Electronic Configuration Research Articles

Atomic Infusion Induced Reconstruction Enhances Multifunctional Thermally Conductive Films for Robust Low‐Frequency Electromagnetic Absorption

AbstractDeterministic fabrication of highly thermally conductive composite film with satisfying low‐frequency electromagnetic (EM) absorption performance exhibits great potential in advancing the application of 5G smart electric devices but persists challenge. Herein, a multifunctional flexible film combined with hetero‐structured Fe6W6C‐FeWO4@C (FWC−O@C) as the absorber and aramid nanofibers (ANFs) as the matrix was prepared. Driven by an atomic gradient infusion reduction strategy, the carbon atoms of absorbers can be precisely relocated from carbon shell to core oxometallate lattice, triggering in situ carbothermic reduction for customization of unique oxometallate‐carbide heterojunctions and surface geometrical structure. Such an atoms reconstruction process effectively regulates interface electronic structure and magnetic configuration, resulting in enhanced polarization loss from abundant heterointerfaces and crystal defects and magnetic loss from hierarchical structure endowed magnetic coupling interaction, which jointly contributes to the efficient low‐frequency EM absorption performance. Eventually, optimized FWC−O@C microplate exhibits a broad absorption bandwidth surpassed the entire C band, and the assembled FWC−O@C/ANFs composite film also performs a high thermal conductivity over 2500 % higher than that of the pure ANFs. These findings provide a new insight into the atomic reconstruction affected EM properties and a generalized methodological guidance for preparing multifunctional thermally conductive composite films.

Modification of the Spin Transition Properties in Hetero‐Anionic Iron(II)‐Triazole Complexes

AbstractThe phenomenon which is called spin crossover is known to occur in some coordination compounds with an octahedral ligand field and electron configurations from 3d4 to 3d7. Thereby, a reversible transition between spin states (high spin and low spin state) is possible, through several external stimuli. Iron(II) triazole complexes exhibit this phenomenon at a wide range of temperatures depending on the ligands and anions used. For this reason, they are often considered for several possible practical applications. It is also possible to combine ligands or anions to modify the transition temperature. The latter of which was rarely discussed in the past. In this study we synthesized a series of iron(II)‐4‐Aminotriazole complexes, with different ratios of chloride‐ and tetrafluoroborate‐anions, of the formula [Fe(Atrz)3]Cl2−X(BF4)X. We show that the combination of these anions leads to transition temperatures between those of their corresponding pure anion complexes. We furthermore present that a simple modification of the synthesis leads to a possible easy way of fine‐tuning transitions temperatures.

Crystalline/Amorphous Interface Engineering and d-sp Orbital Hybridization Synergistically Boosting the Electrocatalytic Performance of PdCu Bimetallene toward Formic Acid-Assisted Overall Water Splitting.

Advanced electrocatalysts capable of bifunctional catalysis for formic acid oxidation (FAOR) and hydrogen evolution reaction (HER) have garnered significant attention due to their exceptional energy efficiency. In this research, we have meticulously designed a PdCu bimetallene characterized by numerous crystalline/amorphous (c/a) interfaces and robust d-sp orbital hybridization, achieved by integrating the p-block metalloid boron within the PdCu matrix (B-PdCu-c/a). The B-PdCu-c/a bimetallene revealed a multitude of surface atoms and unsaturated defect sites, offering abundant catalytic active sites and an optimized electronic structure. The B2-PdCu-c/a exhibited the best performance in FAOR and HER, achieving a mass activity of 1106 mA mgcat-1 and an overpotential of 52 mV, respectively. Significantly, the two-electrode configuration of B2-PdCu-c/a∥B2-PdCu-c/a attained a low cell voltage of 0.19 V at 10 mA cm-2 during formic acid-assisted overall water splitting. Density functional theory (DFT) calculations indicated that c/a interface engineering and d-sp orbital hybridization synergistically optimized the electronic configuration of pristine PdCu bimetallene. This led to an elevation of the d-band center and an accumulation of charge at the c/a interface, which enhanced the adsorption of intermediates, facilitated C-H bond cleavage, and balanced the adsorption-desorption of hydrogen, thereby improving electrocatalytic activities for FAOR and HER, respectively. This study not only presents a viable strategy for effectively tuning the electronic configuration of bimetallene but also offers valuable insights into the development of electrocatalysts.

