Se-induced coordination engineering in MnPX₃ for efficient piezo-photocatalytic H₂O₂ evolution and uranium recovery

The accelerating deployment of nuclear power has intensified the shortage of uranium, making it urgently necessary to recover this resource from mining wastewater. In situ generation of hydrogen peroxide (H₂O₂) via piezo-photocatalysis offers a promising pathway to alleviate the pressure on uranium supply. Herein, we introduce a Se-induced coordination engineering strategy in MnPX₃ (X = S, Se) nanosheets to boost piezo-photocatalytic H₂O₂ evolution for subsequent uranium extraction. The substitution of the larger and less electronegative Se atoms for S introduces lattice strain and distorts the local coordination geometry around the Mn and P centers. This geometric distortion serves as the primary structural effect, which directly enhances the intrinsic piezoelectric response as a secondary effect. The strengthened piezoelectric field facilitates the separation and migration of photo-generated charge carriers, while the modified local coordination concurrently converts the surface-exposed P atoms into active centers for the two-electron oxygen reduction reaction (ORR), both of which are direct consequences of the primary geometric distortion. As a result, under visible light and ultrasonic excitation, MnPSe₃ delivers a H₂O₂ yield of 1059.7 μmol·g⁻¹·h⁻¹, substantially higher than the 168.5 μmol·g⁻¹·h⁻¹ obtained for MnPS₃. The maximum uranium extraction of MnPSe₃ reaches 1450.2 mg·g⁻¹, ∼2.3 times that of MnPS₃ (630 mg·g⁻¹). Additionally, MnPSe₃ also demonstrates exceptional selectivity toward uranium and cycling stability. Our findings provide guiding principles based on Se-induced geometric distortion and its consequential piezoelectric enhancement for developing advanced piezo‑photocatalysts aimed at efficient uranium recovery.