Band gap engineering of a semiconductor in a straightforward and efficient manner is highly desirable, but it remains technically challenging. Herein, we demonstrate a powerful nanoparticle occlusion strategy that enables the band gap of silver phosphate (Ag3PO4) crystals to be readily tailored. Specifically, a series of diblock copolymer nanoparticles of varying morphologies is prepared by polymerization-induced self-assembly (PISA) and subsequently used as a particulate additive during the crystallization of Ag3PO4. Remarkably, these copolymer nanoparticles can be efficiently occluded within Ag3PO4 single crystals, forming organic/inorganic nanocomposite semiconductors whose optical band gap is tunable, depending on the extent of copolymer occlusion. Furthermore, these copolymer nanoparticles can act as "Trojan horses" to incorporate Pd nanoparticles into Ag3PO4, leading to an enhanced photocatalytic degradation of tetracycline under visible-light irradiation. This study provides a brand-new strategy to regulate the band gap of semiconductors, and in principle, it could enable the rational preparation of a wide range of nanocomposite semiconductor materials with controlled properties.

Band Gap Engineering of Silver Phosphate via Efficient Occlusion of Diblock Copolymer Nanoparticles