Critical factors for carbon fixation efficiency in semiconductor-biohybrid systems: insights from a meta-analysis

Semiconductor biohybrid systems are emerging as promising strategies for enhanced carbon dioxide fixation and synthesis of organic compounds, with the potential to transcend biological limitations. However, the effects of experimental variables on the efficiency of CO₂ fixation in these systems have not been systematically explored, which has hindered insights into the general patterns in this field of research. In this study, we pioneered a comprehensive meta-analysis of 300 observations from 28 studies and used machine learning models to assess the effects of key experimental variables (e.g., microbial and material type, reaction temperature and duration, and light intensity) on CO₂ fixation efficiencies and related outcomes (organic compound yields, electron transfer efficiencies, and quantum yields). The results showed that the inorganic semiconductor and bacterial systems outperformed in terms of CO₂ fixation and organic compound yields, while the results emphasized that temperature, light intensity, and reaction time are the main experimental variables determining the CO₂ fixation efficiency. Notably, this study is the first to apply the XGBoost algorithm to predict optimal CO₂ fixation conditions (t = 96.9 h, L = 445.6 W/m² and T = 28.3 ℃). This study paves the way for a rational design of experiments aimed at maximizing CO₂ fixation and organic matter production in semiconductor biohybrid systems.