Highly flexoelectric response for uranium removal and recovery using the organic-inorganic hybrid material

Catalysis was an effective method for uranium recovery and environmental remediation. However, the weak flexoelectric response, despite being universal in dielectric materials, greatly limited its appeal for research and catalytic applications. Here, we proposed a strategy to enhance the flexoelectric response by bridging inorganic chains with metal-organic chains within the structure. The resulting hybrid material, Co[C4H4N2]V2O6, demonstrated excellent uranyl removal performance, surpassing that of state-of-the-art piezocatalysts. Co[C4H4N2]V2O6 showed flexocatalytic uranyl activity across a broad pH range and under high-salinity conditions. Under a dynamic experimental setup, Co[C4H4N2]V2O6 showed strong potential for practical flexocatalytic applications. Co[C4H4N2]V2O6 could efficiently separate uranyl in contaminated potable water, reducing the uranium concentration (~2.0 ppm) to below the drinking water standard (30 ppb). It could also lower the uranium concentration (~5.6 ppm) in mining wastewater to below the discharge limit (300 ppb). Its intrinsic anisotropic mechanical properties and cantilever-like morphology endowed high deformability, which, together with a large dielectric constant, enhanced its flexoelectric polarization. The revealed flexocatalytic mechanism confirmed that uranyl was converted into insoluble (UO2)O2·2H2O by active species generated through dynamic polarization. This work provided a promising avenue for the design of advanced flexocatalysts and offered an effective strategy for uranium recovery and environmental remediation. This study reports a highly flexoelectric organic-inorganic hybrid material for uranium removal from wastewater. The work identifies key factors governing flexocatalytic capacity and offers insights for uranium recovery and environmental remediation.