Entropy‐Engineered HEO/Fe, N‐CNT Bioanode via Flash Joule Heating: Accelerated Electron Harvesting and Directed Geobacter Enrichment for High‐Power Microbial Fuel Cells

Why It Matters

The breakthrough lifts a key performance bottleneck in microbial fuel cells, enabling higher power output and more efficient bioelectrochemical conversion for sustainable energy and sensing applications.

Key Takeaways

• Flash Joule heating creates entropy-stabilized HEO bioanode.
• Power density reaches 3.76 W m⁻², record level.
• Electron tunneling distance reduced to 2.47 Å.
• Geobacter dominates biofilm at 71% abundance.
• Dual direct and mediated EET pathways enhanced.

Pulse Analysis

Microbial fuel cells (MFCs) have long been hampered by sluggish extracellular electron transfer (EET) at the microbe‑anode interface. Conventional carbon‑based electrodes provide limited conductivity and weak biochemical interactions, restricting current generation. By leveraging flash Joule heating, researchers can rapidly synthesize high‑entropy oxides (HEOs) that uniformly coat Fe‑ and N‑doped carbon nanotubes, marrying the metallic conductivity of CNTs with the pseudocapacitive behavior of multicomponent oxides. This entropy‑engineered architecture expands the electronic density of states, creating broader conduction bands that facilitate faster electron hopping.

The resulting HEO/Fe,N‑CNT bioanode achieves a peak power density of 3.76 W m⁻², surpassing the best reported HEO anodes by nearly 10 percent. Density‑functional theory calculations reveal that the entropy‑induced band broadening and a more favorable cytochrome adsorption energy (ΔEads = ‑3.20 eV) shrink the electron tunneling gap to just 2.47 Å, dramatically accelerating charge transfer. Simultaneously, the surface chemistry promotes riboflavin secretion and selects for Geobacter species, which comprise 71 % of the biofilm, thereby reinforcing both direct and mediated EET mechanisms.

Beyond the immediate performance gains, this work demonstrates that entropy modulation can serve as a universal design principle for next‑generation bioelectrochemical systems. The scalable flash Joule heating process is compatible with roll‑to‑roll manufacturing, opening pathways for commercial MFC modules in wastewater treatment, remote power generation, and environmental monitoring. Future research will likely explore other high‑entropy compositions, hybrid nanostructures, and integration with smart sensing platforms to fully exploit the synergistic benefits of materials entropy and microbial metabolism.