Band Center Research Articles

Establishing a Robust Nonlinear Targeted Switch for C1 Electroproduction in Atomic Alloy Cox/Pd Bimetallenes.

Establishing a targeted switch for CO2 conversion under electric drive is essential for achieving carbon-balance by enabling selective chemicals. However, engineering the topological assembly of active sites to precisely regulate the competing pathways for various intermediates has been plagued by unclear structure-function relationships. To tailor the CO/formate pathways, herein we established a robust nonlinear targeted switch with tunable active Cox sites integrated into Pd metallene, which involves Co1/Pd single-atom alloy (favoring CO) and Co2/Pd diatomic alloy (favoring formate). Transitioning from Co1/Pd to Co2/Pd atomic alloy bimetallenes resulted in a nonlinear, high-contrast flip in selectivity, surpassing 94 % for CO and formate productions in both H-cell and flow cell. Furthermore, the superior selectivity and current efficiency for CO (>80 %) and formate (>88 %) were consistently maintained at -150 mA cm-2 over continuous 200 h. Theoretical simulations and in situ spectroscopy analyses unveiled that appropriate adjacent metal site combinations (Pd-Pd, Pd-Co and Co-Co) lead to tunable dz 2 band center and a nonlinear shift in preferred adsorption configurations of intermediates, dictating the C1 pathways. Our finding reveals a desired switch in C1 selectivity and robust stability within Cox/Pd system, providing a new perspective for fine-tuning energy conversion processes through specific topological assembly.

Optimizing the stability of NiFeOOH via oxyanion intercalation for water oxidation at large current densities

In alkaline water splitting, transition metals (Ni, Fe) have received extensive attention, and NiFe-oxyhydroxide (NiFeOOH) is regarded as an exceptionally active electrocatalysts for oxygen evolution reaction (OER). However, maintaining the long-term stability of NiFeOOH at high current densities is challenging due to Fe segregation and catalyst degradation. Herein, this study proposes an approach to enhancing the stability of the Ni/Fe-O covalent bond by intercalating oxyanions (NO3–, PO43-, SO42-, and SeO42-) into the NiFeOOH substrate, improving its resistance to bond breakage. And the NiFeOOH-NO3− electrocatalyst was found to be optimal, achieving an overpotential of 311 mV and stable performance at 1 A cm−2 for several hundred hours. Consequently, NiFeOOH-NO3– exhibited a significantly improved OER stability, with a mere 3.33 % stability attenuation after 100 h, compared to 13.19 % for pristine NiFeOOH. Notably, the presence of NO3– in NiFeOOH effectively mitigates Fe segregation, leading to a fourfold enhancement in long-term stability relative to that of NiFeOOH without NO3– modification. Theoretical calculations show that the introduction of NO3– effectively shifts metal 3d band centers of NiFeOOH closer to the Fermi level. It is suggested that the oxyanions lead to increased strength of the Ni/Fe-O bonds, thereby inhibiting the dissolution of Fe and enhancing the stability of NiFeOOH phase. This research represents a significant advance in controlling Fe segregation to stabilize NiFe-based electrocatalysts for high-current–density water oxidation.

A case study of railway curve squeal radiated from both the outer and inner wheel

