The synthesis of multimodal hierarchically porous materials is of great challenge by facile approach. Herein, we assemble BPO₄ hollow spheres into macroscopic foam materials with multimodal hierarchically porous structure by combining down-to-up process and Ostwald ripening effect. Tailored monolithic B₂O₃@BPO₄ foams were obtained from a sticky hydrogel precursor by a one-step annealing process. The foam has the self-supporting frame of BPO₄ hollow spheres with covering B₂O₃ nanowires and shows excellent permeability and relatively high surface area due to hierarchical structure. The formation mechanism of monolithic B₂O₃@BPO₄ foams mainly undergoes inflation, particle aggregation, and Ostwald ripening process. Monolithic foams exhibit superior catalytic activity in oxidation dehydrogenation of alkanes due to the sufficient exposure of active sites over the special frame structure. Furthermore, various monolithic functionalized BPO₄ foam composites can be easily synthesized and exhibit superior performance in different applications including the oxidation of carbon monoxide, and the self-driven removal of organic pollutants. More interestingly, we also found the sticky hydrogel precursor possesses good heat shielding effect. This work provides a new insight for constructing multimodal hierarchically porous materials with the remaining superior property of nanoscale to cope with various challenges.

Second near-infrared (NIR-II) fluorescence imaging is a recently emerged technique and is highly useful for accurate diagnosis of cancer. Although a diverse array of fluorescent nanomaterials have been developed to enable NIR-II fluorescence in various situations, they normally fail to unify the clinical techniques, such as computed tomography (CT) and magnetic resonance imaging (MRI). Therefore, exploiting multimodal agents to integrate the newly emerged NIR-II fluorescence and traditional clinical techniques would be of key significance. Here, we report a rational fabrication of neodymium (Nd)-doped gadolinium tungstate nanoparticles (NPs) that are subsequentially decorated with a hydrophilic layer and demonstrate that they can achieve the harmonious integration of NIR-II fluorescence imaging, CT, and MRI. The NIR-II fluorescence emission was activated by an incident light with discrete wavelength ranging from 250 to 810 nm. NIR-II fluorescence-CT-MRI associated trimodal imaging was subsequently demonstrated for breast cancer by an 808 nm laser, along with the estimation of NIR-II fluorescence imaging for cervical cancer. The integration of newly emerged and traditional clinical imaging techniques highlights the huge potential of rare-earth-doped NPs for multimodal imaging of different types of cancer.