*Article* **Silver Nanorings Fabricated by Glycerol-Based Cosolvent Polyol Method**

#### **Zhihang Li 1, Dong Guo 2, Peng Xiao 3, Junlong Chen 1, Honglong Ning 1,\*, Yiping Wang 4, Xu Zhang 1, Xiao Fu 1, Rihui Yao 1,5,\* and Junbiao Peng 1**


Received: 17 January 2020; Accepted: 22 February 2020; Published: 25 February 2020

**Abstract:** The urgen<sup>t</sup> demand for transparent flexible electrodes applied in wide bandgap devices has promoted the development of new materials. Silver nanoring (AgNR), known as a special structure of silver nanowire (AgNW), exhibits attractive potential in the field of wearable electronics. In this work, an environmentally friendly glycerol-based cosolvent polyol method was investigated. The Taguchi design was utilized to ascertain the factors that a ffect the yield and ring diameter of AgNRs. Structural characterization showed that AgNR seeds grew at a certain angle during the early nucleation period. The results indicated that the yield and ring diameter of AgNRs were significantly a ffected by the ratio of cosolvent. Besides, the ring diameter of AgNRs was also tightly related to the concentration of polyvinylpyrrolidone (PVP). The di fference of reducibility between glycerol, water, and ethylene glycol leads to the selective growth of (111) plane and is probably the main reason AgNRs are formed. As a result, AgNRs with a ring diameter range from 7.17 to 42.94 μm were synthesized, and the quantity was increased significantly under the optimal level of factors.

**Keywords:** wide bandgap semiconductors; flexible devices; silver nanoring; silver nanowire; polyol method; cosolvent
