Nickel vanadate nitrogen-doped carbon nanocomposites for high-performance supercapacitor electrode

A nickel-vanadium-based bimetallic precursor was produced using the polymerization process by urea-formaldehyde copolymers. The precursor was then calcined at 800 °C in an argon ambiance to form a Ni3V2O8-NC magnetic nanocomposite. Powerful techniques were used to study the physical characteristics and chemical composition of the fabricated Ni3V2O8-NC electrode. PXRD, Raman, and FTIR analyses proved that the crystal structure of Ni3V2O8-NC included N-doped graphitic carbon. FESEM and TEM analyses imaging showed the distribution of the Ni3V2O8 nanoparticles on the layered graphitic carbon structure. TEM images showed the prepared sample has a particle size of around 10–15 nm with an enhanced active site area of 146 m2/g, as demonstrated by BET analysis. Ni3V2O8-NC nanocomposite exhibits magnetic behaviors and a magnetization saturation value of 35.99 emu/g. The electrochemical (EC) studies of the synthesized Ni3V2O8-NC electrode proceeded in an EC workstation of three-electrode. In a 5 M potassium hydroxide as an electrolyte, the cyclic voltmeter exhibited an enhanced capacitance (CS) of 915 F/g at 50 mV/s. Galvanic charge-discharge (GCD) study also exhibited a superior capacitive improvement of 1045 F/g at a current density (It) of 10 A/g. Moreover, the fabricated Ni3V2O8-NC nanocomposite displays a good power density (Pt) of 356.67 W/kg, improved ion accessibility, and substantial charge storage. At the high energy density (Et) of 67.34 W h/kg, the obtained Pt was 285.17 W/kg. The enhanced GCD rate, cycle stability, and Et of the Ni3V2O8-NC magnetic nanocomposite nominate the sample as an excellent supercapacitor electrode. This study paves the way for developing effective, efficient, affordable, and ecologically friendly electrode materials

Rational design of a 2D TiO2-MoO3 step-scheme heterostructure for boosted photocatalytic overall water splitting

The design of step-scheme (S-scheme) heterostructure photocatalysts is a promising strategy for the high utilization of photogenerated charge carriers. Herein, a novel S-scheme two-dimensional (2D) TiO2-MoO3 heterojunction photocatalyst is fabricated by a facile electrochemical method for high water splitting photocatalytic efficiency. According to X-ray photoelectron spectroscopy (XPS) assessment, electrons are transported from TiO2 to MoO3 upon close contact, creating an internal electric field (IEF) directed from TiO2 to MoO3. Hence, upon light irradiation, the photogenerated electrons in MoO3 move toward TiO2 under the IEF effect, as revealed by EPR analysis, implying that the S-scheme heterojunction was established in the TiO2-MoO3 heterostructure and significantly promoted the separation of electron-hole pairs to enhance efficient photocatalytic water splitting. Thanks to the 2D morphology of the TiO2-MoO3 heterojunction and the significantly improved redox capability of the charge carriers in the S-scheme system, the photocatalytic water splitting efficiency of the optimized TiO2-MoO3 is higher than those of both pure MoO3 and TiO2 and commercial TiO2-P25. This study, for the first time, presents the charge transfer pathways in the TiO2-MoO3 heterostructure photocatalyst via an S-scheme system. It will shed new light on the design and fabrication of novel step-scheme heterojunction photocatalysts for overall water splitting

Exo double left right arrow Endo Isomerism, MEP/DFT, XRD/HSA-Interactions of 2,5-Dimethoxybenzaldehyde: Thermal, 1BNA-Docking, Optical, and TD-DFT Studies

The exo double left right arrow endo isomerization of 2,5-dimethoxybenzaldehyde was theoretically studied by density functional theory (DFT) to examine its favored conformers via sp(2)-sp(2) single rotation. Both isomers were docked against 1BNA DNA to elucidate their binding ability, and the DFT-computed structural parameters results were matched with the X-ray diffraction (XRD) crystallographic parameters. XRD analysis showed that the exo-isomer was structurally favored and was also considered as the kinetically preferred isomer, while several hydrogen-bonding interactions detected in the crystal lattice by XRD were in good agreement with the Hirshfeld surface analysis calculations. The molecular electrostatic potential, Mulliken and natural population analysis charges, frontier molecular orbitals (HOMO/LUMO), and global reactivity descriptors quantum parameters were also determined at the B3LYP/6-311G(d,p) level of theory. The computed electronic calculations, i.e., TD-SCF/DFT, B3LYP-IR, NMR-DB, and GIAO-NMR, were compared to the experimental UV-Vis., optical energy gap, FTIR, and H-1-NMR, respectively. The thermal behavior of 2,5-dimethoxybenzaldehyde was also evaluated in an open atmosphere by a thermogravimetric-derivative thermogravimetric analysis, indicating its stability up to 95 degrees C