Spinel-Based Catalysts That Enable Catalytic Oxidation of Volatile Organic Compounds.

Volatile organic compounds (VOCs) have caused serious harm to human health and ecological environment, and have received much attention in recent years. Despite the successful applications of catalytic combustion of VOCs as the core technology of VOCs removal in industry, the development of efficient catalysts that can mineralize VOCs into nontoxic CO2 and H2O at low temperatures remains a great challenge. Recent studies show that spinel-based materials as efficient catalysts were extensively used in the catalytic oxidation VOCs field due to their synergistic effect, manifold compositions, and electron configurations. However, most of the pollutants are complex, consisting of multiple VOCs, water vapor, CO2, SO2 and other substances, which presents a significant challenge in constructing highly active and stable catalysts. To meet the future demand for efficient catalysts capable of removing various types of VOCs, it is urgent to rationally design and scientifically prepare spinel catalysts based on existing knowledge. This work reviews the research and development of various spinel catalysts with an emphasis on their catalytic performance in VOCs oxidation. The catalytic performance of spinel-based catalysts for different sorts of VOCs was summarized and compared. Moreover, the effects of the reaction conditions on the catalytic performance of spinel-based catalysts were examined to accommodate complicated operating conditions. Subsequently, the regulation of spinel oxides in structure and defect was coherently reviewed to guide the development and design of efficient catalysts. Especially, the research techniques for the reaction mechanism over spinel catalysts were displayed to better deepen the understanding of catalytic oxidation of VOCs. Finally, the current development and challenges were proposed and put forward for future research. This review provided a systematic understanding of the VOCs oxidation over spinel-based catalysts and offered guidance for the development of high-performance catalysts for VOCs elimination.

Enhancing the Stability of Cu‐Based Electrocatalyst via Fe Alloy in Electrocatalytic Formaldehyde Oxidation with Long Durability

AbstractElectrocatalytic formaldehyde oxidation with metal Cu electrocatalyst has attracted significant interest since it can produce H2 at the anode and make it possible to construct a bipolar hydrogen production cell with low voltage. However, the activity of the Cu electrocatalyst will be greatly weakened after oxidizing it to Cu+ or Cu2+. Here, a CuFe bimetallic catalyst is developed to efficiently catalyze the electro‐oxidation process of HCHO to produce H2 at a potential of 0.10 VRHE with a current density of 100 mA cm−2. It is confirmed that introducing Fe in a CuFe catalyst can regulate the electron configuration to prevent Cu0 oxidation and improve the stability of the catalysts. The introduction of Fe can reduce the energy barrier of the reaction process, and make the C─H bond more easily split on CuFe. A bipolar hydrogen production device is constructed by combining the anodic oxidation of HCHO with the cathodic hydrogen evolution. The current density of 500 mA cm−2 is achieved at a cell voltage of 0.6 V. The faradaic efficiency is ≈100% and the device is stable for ≈50 h. The research provides a promising path toward the secure, effective, and expandable generation of high‐purity H2 at both anodic and cathodic electrodes.

