ABCABC Stacking-Enabled Non-Centrosymmetry 3R-ZnIn₂S₄ Nanosheets for Piezocatalytic Uranium Extraction

Piezoelectric materials for uranium extraction have attracted increasing attention, as they offer a self-powered, light-independent strategy to harness ambient mechanical energy. However, natural mechanical energies are typically weak and low-frequency, necessitating materials with high flexibility, facile deformation, and large surface area. Herein, we demonstrate that the ABCABC stacking sequence along the c-axis in two-dimensional (2D) 3R- zinc indium sulfide (3R-ZnIn₂S₄) nanosheets induces intrinsic non-centrosymmetry, enabling robust piezocatalysis for on-site hydrogen peroxide (H₂O₂) generation and simultaneous uranium extraction. Density functional theory (DFT) calculations confirm that solvation effects enhance the lattice flexibility and intrinsic dipole moment of 3R- ZnIn₂S₄, resulting in the formation of an electron-rich surface that thermodynamically favors the two-electron oxygen reduction reaction (2e- ORR) for H₂O₂ generation. Under mild ultrasonic agitation (35 kHz, 50 W), the 3R-ZnIn₂S₄ nanosheets achieved a H₂O₂ yield of 276.7 µmol g^-1 h^-1 and a uranium extraction capacity of 763.2 mg g^-1. Mechanistic investigations elucidate that the uranium extraction process proceeds through a dual-coordination pathway, integrating direct piezoelectric reduction and in situ H₂O₂-mediated complexation of uranium species. Notably, 3R-ZnIn₂S₄ demonstrates excellent cycling stability over five cycles, high selectivity toward uranium, and effective anti-biofouling performance under ultrasonic conditions (35 kHz, 50 W). Collectively, our findings establish stacking-induced piezoelectricity as a light-independent strategy for sustainable uranium extraction to support nuclear energy development.