Liang Shi and Yumei Dai, University of Science and Technology of China, Hefei, have found a simple one-step way to selectively prepare germanium sulfide nanosheets and nanowires that are more active than their bulk counterparts. This methode could open the way to lower cost and safer optoelectronics, solar energy conversion, and faster computer circuitry.

The nanomaterials were synthesized from an germanium dichloride-dioxane complex, thiourea, and oleylamine (OLA) using simple “wet” chemistry. GeS nanosheets and nanowires can be selectively fabricated by simply modifying the reaction temperature and heating duration, respectively. Nanosheets formed if the process was carried out for several hours at 593 K. At 613 K, the sheets wind up into nanowires. The team suggests that the rolling up of the nanosheets into nanowires is driven by the surface tension between the sheet and the OLA molecules during the heating.

The structure, morphology, composition and optical absorption properties of the as-prepared samples were characterized using X-ray powder diffraction, transmission electron microscopy, energy-dispersive X-ray spectrometry and scanning electron microscopy.
According to the team, “outstanding photoresponsive behaviour indicates the potential use of as-synthesized GeS nanosheets and nanowires in solar energy conversion systems, such as the fabrication of photovoltaic devices”.

• Synthesis, formation mechanism and photoelectric properties of GeS nanosheets and nanowires,
  Liang Shi, Yumei Dai,
  J. Appl. Cryst. 2014, 47, 527–531.
  DOI: 10.1107/S1600576713034535