Freestanding oxide thin films represent a revolutionary platform for next-generation high-performance electronics, offering unparalleled electrical, optical, and mechanical properties. However, realizing their full potential hinges on overcoming key challenges in scalable fabrication, controlled release, and damage-free integration—particularly when interfacing with delicate two-dimensional (2D) materials or nanoarchitected devices. This review highlights cutting-edge strategies to address these barriers, with a central focus on van der Waals (vdW) integration as a transformative paradigm. Established fabrication techniques-including mechanical exfoliation, chemical vapor synthesis, remote epitaxy, and sacrificial layer-based wet-etching are critically analyzed, while persistent limitations are dissected such as strain control, interface stability, crystalline integrity, and thickness precision. The significant advantages offered by vdW integration are underscored, particularly in reducing carrier scattering, enhancing device performance, and enabling novel functionalities. Successful applications in transistors, memristors, and flexible devices are presented, demonstrating the transformative potential of freestanding oxides. Finally, future pathways are outlined for optimizing fabrication processes and developing scalable manufacturing techniques. These advancements are crucial for unlocking broader applications in disruptive technologies, ultimately positioning freestanding oxides integrated with 2D materials as pivotal hybrid material platform for future electronics.

Two-dimensional (2D) metal oxide α-MoO₃ shows great potentials because of its very high dielectric constant, air stability and anisotropic phonon polaritons. However, a method to produce ultrathin single crystalline α-MoO₃ with high transferability for functional device architecture is lacking. Herein, we report on the controllable synthesis of ultrathin α-MoO₃ single crystals via chemical vapor deposition (CVD) assisted by plasma pretreatment. We also carried out systematic computational work to explicate the mechanism for the slantly-oriented growth of thin nanosheets on plasma-pretreated substrate. The method possesses certain universality to synthesize other ultrathin oxide materials, such as Bi₂O₃ and Sb₂O₃ nanosheets. As-grown α-MoO₃ presents a high dielectric constant (≈40), ultrathin thickness (≈3 nm) and high transferability. Memristors with α-MoO₃ as the functional layers show excellent performance featuring high on/off ratio of approximately 10⁴, much lower set voltage around 0.5 V, and highly repetitive voltage sweep endurance. The power consumption of MoO₃ memristors is significantly reduced, resulted from reduced thickness of the MoO₃ nanosheets. Single crystal ultrathin α-MoO₃ shows great potentials in post-Moore memristor and the synthesis of CVD assisted by plasma pretreatment approach points to a new route for materials growth.