1. Could you explain the significance of your article to the non-specialist? 

Zinc sulfide (ZnS) is a semiconductor that finds applications in many fields, e.g. it is used for fluorescent displays. In our work, we made a new ZnS material that is ultrafine (~ 5 nm) and different in structure from the traditional ZnS materials currently employed in industry. Unlike the traditional ZnS materials that exist either in sphalerite or wurtzite structures, the new material is a blend of the two. Due to its novel optoelectronic properties, this material can find applications in many new fields such as nanodevices, e.g. solar cells and sensors based on nanomaterials.

2. What has motivated you to conduct this work? 

We have been studying nanoparticles of significance to both the environment and technology for many years. Nano-ZnS is one of the systems with relevance in both areas. Detailed structural information for ZnS nanoparticles is fundamental to both the technical applications and the understanding of the natural material. In the nature, nanoparticulate ZnS can be produced by sulfur reducing bacteria in anaerobic systems containing traces of zinc ions. The ZnS sulfide formed as a byproduct of microbial sulphate reduction are nanoparticles that sometime show complex mixed stacking characteristics. In technology, ZnS is an optoelectronic semiconductor that finds applications in many fields. Manipulation of the stacking order may provide a route to improve the performance of ZnS devices/materials. For this purpose, we tried to control the ZnS product by systematically changing the synthesis conditions.

3. Where do you see this work developing in the future? 

We foresee that this novel material will find new applications in many fields. A detailed and comprehensive investigation of its electronic and structural properties is the first step toward such applications. The second step is then to design and develop nanodevices using the novel material, based on the knowledge obtained from the first step.

4. Are there any particular challenges facing future research in this area?

Nanoparticles often aggregate, bind with organic molecules, and/or adsorb water and/or inorganic ions in order to lower the free energy. This is especially true for small nanoparticles, e.g. 3-5 nm nanoparticles such as those produced in our work. If it is not possible to prevent such interactions, particle-particle and particle-adsorbate interactions may lead to structural changes over time, thus decline in device performance. It is challenging to derive electronic information from nanoparticles because the measurements include the contributions from both the nanoparticles and the surface environment. It may be possible to address this problem through extensive computational study and modelling of the experimental data.