Modulation of Si–O bonds under mild conditions has been a challenging issue in the field of material science, which is critical to manufacture high-performance silica-based optical and photonic devices. Herein, we introduce a nondestructive technique to achieve Si–O bond rearrangement, leading to plastic deformation and photoluminescence enhancement of amorphous silica nanoparticles using supercritical carbon dioxides in EtOH/H₂O solution under mild temperature. Specifically, plastic deformation is achieved by treating hollow mesoporous silica nanospheres using supercritical CO₂ at 40 ℃ under 20 MPa. Experimental and theoretical studies revealed the critical role of supercritical CO₂ in the plastic deformation process, which can be intercalated into the hollow mesoporous silica nanospheres with anisotropic stresses and induces the rearrangement of Si–O bonds and transformation of ring structures. This work suggests a novel approach to engineer high-performance nano-silica glass components for numerous optical and photonic devices under mild condition.

Two-dimensional (2D) magnetic semiconductors are crucial in spin-based information-processing technologies due to the combination of the strong 2D quantum effects, surface effects and the control of spin states. However, most experimental approaches for tuning 2D magnets achieve pure ferromagnetism at low temperature. Herein, a defect engineering strategy using supercritical CO₂ is introduced to achieve nanostructure with abundant defects for 2D MoO_3−x, and room-temperature ferromagnetism can be obtained and tuned by introduction of the Mo⁵⁺ ion depending on the change of supercritical pressure. In defective regions, the presence of the pentacoordinated [Mo⁵⁺O₅] centers can achieve ferromagnetic ordering resulting in room-temperature ferromagnetism. With increasing supercritical pressure, it is easier for the supercritical CO₂ to break the Mo–O bonds, achieving enhancement of the ferromagnetic performance with desired Curie temperature (>380 K). The magnetic responses in the MoO_3−x system provide a step closer to the expansion of spin electronics.

Organic redox compounds are attractive cathode materials in aqueous zinc-ion batteries owing to their low cost, environmental friendliness, multiple-electron-transfer reactions, and resource sustainability. However, the realized energy density is constrained by the limited capacity and low voltage. Herein, copper-tetracyanoquinodimethane (CuTCNQ), an organic charge–transfer complex is evaluated as a zinc-ion battery cathode owing to the good electron acceptation ability in the cyano groups that improves the voltage output. Through electrochemical activation, electrolyte optimization, and adoption of graphene-based separator, CuTCNQ-based aqueous zinc-ion batteries deliver much improved rate performance and cycling stability with anti-self-discharge properties. The structural evolution of CuTCNQ during discharge/charge are investigated by ex situ Fourier transform infra-red (FT-IR) spectra, ex situ X-ray photoelectron spectroscopy (XPS), and in situ ultraviolet visible spectroscopy (UV–vis), revealing reversible redox reactions in both cuprous cations (Cu⁺) and organic anions (TCNQ^x-1), thus delivering a high voltage output of 1.0 V and excellent discharge capacity of 158 mAh g⁻¹. The remarkable electrochemical performance in Zn//CuTCNQ is ascribed to the strong inductive effect of cyano groups in CuTCNQ that elevated the voltage output and the graphene-modified separator that inhibited CuTCNQ dissolution and shuttle effect in aqueous electrolytes.

Simultaneously adjusting the surface, crystallographic and electronic structures of nanomaterials provide a new avenue for rational design of advanced photocatalyst yet it is challenging. In this work, a surface and structural engineering strategy is developed to simultaneously realize the 2D amorphous structure and oxygen (O)-doping in graphitic carbon nitride (g–C₃N₄) via the assistance of supercritical carbon dioxide (SC CO₂). The 2D O-doped amorphous g–C₃N₄ nanosheets display greatly enhanced photocatalytic CO₂ reduction and methylene blue degradation performances. The synthesis method as well as the mechanism of the enhanced photocatalytic activity was investigated, wherein the introduction of 2D amorphous structure and O dopant in the g–C₃N₄ contributes to the increased surface area, abundant active sites, wider visible-light absorption range and efficient charge separation property, and thus the outstanding photocatalytic activities can be obtained. Its photocatalytic CH₄ evolution rate and MB degradation rete are 5.1 and 7.0 times enhancement over bulk crystalline g–C₃N₄, respectively. This work presents a great promising way for designing and developing advanced photocatalysts.