Features in the electron elastic scattering cross sections of atoms Sb, Xe and Bi, Rn

Abstract For atoms having pairwise similar electronic configurations, Sb([Cd]5p3), Xe([Cd]5p6) and Bi([Hg]6p3), Rn([Hg]6p6), features in the energy dependences of integral (ICSs) and differential (DCSs) cross sections of electron elastic scattering are considered theoretically. The positions of the Ramsauer-Townsend minimum (RT) and the low-energy maxima in the ICSs are calculated. The minima in the DCSs have been studied within the collision energy range from 0.1 (Sb, Xe, Bi) and 0.5 (Rn) eV up to 1000 (Sb), 2000 (Xe), 3000 (Bi) and 4000 (Rn) eV. The phase shifts, scattering amplitudes and cross sections have been calculated in the relativistic complex optical potential (OP) approximation. The results of the above OP calculation agree well with the experimental and the theoretical data. The energy dependences of the angular positions of the DCSs minima of these atoms are considered in detail. The energy and the angular positions of 15 (Sb), 17 (Xe and Bi) and 18 (Rn) critical minima (CM) in the DCSs have been found. The highest energy CM are located at: Sb – [727.6 eV; 131.89], Xe – [791.4 eV; 133.16], Bi – [1810.8 eV; 137.34], Rn – [1918.8 eV; 137.64]. A high-angle CM are located at: Sb – [233.6 eV; 151.08], Xe – [256.5 eV; 151.05], Bi – [180.3 eV; 157.30], Rn – [204.0 eV; 155.36].

Revealing significant changes in electronic energy configurations via cation atom positions in Co(Gaₓ,Al1-x)₂O₄ spinel oxides

Revealing significant changes in electronic energy configurations via cation atom positions in Co(Gaₓ,Al1-x)₂O₄ spinel oxides

ZIF-67 derived N doped carbon embedded CoxP for superior hydrogen evolution

Abstract Developing a sustainable non-noble hybrid electrocatalyst for effective electrocatalysis is the most crucial task; particularly in sustainable hydrogen energy production in the realm of energy conversion. In this work, effective thermal pyrolysis process followed by phosphorization strategy was employed to prepare and fabricate ZIF-67 (Zeolitic imidazole) assisted Co2P/N doped carbon electrocatalyst for hydrogen evolution reaction (HER). The optimized Co2P/N–C electrocatalyst exhibited hollow porous nanostructures as confirmed from the scanning electron microscopy. The achieved porous nanostructure improved the efficiency of the charge and mass transportation which is confirmed by the BET analysis, has high surface area value of 94.731 m2/g. In addition, a transition metal atom can regulate reactants adsorption and desorption capacity by modulating Co and P electronic configuration. The electrochemical studies of fabricated ZIF-67 derived Co2P/N–C electrode were analyzed using 1.0 M alkaline potassium hydroxide (KOH) medium in 3 electrode system process. Whilst, optimizing the pyrolysis temperature during the phosphorization will remarkably enhance the favourable characteristics of the hydrogen generation. Notably, the optimized ZIF-67 derived Co2P/NC at 350 °C electrode exhibited low overpotential (135 mV) at minimum 10 mA/cm2 and low 120.3 mV/dec Tafel slope. Besides, electrode stability at 10 mA/cm2 current density was verified by chronoamperometry test. Hence, this study furnishes the potential technique for the development of advanced hybrid MOF electrocatalyst as a successful alternative on large scale.

Fine Engineering of d-Orbital Vacancies of ZnN4 via High-Shell Metal and Nonmetal Single-Atoms for Efficient and Poisoning-Resistant ORR.

Atomically dispersed metal-nitrogen-carbon (M-N-C) materials are active oxygen reduction reaction (ORR) catalysts. Among M-N-C catalysts, ZnN4 single-atom catalysts (SACs) due to a nearly full 3d10 electronic configuration insufficiently activate oxygen and display low ORR activity. To finely engineer d-orbital vacancies of ZnN4, we combine high-shell metal and nonmetal SAs as electronic regulators that are ZnN4Cl and carbon vacancy-hosted -Cl motifs, which show complementary electron-withdrawing capacities versus the ZnN4. Under that, the ZnN4 exhibits significantly enhanced ORR activity with a half-wave potential (E1/2) of 0.912 VRHE relative to the unmodified ZnN4 (E1/2 = 0.822 VRHE) and simultaneously robust durability (negligible activity loss after 10,000 potential cycles). Particularly, the engineered ZnN4 possesses high resistance to SCN- poisoning, which is rarely achieved among M-N-C SACs. Our works show that combining high-shell metal and nonmetal SAs can finely engineer d-orbital vacancies of metal centers to an optimal state, thereby intrinsically enhancing their catalytic performance.

