Bovine Hemoglobin-Derived Amyloid Fibrils Mimicking Spirogyra Chloroplasts for Photocatalytic CO2 Reduction

Abstract Efficient noble-metal-free photosynthesis systems for CO2 conversion based on earth-abundant elements have been largely unexplored. On the other hand, large quantities of bovine blood as waste byproducts during meat processing pose environmental challenges. To address these concerns, herein we report a biomimetic photocatalytic platform constructed by hemoglobin, a major component in bovine blood, which structurally and functionally emulates the fibrous chloroplasts of Spirogyra. Under denaturing conditions, hemoglobin molecules self-assemble into heme-containing amyloid-like fibrils, in which the intrinsic heme groups serve as visible-light photosensitizers. Subsequently, iron-based catalytic cores are uniformly deposited along the protein fibrils, generating a hierarchical architecture that integrates heme as a light-harvesting domain and iron cores as catalytic functionalities within a single scaffold. This spatially organized system effectively shortens electron transfer distances and promotes interfacial charge migration. Consequently, the as-prepared biomimetic assembly exhibits efficient visible-light-driven CO2 reduction to formic acid with high activity and selectivity as compared to conventional homogeneous systems. Notably, this work not only provides a noble-metal-free strategy for constructing integrated photocatalytic systems but also demonstrates a viable pathway for transforming biological waste into high-value functional materials.