The catalytic activity and sensing performance of nanocrystals (NCs) is highly dependent on their structure and surface. In their review, Yang Shang and Lin Guo give an overview of facet-controlled synthesis strategies for Cu2O-based NCs and highlight the properties, which make them suitable for numerous applications in sensing and catalysis. The contents of the review are graphically represented on the front cover of Advanced Science Volume 2, Issue 10.
Cu2O-based crystals are interesting for structure–property relationships because they are non-toxic, abundantly available, and show promising optical and electrical properties. A morphology-dependent activity of these crystals has been reported in various applications. In photocatalysis, gas catalysis, organocatalysis, and in sensors the efficiency can be enhanced by optimizing the crystal morphology. Different facets can alter interactions between crystals and reactants, which can weaken chemical bonds, avoid charge recombination, and improve adsorption.
Facet-controlled synthesis of Cu2O-based NCs can be realized via methods such as deposition, etching, and by using sacrificial templates. 
Many of these methods use capping agents to determine surface energy and active sites. Thus, properties can be effectively tailored leading to high-performance NCs. However, the synthetic routes for these NCs still need to be simplified to become convenient.
The authors conclude that the discussed progress in highly defined NC synthesis enables detailed structure–property relationships. By combining experimental results with theoretical calculations and simulations, this will drive the ingenious design and controlled synthesis of NCs. Additionally, the results for Cu2O-based crystals can be transferred to other nanocrystals, widening the field of facet-controlled NCs for numerous applications.
Advanced Science is a new journal from the team behind Advanced Materials, Advanced Functional Materials, and Small. The journal is fully Open Access and is free to read now at www.advancedscience.com.