This case study is presented after observations were made that partially contrast the prevailing picture of railway curve squeal given in the literature. These are observations with significance both for modelling and condition monitoring. The current case study will be followed by a subsequent investigation focused on the validation and application of a simulation model to investigate root-causes for curve squeal at the Stockholm metro. Curve squeal in a 213 m radius curve on the Stockholm metro is studied. Data includes track characteristics (rail profile, rail roughness and gauge width) and noise measured at the trackside as well as by two vehicles equipped with an on-board mounted noise monitoring system. The current case study contrasts field measurements of curve squeal reported in the literature by a relative shift of emitted noise towards higher frequencies. Wayside noise measurements in the studied curve during a few hours showed squeal generation for all vehicle passages with dominating 1/3 octave band centre frequencies in the range between 6.3–15.8 kHz. Noise data measured during one year of regular traffic of two vehicles equipped with a monitoring system were obtained. The occurrence of curve squeal was analysed through an implementation of the curve squeal detection algorithm in operation at the Stockholm metro. This algorithm was also applied to search for events of squeal noise radiation from the outer wheel. Results show emissions of squeal noise from the inner and outer wheel for 65 % and 8 % of the vehicle passages through the studied curve, respectively. Further, the occurrence of curve squeal radiated from the inner wheel was found to increase by 10 % after rail grinding. In the literature, squeal radiated from the outer wheel is described as having an intermittent character with magnified spectral components in the frequency range between 5–10 kHz. In contrast, the current work presents sustained tonal squeal generated from the outer wheel with similar noise characteristics as typically related to ordinary curve squeal.

Phonon-Lithium Ion Interactions: A Case Study of LiM(SeO3)2 (M = Al, Ga, In, Sc, Y, and La).

Li ion diffusion is fundamentally a thermally activated ion hopping process. Recently, soft lattice, anharmonic phonon, and paddlewheel mechanism have been proposed to potentially benefit the ion transport, while the understanding of vibrational couplings of mobile ions and anions is still very limited but essential. Herein, we accessed the ionic conductivity, stability, and especially, lattice dynamics in LiM(SeO3)2 (M = Al, Ga, In, Sc, Y, and La) with two different types of oxygen anions within a LiO4 polyhedron, namely, edge-shared and corner-shared with MO6 polyhedra, the prototype of which, LiGa(SeO3)2, has been theoretically reported before with the similar structural features to NASICON and later experimentally synthesized with the room temperature conductivity ∼0.11 mS cm-1. It is interesting to note that LiM(SeO3)2 with a higher Li phonon band center shows higher Li conductivity, which is in contradiction to the conventional understanding of the importance for soft lattice to superionic conductors. The anharmonic and harmonic phonon interactions as well as the couplings between the vibration of the edge-bonded or corner-bonded anion in Li polyanions and the Li ion diffusion have been studied in detail. With transition metal M changing from La, Y, In, Ga, Al, and Sc, anharmonic phonons increase with reduced activation energy for Li diffusion. The phonon modes dominated by the edge-bonded oxygen anions contribute more to the migration of the Li ion than those dominated by the corner-bonded oxygen anions because of the greater atomic interaction between the Li ion and the edge-bonded anions. Thus, rather than the overall lattice softness, attention shall be given to reduce the frequency of the critical phonons contributing to Li ion diffusion as well as to increase the anharmonicity, i.e., through asymmetric Li polyhedra, for the design of Li ion superionic conductors for all-solid-state batteries.

Near-infrared spectral behavior of space-weathered olivine with varying iron content

Context. Space weathering alters the surfaces of airless celestial bodies, thereby modifying their spectra significantly. Olivine plays a crucial role in responding to space weathering on silicate planets. However, the spectral variations that occur in olivine with varying iron content as a result of space weathering conditions remain unclear. Aims. We aim to systematically characterize the spectral variability of surface iron-rich olivine in the space weathering environments of Phobos and the Moon. Methods. We conducted nanosecond pulsed laser irradiation experiments on a set of synthetic Fe-rich olivine (Fa29, Fa50, Fa71, and Fa100). The energy levels were simulated for Phobos and the Moon. We analyzed the available near-infrared (NIR) spectroscopy. Results. We find that olivine with higher Fe content undergoes stronger weathering under the same irradiation energy, shifting absorption centers around 1.08 µm and 1.35 µm to longer wavelengths. When comparing the high energy and low frequency, spectral changes are more pronounced at low energy and high frequency. The olivine with the same iron content exhibits a more noticeable shift around 1.08 µm under various irradiation levels, while the band center around 1.35 µm remains stable. Conclusions. When the same amount of radiation energy is received, changes in the spectrum are more noticeable at low energy and high impact frequency than at high energy and low impact frequency. The absorption position at ~1.35 µm is a good indicator of the Mg# value of space-weathered olivine.

