The sol–gel technology is an interdisciplinary field combining materials science and chemistry. It utilizes highly active chemicals as precursors, taking part in chemical reactions and treatment such as hydrolysis, polymerization, gelation, etc.. Solid product are often achieved by specific drying, heat treatment, or other processes/conditions. As an advanced wet-chemical preparation method, sol–gel technology finds widespread applications in the fabrication of zero-dimensional to three-dimensional nanomaterials, bulk materials, thin film coatings, fiber materials, etc. Materials obtained through this method exhibit superior characteristics and properties compared to those obtained through traditional methods. Most sol–gel processes are conducted at low temperatures, resulting in lower reaction temperatures compared to traditional methods. Materials prepared using this method possess inherent advantages in terms of chemical homogeneity, doping uniformity, and product purity. Moreover, the design of the early-stage preparation process enables the synthesis of multi-component materials with multi-phase.
Over the past two decades, China has made great progress in the research and application of sol–gel technology. Scientists have developed a wide range of methods for preparing novel materials using sol–gel techniques. These materials have been applied across various domains including optics, electronics, sensing, catalysis, energy storage, pharmaceuticals, separation, and many others. These achievements typically involve the preparation of advanced materials with novel functionalities or enhanced performance using sol–gel processes. Through this overview of the latest developments in the sol–gel academic field, one can appreciate the comprehensive research and significant contributions made in China.
The development of sol–gel technology can be traced back to the mid-19th century. As the 20th century progressed, the method of using gelation to prepare solid materials began to receive increased attention from researchers. More and more scholars began to focus on sol–gel technology, proposing various methods for preparing materials in various forms. These methods have found applications in multiple domains such as electronic devices, catalysis, energy, metal corrosion protection, optics, and others. In 1981,the First International Workshop on Glasses and Glass Ceramics from Gels was held in Padova, Italy, marking the rapid development phase of sol–gel technology. Sol–gel research in China also began in the 1980s, when many research institutions started extensively to work on sol–gel technology during this period. In 1990, the inaugural "National Conference on Sol–Gel Science and Technology" was held at Zhejiang University, marking the beginning of the sol–gel era in China. Subsequently, this conference has been held every 2 to 3 years, providing a high-quality platform for academic exchange in the field of sol–gel technology in China. In 2008, the Sol–gel Committee of the Chinese Ceramic Society was established, signifying the formal establishment of a professional association for sol–gel technology in China. The Sol–gel Committee of the Chinese Ceramic Society not only actively organizes academic activities within China but strives to promote communication with the abroad academic society and to organize international conferences as well. From August 28 to September 2, 2011, the 16th International Sol–gel Conference was held in Hangzhou, China. This marked the first time that China hosted this prestigious academic conference in the sol–gel field, receiving high praise from the international sol–gel community.
In recent years, Chinese research institutions and scholars have published an avalanche of papers in the field of sol–gel. Over the past decade (2014–2023), there has been a steady increase in global publications related to the sol–gel field, with a total of 128 627 papers. Among these, articles authored by Chinese researchers accounted for 32.5% of the global output, with this proportion reaching 50% in the year 2022. This paper focuses on highlighting some research achievements in the preparation of nano-powder materials, fiber materials, and functional coatings using the sol–gel method. It also discusses the application in energy storage, catalysis, electromagnetic shielding, thermal conductivity, luminescence, and thermal insulation.
With the rapid development of sol–gel technology, the achievements of the Chinese sol–gel academic community have also propelled its industrial development. Many new materials developed through sol–gel processes have entered the industrial application stage and become part of people's daily lives. The mass production of nano oxides and ceramic powders using the sol–gel method is well developed in China. It is applied in various fields such as semiconductors, optical component polishing materials, functional coatings, reinforcement of polymer materials, and catalytic carrier materials. Sol-gel technology has also been widely applied in the production of functional coating materials, used in applications such as anti-corrosion coatings for metals, optical coatings, and more.
Summary and prospects Since the concept of sol–gel was proposed, sol–gel technology has demonstrated tremendous potential in various fields, ranging from materials science to life sciences and environmental engineering. It is evident that China has made remarkable progress in both academic and industrial application of sol–gel technology, bringing it into a new stage of vigorous development. By reviewing and summarizing the development of sol–gel technology in China, one can clearly see the remarkable achievements and groundbreaking progress made in this field. Chinese researchers have played a key role in this process, driving the continuous evolution of this technology. China's successful experiences in sol–gel technology are not only evident in scientific research but also widely applied in industrial manufacturing and sectors. Looking ahead, sol–gel technology is expected to focus on several key development directions in the future. In fundamental research, the study of sol–gel technology can focus on the functional design and construction of precursors, their combination with functionalized ionic solvents, and the construction of micro-reactive zones. In terms of industrial technology, sol–gel technology shows promising prospects in the preparation of spherical powders at different scales, deep ultraviolet treatment, non-high-temperature treatment processes such as solvent thermal treatment, as well as aerogels/hydrogels. Sol–gel technology in China holds vast potential for development. We anticipate that sol–gel technology will be widely applied in more fields, especially playing a more crucial role in addressing major issues such as energy, environment, and health. In the future, it will continue to make outstanding contributions to human well-being and technological advancement.