Jiang, Xin
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Publication Access status: Metadata only , A Highly Active Porous Mo2C-Mo2N Heterostructure on Carbon Nanowalls/Diamond for a High-Current Hydrogen Evolution Reaction(2024); ; ; ; Developing non-precious metal-based electrocatalysts operating in high-current densities is highly demanded for the industry-level electrochemical hydrogen evolution reaction (HER). Here, we report the facile preparation of binder-free Mo2C-Mo2N heterostructures on carbon nanowalls/diamond (CNWs/D) via ultrasonic soaking followed by an annealing treatment. The experimental investigations and density functional theory calculations reveal the downshift of the d-band center caused by the heterojunction between Mo2C/Mo2N triggering highly active interfacial sites with a nearly zero ∆GH* value. Furthermore, the 3D-networked CNWs/D, as the current collector, features high electrical conductivity and large surface area, greatly boosting the electron transfer rate of HER occurring on the interfacial sites of Mo2C-Mo2N. Consequently, the self-supporting Mo2C-Mo2N@CNWs/D exhibits significantly low overpotentials of 137.8 and 194.4 mV at high current densities of 500 and 1000 mA/cm2, respectively, in an alkaline solution, which far surpass the benchmark Pt/C (228.5 and 359.3 mV) and are superior to most transition-metal-based materials. This work presents a cost-effective and high-efficiency non-precious metal-based electrocatalyst candidate for the electrochemical hydrogen production industry.Source Type:Article5 - Some of the metrics are blocked by yourconsent settings
Publication HiPIMS deposition of superconducting Nb thin films onto Cu substrates(2023); ; ; ; The use of energetic condensation techniques, such as HiPIMS, has the potential to significantly improve the superconducting performance of coated Cu cavities by producing bulk-like Nb thin films. However, in order to benefit from these techniques, a deeper understanding of the effects of, and the relationship between, the different deposition parameters, the physical properties of the deposited films and the superconducting performance of the films, is still required. This contribution details the effects of different HiPIMS deposition parameters on the morphological, crystallographic and superconducting properties of Nb thin films deposited onto electropolished Cu substrates. Higher duty cycles (8 – 20 %) than previous HiPIMS investigations were used in the majority of the coatings. The films displayed more bulk-like crystallographic properties, indicated here by the lattice parameter, with a “transition zone” apparent in the early stages of film growth. A reduction in the surface roughness as well as interfacial voids, compared to typical DC MS Nb films, was also observed. The superconducting performance of the films, specifically the first magnetic flux entry field, showed a marked reliance on the substrate bias and the film thickness. Conversely, the HiPIMS duty cycle appears to have a comparatively insignificant effect. •Investigation of multiple HiPIMS coating parameters for the deposition of Nb thin films onto Cu substrates.•Predicted improved interface and surface roughness observed across all HiPIMS samples.•A morphological/crystallographic “transition zone” is observed between 1 and 2 μm film thickness.•Superconducting performance of Nb films directly linked to their crystallographic properties, i.e. lattice parameter and crystallite size.•HiPIMS duty cycle does not appear to influence the superconducting performance of Nb thin films.Source Type:Article2 - Some of the metrics are blocked by yourconsent settings
Publication Access status: Metadata only , Interlayer Affected Diamond Electrochemistry(2024); ; ; ; Diamond electrochemistry is primarily influenced by quantities of sp 3 ‐carbon, surface terminations, and crystalline structure. In this work, a new dimension is introduced by investigating the effect of using substrate‐interlayers for diamond growth. Boron and nitrogen co‐doped nanocrystalline diamond (BNDD) films are grown on Si substrate without and with Ti and Ta as interlayers, named BNDD/Si, BNDD/Ti/Si, and BNDD/Ta/Ti/Si, respectively. After detailed characterization using microscopies, spectroscopies, electrochemical techniques, and density functional theory simulations, the relationship of composition, interfacial structure, charge transport, and electrochemical properties of the interface between diamond and metal is investigated. The BNDD/Ta/Ti/Si electrodes exhibit faster electron transfer processes than the other two diamond electrodes. The interlayer thus determines the intrinsic activity and reaction kinetics. The reduction in their barrier widths can be attributed to the formation of TaC, which facilitates carrier tunneling, and simultaneously increases the concentration of electrically active defects. As a case study, the BNDD/Ta/Ti/Si electrode is further employed to assemble a redox‐electrolyte‐based supercapacitor device with enhanced performance. In summary, the study not only sheds light on the intricate relationship between interlayer composition, charge transfer, and electrochemical performance but also demonstrates the potential of tailored interlayer design to unlock new capabilities in diamond‐based electrochemical devices.Source Type:Article5