Ferromagnetic ferroelectricity due to the Kugel-Khomskii mechanism of orbital ordering assisted by atomic Hund's second rule effects

The exchange interactions in insulators depend on the orbital state of magnetic ions, obeying certain phenomenological principles, known as Goodenough-Kanamori-Anderson rules. Particularly, the ferro order of alike orbitals tends to stabilize antiferromagnetic interactions, while the antiferro order of unlike orbitals favors ferromagnetic interactions. The Kugel-Khomskii theory provides a universal view on such coupling between spin and orbital degrees of freedom, based on the superexchange processes: namely, for a given magnetic order, the occupied orbitals tend to arrange in a way to further minimize the exchange energy. Then, if two magnetic sites are connected by the spatial inversion, the antiferro orbital order should lead to the ferromagnetic coupling break the inversion symmetry. This constitutes the basic idea of our work, which provides a pathway for designing ferromagnetic ferroelectrics: the rare but fundamentally and practically important multiferroic materials. After illustrating the basic idea on toy-model examples, we propose that such behavior can be indeed realized in the van der Waals ferromagnet VI3, employing for this analysis the realistic model derived from first-principles calculations for magnetic 3d bands. We argue that the intra-atomic interactions responsible for Hund's second rule, acting against the crystal field, tend to restore the orbital degeneracy of the ionic d2 state in VI3 and, thus, provide a necessary flexibility for activating the Kugel-Khomskii mechanism of the orbital ordering. In the honeycomb lattice, this orbital ordering breaks the inversion symmetry, stabilizing the ferromagnetic-ferroelectric ground state. The symmetry breaking leads to the canting of magnetization, which can be further controlled by the magnetic field, producing a huge change of electric polarization. Published by the American Physical Society 2024

Surface-Reconstructed CdNNi3 Antiperovskite Electrocatalyst: Unlocking Ampere-Level Current Density for Hydrogen Evolution.

Developing conductive electrocatalysts is crucial for decreasing the ohmic loss induced by electric resistance of the catalyst layer in the large-current-density hydrogen evolution reaction (HER), which has been overlooked previously. In this study, we screen a highly conductive antiperovskite CdNNi3 with negligible ohmic loss, as a highly active and durable HER electrocatalyst capable of unlocking ampere-scale current densities. CdNNi3 exhibits an impressive activity (an overpotential of 235 mV) at 1 A cm-2 and maintains its performance steadily at an ampere-scale current density (at 1 A cm-2 over 400 h). Besides, the CdNNi3-enabled anion-exchange membrane water electrolyzer outperforms that of the benchmark Pt/C, evidenced by a reduced cell voltage of 160 mV at 1 A cm-2, and presents a favorable stability at 1 A cm-2. Importantly, this study experimentally discovers the dynamic surface reconstruction phenomena of antiperovskite nitrides during alkaline HER. Theoretical analysis suggests that the presence of Cd in the reconstructed surface effectively adjusts the local electronic configuration of active sites, which promotes the adsorption of OH and reduces the binding strength to H, thereby facilitating the water dissociation step and reducing the energy barrier of the potential-determining step in the HER process.

Regulating the electronic modulation configuration of MnxFeCoNiCu high entropy alloy for reliable sulfur redox kinetics

