Controllable synthesis of silver cyanamide as a new semiconductor photocatalyst under visible-light irradiation

Semiconductor photocatalysis has attracted great interest as a promising strategy to achieve sustainable energy generation and realize environmental remediation. High-efficiency and visible-light-driven semiconductor photocatalysts have been pursued during the past decades to overcome the drawbacks of the widely-studied TiO2 photocatalyst. Here, we report a new n-type silver cyanamide (Ag2NCN) semiconductor with a direct band gap of about 2.30 eV, which can utilize visible-light for water photooxidation and organic contaminant decomposition. In order to investigate the optical, photocatalytic and photoelectrochemical properties, various aqueous solution methods are developed to synthesize Ag2NCN nanoparticles (<100 nm), microparticles (up to 20 mu m) and nanograined (20 nm) thin films. It is found that the as-prepared nanoparticles exhibit unique absorption and photoluminescence properties. Nano/microparticles show high photocatalytic performance for organic dye degradation, indicating that Ag2NCN is an efficient visible-light-driven photocatalyst. Additionally, nanograined thin films can be assembled into a photoelectrochemical cell for water photooxidation and photocurrent generation. These findings have provided the first evidence that transition metal cyanamides may be promising functional materials for solar energy utilization.