Category Chemistry/Nanotechnology

1. The selective solar absorber (SSA) developed by the researchers appears black, and thus absorptive, under sunlight (as shown on the photograph on the left). However, for thermal radiation, it behaves like a non-emissive metal mirror (reflecting the dark blue sky, as shown on the thermograph on the right), and prevents the absorbed solar energy from being radiated away and lost.
—Figure courtesy of Jyotirmoy Mandal and Yuan Yang/Columbia Engineering
2. The researchers make their SSAs using a dip-and-dry technique which is considerably simpler than common manufacturing methods for SSAs.
—Photo courtesy of Jyotirmoy Mandal and Yuan Yang/Columbia Engineering

Metal oxides are promising candidates for cheap and stable photoelectrodes for solar water splitting, producing hydrogen with sunlight. Unfortunately, metal oxides are not highly efficient in this job. A known remedy is a treatment with heat and hydrogen. An international collaboration has now discovered why this treatment works so well, paving the way to more efficient and cheap devices for solar hydrogen production. Credit: HZB

The perovskite material changes size when exposed to light. Reproduced with permission from reference 1.© 2017 WILEY‐VCH Verlag GmbH & Co.

Charge screening in ferroelectric Pb(Zr,Ti)O3 nanorods was used to control their domain pattern. The c-domain fraction markedly increased with as the rod width decreased, while the a-domain formation prevailed by metallization of their sidewall. All the observed results could be explained by the depolarizing field, arising from the imperfect charge screening. This approach could be expanded to other low-dimensional nanoscale ferroelectric systems. Credit: Tomoaki Yamada