Bismuth tungstate hierarchical nest-like structures built by higher order nanoplate alignment have been successfully synthesized by a facile and economical method in the presence of polyvinyl pyrrolidone. The formation mechanism and effect of reaction time on the products were investigated. In addition, studies of the photocatalytic property demonstrate that the as-synthesized Bi2WO6 structures show excellent photocatalytic activity exposure to visible light irradiation. Furthermore, we first explored the electrochemical property of the Bi2WO6 nanostructure as an electrode in a lithium ion battery. Therefore, the preparation and properties studies of Bi2WO6 structures suggest potential future applications in photocatalysis by sunlight and as an electrode candidate in lithium ion batteries.

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Tuning surface strain is a new strategy for boosting catalytic activity to achieve sustainable energy supplies; however, correlating the surface strain with catalytic performance is scarce because such mechanistic studies strongly require the capability of tailoring surface strain on catalysts as precisely as possible. Herein, a conceptual strategy of precisely tuning tensile surface strain on Co S /MoS core/shell nanocrystals for boosting the hydrogen evolution reaction (HER) activity by controlling the MoS shell numbers is demonstrated. It is found that the tensile surface strain of Co S /MoS core/shell nanocrystals can be precisely tuned from 3.5% to 0% by changing the MoS shell layer from 5L to 1L, in which the strained Co S /1L MoS (3.5%) exhibits the best HER performance with an overpotential of only 97 mV (10 mA cm ) and a Tafel slope of 71 mV dec . The density functional theory calculation reveals that the Co S /1L MoS core/shell nanostructure yields the lowest hydrogen adsorption energy (∆E ) of -1.03 eV and transition state energy barrier (∆E ) of 0.29 eV (MoS , ∆E = -0.86 eV and ∆E = 0.49 eV), which are the key in boosting HER activity by stabilizing the HER intermediate, seizing H ions, and releasing H gas.

Engineering the morphology and electronic properties simultaneously of emerging metallene materials is an effective strategy for enhancing their performance as oxygen reduction reaction (ORR) electrocatalysts. Herein, a highly efficient and stable ORR electrocatalyst, Fe-doped ultrathin porous Pd metallene (Fe–Pd UPM) composed of a few layers of 2D atomic metallene layers, was synthesized using a simple one pot wet-chemical method and characterized. Fe–Pd UPM was measured to have enhanced ORR activity compared to undoped Pd metallene. Fe–Pd UPM exhibits a mass activity of 0.736 A mgPd –1 with a loss of mass activity of only 5.1% after 10 000 cycles at 0.9 V versus the reversible hydrogen electrode (vs RHE) in 0.1 M KOH solution. Density functional theory (DFT) calculations reveal that the stable Fe dopant in the inner atomic layers of Fe–Pd UPM delivers a much smaller overpotential during O* hydrogenation into OH*. The morphology, porous structure, and Fe doping were verified to have enhanced ORR activity. We believe that the rational design of metallene materials with porous structures and interlayer doping is promising for the development of efficient and stable electrocatalysts.

overcome the thermodynamic and kinetic stability of CO 2 molecules. [9][10][11] Various products, including CO, formic acid, and C 2+ products, have been achieved. [12][13][14] However, their catalytic efficiency and product selectivity for practical application are still limited by the large overpotential and undesirable competition of the hydrogen evolution reaction (HER). [15][16][17][18] Therefore, it is urgent to accurately control electrocatalysts at the atomic scale to break the inherent scaling relationship for the CO 2 RR.Recently, transition metal single-atom catalysts (SACs) have attracted tremendous attention for the CO 2 RR due to their sufficient atom utilization efficiency and desirable electronic states. [19][20][21] Ni single atom (SA) supported on graphene demonstrates good performance for CO 2 reduction to CO; however, it also suffers from a high onset potential due to the weak binding strengths of the intermediates at the Ni-N-C sites, leading to a high energy barrier to form *COOH intermediates. [22,23] Fe SA exhibits a low onset potential for the CO 2 RR, but unfortunately, the strong binding of *CO at the Fe sites seriously lowers the Faraday efficiency (FE) and stability. [24][25][26][27] Therefore, balancing the adsorption strength for both *COOH and *CO intermediates on only one kind of single metal site is a great challenge. It has been reported that dual-single-atom (DSA) catalysts with substantially different coordination environments and quantum size effects have the potential to surpass the well-established SACs for the CO 2 RR. [28][29][30][31][32] However, insufficient theory-designed DSA catalysts impede the development of DSA catalysts with specific catalytic activity. [31] Furthermore, the understanding regarding the mechanism for the enhanced catalytic process lacks in-depth research both experimentally and theoretically. [32] Most of the reported DACs have primarily focused on the thermodynamic pathway, for example, the Gibbs free energy, while the electron interactions between dual atoms and the kinetic pathway are equally indispensable for obtaining a thorough comprehension of this enhanced CO 2 RR process. [33][34][35][36][37] Therefore, the rational design of high-performance DSA remains conceptually challenging, and the electronic variation of each metal site during the CO 2 RR process has yet to be explored.Herein, we design a DSA catalyst consisting of atomically dispersed Cu and Ni bimetal sites, and the electronegativity offset between the Cu and neighboring Ni atoms significantly Achieving efficient efficiency and selectivity for the electroreduction of CO 2 to value-added feedstocks has been challenging, due to the thermodynamic stability of CO 2 molecules and the competing hydrogen evolution reaction. Herein, a dual-single-atom catalyst consisting of atomically dispersed CuN 4 and NiN 4 bimetal sites is synthesized with electrospun carbon nanofibers (CuNi-DSA/CNFs). Theoretical and experimental studies reveal the strong electron interactions induced by the electro...