Bifunctional catalytic activity of anion-doped LaSrCoO4 for oxygen reduction and evolution reactions.

Here, we synthesized Co-based, anion-incorporated‍ ‌R‌u‌d‌d‌l‌e‌s-d‌e‌n‌-‌Popper perovskite electrocatalysts (LaSrCoO4-x X y ) and compared their catalytic performances in the oxygen reduction reaction (ORR) and oxygen evolution reaction (OER). The ORR mechanism with the newly synthesized F-doped LaSrCoO4 catalyst was dominated by a four-electron process, and the number of electrons involved in the reaction increased compared with that for LaSrCoO4. The OER activity of the hydride-doped LaSrCoO4 catalyst was the highest among the LaSrCoO4 system catalysts. Density functional theory calculations revealed that there is a correlation between the Co 3d unoccupied orbital band centre and the OER activity. The addition of anions and substitution of metal sites improved the ORR and OER activities of the catalysts. Our findings confirmed that the addition of heteroatom anions can improve the activity of perovskite-type electrocatalysts, promoting their application in various fields.

High resolution analysis of the CD[formula omitted] deuterated methane: Extended investigation of the pentad region

A highly accurate rotational–vibrational analysis of Fourier transform infrared spectra of the 12CD4 molecule is presented. The high resolution infrared spectra were measured with a IFS125 HR Fourier transform interferometer from Bruker at an optical resolution of 0.003 cm−1 and analyzed in the 1750–2400 cm−1 region. Here the 2ν2, ν2+ν4, 2ν4, ν1 and ν3 bands (altogether, nine sub-bands of different symmetry) of the pentad are located. The number of 1213/1993/1576/77/1582 transitions with the Jmax = 23/23/23/14/32 were assigned to the 2ν2, ν2+ν4, 2ν4, ν1 and ν3 bands of 12CD4. The obtained experimental data were used for the determination of the upper ro-vibrational energy values. To provide more correct values of the upper energies, more than 7800 highly accurate “hot” transitions from the dyad region were additionally processed. In general, 4088 upper ro-vibrational energies of the pentad (for comparison, 2525 upper ro-vibrational energies with the value of Jmax=20 are known in the modern literature up to now) were determined, which were used then in the weighted fit procedure with a goal to determine the spectroscopic parameters (band centers, rotational, centrifugal distortion, tetrahedral splitting and resonance interaction parameters) of the effective Hamiltonian. The obtained drms value is 5.5×10−4 cm−1 which is almost one hundred times better than the reproduction of the same set of experimental data by the parameters known in the earlier literature.

Machine learning-based design of electrocatalytic materials towards high-energy lithium||sulfur batteries development

The practical development of Li | |S batteries is hindered by the slow kinetics of polysulfides conversion reactions during cycling. To circumvent this limitation, researchers suggested the use of transition metal-based electrocatalytic materials in the sulfur-based positive electrode. However, the atomic-level interactions among multiple electrocatalytic sites are not fully understood. Here, to improve the understanding of electrocatalytic sites, we propose a multi-view machine-learned framework to evaluate electrocatalyst features using limited datasets and intrinsic factors, such as corrected d orbital properties. Via physicochemical characterizations and theoretical calculations, we demonstrate that orbital coupling among sites induces shifts in band centers and alterations in the spin state, thus influencing interactions with polysulfides and resulting in diverse Li-S bond breaking and lithium migration barriers. Using a carbon-coated Fe/Co electrocatalyst (synthesized using recycled Li-ion battery electrodes as raw materials) at the positive electrode of a Li | |S pouch cell with high sulfur loading and lean electrolyte conditions, we report an initial specific energy of 436 Wh kg−1 (whole mass of the cell) at 67 mA and 25 °C.

Topological Synthesis of 2D High-Entropy Multimetallic (Oxy)hydroxide for Enhanced Lattice Oxygen Oxidation Mechanism.

