MSE Webinar – Dr. Xun Guan (2 April 2025)

Advanced material interfaces play a crucial role in addressing challenges at the intersection of energy, chemistry, and the environment. This talk will explore two key research directions: material-microbe interfaces for chemical transformations and electrochemical systems for CO₂ capture.
The first part of the talk will focus on the unique material-microbe interfaces that drive various chemical reactions. Interfacing artificial materials with microbial biomachinery offers a promising approach for conducting highly efficient chemical reactions. However, it remains unclear where all electrons provided by materials will be transferred through the material-microbe interface for chemical production and whether the catalytic interface will beneficially affect the microbial metabolism. We present a microbe-semiconductor hybrid system for CO₂ and N₂ fixation, achieving internal quantum efficiencies approaching biochemical limits. Photophysical studies reveal fast and efficient charge transfer at material-microbe interfaces, while omics analyses uncover metabolic adaptations that enable more efficient energy-to-chemical conversion. Additionally, an electricity-driven material-microbe hybrid system is demonstrated for defluorination, exhibiting chemical reactivities beyond purely material-based or biological systems. Mechanistic investigations highlight the potential of material-microbe interfaces to enable new chemical reactions and modulate microbial behavior for enhanced system performance.
The second part of the talk will introduce a purely electrochemical approach to CO₂ capture via seawater alkalization. Increasing seawater alkalinity offers a viable and scalable strategy for direct air capture. However, traditional seawater alkalization processes, such as the chlor-alkali method, require a large cell voltage due to the distinct chemical reactions occurring at the cathode and anode. This work demonstrates a symmetric reaction couple—hydrogen evolution and hydrogen oxidation—for seawater alkalization. Experimental results show base production with an energy consumption of just 0.63 kWh/kg NaOH, only 38% of the energy required by conventional chlor-alkali processes.
This talk highlights the potential of material-microbe interfaces and electrochemical technologies in advancing sustainable chemical processes and addressing pressing environmental and energy challenges.