From Waste to Fertilizer: Doctoral Researcher at TUM Pioneers Green Catalysts for Energy-Efficient Urea Production

Yixiao places a sample in the microscope. The samples were mounted onto aluminum stubs with conductive carbon tape to ensure proper grounding and stability. The mounted specimens are then transferred under vacuum conditions from the load lock chamber (shown in the image) to the main chamber of the scanning electron microscope (SEM) to prevent contamination and maintain imaging conditions.

(IN BRIEF) At the Technical University of Munich, doctoral researcher Yixiao Zhang is pioneering the development of nanoscale catalysts that transform pollutants in wastewater into valuable materials such as urea, the world’s most widely used solid fertilizer. Her research seeks to make chemical production more energy-efficient through electrochemical synthesis, offering a sustainable alternative to traditional industrial processes. By fine-tuning copper-based catalysts, Zhang aims to enhance urea selectivity while reducing waste and emissions. Alongside her scientific work, she co-created “Escape from Carbonia,” an award-winning science outreach project that gamifies renewable energy research. Her work reflects both the innovative spirit and societal engagement central to TUM’s sustainability mission.

(PRESS RELEASE) MUNICH, 31-Oct-2025 — /EuropaWire/ — At the Technical University of Munich (TUM) School of Natural Sciences, doctoral researcher Yixiao Zhang is working on transforming pollutants into useful resources. Her research focuses on designing nanoparticle catalysts that can convert harmful substances found in wastewater into valuable products such as urea, a vital component in fertilizers.

Originally from China, Yixiao began her academic journey in Germany in 2013, later studying chemistry in the Netherlands and completing a Master’s in Chemical Biotechnology at TUM Campus Straubing. Since April 2024, she has been pursuing her PhD in the Physics of Energy Conversion and Storage research group led by Prof. Dr. Aliaksandr Bandarenka.

Her work addresses a pressing challenge: developing energy-efficient chemical processes that both protect the environment and recover valuable compounds. Traditional urea production through the Bosch–Meiser process is energy-intensive and contributes significantly to carbon emissions. Yixiao is exploring electrochemical synthesis as a cleaner, electricity-driven alternative that operates at lower temperatures and pressures.

Yixiao with Silke Mayerl-Kink and Caroline Zörlein (from left to right) from the Cluster of Excellence “e-conversion”, in action during the escape room game “Escape from Carbonia”.

However, this approach presents scientific challenges — chiefly, how to ensure that the process produces primarily urea rather than unwanted by-products. Zhang’s research aims to solve this by engineering highly selective, copper-based bimetallic catalysts at the nanoscale. “My goal is to establish design principles for catalysts that not only enhance urea selectivity but also enable sustainable nitrogen utilization through upcycling,” she explains. By stabilizing specific reaction intermediates, her catalysts could make it possible to efficiently remove nitrates from wastewater while generating useful compounds, achieving both pollution control and resource recovery.

In the long term, such innovations could play a critical role in sustainable agriculture and environmental protection, contributing to reduced energy use, lower emissions, and circular resource management.

Beyond her research, Yixiao is dedicated to making science engaging and accessible. Together with colleagues from TUM’s Cluster of Excellence e-conversion, she co-developed the interactive escape-room experience “Escape from Carbonia”, a game that introduces the public to renewable energy research in a fun and interactive way. The project won the 2025 University Competition organized by Wissenschaft im Dialog and has been showcased at venues such as the Deutsches Museum and Kunstareal München.

Through her scientific and outreach work, Yixiao Zhang embodies a new generation of researchers combining innovation, sustainability, and creativity to advance the transition to a cleaner future.