Owing to sluggish reaction kinetics and high potential, oxygen evolution reaction (OER) electrocatalysts face a trade-off between activity and stability. Herein, an innovative topological strategy is presented for preparing 2D multimetallic (oxy)hydroxide, including ternary CoFeZn, quaternary CoFeMnZn, and high-entropy CoFeMnCuZn. The key to the synthesis lies in using Ca-rich brownmillerite oxide as a precursor, which possesses inherent structural flexibility enabling tailored elemental adjustments and topologically transforms from a point-shared structure of metal-oxygen octahedrons into an edge-shared structure under alkaline conditions. The presence of Zn in the catalysts causes a shift in the center of the O2p band toward the Fermi level, resulting in more Co4+ species, which drive holes into oxygen ligands to promote intramolecular oxygen coupling. The triggered lattice oxidation mechanism is identified by detecting peroxo-like (O2 2-) negative species using tetramethylammonium chemical probe, along with 18O isotope labeling experiments. As a result, the catalyst demonstrates an overpotential of 267mV at 10 mA cm-2, ranking it among the top-performing non-Ni-based catalysts. Importantly, the catalysts also show high Fe-leaching resistance during OER compared to conventional NiFe and CoFe hydroxides/(oxy)hydroxides. The assembled zinc-air battery enables stable operation for over 225 h at a low charging voltage of 1.93V.

Modulation of p-Block Electron Orbits in Metal-Organic Frameworks for CO2 Capture and Electrochemical Reduction.

Developing catalysts with excellent CO2 capture capability and electrochemical CO2 reduction reaction (CO2RR) at a wide potential range simultaneously is significant but remains a formidable challenge. Here, two novel InMg defective trinuclear cluster-based MOFs (SNNU-41 and SNNU-42) with abundant p-block unsaturated coordinated sites were reported and exhibited good CO2 capture and CO2RR performance simultaneously. Due to the suitable micropores, SNNU-41 showed higher CO2 capture ability at different adsorption pressure conditions. On account of the rigid framework and the closer p band center to Fermi level, SNNU-42 accelerated the conversion of CO2 molecule to C1 efficiency. Notably, via adjusting the ratio of p-block metal (In) in the SNNU-42 framework, the performance of the CO2RR was promoted drastically. SNNU-42 with the InMg (1:1.8) mixed cluster delivered an excellent Faradaic efficiency of 91.3% for C1 products and high selectivity of 72.0% for HCOOH at -2.5 V (vs Ag/Ag+) with a total current density of 77.2 mA cm-2. This work provides a possibility for efficient CO2 capture and CO2RR electrocatalysts through the modulation of electronic structures and composition in MOFs.

Fe-S dually modulated adsorbate evolution and lattice oxygen compatible mechanism for water oxidation.

Simultaneously activating metal and lattice oxygen sites to construct a compatible multi-mechanism catalysis is expected for the oxygen evolution reaction (OER) by providing highly available active sites and mediate catalytic activity/stability, but significant challenges remain. Herein, Fe and S dually modulated NiFe oxyhydroxide (R-NiFeOOH@SO4) is conceived by complete reconstruction of NiMoO4·xH2O@Fe,S during OER, and achieves compatible adsorbate evolution mechanism and lattice oxygen oxidation mechanism with simultaneously optimized metal/oxygen sites, as substantiated by in situ spectroscopy/mass spectrometry and chemical probe. Further theoretical analyses reveal that Fe promotes the OER kinetics under adsorbate evolution mechanism, while S excites the lattice oxygen activity under lattice oxygen oxidation mechanism, featuring upshifted O 2p band centers, enlarged d-d Coulomb interaction, weakened metal-oxygen bond and optimized intermediate adsorption free energy. Benefiting from the compatible multi-mechanism, R-NiFeOOH@SO4 only requires overpotentials of 251 ± 5/291 ± 1 mV to drive current densities of 100/500 mA cm-2 in alkaline media, with robust stability for over 300 h. This work provides insights in understanding the OER mechanism to better design high-performance OER catalysts.

