Tetrapod-shaped Ag 3 PO 4 microcrystals with an increased percentage of exposed {110} facets have been successfully prepared for the first time, and a possible growth mechanism is proposed. The as-prepared Ag 3 PO 4 tetrapods exhibit excellent photocatalytic activities under visible light illumination, which may be ascribed to the relatively higher reactivity of {110} facets.Semiconducting crystals with desirable morphologies and tailored facets have been intensively pursued and well developed in the past decades for their shapes and facet-dependent properties. [1][2][3][4][5][6] As a class of anisotropically shaped micro-or nanocrystals in threedimension, tetrapods exhibit a variety of interesting mechanical, electrical, and optical properties, having potential advantages in photovoltaic devices, photocatalysts, multiterminal sensing and DNA transfection. [7][8][9][10] Group II-VI materials with each atom tetrahedrally coordinated by ones of the opposite species are easy to form a tetrapodal architecture, such as ZnO, ZnS, CdS, CdSe and CdTe tetrapods. [11][12][13][14][15][16] Meanwhile, semiconducting nano-or microcrystals with exposed high-reactivity facets usually exhibit enhanced performance in facet-dependent properties, such as photocatalytic activities, gas sensing and magnetic properties. 17-21 Therefore, the architecture which integrates three-dimensional tetrapodal structure and high-reactivity exposed facets should be favourable to improve the related properties.Ag 3 PO 4 , as a novel visible light photocatalyst with an indirect bandgap of 2.36 eV, has attracted wide attention recently. 22 It has an extremely high quantum yield of about 80% at wavelengths less than y480 nm for O 2 evolution, and exhibits excellent photodegradation performance toward organic dyes. 23,24 However, the synthesis of regular Ag 3 PO 4 nanostructures and the studies of morphology and facet-dependent properties have rarely been reported. 24,25 Herein, we report the successful preparation of tetrapod-shaped Ag 3 PO 4 microcrystals with an increased percentage of exposed {110} facets for the first time, and propose a possible growth mechanism. Moreover, the studies of their photocatalytic properties showed that the as-prepared Ag 3 PO 4 tetrapods exhibited enhanced activities toward the photodegradation of methyl orange (MO) dye, which may be attributed to the high reactivity of {110} facets.The tetrapod-shaped Ag 3 PO 4 microcrystals were synthesized through a facile precipitation route directly from a reaction of silver-amino ([Ag(NH 3 ) 2 ] + ) complex and Na 2 HPO 4 in aqueous solution without surfactant. The as-prepared sample was characterized by scanning electron microscopy (SEM), and it can be seen that the products are composed of three-dimensional tetrapodal Ag 3 PO 4 microcrystals, whose arms are hexagonal prisms stretching out in four {111} directions. The four hexagonalprism arms are 2-3 mm in length and about 800 nm in side length. The structure of tetrapodal Ag 3 PO 4 is clearly seen from different viewing angles...