ca 2 fe 2 o 5 (cfo) is a potentially viable material for alternate energy applications. incorporation of nitrogen in ca 2 fe 2 o 5 (CFO-N) lattice modifies the optical and electronic properties to its advantage. Here, the electronic band structures of cfo and cfo-n were probed using Ultraviolet photoelectron spectroscopy (UPS) and UV-Visible spectroscopy. The optical bandgap of CFO reduces from 2.21 eV to 2.07 eV on post N incorporation along with a clear shift in the valence band of CFO indicating the occupation of N 2p levels over O 2p in the valence band. Similar effect is also observed in the bandgap of CFO, which is tailored upto 1.43 eV by N + ion implantation. the theoretical bandgaps of cfo and cfo-n were also determined by using the Density functional theory (Dft) calculations. the photoactivity of these CFO and CFO-N was explored by organic effluent degradation under sunlight. The feasibility of utilizing cfo and cfo-n samples for energy storage applications were also investigated through specific capacitance measurements. The specific capacitance of CFO is found to increase to 224.67 Fg −1 upon n incorporation. cfo-n is thus found to exhibit superior optical, catalytic as well as supercapacitor properties over cfo expanding the scope of brownmillerites in energy and environmental applications.Multifunctional brownmillerite Ca 2 Fe 2 O 5 is a promising material for energy and environmental applications such as fuel cells, supercapacitors, batteries, H 2 production and CO 2 capture, attributed mostly to its multifaceted property like those in catalysis and mixed ionic electronic conduction (MIEC) 1-5 . Presence of a visible region bandgap along with its catalytic activity also enables it as a photoactive material and most importantly as material for textile waste water remediation. There is a huge need for industrial waste water purification of the effluents from the textile industries before releasing it to water bodies. A lower cost and energy requirement pushes us to explore more efficient materials which can absorb a larger percentage of incident natural sunlight and make their impact felt on the environment 6-10 . Well known wide band gap semiconductors, such as TiO 2 and ZnO (bandgap > 3 eV), cannot perfectly match the broad ranges of solar radiation emphasizing the need to investigate new materials/composites with narrow bandgap 11 . Quite recently perovskite metal oxides, such as PbTiO 3 (2.75 eV), AgNbO 3 (2.86 eV), SrNbO 3 (1.9 eV), BiFeO 3 (2.1 eV), LaFeO 3 (2.4 eV), LaNiO 3 (2.42 eV) have been found to possess reasonable catalytic efficiency [12][13][14][15][16][17][18][19] . This encourages us to work with novel materials like oxygen deficient perovskites for sunlight-driven photocatalysis.To meet the above objectives, it is desirable to modify such structures with transition metal-N x active sites to enhance the charge transport features and hence the catalytic activity towards remediation of industrial wastewater 20,21 . Recently, Nitrogen-doped layered perovskite K 2 La 2 Ti 3 O 10 was sh...
KBiFe 2 O 5 (KBFO) is an upcoming promising brownmillerite-structured multiferroic photoactive material for next-generation photovoltaic and photocatalytic applications. In the present work, KBFO has been developed using multistep thermal treatment method to reduce the volatility of constituent elements and improve the stability of compound. The band gap of KBFO (found to be ∼1.68 eV) extends to the near-infrared region compared to traditional perovskite-structured multiferroics. The magnetic and dielectric transitions occur in the same temperature range (740 K–800 K), reflecting the existence of magneto-dielectric effect in the as-synthesized sample. It also shows promising photocatalytic activity by degrading organic effluents under natural sunlight compared to regular perovskite BiFeO 3 photocatalyst (operating under visible light). A new application of brownmillerite multiferroic KBFO photocatalyst in environmental and energy applications has been explored by integrating the structural, optical, magnetic, and dielectric properties of the same.
Magnetic hyperthermia treatment using calcium phosphate nanoparticles is an evolutionary choice because of its excellent biocompatibility. In the present work, Fe3+ is incorporated into HAp nanoparticles by thermal treatment at various temperatures. Induction heating was examined within the threshold Hf value of 4.58 × 106 kA m–1 s–1 (H is the strength of alternating magnetic field and f is the operating frequency) and sample concentration of 10 mg/mL. The temperature-dependent structural modifications are well correlated with the morphological, surface charge, and magnetic properties. Surface charge changes from +10 mV to −11 mV upon sintering because of the diffusion of iron in the HAp lattice. The saturation magnetization has been achieved by sintering the nanoparticles at 400 and 600 °C, which has led to the specific absorption rate of 12.2 and 37.2 W/g, respectively. Achievement of the hyperthermia temperature (42 °C) within 4 min is significant when compared with the existing magnetic calcium phosphate nanoparticles. The systematic investigation reveals that the HAp nanoparticles partially stabilized with FeOOH and biocompatible α-Fe2O3 exhibit excellent induction heating. In vitro tests confirmed the samples are highly hemocompatible. The importance of the present work lies in HAp nanoparticles exhibiting induction heating without compromising the factors such as Hf value, low sample concentration, and reduced duration of applied field.
Abstractg-C3N4/Ca2Fe2O5 heterostructures were successfully prepared by incorporating g-C3N4 into Ca2Fe2O5 (CFO). As prepared g-C3N4/CFO heterostructures were initially utilized to photodegrade organic effluent Methylene blue (MB) for optimization of photodegradation performance. 50% g-C3N4 content in CFO composition showed an enhanced photodegradation efficiency (~ 96%) over g-C3N4 (48.15%) and CFO (81.9%) due to mitigation of recombination of photogenerated charge carriers by Type-II heterojunction. The optimized composition of heterostructure was further tested for degradation of Bisphenol-A (BPA) under direct sunlight, exhibiting enhanced photodegradation efficiency of about 63.1% over g-C3N4 (17%) and CFO (45.1%). The photoelectrochemical studies at various potentials with and without light illumination showed significant improvement in photocurrent response for g-C3N4/Ca2Fe2O5 heterostructures (~ 1.9 mA) over CFO (~ 67.4 μA). These studies revealed efficient solar energy harvesting ability of g-C3N4/Ca2Fe2O5 heterostructures to be utilized for organic effluent treatment.
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