Bifunctional Core-Shell Architecture of nFe⁰@CNT Enables Efficient Biocatalytic Reduction

Typical biotic-abiotic hybrid systems utilize external energy (e.g., light or electricity) to boost biocatalytic reduction reactions. In this study, we propose a bifunctional core-shell architecture (graphitized carbon-coated nano iron, nFe⁰@CNT) to improve biocatalytic reduction performance without relying on external energy to deliver electrons into the cells. The carbon shell increased the substrate utilization rate by 87%, along with an increased pool of the intracellular electron carrier nicotinamide adenine dinucleotide (NADH). Concurrently, the nano iron core enhanced the activities of NADH dehydrogenase and functional enzymes by 66.5% and 69.3%, respectively, increasing the capacity for NADH utilization. This simultaneous enhancement of substrate utilization and enzyme activities markedly promoted bio-denitrification and biosynthesis. Life cycle assessment and economic analysis demonstrate that this strategy yields lower environmental impacts relative to conventional strategies for enhancing biocatalysis, with carbon emissions reduced by 50.0%-86.0% and costs decreased by 79.2%-89.2%. This work provides a new paradigm for enhancing biocatalytic reduction by functional materials without external energy input.