Carbon-based sensors are poised to facilitate a seamless human-machine interface
image: (a) Electrochemical fiber-optic bubble monitoring system. (b) The structural illustration of fiber optic sensor. (c) Illustration of evanescent field generation and bubble monitoring mechanism based on fiber optic sensor.
Credit: Nano Research, Tsinghua University Press
“Electrochemical reactions play a pivotal role in sustainable energy and chemical manufacturing processes, such as water electrolysis and the chlor-alkali industry,” said the lead researcher of the study. “Among these, gas-evolving reactions like the hydrogen evolution reaction (HER) are particularly affected by the formation, growth, and detachment of gas bubbles at the electrode interface. These bubbles can significantly impact the effective reaction area, mass transport, and local resistance, leading to considerable energy loss.”
Current approaches to improve catalytic performance often involve bubble management strategies, including surface patterning, 3D structural design, and chemical modification of catalyst surfaces. However, these methods are typically guided by empirical optimization and lack a quantitative understanding of bubble behavior. This gap highlights the urgent need for advanced monitoring technologies that can reveal detailed bubble dynamics in real time.
Traditional methods—such as optical microscopy, high-speed imaging, and electrochemical impedance techniques—have been employed to study bubble dynamics. While optical approaches like SPR microscopy and TIRF microscopy offer high spatial resolution, and high-speed imaging provides excellent temporal resolution, these methods typically depend on extensive image acquisition and post-processing, limiting their utility for real-time quantification. Electrochemical techniques, though capable of monitoring dynamic behavior, often face challenges such as low sampling rates and signal overlap at high current densities. These limitations highlight the urgent need for in situ sensing technologies capable of accurately capturing bubble parameters in real time during electrochemical reactions.”
“Fiber optic sensors are uniquely suited for this challenge, offering high sensitivity, excellent spatial resolution, and robust performance even in harsh environments,” said the corresponding author. “These sensors have already proven effective in lithium-ion batteries, enabling real-time monitoring of internal temperature and pressure.”
“Building on these advantages, the research team developed an in-situ fiber optic sensing platform tailored to the HER process. Unlike traditional imaging-based methods, this platform enables direct, real-time monitoring of bubble behavior with minimal interference. Using linear regression analysis, the team successfully established a quantitative correlation between spectral signals and bubble dynamics. Key parameters—including bubble growth rate, detachment rate, intake/output (I/O) ratio, and detaching size—were defined to evaluate bubble behavior with high precision.
To validate the approach, two catalytic systems composed of Pt/C-loaded carbon papers with differing catalytic activities were analyzed. The spectral signatures and resulting bubble parameters clearly reflected the performance differences between the two materials.”
“Our work demonstrates a new paradigm for real-time bubble monitoring during electrochemical reactions,” the lead researcher added. “This method not only supports catalyst screening and performance evaluation, but also provides a data-rich foundation for rational design of next-generation catalytic systems.” said Kehan Yu.
Other contributors include Xian Wei, Jiaqi Li, Wenhao Liang, Chen Ma, Tianfan Zhou, Qi Zhang, Longlu Wang and Wei Wei from the Nanjing University of Posts and Telecommunications.
This work is supported by the following: National Natural Science Foundation of China (No. 62405141, 22479079); Natural Science Research Start-up Foundation of Recruiting Talents of Nanjing University of Posts and Telecommunications (No. NY222178).
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 7,000 articles. In 2024 InCites Journal Citation Reports, its 2024 IF is 9.0 (8.7, 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.