Valence control unlocks bifunctional copper catalyst for sustainable chemical production

In a major leap forward for electrocatalysis, researchers from Shaanxi Normal University have engineered a versatile copper-based catalyst capable of tackling two pressing challenges: nitrate pollution and the valorization of glycerol, a biodiesel byproduct. Published in Nano Research on August 3, 2025, their study introduces a unified catalyst platform that leverages valence state engineering of copper oxide nanorods to achieve remarkable efficiency in both cathodic nitrate reduction and anodic glycerol oxidation.

Nitrate contamination in water poses a significant environmental threat, while glycerol, abundant from biodiesel production, remains a largely untapped resource. Addressing these issues, the team, led by Dr. Xue Xiao and Prof. Yu Chen , developed copper oxide nanorods with tailored oxidation states. For nitrate reduction, partially reduced copper oxide nanorods (r-CuO NRs) delivered a faradaic efficiency of 96.8%, converting nitrate to ammonia with high precision. This performance stems from the mixed valence states of copper, which enhance electron transfer and activate nitrate bonds.

On the flip side, fully oxidized copper oxide nanorods (CuO NRs) excelled at glycerol oxidation, achieving a Faradaic efficiency of 93.3% for formate production. The oxygen-rich surface of these nanorods stabilizes reaction intermediates, boosting the oxidation process. This dual functionality allows a single catalyst platform to streamline electrochemical systems, reducing complexity and costs.

"Our approach showcases how valence state control can unlock a catalyst's potential for multiple reactions," said Dr. Xue Xiao and Prof. Yu Chen, the study's corresponding authors. "This innovation not only cleans up nitrate pollution but also turns waste glycerol into a valuable chemical, advancing sustainability on two fronts."

The team employed cutting-edge techniques like X-ray diffraction (XRD), transmission electron microscopy (TEM), and in situ Fourier-transform infrared spectroscopy (FTIR) to unravel the catalysts' structure and reaction pathways. Their findings reveal a promising reaction sequence for nitrate reduction—progressing from nitrate to ammonia via key intermediates—and confirm formate as the primary product of glycerol oxidation in alkaline conditions.

This bifunctional catalyst could revolutionize electrochemical setups by enabling simultaneous nitrate reduction and glycerol oxidation in a single system. Such integration promises environmental benefits by mitigating water pollution and economic gains by valorizing glycerol into high-value formate, a chemical used in fuel cells and industrial processes.

Potential applications include decentralized ammonia synthesis from agricultural runoff and integrated biorefineries for biodiesel co-product upgrading. The team is now optimizing scalability and investigating industrial wastewater streams.

Other contributors include Si-Ye Lv, Han-Yue Yang, and Qing-Ling Hong from the School of Materials Science and Engineering at Shaanxi Normal University in Xi'an, China.

This research was supported by National Key Research and Development Program of China (2024YFE0211200), China Postdoctoral Science Foundation (2025M770156), Shaanxi Province Postdoctoral Science Foundation (2024BSHSDZZ080), Science and Technology Innovation Team of Shaanxi Province (2023-CX-TD-27 and 2022TD-35), Fundamental Research Funds for the Central Universities (GK202506037 and GK202505036), the Technology Innovation Leading Program of Shaanxi in China, and the Technology Innovation Teams in Shaanxi Province in China.

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.