One-Step Hydrothermal Synthesis of Anatase TiO2 Nanotubes for Efficient Photocatalytic CO2 Reduction

The hydrothermal dissolution-recrystallization process is a key step in the crystal structure of titania-based nanotubes and their composition. This work systematically studies the hydrothermal conditions for directly synthesizing anatase TiO2 nanotubes (ATNTs), which have not been deeply discussed elsewhere. It has been well-known that ATNTs can be synthesized by the calcination of titanate nanotubes. Herein, we found the ATNTs can be directly synthesized by optimizing the reaction temperature and time rather than calcination of titanate nanotubes, where at each temperature, there is a range of reaction times in which ATNTs can be prepared. The effect of NaOH/TiO2 ratio and starting materials was explored, and it was found that ATNTs can be prepared only if the precursor is anatase TiO2, using rutile TiO2 leads to forming titanate nanotubes. As a result, ATNTs produced directly without calcination have excellent photocatalytic CO2 reduction than titanate nanotubes and ATNTs prepared by titanate calcination

Construction of Bi2S3/TiO2/MoS2 S-Scheme Heterostructure with a Switchable Charge Migration Pathway for Selective CO2 Reduction

Switching between the redox potential of an appropriate semiconductor heterostructure could show critical applications in selective CO2 reduction. Designing a semiconductor photocatalyst with a wavelength-dependent response is an effective strategy for regulating the direction of electron flow and tuning the redox potential. Herein, the switching mechanism between two charge migration pathways and redox potentials in a Bi2S3/TiO2/MoS2 heterostructure by regulating the light wavelength is achieved. In situ irradiated X-ray photoelectron spectroscopy (ISI-XPS), electron spin resonance (ESR), photoluminescence (PL), and experimental scavenger analyses prove that the charge transport follows the S-scheme approach under UV–vis–NIR irradiation and the heterojunction approach under vis–NIR irradiation, confirming the switchable feature of the Bi2S3/TiO2/MoS2 heterostructure. This switchable feature leads to the reduction of CO2 molecules to CH3OH and C2H5OH under UV–vis–NIR irradiation, while CH4 and CO are produced under Vis–NIR irradiation. Interestingly, the apparent quantum efficiency of the optimal composite at λ = 600 nm is 4.23%. This research work presents an opportunity to develop photocatalysts with switchable charge transport and selective CO2 reduction.The authors are thankful to the DST National Single Crystal Diffractometer Facility Laboratory, DoS in Physics, UPE, IOE, and DST-PURSE, Vijnana Bhavana, University of Mysore, Mysuru, for providing the required facilities. The authors extend their appreciation to the Researchers Supporting Project number (RSP-2021/381), King Saud University, Riyadh, Saudi Arabia.Scopu

Surface defect-engineered CeO2−x by ultrasound treatment for superior photocatalytic H2 production and water treatment

Semiconductor photocatalysts with surface defects display incredible light absorption bandwidth and these defects function as highly active sites for oxidation processes by interacting with the surface band structure. Accordingly, engineering the photocatalyst with surface oxygen vacancies will enhance the semiconductor nanostructure's photocatalytic efficiency. Herein, a CeO2−x nanostructure is designed under the influence of low-frequency ultrasonic waves to create surface oxygen vacancies. This approach enhances the photocatalytic efficiency compared to many heterostructures while keeping the intrinsic crystal structure intact. Ultrasonic waves induce the acoustic cavitation effect leading to the dissemination of active elements on the surface, which results in vacancy formation in conjunction with larger surface area and smaller particle size. The structural analysis of CeO2−x revealed higher crystallinity, as well as morphological optimization and the presence of oxygen vacancies is verified through Raman, X-ray photoelectron spectroscopy, temperature-programmed reduction, photoluminescence, and electron spin resonance analyses. Oxygen vacancies accelerate the redox cycle between Ce4+ and Ce3+ by prolonging photogenerated charge recombination. The ultrasound-treated pristine CeO2 sample achieved excellent hydrogen production showing a quantum efficiency of 1.125% and efficient organic degradation. Our promising findings demonstrated that ultrasonic treatment causes the formation of surface oxygen vacancies and improves photocatalytic hydrogen evolution and pollution degradation