Photoelectrochemical water oxidation properties of bismuth vanadate photoanode irradiated by swift heavy ions

Photoelectrochemical (PEC) water splitting is a promising route for solar energy harvesting and storage. The most challenging obstacle for efficient water splitting is development of catalysts for oxygen evolution reaction (OER). Monoclinic bismuth vanadate (BiVO4, BVO) stands out as an excellent photoanode material due to its high stability in near-neutral electrolytes, suitable band structure and low-cost synthesis. However, pronounced charge recombination is a huge limiting factor and understanding the effects contributing to it is important for further improvements. In present study, we report the effect of swift heavy ion (SHI) irradiation (Xe, 150 MeV, 1 × 1010 – 5 × 1011 ions cm-2 ) on physicochemical properties of hydrothermally synthesized BVO thin films. X-ray diffraction (XRD) study showed that irradiated material preserved initial monoclinic scheelite phase and preferential growth along [010] direction together with the presence of notable amorphization at the highest fluence. Scanning electron microscopy (SEM) of all samples showed prismatic grains with an average size of 600 nm with the appearance of ion tracks after irradiation. More detailed examination of 1 × 1010 ions cm-2 irradiated sample by transmission electron microscopy (TEM) revealed presence of amorphous ion tracks (~ 10 nm in diameter) and hillocks at the BVO surface (~ 10 nm in height). Raman spectra showed bands that correspond to the monoclinic scheelite phase as well as the presence of new bands for 5 × 1011 ion cm-2 irradiated sample at 420 and 915 cm-1 that originate from complex vanadium oxides. X-ray photoelectron spectroscopy (XPS) after SHI irradiation showed an increase of V4+ states and oxygen vacancies, especially at higher fluences. Diffuse reflectance spectroscopy (DRS) measurements showed decrease of band gap with the increase of fluence. Photocurrent densities, obtained from 1-hour-long chronoamperometry measurements, showed that irradiation with 1 × 1010 ions cm-2 fluence leads to gradual recovery of PEC oxygen evolution with time. XRD, SEM and XPS measurements performed after PEC reveal complex changes in the BVO, including dissolution of the material along ion tracks.Twenty-First Young Researchers’ Conference - Materials Science and Engineering: Program and the Book of Abstracts; November 29 – December 1, 2023, Belgrade, Serbi

Influence of the Structure on Magnetic Properties of Calcium-Phosphate Systems Doped with Iron and Vanadium Ions

The aim of this study was to prepare and characterize the glasses made of x(Fe$_{2}$O$_{3}$∙V$_{2}$O$_{5}$)∙(100 − x)[P$_{2}$O$_{5}$∙CaO] with x ranging of 0–50%. The contribution of Fe$_{2}$O$_{3}$ and V$_{2}$O$_{5}$ amount on the structure of P$_{2}$O$_{5}$·CaO matrix was investigated. The vitreous materials were characterized by XRD (X-ray diffraction analysis), EPR (Electron Paramagnetic Resonance) spectroscopy, and magnetic susceptibility measurements. A hyperfine structure typical for isolated V4+ ions was noticed to all spectra containing low amount of V$_{2}$O$_{5}$. The XRD spectra show the amorphous nature of samples, apart x = 50%. An overlap of the EPR spectrum of a broad line without the hyperfine structure characteristic of clustered ions was observed with increasing V2O5 content. The results of magnetic susceptibility measurements explain the antiferromagnetic or ferromagnetic interactions expressed between the iron and vanadium ions in the investigated glass

Physicochemical properties of bismuth vanadate photoanode irradiated by swift heavy ions

Program and book of abstracts / 2nd International Conference on Innovative Materials in Extreme Conditions i. e. (IMEC2024), 20-22 March 2024 Belgrade, Serbia

Influence of N5+ ion irradiation on physicochemical properties of bismuth vanadate

Photoelectrochemical (PEC) cells for solar-energy conversion have received huge interest as a promising technology for renewable energy production. For the efficient application of such cells, it is necessary to develop adequate photoelectrodes. Recently, bismuth vanadate (BiVO4) has emerged as a promising photoanode due to its visible light harvesting properties, band edge positions and low-cost of synthesis. In this study, the effects of N5+ ion irradiation (75keV, 2 × 1014 and 4 × 1014 ions/cm2 ) on physicochemical properties of hydrothermally synthesized BiVO4 thin films were examined. From X-ray diffraction (XRD) study can be concluded that initial monoclinic material didn’t sustain any phase transition after irradiation. Also, preferential orientation remained dominantly along [010] direction with a slightly increasing share of [121] oriented growth, especially after irradiation with 2 × 1014 ions/cm2 . XRD measurements showed shift towards the higher 2θ after irradiation which indicates that interplanar distances decreases. The highest level of crystallinity was observed for the sample irradiated with fluence of 4 × 1014 ions/cm2 . Scanning electron microscopy (SEM) revealed prismatic morphology of all samples with an average grain size of 600 nm without visible traces of irradiation.Raman spectroscopy confirmed presence of bands that correspond to the monoclinic scheelite phase. X-ray photoelectron spectroscopy (XPS) analysis of V 2p confirmed presence of V5+ and V4+ while analysis of O 1s confirmed presence of oxygen in the form of lattice oxygen and in the form of hydroxide. UV-Vis Diffuse Reflectance spectroscopy revealed that calculated band gap decreases with the increase of fluence

The effect of swift heavy ion irradiation on physicochemical properties of monoclinic bismuth vanadate