Current research on sulfur redox catalysis primarily focuses on the adsorption and catalytic conversion of lithium polysulfides (LiPSs). However, it often neglecting the modulation of the catalysts' electronic structure, which includes charge transfer and orbital interactions that significantly affect adsorption and catalytic properties. In this work, multi-channel carbon nanotubes modified with high entropy alloy nanoparticles (MnxFeCoNiCu/MCCFs) are elaborately synthesized as hosts to reveal the relationship between the catalytic activity and surface electronic configuration for reliable sulfur electrochemistry. Combining density functional theory (DFT) calculations with detailed experimental investigations, we demonstrate that modulating the electron consumption center of this intrinsic electron transfer-replenishment mechanism, the surface charge distribution is reestablished, thereby improving the performance of multi-electron reactions. Achieving a balance between adsorption and desorption significantly enhance the catalytic efficiency for LiPSs conversion. Consequently, the as-prepared Mn1.00/MCCFs with an optimized electronic structure as sulfur host can deliver a high capacity of 938 mAh g−1, corresponding to an ultralow capacity decay of 0.013 % per cycle over 500 cycles at 1.0 C.

Modulating Built‐In Electronic Configuration via Variable Al Doping for Robust Oxygen Evolution Reaction

Transition metal‐based electrocatalysts play a crucial role in the oxygen evolution reaction (OER). However, their heavy reliance on free electrons at the <i>d</i>‐band significantly limits the screening of potentially efficient, earth‐abundant alternatives. Despite extensive exploration of catalyst engineering through multi‐metal cooperation to modulate electron configuration by introducing additional transition metals, practical success remains elusive. Here, we present a straightforward electrodeposition method for preparing amorphous FeCoAl hydroxide catalysts. The introduction of Al contributes external free electrons, enabling a well‐defined electron configuration for intermediate adsorption. Al doping also adjusts the <i>d</i>‐band position of adjacent Co atoms, bringing them closer to the Fermi level and significantly enhancing intrinsic activity at the active sites. Furthermore, Al dopants facilitate rapid mass and charge transfer near the catalyst layer, promoting faster reaction kinetics. Leveraging these properties, the FeCoAl hydroxide catalyst achieves a large current density of 100 mA cm <sup>‐2</sup> at an overpotential of 340 mV, with a small Tafel slope of 29.1 mV dec <sup>‐1</sup>. Our work provides valuable insights for designing efficient electrocatalysts by leveraging free electron‐rich metal doping and expanding the parameter space for catalyst engineering.

Metalloid Phosphorus Induces Tunable Defect Engineering in High Entropy Oxide Toward Advanced Lithium‐Ion Batteries

AbstractThe inferior electrical conductivity and sluggish lithium storage kinetics of conventional high‐entropy oxide (HEO) are critical issues hindering their commercialization. The high electronegativity of metalloids can ameliorate this predicament by altering the electronic configuration of HEO compared to metals. Herein, metalloid phosphorus doping in spinel‐type HEO (PxA1‐x)B2O4 (A/B = Cr, Mn, Fe, Co, Ni) (P‐HEO) is achieved through a facile sol–gel process. The metalloid phosphorus doping facilitates the transfer of electrons from transition metal sites to phosphorus‐doped sites, resulting in the formation of electron‐rich and electron‐deficient local regions on the HEO surface and is conducive to an increase in the total number of active lithium sites in the electrochemical reaction process. Density functional theory calculation reveals Li adsorption energy on the synthesized P‐HEO is only −1.102 eV, demonstrating that the phosphorus doping enables a strong electronic coupling between lithium ions and P‐HEO. Furthermore, metalloid phosphorus doping also leads to oxygen vacancies formation and lattice distortion, which significantly enhances charge transfer efficiency and diffusion kinetics and results in the enhanced lithium storage performance with impressive rate capability and long‐term stability. These findings provide valuable insights for the design of lattice‐engineered HEO as versatile electrodes for future energy storage applications.

