Ru-based catalyst drives electrified lignin upgrading into high-value fuels
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Researchers have developed an electricity-driven catalytic system that converts lignin, an abundant plant-based aromatic polymer, into valuable phenolic chemicals and fuel-related molecules with high efficiency. By combining a Ru@Bi/N-C catalyst with a HPW-HFIP electrolyte, the system directs active hydrogen toward useful reactions while suppressing hydrogen gas formation, offering a greener route for upgrading biomass into sustainable chemicals and aviation-fuel precursors.
view moreCredit: Chinese Journal of Catalysis
Lignin is one of the most abundant renewable aromatic resources on Earth. As a major component of plant biomass, it contains rich benzene-ring structures that could be transformed into high-value chemicals and fuel molecules. However, lignin is also highly complex and difficult to break down efficiently because its structural units are connected by strong C-O and C-C bonds.
Electrocatalytic hydrogenation offers a promising way to upgrade lignin under mild conditions using electricity instead of high-pressure hydrogen gas. This approach is attractive because it can be coupled with renewable electricity and provides precise control over the reaction process. However, a major challenge remains: during electrochemical reactions, active hydrogen species are often consumed by the competing hydrogen evolution reaction, producing H2 gas rather than participating in lignin conversion. This lowers energy efficiency and limits product formation.
Recently, a research team led by Prof. Junming Xu from the Institute of Chemical Industry of Forest Products, Chinese Academy of Forestry, China developed an interface-engineered Ru@Bi/N-C catalyst coupled with a multifunctional HPW-HFIP electrolyte system for efficient electrocatalytic hydrogenation upgrading of lignin. The study reveals that the Bi-Ru interfacial structure and neighboring N-defect sites can precisely regulate active hydrogen migration, suppress the competing hydrogen evolution reaction, and promote selective cleavage of lignin linkages. This catalyst-electrolyte synergistic strategy enables highly efficient conversion of lignin model compounds into valuable aromatic monomers and fuel-related chemicals, providing a promising route for sustainable biomass valorization. The results were published in Chinese Journal of Catalysis (DOI:10.1016/S1872-2067(26)65005-X).
In this system, the Bi-Ru interface suppresses excessive hydrogen gas formation on Ru sites, while promoting the migration of active hydrogen toward nearby nitrogen-defect sites. These neighboring sites provide suitable adsorption strength for lignin model compounds, allowing them to undergo efficient bond cleavage and rapid product desorption. In simple terms, the catalyst helps active hydrogen choose the “right pathway”: reacting with lignin molecules rather than forming hydrogen gas.
The electrolyte also plays a crucial role. Phosphotungstic acid, abbreviated as HPW, acts as an electron and proton mediator. It can reversibly accept and release electrons, helping generate active hydrogen species on the suspended catalyst surface. Meanwhile, HFIP, a highly polar additive, promotes the activation of hydroxyl groups in lignin-derived molecules and lowers the energy barrier for C-O bond cleavage. Together, the HPW-HFIP electrolyte creates a favorable reaction microenvironment for efficient biomass upgrading.
Using 2-phenoxy-1-phenylethanol as a representative lignin model compound, the Ru@Bi/N-C catalyst achieved a conversion of 93.64% and a Faradaic efficiency of 91.92%. The reaction produced several valuable aromatic monomers, including phenol and phenylethanol derivatives. Further mechanistic studies using electrochemical measurements, in-situ Raman spectroscopy, hydrogen temperature-programmed desorption, and theoretical calculations confirmed that the high performance originates from the synergistic regulation of hydrogen migration, substrate adsorption, and electrolyte-assisted activation.
About the Journal
Chinese Journal of Catalysis is co-sponsored by Dalian Institute of Chemical Physics, Chinese Academy of Sciences and Chinese Chemical Society, and it is currently published by Elsevier group. This monthly journal publishes in English timely contributions of original and rigorously reviewed manuscripts covering all areas of catalysis. The journal publishes Reviews, Accounts, Communications, Articles, Highlights, Perspectives, and Viewpoints of highly scientific values that help understanding and defining of new concepts in both fundamental issues and practical applications of catalysis. Chinese Journal of Catalysis ranks among the top one journals in Applied Chemistry with a current SCI impact factor of 17.7. The Editors-in-Chief are Profs. Can Li and Tao Zhang.
