α- and β-Ag 4 P 2 S 7 : Two Semiconductors with Promising Photocatalytic Hydrogen Production Based on a Density Functional Theory Study.

Herein, a new chiral compound with short Ag-Ag distances, namely, β-Ag 4 P 2 S 7 ( P 3 1 21), has been discovered by a solid-state method. Density functional theory (DFT) calculations show that both α and β phases exhibit suitable band gaps, low reduction potentials, and large visible-light absorption coefficients, as well as excellent band edges for carrier separation, suggesting their promising application in photocatalytic hydrogen production.