Sub-Nano Gaδ+ clusters confined by porous carbon spheres and coupled with SnS2 for efficient photocatalytic extraction of uranium

Extracting uranium from uranium waste streams, particularly utilizing zero-carbon emission photochemistry, emerges as a promising and sustainable strategy. Herein, we construct an SS@Ga/PCS composite photocatalyst, consisting of SnS₂ nanosheets as well as a metal − support produced by confining sub-nano Ga^δ+ clusters in the hollow porous carbon spheres (PCS). The Ga^δ+ clusters are innovatively introduced as active sites with localized hole capability to simultaneously improve visible light response and carrier separation. In-situ characterizations and theoretical calculations reveal that Ga^δ+ clusters induced metal-support interaction (MSI) by optimizing the electronic structure in the PCS host; In addition, Ga^δ+ clusters act as plasma excitation elements to enhance the visible light responsiveness and carrier separation of SS@Ga/PCS. Ultimately, the inhomogeneous photocatalysis of uranium extraction achieved superior performance as compared to the pure components, corresponding to an encouraging removal rate of 97.87 % and a photo-extraction capacity of up to 1867.30 mg g⁻¹ in 50 mL of uranium waste solution, as well as a wide-concentration window adaptability and excellent catalytic robustness. More significantly, this ingenious nano-confined strategy extends the design ideas of highly dispersed sub-nanometallic cluster co-catalysts and stimulates the study of the availability of abundant reactive active sites combined with monomer strong interactions, which provides a novel insight into the mechanism of photocatalytic uranium extraction.