSCs has approached 24%. Due to the inherent properties and application scenarios of f-PSCs, the study of strain in these devices is recognized as one of the key factors in obtaining ideal devices and promoting commercialization. The strains mainly from the change of bond and lattice volume can promote phase transformation, induce decomposition of perovskite film, decrease mechanical stability, etc. However, the effect of strain on the performance of f-PSCs has not been systematically summarized yet. Herein, the sources of strain, evaluation methods, impacts on f-PSCs, and the engineering strategies to modulate strain are summarized. Furthermore,the problems and future challenges in this regard are raised, and solutions and outlooks are offered. This review is dedicated to summarizing and enhancing the research into the strain of f-PSCs to provide some new insights that can further improve the optoelectronic performance and stability of flexible devices.

Effect of the gas flow rate in the focused-oxygen plasma treatment of solution-processed indium oxide thin film transistors

In2O3 is a transparent semiconductor layer due to its transparency, high mobility, and solution processability. In this paper, we study the effect of focused oxygen plasma treatment on solution processed indium oxide films annealed at 250 °C and analyze the effect of the gas flow rate. Thin film transistor devices were prepared based on pristine In2O3 films and films treated with oxygen plasma using flow rates of 3, 6, and 9 sccm. The results show that controlling the plasma flow rate can be used to finetune the device characteristics, and the selecting the optimal flow rate is important to improve the electron mobility, threshold voltage, on/off current ratio, and the electrical stability of the devices. The In2O3 TFTs treated at 6 sccm showed the best performance with mobility of 2.19 cm2V−1s−1, threshold voltage of of 4.25 V, and on/off current ratio of 2.13 × 106. The successful fabrication of high-performance, low-temperature solution deposited indium oxide transistors using the focused oxygen plasma treatment for electrical device applications demonstrates the practical potential of this treatment method for future transparent electronics.

Black Phosphorus-Based ZnO-Ag Nanocomposite for Antibacterial Activity against Tigecycline-Resistant Acinetobacter baumannii

Acinetobacter baumannii is a critically hard-to-treat gram-negative pathogen responsible for a range of infectious diseases. Tigecycline is a last-resort antibiotic for A. baumannii infection; however, tigecycline-resistant (TIG-R) A. baumannii has been increasingly reported. Therefore, new strategies must be developed to treat these detrimental infections. Nanoantibiotics composed of two-dimensional (2D) black phosphorus (BP) and its derived nanocomposites have emerged as excellent alternatives to current antibiotics. However, the development of unique materials to target specific pathogens is challenging. Here, we report the preparation of a BP-based ZnO-Ag (ZPBA) nanocomposite. A low-temperature solution synthesis method was used to prepare ZnO and Ag nanoparticles immobilized on BP nanosheets. X-ray diffraction, transmission electron microscopy, and X-ray photoelectron spectroscopy were used to characterize the ZPBA nanocomposite. The antibacterial activity of ZPBA nanocomposite was assessed by determining its minimum inhibitory concentration against type (ATCC 19606, ATCC 15150) and TIG-R (ATCC 19606-R) A. baumannii strains. From the assays, ZPBA showed superior activity against TIG-R A. baumannii strain with MIC of 12.5 µg·mL−1 compared to all other prepared samples. Finally, the combination of bacterial membrane disruption and ROS generation was demonstrated to be a potential antibacterial mechanism of ZPBA. Our results show that ZPBA could be a potential nanoantibiotic platform for eradicating TIG-R A. baumannii.

Hydrogen adsorption by a porous bimetallic solid solution carbide MAX phases synthesized in an open atmosphere

