# Synergistic Coupling of Intrinsic Internal Electric Field and Macroscopic Polarization in a Photocatalytic Fuel Cell for Efficient Antibiotic Degradation

## TL;DR

This paper introduces a new photocatalytic fuel cell design that efficiently degrades antibiotics by combining internal electric fields and polarization effects.

## Contribution

The novel contribution is the engineered oxygen vacancies in a BiOBr-doped TiO2 nanotube array to enhance charge separation and antibiotic degradation.

## Key findings

- The charge separation efficiency improved fourfold compared to pure TiO2 nanotube arrays.
- The PFC achieved 78% sulfamethoxazole degradation in 180 minutes, a 1.38-fold improvement.
- Electric field-driven charge regulation was identified as critical for high-performance PFCs.

## Abstract

The concurrent challenges of environmental pollution and energy scarcity necessitate advanced sustainable technologies. Photocatalytic fuel cells (PFCs) offer a promising route by coupling pollutant degradation with energy recovery. However, the synergistic interplay between anode intrinsic properties and macroscopic polarization effects remains inadequately understood. Herein, a BiOBr-doped TiO2 nanotube array photoanode with engineered oxygen vacancies was developed to construct a synergistically enhanced PFC system. XPS, EPR, and DFT analyses confirm the formation of oxygen vacancies and favorable band bending, inducing an internal electric field that markedly promotes charge separation and interfacial reaction kinetics. As a result, the charge separation efficiency is enhanced by approximately fourfold relative to pristine TiO2 nanotube arrays. Under the combined action of the internal electric field and self-bias-induced polarization field, photogenerated electrons and holes undergo directional transport and effective utilization. The optimized PFC achieves 78% sulfamethoxazole degradation within 180 min, representing a 1.38-fold improvement. Degradation pathways and toxicity evolution were further elucidated using LC–MS and Fukui function analysis, highlighting the critical role of electric field-driven charge regulation in high-performance PFCs.