Research on contact-electro-catalytic technology and its applications: Current status, development and challenges

<p indent="0mm">Contact-electro-catalysis (CEC), by utilizing the electron transfer generated by contact electrification (CE) at solid-liquid or liquid-liquid interfaces, has been developed as a novel catalytic technology to drive redox reactions for various applications. The CEC can be stimulated by an external mechanical energy source on the organic or inorganic solid materials, regardless of whether it has chemical or catalytic inertness, including the pristine polymers, semiconductors, highly hydrophobic ceramics, and so on. Thus CEC technology offers a greater scope for the development of novel environmental friendly catalysts and innovates the exploration of broader application areas, which will spearhead a multitude of cutting-edge catalytic fields. However, despite the substantial potential of CEC technology, its development and investigation remain in the nascent stage. The reaction mechanism and potential applications still require further exploration. A comprehensive summary on the definition, performance, mechanism, development and challenges is thus needed to promote the rapid development of CEC technology. In this review, the working mechanism of CEC technology is firstly introduced, including its implementation process, initiation methods, influencing factors and distinctions from friction catalysis. In detail, the realization of CEC technology is contingent upon the electronic exchange induced by external mechanical stimuli. These typical initiation strategies, like ultrasound or ball milling, can facilitate the introduction of effective contact-separation cycles at the target interface, thereby creating conditions conducive to electronic exchange. However, the efficacy of CEC during this process is influenced by a number of factors, including the CE performance of medium materials, contact separation cycle process, temperature fluctuations, ionic strength, and interface electric fields. Moreover, the distinctions between CEC and friction catalysis are elucidated by comparing material types and reaction mechanisms. Then, a comprehensive overview of the research progress in CEC technology is provided, covering its applications in various areas such as the removal of organic synthetic dyes, degradation of antibiotics and perfluoroalkyl substances, recycling of spent lithium-ion batteries, reduction of precious metals, resource utilization of methane, and direct synthesis of hydrogen peroxide. Furthermore, potential strategies for enhancing CEC efficiency are proposed, including the design of novel catalysts, modification of existing catalysts in terms of morphology and structure, and the coupling and synergy of various reaction conditions. Therein, the development of materials with robust CE properties and the optimization of initiation methods are emphasized as the crucial pathways, such as the combination of typical initiation strategies, catalytic methods, and support of external conditions. Finally, this study provides an overview of the development, challenges as well as the promising avenues for CEC technology. Future research can concentrate on the design and recovery of high CE performance catalytic materials, the exploration of catalytic method combinations, an in-depth investigation and expansion of catalytic mechanisms and the broadening of application fields. In summary, CEC technology paves a new path for catalysis, offering a broader range of material candidate and enhancing the catalytic performance of various processes, which holds significant promise in the fields of environmental remediation, resource utilization and pharmaceutical chemistry. By summarizing the existing research and exploring the characteristics and advantages in CEC technology, this paper provides an in-depth analysis and discussion of various aspects of CEC technology, aiming to advance its application and development. Overall, the paper is aspired to offer valuable insights and guidance for the further advancement of CEC technology in the areas of carbon neutrality, new energy, water resources, pharmaceuticals, and chemicals, ultimately contributing to greener and more sustainable scientific and technological innovation.