Controllable synthesis of porous silver cyanamide nanocrystals with tunable morphologies for selective photocatalytic CO2 reduction into CH4

Abstract

The conversion of CO2 driven by solar energy into carbon-containing fuel has huge potential applications. However, most photocatalysts can only promote the two-electron reduction process to generate CO, and it is difficult to produce eight-electron CH4, which is more valuable and can store more solar energy. Herein, we prepared porous silver cyanamide nanocrystals with tunable morphologies via a facile synthesis strategy. Compared with ball/rectangular plate (RAP) and ball/leaf-like plate (SAP), the ball/porous leaf-like plate (LAP) can provide more internal reaction microenvironment, which is not only conducive to the transport of photoinduced charge carriers, but also can expand the active sites for photocatalytic CO2 reduction. Moreover, the suitable band gap of LAP sample can capture more visible light to provide more photoinduced electron-hole pairs to participate in the reduction reaction. Consequently, the LAP sample can convert CO2 to CH4 with remarkable activity and high selectivity (nearly 100%) without cocatalyst and photosensitizer under visible light irradiation. This work provides a promising way to design new photocatalysts for various applications in solar energy conversion.