**About the Editor**

#### **C ´eline Ternon**

Celine Ternon graduated with PhD degrees from the University of Caen in 2002. Her ´ doctoral research involved the growth, modelling and study of luminescent silica and silicon-based nanostructures. She joined the Grenoble INP Institute of Engineering, Univ. Grenoble Alpes in 2003, where she is currently associate professor, gender equality officer and head of the department Physical Engineering for Photonics and Microelectronics.

She conducts research at LMGP in France in the field of nanomaterials and nanotechnologies. Her research interest lies at the interface between material science and device application, with a particular interest for the field of biosensing. One of her main objective is to develop new processes allowing the easy manipulation and integration of the nanomaterials into devices. In 2010, she launched an original activity based on semiconducting randomly oriented nanowire networks also called nanonets. Since then, she has worked tirelessly to demonstrate the value of these extremely versatile and innovative materials. She has more than 50 peer-reviewed scientific papers and several pedagogical publications.

## *Editorial* **Silica- and Silicon-Based Nanostructures**

**Céline Ternon**

Univ. Grenoble Alpes, CNRS, Grenoble INP (Institute of Engineering Univ. Grenoble Alpes), LMGP, F-38000 Grenoble, France; celine.ternon@grenoble-inp.fr

As depicted in Figure 1, studies on silicon and silica-based nanostructures first appeared in the early 1990s, and their numbers grew until the mid-2010s. Since then, the level of scientific research has decreased for silica-based nanostructures and started to decrease for silicon-based nanostructures. An extensive literature review of silicon-based nanostructures clearly shows that the major areas affected by the decline in the number of studies are "applied physics" and "engineering electrical electronic", whereas numerous applied fields are the subject of increased interest, particularly the applications of energy.

**Citation:** Ternon, C. Silica- and Silicon-Based Nanostructures. *Nanomaterials* **2022**, *12*, 1270. https:// doi.org/10.3390/nano12081270

Received: 16 March 2022 Accepted: 25 March 2022 Published: 8 April 2022

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**Figure 1.** Number of articles published per year about silicon or silica nanostructures, based on a search using the keywords "Silicon AND Nano\*" or "Silica AND Nano\*" on the website Web of Science. The star \* at the end of nano means that all words beginning with "nano" are considered in the search (nanoparticles, nanowires . . . ).

For silicon nanostructures, such a decrease in research is a sign that structures and technologies have been mastered and that the most popular applications, such as electronic devices, have been explored. Research teams are now exploring new areas and applications for these nanostructures.

The purpose of this Special Issue is to bring together state-of-the-art innovations in the field and allow the emergence of novel ideas and concepts for silicon- and silica-based nanostructures. The three reviews in this Special Issue [1–3] offer an original view of the last 10 years of research on silicon nanostructures, especially for black silicon [1], bottom-up nanowires [2], and mesoporous silicon [3]. Most interestingly, these reviews outline the areas of interest for the future of these materials. In line with this, some studies [4–10] clearly illustrate the thematic shift of research into these materials, with a growing interest in ecoresponsive areas, such as biomass synthesis [4], environmental sensors [5], batteries [6,7] or depollution [3].

In conclusion, we hope that the readers will enjoy the works and articles collated in this Special Issue, inspiring ideas and providing information to inform further studies of these fascinating nanomaterials, as well as generating new projects and topics.

**Acknowledgments:** I would like to thank all the authors who contributed their most recent research to this Special Issue. We would like to thank all those who contributed to the success of this Special Issue for their patience, help and dedication.

**Conflicts of Interest:** The authors declare no conflict of interest.

#### **References**

