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Physiochemical properties of polycaprolactone-hydroxyapatite (PCL-HAp) composites were investigated in the pristine and after irradiation of γ rays (25, 50, 75, and 100 kGy). PCL-HAp composites were synthesized by solvent evaporation and characterized using spectroscopic methods as well as biological assays. The surface roughness (RMS) of the irradiated composite film (at 75 kGy) was 80 times higher than that of the pristine. Irradiation tailors the contact angle of the films from 77° to 90° (at 100 kGy). A decrease in particle size (at 100 kGy) of HAp nanorods in PCL-HAp composites film was observed. The XRD peak of PCL was slightly shifted from 21.2° to 21.7° (at 100 kGy) with the decrease in crystallite size. The peak intensity of the PCL and HAp altered on irradiation that was confirmed by FTIR and Raman analysis. Further, the bandgap of the irradiated film was lowered by 13 % (at 25 kGy). The luminescence intensity decreased due to the non-radiative process induced by the irradiation defects. All the samples possess hemocompatibility percentage of <10 % as per ASTM standards. At 75 kGy, fibroblast cell proliferation was higher than the pristine and other doses. The gamma-irradiated PCL-HAp composite films are potential candidates for tissue engineering applications., Competing Interests: Declaration of competing interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Elsevier B.V. All rights reserved.)

Bismuth vanadate (BiVO 4 ) has attracted substantial attention on account of its usefulness in producing hydrogen by photoelectrochemical (PEC) water splitting. The exploitation of BiVO 4 for this purpose is yet limited by severe charge recombination in the bulk of BiVO 4 , which is caused by the short diffusion length of the photoexcited charge carriers and inefficient charge separation. Enormous effort has been made to improve the photocurrent density and solar-to-hydrogen conversion efficiency of BiVO 4 . This study demonstrates that modulating the composition of the electrode and the electronic configuration of BiVO 4 by decoration with silver nanoparticles (Ag NPs) is effective in not only enhancing the charge carrier concentration but also suppressing charge recombination in the solar water splitting process. Decoration with a small number of Ag NPs significantly enhances the photocurrent density of BiVO 4 to an extent that increases with the concentration of the Ag NPs. At 0.5% Ag NPs, the photocurrent density approaches 4.1 mA cm -2 at 1.23 V versus a reversible hydrogen electrode (RHE) under solar simulated light illumination; this value is much higher than the 2.3 mA cm -2 of pure BiVO 4 under the same conditions. X-ray absorption spectroscopy (XAS) is utilized to investigate the electronic structure of pure BiVO 4 and its modification by decoration with Ag NPs. Analytical results indicate that increased distortion of the VO 4 tetrahedra alters the V 3d-O 2p hybridized states. Additionally, as the Ag concentration increases, the oxygen vacancy defects that act as recombination centers in BiVO 4 are reduced. In situ XAS, which is conducted under dark and solar illumination conditions, reveals that the significantly enhanced PEC performance is attributable to the synergy of modulated atomic/electronic structures and the localized surface plasmon resonance effect of the Ag nanoparticles.

Defect engineering is an important means of improving the electrochemical performance of the Co 3 O 4 electrocatalyst in the oxygen evolution reaction (OER). In this study, operando soft X-ray absorption spectroscopy (SXAS) is used to explore the electronic structure of Co 3 O 4 under OER for the first time. The defect-rich Co 3 O 4 (D-Co 3 O 4 ) has a Co 2.45+ state with Co 2+ at both octahedral (O h ) and tetrahedral (T d ) sites and Co 3+ at O h , whereas Co 3 O 4 has Co 2.6+ with Co 2+ and Co 3+ at T d and O h sites, respectively. SXAS reveals that upon increasing the voltage, the Co 2+ in D-Co 3 O 4 is converted to low-spin Co 3+ , some of which is further converted to low-spin Co 4+ ; most Co 2+ in Co 3 O 4 is converted to Co 3+ but rarely to Co 4+ . When the voltage is switched off, Co 4+ intermediates quickly disappear. These findings reveal Co(O h ) in D-Co 3 O 4 can be rapidly converted to active low-spin Co 4+ under operando conditions, which cannot be observed by ex situ XAS.