The Jahn–Teller distortion‐induced electronic structure regulation of Mn‐doped Co3O4 for enhanced acetone detection

AbstractThe modulation of the electronic structure of metal oxides is crucial to enhance their gas‐sensing performance. However, there is lacking in profound study on the effect of electronic structure regulation on sensing performance. Herein, we propose an innovative strategy of Jahn–Teller distortion‐induced electronic configuration regulation of Co3O4 to improve acetone sensing performance. After the introduction of Mn3+ into Co3O4 (Mn‐Co3O4), the Jahn–Teller distortion of high‐spin Mn3+ (t2g3eg1) conversed to low‐spin Mn4+ (t2g3eg0), resulting in conversion of Co3+ (t2g6eg0) into Co2+ (t2g6eg1). As expected, Mn‐Co3O4 exhibits a high response value of 46.7 toward 100 ppm acetone, low limit of detection of 0.75 ppb, high selectivity, and high stability, which are overwhelmingly superior to previous Co3O4‐based acetone sensors. The dynamics and thermodynamics analysis demonstrate that the Mn doping improves sensing reaction rate, reduces reaction barrier, and promotes the charge transfer. The theoretical calculations further prove the charge transfer from Mn to Co derived from Jahn–Teller distortion and support promoting the adsorption of acetone on Co3O4 by Mn dopant. Moreover, we demonstrated the substantial potential application of Mn‐Co3O4 sensor as a monitoring gas sensor in pest resistance of Arabidopsis. This work provides a new strategy to design sensing materials from electronic configuration perspective.image

Electronic Structure of Diatomic Nickel Sulfide.

The nature of the Ni-S bond is investigated due to its role in the absorption of atmospheric Lewis acid gases such as SO2 and SO3 onto Ni surfaces. The vibrational frequency and electronic structure of NiS were predicted using CCSD(T), CASSCF, and internally contracted multireference configuration interaction (icMRCI) + Q. 43 density functional theory (DFT) functionals were benchmarked. CASSCF predicted the ground state of NiS to be the 5Δ state arising from the 3d8(3F)4s2 (3F) and 3d9(2D)4s (3D) electronic configurations of Ni. When dynamical correlation effects are included at the icMRCI + Q level, the ground state of Ni-S is predicted to be 3Σ- consistent with the experiment. The vibrational frequency of Ni-S is calculated to be 519.1 cm-1 at the icMRCI + Q level, in reasonable agreement with the experimental value of 512.68 cm-1. CCSD(T) predicts the frequency of Ni-S to be 543.2 cm-1 when extrapolated to the complete basis set (CBS) limit. The Feller-Peterson-Dixon value based on the CCSD(T)/CBS extrapolation for the bond dissociation energy of NiS is 350.6 kJ/mol, within <4 kJ/mol of experiment. Of the 43 DFT functionals, BP86 and O3LYP predicted the vibrational frequency in closest agreement with the experiment. The applicability of DFT to such acid gas systems was further demonstrated by calculating the energy for displacement of NiO by SO to yield NiS and O2. This displacement energy was calculated to be within experimental error for ∼50% of the DFT functionals, but large differences were also predicted for some functionals.

DFT + U Study of Plutonium Hydrides with Occupation Matrix Control.

The magnetic order of plutonium hydrides (PuHx) has long been a subject of controversy, both experimentally and theoretically. The magnetic, structural, electronic, and thermodynamic properties of PuHx are investigated using Hubbard-corrected density functional theory (DFT + U), with U derived from linear response calculations. To address the issue of electronic metastable states within DFT + U, we employ an occupation matrix control method as well as allowing 5f orbitals to break the structural symmetry. This advanced computational approach establishes that the ground-state magnetic order for PuH2 is antiferromagnetic and that for PuH3 is ferromagnetic, consistent with Faraday and nuclear magnetic resonance experiments. Using the conventional hydrogen-vacancy model for PuHx, the hydrogen-content-induced magnetic transition and anomalous variation of the magnetic moment are successfully reproduced. In particular, the calculated transition point of x matches the experimental findings. Furthermore, the electronic configuration of the Pu atom in PuHx is determined to be 5f5, which is consistent with observations from X-ray photoemission spectroscopy. Our calculated values for enthalpy of formation, heat capacity, and entropy are in good agreement with experimental data, thereby validating the robustness of our theoretical framework.

