Sintering protonic zirconate cells with enhanced electrolysis stability and Faradaic efficiency
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Urine electrooxidation for energy–saving hydrogen generation
Urea electrooxidation offers a cost-effective alternative to water oxidation for energy-saving hydrogen production. However, its practical application is limited by expensive urea reactants and sluggish reaction kinetics. Here, we present an efficient urine electrolysis system for hydrogen production, using cost-free urine as feedstock. Our system leverages a discovered Cl-mediated urea oxidation mechanism on Pt catalysts, where adsorbed Cl directly couple with urea to form N-chlorourea intermediates, which are then converted into N2 via intermolecular N–N coupling. This rapid mediated-oxidation process notably improves the activity and stability of urine electrolysis while avoiding Cl-induced corrosion, enabling over 200 hours of operation at reduced voltages. Accordingly, a notable reduction in the electricity consumption is achieved during urine electrolysis (4.05 kWh Nm−3) at 300 mA cm−2 in practical electrolyser for hydrogen production, outperforming the traditional urea (5.62 kWh Nm−3) and water (4.70–5.00 kWh Nm−3) electrolysis.
Distance-controlled direct ink writing of titanium alloy with enhanced shape diversity and controllable porosity
Porous titanium alloys have been extensively used for diverse engineering applications. However, current additive manufacturing (AM) strategies face significant challenges (e.g., low fabrication efficiency and limited shape diversity) in producing porous titanium alloys. This work aims to develop a distance-controlled direct ink writing (DC-DIW) approach for constructing macroscale 3D architectures from titanium alloy powders. This approach integrates a constant interlayer distance control with traditional DIW, breaking through the angle limit in current porous metal printing from 60° to 30°. Additionally, subsequent heat treatment is applied to control microstructures. To demonstrate the capabilities of this approach, three representative structures, including a bifurcated tube, an orbital implant, and a knee implant, are successfully printed and treated, achieving suitable mechanical properties and high shape fidelity. This work provides a viable and efficient AM strategy for fabricating porous titanium alloys with enhanced shape diversity and controllable porosity suitable for various engineering applications.
Fully screen printed stretchable liquid metal multilayer circuits using green solvents and scalable water-spray sintering
Stretchable circuits based on liquid metals are promising for wearables but the lack of scalable processes for sintering of printed liquid metal dispersions constitutes a challenge for large-area and high-volume manufacturing. In this work, materials and methods for fully screen printed stretchable liquid metal multilayer circuits have been developed. The ink is based on liquid metal droplets dispersed in the green solvent propylene glycol using the harmless dispersion agent polyvinylpyrrolidone. The development of a scalable water-spray sintering method in combination with ink optimization yielded highly conductive prints of ≈7.3 × 105 S/m. Interestingly, the printed conductors experienced a resistance increase of less than 10% during 50% strain cycling, which is far below the expected 125% increase due to the geometry factor. The process allows for printing of high-performance multilayer circuits, which is demonstrated by the development of printed stretchable near-field communication tags.
Laser sintering of Cu particle-free inks for high-performance printed electronics
This study investigates laser sintering of Cu particle-free ink (Cu formate tetrahydrate—amino-2-propanol complex) as an alternative to conventional sintering in an oven (under inert/reducing atmosphere). Utilizing benefits of high-speed localized heating using laser, substrate damage can be prevented for low-melting substrates such as Polyethylene Terephthalate (PET). Firstly, a suitable sintering process window is achieved based on energy density for two different flexible polymeric susbtrates: Polyimide and PET using different laser parameters (laser power, scan rate and spot diameter). Subsequently, characterization of laser sintered traces are also made using different laser optic profiles (Gaussian and top hat). Different methodologies for fabrication of metallized Cu layer were also demonstrated. A very low bulk resistivity of 3.24 µΩcm (1.87 times of bulk Cu) was achieved on trace thickness of 0.85 ± 0.15 µm exhibiting good adherence to polymeric substrates. A promising fabrication process of low-cost and reliable flexible printed electronic devices is demonstrated.
Relationship between degradation mechanism and water electrolysis efficiency of electrodeposited nickel electrodes
This work investigates the degradation or corrosion of bulk and mesoporous (MP) electrodeposited nickel electrodes in alkaline water electrolysis in the absence and presence of magnetic field. Based on the electrochemical and analytical tests and morphological evaluation, both bulk and MP electrodes show improved properties of alkaline water electrolysis in the presence of magnetic field due to the impaired formation of gas bubbles and more stable hydroxide layer formed on nickel. However, mesoporous Ni electrodes exhibited significantly less damage due to the presence of higher active sites and inherent porosity which reduce either number of size of bubbles, thereby mitigating stress and minimizing harm to the hydroxide layer. Although scaling up magnetic water electrolysis for industrial electrolyzers demands great economical and technical challenges, our approach using mesoporous nickel electrodes offers promise by reducing degradation and partially offsetting costs through improved efficiency.
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