Efficient synthesis of ultra-long, high-yield Ag nanowires via supersaturation modulation for transparent conductors
image: Thermodynamic analysis reveals that penta-twinned Ag seeds, enclosed with 10 (111) facets, form preferentially in low-supersaturation solution due to their low facet energy and low chemical potential for bulk structure. This requirement can be satisfied by adding appropriate 2D materials (e.g., g-C3N4), which significantly suppresses random nucleation and allows the in-situ formation of high-purity seeds for growing high-quality Ag NWs.
Credit: Nano research, Tsinghua University Press
The rapid development of flexible electronics, smart displays, and photovoltaic technologies has created an urgent need for high-performance flexible transparent conductors (TCs). Thin films of indium tin oxide (ITO), the traditional TCs, have long dominated the market due to their balanced optical and electrical properties. However, their inherent limitations, including brittleness, limited indium resources, and high fabrication costs, have increasingly hindered their application in flexible electronics. Thanks to their excellent conductivity, high transparency, and superior flexibility, thin films of silver nanowires (Ag NWs) have emerged as the most promising candidate to replace ITO TCs. However, the current synthesis methods mainly rely on empirical trial-and-error approaches, lacking a universal theoretical framework to guide the synthesis of high-quality Ag NWs, particularly ultra-long nanowires with uniform morphology and high yield.
To address these challenges, the cooperated research team, at Hunan University and Xiamen University, China, proposed a supersaturation modulation strategy for the synthesis of Ag NWs, and published the research findings titled "Efficient synthesis of ultra-long, high-yield Ag nanowires via supersaturation modulation for transparent conductors (DOI: 10.26599/NR.2025.94908275)" in the internationally renowned journal Nano Research. This breakthrough paves the way for a new theory-driven phase in the large-scale synthesis of high-quality Ag NWs.
"The in-situ formation of high-purity penta-twinned Ag seeds enclosed by 10 (111) facets, the precursors of Ag NWs, is the key to synthesize high-quality Ag NWs," explained Prof. Zhaoxiong Xie, one of the authors. “According to the energy conservation during the crystallization process, the variation of Gibbs free energy (dG) can be expressed by dG = mldnl + mcdnc + sdS = 0 in an ideal adiabatic system, where μl and μc are respectively the chemical potentials of crystal growth units and bulk crystal, n is the number of moles of the corresponding species that transform from crystal growth units to crystallites (dnl is negative value and dnc is positive value), S is the specific surface area of crystallites, s is the specific surface energy of crystallites. As a result, by modulating the chemical potential of crystal growth units (μl) of the crystallization system, it is possible to tune bulk structure (related to μc) and surface structure (related to s) of the nuclei. A lower chemical potential of crystal growth units (i.e. a lower ml) during nucleation process would result in nuclei with a lower mc and/or crystal facets with lower surface energies. Evidently, modulation of critical nucleation supersaturation (Dμ = μl - μc) will tune nuclei with different bulk structure and/or surface structure.”
The research team found that this requirement can be readily met by adding a series of two-dimensional materials, such as g-C₃N₄, MoS2, WS2, Ti3C2Tx, and GO, into the reaction system along with the agents, which allows in-situ formation of high-purity penta-twinned Ag seeds with low chemical potential via heterogeneous nucleation, for the growth of Ag NWs. The optimal Ag NWs exhibit an average length exceeding 227 μm, an aspect ratio (length/diameter) over 2200, and a yield of 93 %, significantly outperforming conventional Ag NWs synthesized via traditional methods. Owing to their ultra-long nature of the synthesized Ag NWs, the Ag NW TCs demonstrate remarkable flexibility. After 1,400 bending cycles with a radius of 5 mm, its relative sheet resistance (R/R0) only increases by 1.2 times, signaling a critical advantage for flexible electronic applications. Meanwhile, the Ag NW TCs achieves a low sheet resistance of ~5 Ω/sq and a high optical transmittance of 87% at 550 nm, surpassing commercial ITO films. Furthermore, the transparent heaters fabricated from the Ag NWs, achieve a rapid heating rate of 10.5 °C/s and a maximum temperature of approximately 118 °C at a low voltage of merely 5 V, along with excellent heating cycle performance.
"The prominent advantage of this research lies in the utilization of thermodynamic theory to guide the synthesis of high-quality Ag NWs. This significantly improves the synthesis efficiency, the quality of the Ag NWs, and their yield, making Ag NWs more competitive as TCs in terms of performance and cost-effectiveness," noted Prof. Jiawen Hu, one of the corresponding authors.
Looking ahead, the research team plans to further extend the supersaturation modulation strategy to enable large-scale synthesis of Ag NWs. Concurrently, they aim to collaborate with industry partners to develop Ag NW-based TCs for practical applications. "Our ultimate goal is to provide a reliable alternative to ITO, thereby driving the commercialization of low-cost, next-generation flexible TCs," Prof. Jiawen Hu concluded.
Other contributors include Pu Chen, Yuan Feng, Jiang Zhong, Dong Li, Huan Cheng, Shijie Zhou, Jing Tang, and Xidong Duan from the College of Chemistry and Chemical Engineering, Hunan University, China.
This research was financially supported by the Natural Science Foundation of Changsha of Hunan Province, China (Grant No. kq2402055) and the National Natural Science Foundation of China (Grant No. 21872047).
DOI Link:
https://doi.org/10.26599/NR.2025.94908275
About Nano Research
Nano Research is a peer-reviewed, open access, international and interdisciplinary research journal, sponsored by Tsinghua University and the Chinese Chemical Society, published by Tsinghua University Press on the platform SciOpen. It publishes original high-quality research and significant review articles on all aspects of nanoscience and nanotechnology, ranging from basic aspects of the science of nanoscale materials to practical applications of such materials. After 18 years of development, it has become one of the most influential academic journals in the nano field. Nano Research has published more than 1,000 papers every year from 2022, with its cumulative count surpassing 8,000 articles. In 2025 InCites Journal Citation Reports, its 2025 IF is 9.4 (8.3, 5 years), and it continues to be the Q1 area among the four subject classifications. Nano Research Award, established by Nano Research together with TUP and Springer Nature in 2013, and Nano Research Young Innovators (NR45) Awards, established by Nano Research in 2018, have become international academic awards with global influence.