Band modulation and photoelectric synergy promote oxygen reduction: Interface design and performance improvement mechanism of Ce-HHTP@MgIn2S4 ohmic junction

Microbial fuel cells (MFCs) is a sustainable system that simultaneously achieves wastewater treatment and energy recovery by coupling the metabolism of electroactive microorganisms at the anode with oxygen reduction at the cathode. However, their overall energy conversion efficiency is constrained by the inherently sluggish oxygen reduction reaction (ORR) at the cathode. It is hypothesized that an ohmic-contact heterojunction can reduce charge-transfer resistance and regulate the d-band center, thereby accelerating electron transport and enhancing ORR kinetics. In this study, the Ce-HHTP@MgIn 2 S 4 photo-electrocatalyst with a distinct ohmic-contact heterojunction was successfully synthesized via electrostatic self-assembly and characterized using density functional theory (DFT) calculations, along with in-situ XPS and EPR analyses. Under visible-light irradiation in a dual-chamber MFCs, the catalyst achieved an output voltage of 403 mV, a peak power density of 304.01 mW m −2 , a chemical oxygen demand (COD) removal rate of 95.98 %, and a coulombic efficiency of 16.58 %, all surpassing Pt/C benchmarks. This study provides valuable insights into interface engineering and photoelectronic synergy modulation for efficient MFCs cathode catalysts, offering a scalable approach for wastewater treatment and renewable energy recovery. • A Ce-HHTP@MgIn 2 S 4 ohmic junction was constructed. • Higher COD removal and CE are achieved by Ce-HHTP@MgIn 2 S 4 over Pt/C in real sewage. • Synergistic light–electric coupling in Ce-HHTP@MgIn 2 S 4 boosts MFC power to 304.01 mW m −2 . • Charge transfer mechanism in Ce-HHTP@MgIn 2 S 4 was verified by in-situ XPS.