Defect-engineered Fe-Ti anodes with oxygen-vacancy-associated spin activity promote electroactive biofilm formation and interfacial electron transfer.

Authors

Zian Wang, Kun Lu, Zhengtao Li, Yunrong Wu, Lulu Wang, Yuxin Wang, Meizhen Wang

Published in

Bioresource technology. Pages 136155. Oct 31, 2026. Epub Oct 31, 2026.

Abstract

Extracellular electron transfer (EET) across the biofilm-anode interface governs current generation and electron recovery in microbial fuel cells (MFCs). Although engineering the electronic structure of bioanodes offers a promising strategy for accelerating EET, the contribution of electrode spin states remains poorly understood. Here, oxygen-vacancy-rich, spin-polarized Fe-Ti anodes (SP-Fe-Ti) and vacancy-suppressed, spin-depressed controls (SD-Fe-Ti) were prepared and then compared to determine how their distinct electronic structures influenced electroactive biofilm development and interfacial electron transfer during 73 d of MFC operation. Our results showed that SP-Fe-Ti increased the full-period mean current density and the stable-period mean current density. The cumulative charge density of SP-Fe-Ti increased from 2780.7 ± 600.0 to 5163.2 ± 459.2 kC m^-2, 1.86 to 4.5-fold higher than that of SD-Fe-Ti. Voltammetric and impedance analyses revealed SP-Fe-Ti had a stronger turnover, non-turnover, and EPS-associated redox responses for SD-Fe-Ti, together with a lower fitted interfacial resistance. The spin-active interface of SP-Fe-Ti also promoted biofilm development, increasing the attached protein content by 3.30-fold, selectively enriching bound extracellular polymeric substances (EPS), and decreasing the membrane-compromised cell fraction from 63.29 ± 5.26 % to 26.49 ± 1.67 %. More importantly, SP-Fe-Ti-derived EPS exhibited a normal apparent kinetic isotope effect, KIE(H/D), of 2.94, whereas SD-Fe-Ti-derived EPS showed a pronounced inverse response of 0.050, indicating potentially distinct protonation- and hydrogen-bond-dependent redox environments. Collectively, these findings highlight spin‑electronic engineering as a promising avenue for tuning microbe‑electrode interactions and improving microbial bioelectrochemical energy conversion.

PMID:
42966539
Bibliographic data and abstract were imported from PubMed on 01 Nov 2026.

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