Monoclinic bismuth vanadate (BiVO4) is considered to be one of the most promising photoanode materials for photoelectrochemical (PEC) water splitting due to its suitable band gap and band structure, good stability and low-cost synthesis. However, BiVO4 has poor charge transfer properties due to the high rate of electron-hole recombination and understanding the effects contributing to it is important for further improvements. Herein, we report the effect of swift heavy ion irradiation (Xe, 150 MeV, 1010 – 5×1011 ions/cm2 ) on physicochemical properties of hydrothermally synthesized BiVO4 thin films. X-ray diffraction study (XRD) showed that irradiated material preserved initial monoclinic scheelite crystal phase and preferential growth along [010] direction. As the fluence increased, a shift of the diffraction maxima towards lower 2θ values was observed indicating increased interplanar distances. Also, for the 5×1011 ions/cm2 irradiated sample, high degree of amorphization was noticed. Scanning electron microscopy (SEM) of all samples showed prismatic grains with an average size of 600 nm. In irradiated samples formation of ion tracks, ~10 nm in diameter, was observed. X-ray photoelectron spectroscopy (XPS) analysis of Bi 4f, V 2p and O 1s states showed that, after irradiation, increased amounts of V4+ and oxygen in the form of hydroxide occurred, especially at higher fluences. By using UV-Vis Diffuse Reflectance spectroscopy we showed that band gap decreased with the increase of fluence. Photocurrent densities obtained from linear sweep voltammetry indicated that irradiation with fluences higher than 1010 ions/cm2 have a notable negative effect on PEC oxygen evolution reaction. However, 1-hour-long chronoamperometry measurements of 1010 ions/cm2 irradiated sample revealed an increase of photocurrent densities. In order to get a better insight into preceding phenomena, we performed XRD, SEM and XPS analysis after PEC process

Exploring the Conformation and Thermal Stability of Human Serum Albumin Corona of Ferrihydrite Nanoparticles

In the last few years, a great amount of attention has been given to nanoparticles research due to their physicochemical properties that allow their use in analytical instruments or in promising imaging applications on biological systems. The use of ferrihydrite nanoparticles (Fh-NPs) in practical applications implies a particular control of their magnetic properties, stability, biocompatibility, interaction with the surface of the target, and low toxicity. In this study, the formation and organization of human serum albumin (HSA) molecules around the simple Fh-NPs and Fh-NPs doped with Co and Cu were examined by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM) in terms of morphology and particle size. The topology of all Fh-NPs shows an organized area of HSA around each type of Fh-NP. Molecular docking studies were used in order to determine the probable location of the ferrihydrite in the HSA structure. The thermal stability of these nanohybrids was further investigated by fluorimetry, using 214-Trp residue from HSA as a spectral sensor. The denaturation temperature (Tm) was determined, and stabilization of the HSA structure in the presence of Fh-NPs was discussed. This study could be a starting point for the development of different applications targeting the structure and stability of Fh-NPs complexes with proteins

Interactions of Chemically Synthesized Ferrihydrite Nanoparticles with Human Serum Transferrin: Insights from Fluorescence Spectroscopic Studies

Human serum transferrin (HST) is a glycoprotein involved in iron transport that may be a candidate for functionalized nanoparticles to bind and target cancer cells. In this study, the effects of the simple and doped with cobalt (Co) and copper (Cu) ferrihydrite nanoparticles (Fh-NPs, Cu-Fh-NPs, and Co-Fh-NPs) were studied by spectroscopic and molecular approaches. Fluorescence spectroscopy revealed a static quenching mechanism for all three types of Fh-NPs. All Fh-NPs interacted with HST with low affinity, and the binding was driven by hydrogen bonding and van der Waals forces for simple Fh-NPs and by hydrophobic interactions for Cu-Fh-NPs and Co-Fh-NPs binding, respectively. Of all samples, simple Fh-NPs bound the most to the HST binding site. Fluorescence resonance energy transfer (FRET) allowed the efficient determination of the energy transfer between HST and NPs and the distance at which the transfer takes place and confirmed the mechanism of quenching. The denaturation of the HST is an endothermic process, both in the case of apo HST and HST in the presence of the three types of Fh-NPs. Molecular docking studies revealed that Fh binds with a low affinity to HST (Ka = 9.17 × 103 M−1) in accord with the fluorescence results, where the interaction between simple Fh-NPs and HST was described by a binding constant of 9.54 × 103 M−1

The impact of swift heavy ion irradiation on bismuth vanadate photoanode for photoelectrochemical water oxidation

The 27st International Scientific Conference of Young Scientists and Specialists (AYSS-2023); Oct 30 - Nov 3, 2023, JINR, Dubna, Russi

Influence of the Structure on Magnetic Properties of Calcium-Phosphate Systems Doped with Iron and Vanadium Ions

The aim of this study was to prepare and characterize the glasses made of x(Fe2O3∙V2O5)∙(100 − x)[P2O5∙CaO] with x ranging of 0–50%. The contribution of Fe2O3 and V2O5 amount on the structure of P2O5·CaO matrix was investigated. The vitreous materials were characterized by XRD (X-ray diffraction analysis), EPR (Electron Paramagnetic Resonance) spectroscopy, and magnetic susceptibility measurements. A hyperfine structure typical for isolated V4+ ions was noticed to all spectra containing low amount of V2O5. The XRD spectra show the amorphous nature of samples, apart x = 50%. An overlap of the EPR spectrum of a broad line without the hyperfine structure characteristic of clustered ions was observed with increasing V2O5 content. The results of magnetic susceptibility measurements explain the antiferromagnetic or ferromagnetic interactions expressed between the iron and vanadium ions in the investigated glass