Boosting biodiesel production over silicon heterojunction with visible light irradiation

[Display omitted] •Visible light irradiated enhanced photocatalytic biodiesel production was evaluated.•A visible light irradiated biodiesel yield of 96% was attained after 3.5 h of reaction.•Light-molecule interactions at plasmonic-metal/support heterojunctions were performed.•The photocatalytic transesterification mechanism of Si/MgO heterojunction was proposed. Renewable energy sources offer greater reliability and resilience compared to traditional sources. Biodiesel, derived from renewable resources that absorb carbon dioxide during growth and production, boasts a significantly lower carbon footprint than petroleum-based diesel fuel. Heterojunction photocatalysts have emerged as a promising solution for environmental challenges. This study focused on efficient biodiesel production using visible light-irradiated Si/MgO heterojunctions. The XPS analysis confirmed the crucial role of surface functionality in achieving high photocatalytic efficiency. Transesterification occurs through SiH and SiOH bond formation on the catalyst. Finite-difference time-domain (FDTD) predicts the structure–activity relationship, showing stronger plasmonic nearfields in Si/MgO due to distinct dielectric constants. The Si/MgO photocatalyst exhibited superior photocatalytic activity under visible light, consistent with FDTD results. Biodiesel production was attained to 96% yield using 2 wt% catalysts, a 12:1 M ratio of methanol to Jatropha curcas oil, and a 3.5 hrs reaction time. Therefore, the work provided valuable insights into the mechanism of efficient plasmonic photocatalysis, paving the way for future advancements in novel high-performance photocatalysts.