Multilayer and porosity are significant traits for energy storage materials, especially for hydrogen storage and utilization. However, the material must first undergo subsequent sequential investigation for accurate quantification to be a candidate for hydrogen storage. The mixed metallic MAX phase and their derivatives MXene have the potential to be used for hydrogen storage. In this paper, we describe the formation of low temperature (1100 °C), porous, and high purity (84.92 %) bimetallic solid solution Titanium Vanadium Aluminum Carbide (TiVAlxC) MAX phases in an open atmosphere, where the variation of x, e.g., Al mole content, is critical for obtaining high purity metallic solid solution MAX phases. The BET comparative analysis shows the textural features of the TiVAlxC with change in Al and end phases, i.e., Ti2AlC (Titanium Aluminum Carbide) and (Vanadium Aluminum Carbide) V2AlC. The outcomes are evident that impurity, crystallinity, and crystallite size impact the textural properties of the synthesized MAX phases. Corelative findings on accurate quantification of hydrogen uptake based upon textural properties. The gravimetric hydrogen storage capacity of Ti2AlC, TiVAl1.3C, and V2AlC phases are 0.33, 0.62, and 1.29%wt, respectively. The gravimetric analysis provided valuable insights into the isothermal hydrogen adsorption of TiVAlxC and its end phases, demonstrating these materials' ability to be used for future hydrogen storage.

Low-temperature solution processing route for potassium sodium niobate (KNN) thin films

Low-temperature solution processing route for potassium sodium niobate (KNN) thin films

Fine-Tuning of Air Electrode Microstructure and Its Composition as a Way to Enhance the Performance and Durability of Solid Oxide Electrolyzer - preliminary results

Among actions undertaken to reach a net-zero economy by 2050, implementation of the hydrogen technologies into various sectors e.g. energy and transport seems to be crucial. The significant increase of the installed capacity of electrolyzer in the last few years has been observed, which will accelerate in next decades to meet declared by many countries goals of their national hydrogen strategies. Nowadays, a dominant role on the electrolyze markets possess low temperature solution, namely, alkaline and PEM electrolyzes. However, due to higher efficiency – lower energy demand for hydrogen production, it is forecast that solid oxide electrolyzers (SOE) will take part of the market. The development of SOE, which are on the final R&D phase, is mainly focused on the extension of their lifespan and minimizing their manufacturing costs.The La1-xSrxCoO3-δ (LSC) and La1-xSrxCoyFe1-yO3-δ (LSCF) oxides due to their good catalytic activity and high mixed ionic-electronic conductivity are recognized as state-of-the-art air electrodes for SOC. However, Co-based perovskites are characterized by high thermal and chemical expansion, which might cause a mechanical mismatch with electrolyte, resulting in intensified SOC degradation. To mitigate mentioned issues different strategies have been proposed in the literature. Through the combined approach focused on modification of the bulk properties, simultaneously tailoring the microstructure of the electrodes and electrode/solid electrolyte interface, it is possible to overcome the kinetic limitations of operation at decreased temperatures.To maximize cell performance, and prevent the potential electrode degradation (i.e. its delamination) composite GDC-LSC/LSFC electrodes with gradual changes of the composition from electrolyte-electrode interphase to the electrode surface, were proposed. Furthermore, the impact of modification of electrode microstructure by an increase of its porosity and infiltration of the electrode surface with catalytically active oxides (e.g. PrxOy) was investigated. Fine-tuning of electrode porosity was achieved by the addition of the pore-forming agent, and the selection of its type (graphite or PMMA), amount, and size of its grains. Moreover, the work presents an approach to optimize the buffer layer, inter alia by its densifying, to mitigate Sr diffusion to the electrolyte and prevent air electrode delamination.The developed composite air electrodes were screen-printed (with an active area of 16 cm2) on the fuel electrode-supported cell and evaluated in the SOE mode at the 650-750 °C temperature range. Tests included measurements of j-V dependences and EIS spectra (at different temperatures, current densities, and for different gas flow delivered at the air side of the cell). In order to assess the impact of the added amount and type of pore-forming agent on the microstructure of the electrode layer, as well as to investigate possible microstructural changes of the cell after testing SEM, SEM-EDS, and FIB-SEM analysis were performed. The proposed modification of the composition and microstructure resulted in higher current densities and reduced cell polarization compared to standard cells with LSC and LSCF as the air electrode.AcknowledgmentsThe presented research was financially supported by: the National Centre for Research and Development, Poland, within project no. LIDER/1/0003/L-12/20/NCBR/2021 (research related to composite GDC-LSC/LSFC electrodes), and Ministry of Science and Higher Education through the statutory grant, within grant no. CPE.4000.001.2023 (research related to the improvement of the buffer layer-electrode interphase).

