Urchin-like LaPO4 hollow spheres were successfully synthesized by a facile
solution route using citric acid (CA) as a structure-directing agent. The size
of the three-dimensional (3D) hollow spheres was tuned by changing the
concentration of CA. The formation mechanism of the 3D LaPO4 hollow spheres
was revealed by studying the time-dependent morphology evolution process.
Importantly, compared with monodispersed one-dimensional (1D) LaPO4 nanorods,
the 3D LaPO4 hollow spheres self-assembled from nanorods showed a 6.8-fold
enhancement in photocatalytic activity for CO2 reduction, which is attributed to
the synergistic effect of their hierarchical hollow structure, higher light-harvesting
capacity, and faster electron transfer. Our findings provide not only a simple,
facile method for the synthesis of hierarchical hollow micro/nanoarchitectures
but also an efficient route for enhancing the photocatalytic performance.