Inorganic chalcohalides are attracting a tremendous amount of attention because of their remarkable structural variety and desirable physical properties. Although great advances have been made in recent years, functional inorganic chalcohalides with two-dimensional neutral layers are still rare. Herein, two novel chalcohalides CdSnSX 2 (X = Cl or Br) with high yields were obtained by reacting CdX 2 with SnS using a traditional solid-state method at 823 K. Both of these chalcohalides adopt orthorhombic space group Cmcm (No. 63) with the following structural values: a = 4.014(4)−4.064(2) Å, b = 12.996(2)−13.746(3) Å, c = 9.471(2)−9.621(2) Å, V = 494.1(8)−537.5(2) Å 3 , and Z = 4. The prominent architectural feature is the unique two-dimensional [CdSnSX 2 ] neutral layer consisting of composite [CdX 2 ] and [SnS] sublattices that are connected alternately through the Cd−S−Sn bonds along the ac plane. The [CdX 2 ] sublattice consists of a single octahedral chain of Cd-centered [CdX 4S 2 ] groups sharing cis-X edges, while the [SnS] sublattice consists of a bend-shaped chain of unusual [SnS 2 X 2 ] units sharing vertices of S atoms. Significantly, each CdSnSX 2 form (X = Cl or Br) shows high visible-light-induced photocatalytic activity for rhodamine B degradation, which is ∼7.0 times higher than that of nitrogen-doped TiO 2 (TiO 2−x N x ) under the same experimental conditions. This discovery enriches the categories of inorganic chalcohalides and provides more choices of candidate materials for photocatalytic applications.

Diamond-like (DL) chalcophosphates, which possess the merits of impressive second-harmonic-generation (SHG) responses, strong laser-induced damage thresholds, and low melting points, are highly desirable for IR nonlinear-optical (NLO) applications. Herein, a new quaternary DL chalcophosphate, Cu 5 Zn 0.5 P 2 S 8 , is successfully discovered, taking known Cu 3 PS 4 as the template via a single-site aliovalent-substitution strategy. It crystallizes in the orthorhombic system with noncentrosymmetric space group Pmn2 1 , and the 3D DL structure is built by corner-shared [(Cu/Zn)S 4 ], [CuS 4 ], and [PS 4 ] tetrahedra. Compared with its parent Cu 3 PS 4 , Cu 5 Zn 0.5 P 2 S 8 exhibits a good phase-matching capability and a sharply enhanced SHG effect (10Cu 3 PS 4 ) benefiting from partial Zn substitution. Moreover, the structure−performance relationships have been illustrated by means of theoretical investigations. Such an aliovalent-substitution strategy based on known DL semiconductors might be widely applied for the discovery of high-performance IR NLO crystals.