Developing a Light-Regulated Localized Thermo SSF System with Ti3O5/PDA Heterostructures to Enhance Cellulosic Ethanol Production

Abstract The promotion of cellulosic ethanol is highly significant for enhancing energy security, mitigating environmental challenges, and advancing sustainable development, with simultaneous saccharification and fermentation (SSF) being the most widely used method for its commercialization. However, the disparity between the optimal operating temperatures of yeast cells (∼35 °C) and cellulase (∼48 °C) poses a major constraint on the efficiency of SSF processes. To address this challenge, this study presents a strategy for constructing SSF systems based on photocontrolled localized thermal effects. Heterostructured Ti3O5 nanospheres were surface-coated with polydopamine (PDA) to enhance photothermal performance, followed by grafting azobenzene-containing polymer brushes as a thermal energy reservoir to immobilize cellulase. By precisely modulating the microenvironmental temperature around the enzymes, this approach enables both cellulase and yeasts to operate near their respective optimal temperatures in the SSF reactor. Experimental results demonstrate that the ethanol yield achieved using the developed system is 23% higher than that obtained under conventional compromise temperature conditions. This method offers a promising and practical pathway to improve the production efficiency of cellulosic ethanol, with considerable potential for industrial application.