At Elsevier http://www.journals.elsevier.com/chinese-journal-of-catalysis
Manuscript submission https://mc03.manuscriptcentral.com/cjcatal
Journal
Chinese Journal of Catalysis
Article Title
Highly efficient electrocatalytic reductive cleavage of lignin model compounds over Ru@Bi/N-C: Interfacial and defect effects
Toward battery-free artificial photosynthesis: Stable fuel production at lower cost
Redesigned electrolyzer generated enough power to run a diorama at Osaka Expo
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The artificial photosynthesis system produces formic acid from carbon dioxide and water. The right image shows the group’s unique electrolyzer.
view moreCredit: Osaka Metropolitan University
Researchers at Osaka Metropolitan University have developed an artificial photosynthesis system capable of producing solar fuels more stably by integrating a self-regulating chemical component directly into the electrolyzer itself. The new device doesn’t rely on a battery-powered control method, removing an expensive component of such systems.
Similar to its natural version, artificial photosynthesis uses sunlight to convert water and carbon dioxide into useful fuels such as formic acid.
In artificial photosynthesis systems, the electrolyzer plays a central role by converting electricity generated by solar cells into chemical energy that can be stored as fuel in the form of formic acid.
To keep this energy conversion operating efficiently under changeable sunlight conditions, many systems use Maximum Power Point Tracking (MPPT), a control method that continuously adjusts the voltage and current to maximize the power output of the solar cells. However, MPPT systems typically rely on batteries or additional electronics to stabilize energy flow, increasing both the cost and complexity of the overall system.
A research group led by Associate Professor Yasuo Matsubara and Professor Yutaka Amao at the Research Center for Artificial Photosynthesis, Osaka Metropolitan University, in collaboration with Iida Group Holdings Co., Ltd, redesigned the system to incorporate a special solid electrolyte into the electrolyzer. In their new system, the electrolyzer itself performs the MPPT function automatically, eliminating the need for batteries.
Instead of using external electronics, batteries, and converters to keep the solar cell operating efficiently, the electrolyzer autonomously adjusts its own electrical behavior through its thermal and impedance properties.
“As sunlight increases, the electrolyzer naturally heats up. The system is designed so that this warming causes the electrical resistance to drop, allowing electricity to flow more freely,” Professor Amao explained. “This makes the system automatically adjust its electrical behavior.”
“This self-regulating behavior helps keep fuel production more stable throughout the day and automates the system, while reducing dependence on batteries and costly external components,” he added.
When the team tested a device incorporating the technology, it stably produced formic acid from water and CO2 under real sunlight conditions, even when light intensity fluctuated.
“We were confident that it would be successful, as we previously showcased this research at the ‘Joint Pavilion Iida Group × Osaka Metropolitan University’ exhibition as part of the Osaka Kansai Expo 2025,” Professor Matsubara said. “It successfully generated enough formic acid to power a miniature diorama in the pavilion, showing its potential as an efficient artificial photosynthesis system that could potentially be used to charge applications in our homes.”
The study was published in EES Solar.
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About OMU
Established in Osaka as one of the largest public universities in Japan, Osaka Metropolitan University is committed to shaping the future of society through “Convergence of Knowledge” and the promotion of world-class research. For more research news, visit https://www.omu.ac.jp/en/ and follow us on social media: X, Instagram, LinkedIn.
Journal
EES Solar
Method of Research
Experimental study
Subject of Research
Not applicable
Article Title
Chemical Maximum-Power-Point Tracking System for Stabilized Liquid Solar-Fuel Production
Article Publication Date
20-Mar-2026
COI Statement
The authors have a Japan patent application (2024-124743) on the chemical MPPT system. H. K. and Y. K. are employees of Iida Group Holdings Co., Ltd.
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