In this work, we reported a series of monolithic 3D-printed Ni–Mo alloy electrodes for highly efficient water splitting at high current density (1500 mA cm⁻²) with excellent stability, which provides a solution to scale up Ni–Mo catalysts for HER to industry use. All possible Ni–Mo metal/alloy phases were achieved by tuning the atomic composition and heat treatment procedure, and they were investigated through both experiment and simulation, and the optimal NiMo phase shows the best performance. Density functional theory (DFT) calculations elucidate that the NiMo phase has the lowest H₂O dissociation energy, which further explains the exceptional performance of NiMo. In addition, the microporosity was modulated via controlled thermal treatment, indicating that the 1100 ℃ sintered sample has the best catalytic performance, which is attributed to the high electrochemically active surface area (ECSA). Finally, the four different macrostructures were achieved by 3D printing, and they further improved the catalytic performance. The gyroid structure exhibits the best catalytic performance of driving 500 mA cm⁻² at a low overpotential of 228 mV and 1500 mA cm⁻² at 325 mV, as it maximizes the efficient bubble removal from the electrode surface, which offers the great potential for high current density water splitting.

Sensors are crucial in the understanding of machines working under high temperatures and high-pressure conditions. Current devices utilize polymeric materials as electrical insulators which pose a challenge in the device's lifespan. Ceramics, on the other hand, is robust and able to withstand high temperature and pressure. For such applications, a co-fired ceramic device which can provide both electrical conductivity and insulation is beneficial and acts as a superior candidate for sensor devices. In this paper, we propose a novel fabrication technique of complex multi-ceramics structures via 3D printing. This fabrication methodology increases both the geometrical complexity and the device's shape precision. Structural ceramics (alumina) was employed as the electrical insulator whilst providing mechanical rigidity while a functional ceramic (alumina-doped zinc oxide) was employed as the electrically conductive material. The addition of sintering additives, tailoring the printing pastes' solid loadings and heat treatment profile resolves multi-materials printing challenges such as shrinkage disparity and densification matching. Through high-temperature co-firing of ceramics (HTCC) technology, dense high quality functional multi-ceramics structures are achieved. The proposed fabrication methodology paves the way for multi-ceramics sensors to be utilized in high temperature and pressure systems in the near future.

The increasing energy requirements to power the modern world has driven active research into more advanced electrochemical energy storage devices (EESD) with both high energy densities and power densities. Wide range of newly discovered materials with promising electrochemical properties has shown great potential for next-generation devices, but their performance is normally associated with contradicting demands of thin electrodes and high mass loading that can be hardly achieved for practical applications. Design of three-dimensional (3D) porous electrodes can increase the mass loading while maintaining the effective charge transport even with thick electrodes, which has proven to be efficient to overcome the limitations. 3D structures have also been demonstrated excellent structural stability to withstand strong strains and stresses generated during charge/discharge cycle. 3D printing, which can fabricate various delicate and complex structural designs, thus offering brand-new opportunities for the rational design and facile construction of next-generation EESDs. The recent developments in 3D printing of next-generation EESDs with high performance are reviewed. Advanced/multiscale electrode structures, such as hierarchically porous structure that can be constructed via high-resolution 3D printing or with post-treatment, are further emphasized. The ability of current 3D printing techniques to fulfill multimaterial printing to fulfill simple packaging will be covered.

Magnetic single-domain islands based on in-plane anisotropy (usually, shape anisotropy) and their dipole-dipole interactions have been investigated extensively in recent years. This has been driven by potential applications in magnetic recording, spintronics, magneto-biology, etc. Here, we propose a concept of outof-plane magnetic clusters with configurable domain structures (multi-flux states) via dipole-dipole interactions. Their flux stages can be switched through an external magnetic field. The concept has been successfully demonstrated by patterned [Co/Pd] islands. A [Co/Pd] multilayer exhibits a large perpendicular anisotropy, a strong physical separation, and uniform intrinsic properties after being patterned into individual islands by electron beam lithography. A threeisland cluster with six stable flux states has been realized by optimizing island size, thickness, gap, anisotropy, saturation magnetization, etc. Using [Co/Pd] multilayers, we have optimized the island structure by tuning magnetic properties (saturation magnetization and perpendicular anisotropy) using Landau-Liftshitz-Gilbert (LLG) simulation/calculation. Potential applications have been proposed, including a flexi-programmable logic device with AND, OR, NAND, and NOR functionalities and a magnetic domino, which can propagate magnetic current as far as 1 μm down from the surface via vertical dipole-dipole interactions.

Magnetite Fe₃O₄ (ferrite) has attracted considerable interest for its exceptional physical properties: It is predicted to be a semimetallic ferromagnetic with a high Curie temperature, it displays a metal-insulator transition, and has potential oxide-electronics applications. Here, we fabricate a high-magnetization (> 1 Tesla) high-resistance (~0.1 Ω·cm) sub-nanostructured (grain size < 3 nm) Fe₃O₄ film via grain-size control and nano-engineering. We report a new phenomenon of spin-flipping of the valence-spin tetrahedral Fe³⁺ in the sub-nanostructured Fe₃O₄ film, which produces the high magnetization. Using soft X-ray magnetic circular dichroism and soft X-ray absorption, both at the Fe L_{3, 2^-} and O K-edges, and supported by first-principles and charge-transfer multiple calculations, we observe an anomalous enhancement of double exchange, accompanied by a suppression of the superexchange interactions because of the spin-flipping mechanism via oxygen at the grain boundaries. Our result may open avenues for developing spin-manipulated giant magnetic Fe₃O₄-based compounds via nano-grain size control.