Aluminium-doped vanadium nitride as cathode material for high-performance aqueous zinc-ion batteries

Aqueous zinc-ion batteries (AZIBs) are increasingly favored for their environmentally friendly and impressive energy storage performance. Vanadium nitride (VN) is receiving much attention as a cathode material for AZIBs due to its high electrical conductivity and controllable structure. However, the direct use of VN in AZIBs presents challenges such as sluggish kinetics, insufficient specific capacity and limited stability. Herein, a heteroatom doping strategy is utilized to improve the electrochemical energy storage performance of the VN by incorporating aluminium (Al) via a hydrothermal process and a subsequent calcination treatment. Electrochemical characterizations indicate that the as-synthesized aluminium-doped VN (Al-doped VN) exhibits an outstanding specific capacity of 544 mAh·g−1 at 1 A g−1 and retains a high rate capacity of 275.6 mAh·g−1 at 10 A g−1. Further studies show that the Al incorporation effectively modulates the electronic configuration of the VN, which accelerates the charge transfer kinetics and thus enhances the electrochemical storage performance of VN. The phase transformation mechanism of the Al-doped VN is also investigated and the results show that the VN undergoes partial conversion into Zn3(OH)2V2O7·2H2O during the charge/discharge process.

Mixed atomic-scale electronic configuration as a strategy to avoid cocatalyst utilization in photocatalysis

To enhance the activity of photocatalysts for hydrogen production and CO2 conversion, noble metal cocatalysts as electron traps and/or acceptors such as platinum or gold are usually utilized. This study hypothesizes that mixing elements with heterogeneous electronic configurations and diverse electronegativities can provide both acceptor and donor sites of electrons to avoid using cocatalysts. This hypothesis was examined in high-entropy oxides (HEOs), which show high flexibility for atomic-scale compositional changes by keeping their single- or dual-phase structure. A new high-entropy oxide was designed and synthesized by mixing elements with an empty d orbital (titanium, zirconium, niobium and tantalum) and a fully occupied d orbital (gallium). The synthesized oxide had two phases (88 wt% orthorhombic (Pbcn) and 12 wt% monoclinic (I2/m)) with an overall composition of TiZrNbTaGaO10.5. It exhibited UV and visible light absorbance with a low bandgap of 2.5 eV, low radiative electron-hole recombination and oxygen vacancy generation due to mixed valences of cations. It successfully acted as a photocatalyst for CO and CH4 production from CO2 conversion and hydrogen production from water splitting without cocatalyst addition. These findings confirm that introducing heterogeneous electronic configurations and electronegativities can be considered as a design criterion to avoid the need to use cocatalysts.

Impact of Al3+ substitution on structural, Raman, transport electromagnetic properties of LiFe2O4 nanoparticles

Nanocrystalline Li0.5AlxFe2.5-xO4(x = 0.0 to 0.8 in steps, x = 0.2) compounds were prepared using the sol-gel auto-combustion technique. X-ray diffraction (XRD) analysis confirmed the single-phase cubic spinel structure, which showed that the lattice constant changed significantly, especially in the x = 0.6 sample, where it decreased clearly. The crystallite size decreased with increasing Aluminium content, reaching a small value of about 5 nm for the composition x = 0.8 sample. Raman peaks of pure LiFe2O4 were determined in both phases (alpha and beta), while smaller peaks at 198 and 236 cm−1 that related to the alpha phase were distinguished. All peaks diminished in intensity after Al3+ ions were doped to LiFe2O4 except for the peak at 700, where it became predominantly. The bandgap of the samples was deduced and analyzed from Tauc's plot according to UV–Vis spectra. The change in the electronic structure of the Li-Al ferrites, at which the size of the ferrite becomes close to the de Broglie wavelength, results in a band gap for the Al replaced by LiFe2O4 with different electronic configurations. The variation of the fundamental part of the dielectric constant (ε′), loss tangent (tan δ), and AC conductivity with frequency has been discussed with composition. The increase in Al3+ ion content affected the coercive force, as it decreased, while the saturation magnetism increased when adding Aluminium (x = 0.2) and then began to decline gradually.