Investigation of the dynamic compression behavior of 3D braided composites based on a virtual fiber embedding method

The three-dimensional braided composites (3DBCs) possess a complex spatial structure, which can lead to microscopic deformation of fibers under high-speed impact. This paper proposes a quasi-fiber scale model using virtual fiber-embedded (VFE) method to simulate the impact behavior and failure of 3DBCs. The results reveal that the maximum eccentricity of the VFE model yarn cross-section is 0.318, representing a 194% improvement compared to solid yarns. According to the characteristics of damage, it can be deduced that interactions among fibers play a pivotal role in determining the failure behavior of composites, particularly concerning non-linear changes. The modulus, strength and the time of initial damage rise with an increasing braiding angle, whereas the resin stress, yarn stress, and degree of damage exhibit opposite trends. The stress distribution over the braiding path shows that the main load-bearing component at 20° braiding angles is internal yarns, whereas the surface yarns take precedence at 40°. The maximum deformation of the yarn cross-section always occurs at the center of the shear band, with a maximum eccentricity of 0.456 at 20° braiding angles. The deformation in yarn flexing and cross-section flattening cause an uneven distribution of stress and strain, leading to localized damage and ultimately catastrophic destruction.

The Prevalence of Chronic Interosseous Membrane Lesions Following Mason II and III Radial Head Fractures in Complex Elbow Instability-A Retrospective Observational Cohort Study.

The primary aim of the present study was to assess the prevalence of chronic lesions of the central band of the interosseous membrane (cbIOM) in complex elbow instability (CEI) in a consecutive series of patients who had previously undergone surgical treatment for Mason II and III radial head (RH) fractures. The secondary aim was to define its clinical significance. We performed a retrospective study on a prospective database. Our study population comprised 93 patients affected by CEI with type II or III RH fractures according to Mason's classification who were analyzed in the chronic setting. All patients were treated according to the current therapeutic algorithms. At the last follow-up, the "muscular hernia sign" was investigated by means of a bilateral ultrasonographic examination to assess any chronic cbIOM lesions; the Mayo Elbow Performance Score (MEPS) was used to evaluate the clinical significance of these lesions. All 93 patients were assessed after a mean time of 7.3 years (range: 2-12). No positive "hernia signs" were found, while five patients (5.4%) displayed an increased laxity of the cbIOM when compared with the contralateral side despite a negative "hernia sign". The clinical outcome in all five patients was excellent with a mean MEPS of 96 (range, 90-100). Chronic cbIOM lesions are very rare in CEI with RH fractures. No patients in this large sample displayed a cbIOM complete lesion; in cases with increased laxity, satisfactory mid-term clinical results were observed. Considering that previous studies reported (1) a high prevalence of cbIOM lesions in patients with Mason II and III RH fractures and (2) the current expert opinion about the scarce healing potential of the cbIOM, this study also suggests that the IOM may heal better than previously believed when RH fractures are treated appropriately in the acute setting.

Quantitative analysis of spectral properties and composition of primitive achondrites (acapulcoites, lodranites and winonaites)

The establishment of robust meteorite-asteroid links has been a major focus of planetary exploration, and a major driver of asteroid sample return missions. Reflectance spectroscopy has been shown to be a powerful tool for this purpose. For the meteorites dominated by silicate minerals, quantitative analysis of spectral absorption features caused by the Fe2+-bearing minerals (mainly olivine and pyroxene) is a common method to determine mafic silicate mineralogy and end member abundances, and establish the relationship between them and possible parent bodies. In this study, the reflectance spectra of 22 primitive achondrites (acapulcoites, lodranites and winonaites) from NASA RELAB database were analyzed to determine their positions in the plot of the band area ratio (BAR) and 1 μm band center (Band I center). We found that Band I center and BAR of acapulcoites and lodranites are in roughly the same range. Acapulcoite-lodranite partially overlap with the field of H chondrites in the plot of the BAR and Band I center. This overlap means that spectral calibrations (also referred to as mineralogical formulas) based on the two types of meteorites needs to be applied with caution. The 2 μm band center of acapulcoite–lodranite is significantly lower than that of H chondrites, which is consistent with the conclusion of previous studies and provides a means to separate these two groups. In addition, the choice of spectral parameter analysis techniques may be a potential error source in similar studies. We provide generalized spectral fields of primitive achondrites in the plot of the BAR and Band I center derived from two widely used technologies.