Herein, we fabricated a feasible and accurate sensing platform for the quantification of toxic organic pollutant 2-nitroaniline (2-NA) in water samples through electrocatalyst made up of bismuth molybdate (Bi 2 MoO 6 , BMO) functionalized carbon nanofiber (f-CNF) modified electrode. The preparation of BMO/f-CNF composite is of two methods, such as co-precipitation (C-BMO/f-CNF) and ultrasonication method (U-BMO/f-CNF). The physicochemical properties of the composites were characterized by XRD, FTIR, Raman, BET, FE-SEM, and HR-TEM techniques. At U-BMO/f-CNF, the charge transfer resistance was low (R ct = 12.47 Ω) compared to C-BMO/f-CNF because nanosized U-BMO particles correctly aim at the defective sites of the f-CNF surface wall. Further, the electrocatalytic activity of C&U-BMO/f-CNF composites was examined by cyclic voltammetry (CV) and differential pulse voltammetry techniques (DPV) for the electrochemical detection of 2-nitroaniline (2-NA). The U-BMO/f-CNF/GCE shows a higher cathodic current, wide dynamic linear range of 0.01-168.01 µM, and superior electrocatalytic activity with a low detection limit (0.0437 µM) and good sensitivity (0.6857 μA μM -1 cm -2 ). The excellent selectivity nature of U-BMO/f-CNF/GCE was observed in the presence of various organic pollutants and a few toxic metal cations. The practical applicability such as stability, repeatability towards 2-NA outcomes with accepted results. Besides, the practical viability of as proposed U-BMO/f-CNF sensor was investigated in soil and lake water samples delivers good recovery results. Hence from these analyses, we conclude that U-BMO/f-CNF/GCE potential for the determination of hazardous environmental pollutant 2-NA., (Copyright © 2020 The Authors. Published by Elsevier Inc. All rights reserved.)

Sn-based materials are identified as promising catalysts for the CO 2 electroreduction (CO2RR) to formate (HCOO - ). However, their insufficient selectivity and activity remain grand challenges. A new type of SnO 2 nanosheet with simultaneous N dopants and oxygen vacancies (V O -rich N-SnO 2 NS) for promoting CO 2 conversion to HCOO - is reported. Due to the likely synergistic effect of N dopant and V O , the V O -rich N-SnO 2 NS exhibits high catalytic selectivity featured by an HCOO - Faradaic efficiency (FE) of 83% at -0.9 V and an FE of > 90% for all C1 products (HCOO - and CO) at a wide potential range from -0.9 to -1.2 V. Low coordination Sn-N moieties are the active sites with optimal electronic and geometric structures regulated by V O and N dopants. Theoretical calculations elucidate that the reaction free energy of HCOO* protonation is decreased on the V O -rich N-SnO 2 NS, thus enhancing HCOO - selectivity. The weakened H* adsorption energy also inhibits the hydrogen evolution reaction, a dominant side reaction during the CO2RR. Furthermore, using the catalyst as the cathode, a spontaneous Galvanic Zn-CO 2 cell and a solar-powered electrolysis process successfully demonstrated the efficient HCOO - generation through CO 2 conversion and storage., (© 2020 Wiley-VCH GmbH.)

Single-component transition-metal oxide (TMO: FeO x , NiO x , or CoO x ) nanosheets grown on nickel foam (NF) were electrochemically optimized with Li ion (Na ion)-induced conversion reaction for bifunctional electrocatalysis. The optimum FeO x /NF-Li electrocatalyst exhibits low overpotentials of 239 mV for hydrogen evolution reaction and 276 mV for oxygen evolution reaction at a current density of 100 mA cm -2 . A two-electrode water splitting cell using FeO x /NF-Li as both anode and cathode requires only 1.60 V to achieve a current density of 10 mA cm -2 . The impressive water splitting performance of the FeO x /NF-Li electrode is revealed to be attributed to Li-induced electrochemical conversion, which alters the crystal structure, creating more active sites for electrocatalytic reactions, as well as introduces O vacancies increasing the electron density and the intrinsic conductivity. More importantly, the atomic arrangement is regulated from tetrahedral Fe(Td) to octahedral Fe(Oh) coordination, which acts as catalytically active sites with reduced Gibbs free energy for the rate-determining steps. This electrochemical conversion reaction can be extended to other TMOs (i.e., NiO x /NF and CoO x /NF) for promoted electrocatalytic water splitting performances. This study provides an in-depth understanding on the nature of atomic and electronic structure evolution to promote the electrocatalytic activity.