Tailored auto-combustion synthesis and optical and structural characterization of TiO2:Dy3+(1–11 mol%) nanostructures for wLED and latent finger print applications

Un-doped and dysprosium (Dy3+) doped (1–11 mol%) titanium dioxide (TiO2) nanoparticles (NPs) were synthesized by low temperature solution combustion route. The structural, morphological and nanostructural characterization of NPs were performed by powder x-ray diffraction (PXRD), field emission scanning electron microscopy (FESEM) and transmission electron microscopy (TEM) analysis, respectively. Rarely found rutile to anatase phase transition was observed by Dy3+ doping in TiO2 NPs using PXRD. The energy gap (Eg) of un-doped and Dy3+ doped TiO2 NPs were estimated by diffused reflectance spectra (DRS) between 2.92 and 3.07 eV. The active vibrational Raman modes of pure TiO2 were observed at 141, 446 and 608 cm−1. The mode alleged at 229 cm−1 indicates the rutile phase of TiO2 caused by second order effect. Studies of CIE and CCT confirmed that the NPs may be used in wLED applications. A rise of asymmetry ratio from 1.326 to 1.3453 with dopant concentration was observed in the photoluminescence (PL) spectra. The optimized TiO2:Dy3+ (9 mol%) nanostructures were used for the visualization of latent finger prints (LFPs) on porous and non-porous surfaces from level I to level III of ridge features.

Self-powered and broadband CuSCN/Si heterojunction photodetector for multi-color imaging based on diffuse reflection mode

Copper thiocyanate (CuSCN) has been widely used in photodetectors (PDs). However, the reported CuSCN-based PDs are suffered from narrow operating wavelength range and relatively low photodetection performance. Here, we fabricate an CuSCN/Si heterojunction PD by a simple low-temperature solution spin-coating method achieving excellent performance. Our designed CuSCN/Si PD exhibits a broadband response range covering ultraviolet–visible-infrared, a high detectivity of 2.26 × 1012 Jones coming from an ultralow dark current of 23 pA, and a decent responsivity of 11 mA W−1, a high linear dynamic range of 122 dB, and short response time of 25/150 μ (rise and decay time). Moreover, we demonstrate multi-color imaging across the wide wavelength range, indicating the CuSCN/Si PD has a promising potential in the imaging field. This work may pave the way for fabricating low-cost, nontoxicity, and high-performance CuSCN-based PD and broadening its applications.

Reducing the oxygen vacancy concentration in SrTiO3-δ thin films via an optimized O2 plasma treatment for enhancing device properties

Perovskite materials, specifically strontium titanate (SrTiO3, STO) thin films, have gained significant attention in materials science and electronics owing to their unique properties. However, low-temperature fabrication via sputtering can introduce oxygen vacancies that compromise film quality. O2 plasma treatment (OPT) has the potential to improve film properties, such as bond recomposition, electrical conductivity, and optical properties, by reducing the number of oxygen vacancies. In this study, STO films treated by O2 plasma were characterized using analytical techniques to understand the OPT-induced microstructural, morphological, and optical changes in these films. In addition, the possibility of improving device properties by low-temperature processes was confirmed by exploring the correlation between the number of oxygen vacancies reduced by the OPT process and the enhanced film properties. This result is expected to promote the application of STO thin films in flexible electronic devices and display components and provides insights into the role of oxygen vacancies and the effectiveness of OPT as a low-temperature solution for reducing their number.