Developing highly efficient electrocatalysts while revealing the active site and reaction mechanism is essential for electrocatalytic water splitting. To overcome the number and location limitations of defects in the electrocatalyst induced by conventional transition-metal atom (e.g. Fe, Co, and Ni) surface doping, we report a facile strategy of substitution with lower electronegative vanadium in the cobalt carbide, leading to larger amounts of defects in the whole lattice. The self-supported and quantitatively substituted V x Co3–x C (0 ≤ x ≤ 0.80) was one-step synthesized in the electrospun carbon nanofibers (CNFs) through the solid-state reaction. Particularly, the V0.28Co2.72C/CNFs exhibit superior hydrogen evolution reaction and oxygen evolution reaction activity and deliver a current density of 10 mA cm–2 at 1.47 V as the alkaline electrolyzer, which is lower than the values for the Pt/C–Ir/C couple (1.60 V). The operando Raman spectra and density functional theory calculations show that the enhanced electron transfer from V to the orbit of the Co atom makes Co a local negative charge center and leads to a significant increase in efficiency for overall water splitting.

Whilst vibration analysis of planetary gearbox faults is relatively well established, the application of Acoustic Emission (AE) to this field is still in its infancy. For planetary-type gearboxes it is more challenging to diagnose bearing faults due to the dynamically changing transmission paths which contribute to masking the vibration signature of interest.The present study is aimed to reduce the effect of background noise whilst extracting the fault feature from AE and vibration signatures. This has been achived through developing of internal AE sensor for helicopter transmission system. In addition, series of signal processing procedure has been developed to improved detection of incipient damage. Three signal processing techniques including an adaptive filter, spectral kurtosis and envelope analysis, were applied to AE and vibration data acquired from a simplified planetary gearbox test rig with a seeded bearing defect. The results show that AE identified the defect earlier than vibration analysis irrespective of the tortuous transmission path.

The appropriate catalyst model with a precisely designed interface is highly desirable for revealing the real active site at the atomic level. Herein, we report a proof-of-concept strategy for creating an exposed and embedding interface model by constructing a unique Co9S8 core with a full WS2 shell (Co9S8/FWS2) and a half WS2 shell (Co9S8/HWS2) to uncover the synergistic effect of heterointerfaces on the catalytic performances. Tailoring the heteroepitaxial growth of WS2 shell, Co9S8/HWS2 with exposed Co–S–W interfaces leads to the exceptional electron density changes on edged-S atoms with large amounts of lone-pair electrons. Meanwhile, the unique Co9S8/HWS2 could accelerate the kinetic adsorption of hydrogen- and oxygen-containing intermediates. Such Co9S8/HWS2 electrocatalysts show extremely low overpotentials of 78 and 290 mV at a current density of 10 mA cm–2 for hydrogen evolution reaction (HER) and oxygen evolution reaction, respectively. Using Co9S8/HWS2 as both the cathode and anode, an alkali electrolyzer delivers a current density of 10 mA cm–2 at a quite low cell voltage of 1.60 V. The results of both operando Raman spectroscopy and electron spin resonance indicate the presence of S–S terminal and S–S bridging with unsaturated S atoms during the HER process. The present work reveals the synergistic effects of nanoscale interfaces on overall electrocatalytic water splitting.