Cellobiose and glucose photorefining over non-noble Bi0-modified TiO2 with oxygen vacancies: unraveling the effects of lignocellulosic derivatives and oxidation mechanism

Abstract

Solar-driven biomass refining holds sustainable potential for producing value-added chemicals under mild conditions. However, the efficiency of current advanced biomass photorefining systems is often hampered by their reliance on precious metal-based cocatalysts and harsh reaction conditions (e.g., alkaline conditions or organic solvents). To address these limitations, we report an in situ constructed non-noble Bi⁰-modified TiO₂ catalyst with abundant oxygen vacancies (OVs) for the efficient photorefining of cellobiose and glucose under mild, neutral conditions. The significantly improved performance stems from the Bi⁰/OV synergy, which enhances visible-light absorption, facilitates charge separation, and promotes the generation of superoxide radicals (˙O₂⁻). We identified that ˙O₂⁻ acts as the driving force for the oxidation pathway and proposed the corresponding ˙O₂⁻-mediated oxidation mechanism. Crucially, we systematically elucidate the effects of inherent derivatives in authentic lignocellulosic hydrolysates (e.g., sugars, phenols, furans, lignin derivatives, and metal ions) on the photorefining of glucose to arabinose, clarifying their roles from a molecular-level perspective. This work not only demonstrates the viability of Bi⁰/V_O-TiO₂ for solar-driven biomass valorization but also establishes a theoretical foundation for designing interference-resistant photorefining processes. It thereby provides new perspectives for enhancing the value of biomass resources under mild, environmentally friendly conditions.