Built-in Electric Field in 1D/2D Heterostructure Boosts Zinc Air Battery Performance.

The realization of a rechargeable zinc-air battery (ZAB) is hindered by the low intrinsic oxygen evolution reaction (OER) and oxygen reduction reaction (ORR) activities. In this work, an abundant built-in electric field is noticed in a 1D/2D CoO/CoS2 heterostructure, triggering electron transfer from CoO to CoS2 associated with a downshifted d band center of the Co atom mitigating the strong electrochemical adsorption of *OH species on active sites; thereby, boosted OER and ORR performance are achieved. Namely, the OER specific activity of CoO/CoS2 is enhanced by 3.8- and 2.2-fold compared to the counterpart of CoO and CoS2, respectively. Furthermore, the kinetic current density of CoO/CoS2, a fingerprint of intrinsic ORR activity, is promoted by 46 and 6.6 times relative to CoO and CoS2. The rechargeable ZAB performance attains 215.6 mW cm-2, 1.6-times better than Pt/C-IrO2. Moreover, the superior performance remained for 600 h. Besides, the battery performance of the all-solid-state ZAB reaches 83.8 mW cm-2, revealing its promising application in wearable device.

Integrating Multiple Strategies Using Biotechnology to Design High‐Performance Electrocatalysts for Hydrogen and Oxygen Evolution

AbstractCombining multiple design strategies often enhances catalyst performance but usually comes with high costs and low reproducibility. A technique that enhances catalyst performance in multiple strategies is urgently needed. Herein, a novel bioregulation technique is introduced, allowing simultaneous control over morphology, particle size, doping, interface engineering, and electronic properties. Bioregulation technique utilizes the soluble extracellular polymer from Aspergillus niger as a templating agent to construct high‐performance catalysts for hydrogen and oxygen evolution reaction (HER and OER). This technique controls catalyst morphology, introduces biological N and S doping, and regulates the electronic structure of the catalyst surface. Biomolecule modification enhances surface hydrophilicity, and the nanostructure increases surface roughness and gas‐release efficiency. Theoretical calculations show that the bioregulation technique shortens the d/p‐band center, optimizing reaction intermediate adsorption and desorption. The Bio‐Pt/Co3O4 catalyst with trace Pt on the surface, designed with these strategies, achieves HER (η10 of 42 mV), OER (η10 of 221 mV), and overall water‐splitting performance (1.51 V at 10 mA cm−2), maintaining stability for over 50 h, outperforming most Pt‐based catalysts. Notably, using spent lithium‐ion battery cathodes leachate, rich in Co2⁺, successfully replicates the experiment. This approach holds promise as a mainstream method for synthesizing high‐performance materials in the future.

Electron-Spin Regulation Driving Heterointerface Electron Distribution and Phase Transition toward Ultrafast and Durable Sodium Storage.

Phase engineering is an effective strategy for modulating the electronic structure and electron transfer mobility of cobalt selenide (CoSe2) with remarkable sodium storage. Nevertheless, it remains challenging to improve fast-charging and cycling performance. Herein, a heterointerface coupling induces phase transformation from cubic CoSe2 to orthorhombic CoSe2 accompanied by the formation of MoSe2 to construct a CoSe2/MoSe2 heterostructure decorated with N-doped carbon layer on a 3D graphene foam (CoSe2/MoSe2@NC/GF). The incorporated Mo cations in the bridged o-CoSe2/MoSe2 not only act an electron donor to regulate charge-spin configurations with more active electronic states but also trigger the upshift of d/p band centers and a decreased ∆d-p band center gap, which greatly enhances ion adsorption capability and lowers the ion diffusion barrier. As expected, the CoSe2/MoSe2@NC/GF anode demonstrates a high-rate capability of 447 mAh g-1 at 2 A g-1 and an excellent cyclability of 298 mAh g-1 at 1 A g-1 over 1000 cycles. The work deepens the understanding of the elaborate construction of heterostructured electrodes for high-performance SIBs.

