Xinyuan Zhang

Electrostatic capacitors are foundational components of advanced electronics and high-power electrical systems owing to their ultrafast charging-discharging capability. Ferroelectric materials offer high maximum polarization, but high remnant polarization has hindered their effective deployment in energy storage applications. Previous methodologies have encountered problems because of the deteriorated crystallinity of the ferroelectric materials. We introduce an approach to control the relaxation time using two-dimensional (2D) materials while minimizing energy loss by using 2D/3D/2D heterostructures and preserving the crystallinity of ferroelectric 3D materials. Using this approach, we were able to achieve an energy density of 191.7 joules per cubic centimeter with an efficiency greater than 90%. This precise control over relaxation time holds promise for a wide array of applications and has the potential to accelerate the development of highly efficient energy storage systems.

Integration of functional thin films onto flexible substrates is driven by the need to improve the performance and durability of flexible electronic devices. A van der Waals epitaxy technology that accomplishes the transfer of oxide or metal thin films via exfoliation or dissolution of sacrificial α‐MoO 3 layers produced by sputtering is presented. The α‐MoO 3 thin films, consisting of weakly bonded 2D layers, grow epitaxially on SrTiO 3 (001) substrates, exhibiting mosaic domains rotated by 90°. Metallic Au films grown on the α‐MoO 3 are transferred by mechanical exfoliation or by dissolving the α‐MoO 3 in water at 45 °C. Spinel‐structured CoFe 2 O 4 thin films grown on α‐MoO 3 layers are easily transferred to flexible substrates via mechanical exfoliation, and the magnetic anisotropy of the transferred CoFe 2 O 4 films is modulated by bending.