Enabling low-drift flexible perovskite photodetectors by electrical modulation for wearable health monitoring and weak light imaging

Metal halide perovskites are promising for next-generation flexible photodetectors owing to their low-temperature solution processability, mechanical flexibility, and excellent photoelectric properties. However, the defects and notorious ion migration in polycrystalline metal halide perovskites often lead to high and unstable dark current, thus deteriorating their detection limit and long-term operations. Here, we propose an electrical field modulation strategy to significantly reduce the dark current of metal halide perovskites-based flexible photodetector more than 1000 times (from ~5 nA to ~5 pA). Meanwhile, ion migration in metal halide perovskites is effectively suppressed, and the metal halide perovskites-based flexible photodetector shows a long-term continuous operational stability (~8000 s) with low signal drift (~4.2 × 10−4 pA per second) and ultralow dark current drift (~1.3 × 10−5 pA per second). Benefitting from the electrical modulation strategy, a high signal-to-noise ratio wearable photoplethysmography sensor and an active-matrix photodetector array for weak light imaging are successfully demonstrated. This work offers a universal strategy to improve the performance of metal halide perovskites for wearable flexible photodetector and image sensor applications.

Salt transport of the carboxylated aromatic polyamide: Efforts to elucidate the structure-function relation of polyamide TFC desalination membranes

Five carboxylated polyamides with the number average molecular weight in the range of 15000–17000 Da, are synthesized via low-temperature solution polycondensation to study the effect of carboxyl group (-COOH) content on the carboxylated polyamide salt transport property. The glass transition temperature (Tg) of the carboxylated polyamide increases with the –COOH content due to the formation of more hydrogen bonds, which also leads to a decrease in free volume fraction (FFV). Interestingly, we observe that polymer having the –COOH content of 80%–100% possesses similar water uptake and KW, which provides a special perspective that how the –COOH group influences salt transport by excluding the effect of water content in polymer membranes. Water sorption can disrupt the hydrogen bonding within the –COOH groups, so setting out –COOH groups to bind water, leading to lower free water content and enhanced water/salt sorption selectivity. As the content of –COOH increases, the more negatively charged surface and stronger hydrogen bond interactions result in significant decrease in salt permeability (PS) and salt diffusivity (DS). These results implicate that the introduction of more –COOH groups to the polyamide layer can enhance the water/salt selectivity of TFC membrane without by changing the water sorption.

Flexible resistive memory device based on agar

Potential applications of natural materials in environmentally friendly electronics include for information storage. In this work, natural material–agar was used to fabricate a flexible resistive memory device. Agar is one of the most widely used biomaterials for tissue engineering, medicine and other biotechnological applications. Agar is a suitable material for flexible electronics due to its good film formation, biocompatibility, low-temperature solution processability, transparency and flexibility. The flexible agar memory device described in this article exhibits an ON/OFF ratio of 103 under a bending radius of 5 mm, good bending endurance and a stable data retention time of over 104 s. Moreover, the agar could easily use a leaf as a substrate to make a fully biodegradable device. Agar, due to its exceptional flexibility, is emerging as a promising candidate for wearable and skin-compatible electronics, particularly in memory devices.

Synthesis, Characterization and Investigation of Optical and Electrical Properties of Polyaniline/Nickel Ferrite Composites.

Nickel ferrite nanoparticles are prepared by using a low-temperature self-propagating solution combustion method using urea as fuel. The prepared nickel ferrite nanoparticles were doped with polyaniline in the three different weight ratios of 10%, 30% and 50% by using an in situ polymerization method and by adding ammonium persulfate as an oxidizing agent. The obtained samples were characterized by using XRD, FTIR, SEM and a UV-visible spectrophotometer. XRD examined crystalline peaks of ferrites and amorphous peak of polyaniline and confirmed the formation of the composites. FTIR examined the chemical nature of samples and showed peaks due to polyaniline and the characteristic peaks that were less than 1000 cm-1 wavenumber were due to metal-oxygen bond vibrations of ferrites. AC conductivity increased with frequency in all samples and the highest AC conductivity was seen in polyaniline/nickel ferrite 50%. DC conductivity increased in all samples with the temperature showing the semiconducting nature of the samples. Activation energy was evaluated by using Arrhenius plots and there was a decrease in activation energy with the addition of ferrite content. The UV-visible absorption peaks of polyaniline showed shifting in the composites. The optical direct and indirect band gaps were evaluated by plotting Tauc plots and the values of the optical band gap decreased with addition of ferrite in polyaniline and the Urbach energy increased in the samples with 10%, 30% and 50% polyaniline/nickel ferrite composites. The optical properties of these composites with a low band gap can find applications in devices such as solar cells.