Manipulation in local coordination of platinum single atom enables ultrahigh mass activity toward hydrogen evolution reaction

Atomic-engineering of noble metal into single-atom electrocatalysts with well-defined active sites has been considered as an effective approach to enhance the mass-activity towards hydrogen evolution reaction (HER), crucial for the practical implementation of this sustainable technology. Herein, we devise a metallic-coordination strategy via a facile one-step pyrolysis method, for the atomic isolation of a small amount of platinum (Pt, 0.45 wt%) atoms in the surface of nickel (Ni) nanoparticles (Pt1@Ni) encapsulated into nitrogen-doped carbon nanotubes (Pt1@Ni/NCNT). Such a Pt1@Ni/NCNT single-atom alloy catalyst exhibits a record-high and all-round superior HER performance including mass-activity (up to 350.7 A mgPt−1@η150), stability (>50 h at 100 mA cm−2), pH-tolerance by comparison with Pt1@NC. Our density functional theory calculations combined with in situ Raman spectroscopic studies reveal a synergistic dual-active-site catalytic mechanism, involving the fast hydrogen spillover effect on coordinated Ni supports and accelerated water dissociation in acidic and alkaline medium, respectively. A strong electronic hybridization of 5d orbital of alloyed Pt and 3d orbital of Ni atoms modulates the d band center of Pt, which not only boosts HER activity but also stabilizes Pt single atoms. Due to the double protecting strategy from strong anchoring effect in Ni support and chemically stable NCNT shell, a robust stability is achieved for Pt1@Ni/NCNT hierarchal catalyst. Our findings open up a new avenue to substantially tailor the activity of surface Pt atoms for the design of highly efficient and durable noble metal-based catalysts.

Effect of A-site cation doping on the catalytic oxidation of toluene over mullite catalyst GdMn2O5

Manganese-based mullite (AMn2O5) catalysts are promising for the catalytic oxidation of VOCs, with their oxidation reaction performance being tunable by modifying the composition of the A-site elements. In this work, various manganese-based mullite catalysts (Gd0.9X0.1Mn2O5, X =Sr, Ce, or Ca) with different A-site elements doping were prepared by the citric acid sol–gel method and applied to the catalytic oxidation of toluene. The activity tests indicated that the enhancement of catalytic performance by doping elements was in the order of Sr > Ce > Ca. Notably, the T90 of the Gd0.9Sr0.1Mn2O5 catalyst was 235.6 °C, a lower 37.8 °C than that of the GdMn2O5. Comprehensive characterization and density functional theory (DFT) simulations revealed that Sr doping facilitates the reduction of Mn4+ to Mn3+, increases the electron occupancy of the eg orbitals in octahedral Mn sites, and elevates the Mn-d band center, thus facilitating the adsorption and activation of O2. Additionally, the raised O-p band center caused by Sr doping enhances lattice oxygen mobility. In situ DRIFTS analysis indicated that the introduction of Sr at the A-site optimizes the toluene reaction pathway and accelerates the reaction rate. This work reveals that a simple A-site cation doping strategy can effectively regulate manganese-based mullite catalysts’ electronic structure and surface reaction activity, providing a feasible method for the large-scale preparation of manganese-based mullite catalysts with excellent catalytic performance.

Swelling the d/p‐Band Center Difference Induced by Heterostructure Self‐Optimization Engineering for Enhanced Water Oxidation

Swelling the <i>d</i>/<i>p</i>‐Band Center Difference Induced by Heterostructure Self‐Optimization Engineering for Enhanced Water Oxidation