Article Highlight | 28-Dec-2025

Engineering bipolar doping in a Janus dual‑atom catalyst for photo‑enhanced rechargeable Zn‑Air battery

Shanghai Jiao Tong University Journal Center

Engineering Bipolar Doping in a Janus Dual‑Atom Catalyst for Photo‑Enhanced Rechargeable Zn‑Air Battery

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  • Janus dual-atom catalyst (JDAC) with bifunctional centers was synthesized via a single-step bipolar doping strategy to promote efficient charge separation and superior electrocatalytic performance.
  • The in situ X-ray absorption near-edge structure and Raman spectroscopy analyses demonstrated that Ni and Fe centers in JDAC function as effective sites for oxygen evolution reaction and oxygen reduction reaction, and effectively suppress photoelectron recombination while enhancing photocurrent generation.
  • The assembled JDAC-based light-assisted rechargeable zinc–air batteries exhibited extraordinary stability at large current densities (300 cycles at 50 mA cm−2, and 6000 cycles at 10 mA cm−2 under light illumination).
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Credit: Ning Liu, Yinwu Li, Wencai Liu, Zhanhao Liang, Bin Liao, Fang Yang, Ming Zhao, Bo Yan, Xuchun Gui, Hong Bin Yang, Dingshan Yu*, Zhiping Zeng*, Guowei Yang.

While rechargeable zinc-air batteries (RZABs) promise >1 kWh kg-1 at low cost, their air cathodes still struggle with sluggish oxygen redox kinetics and poor photon harvesting. Now researchers at Sun Yat-sen University—Prof. Zhiping Zeng and Prof. Dingshan Yu—report a one-step “bipolar-doped” Janus dual-atom catalyst (JDAC) that couples Ni-N4 and Fe-N4 sites on a narrow-band-gap C4N matrix. The material simultaneously splits water and sunlight, cutting charge voltage by 620 mV and extending cycle life to 6 000 cycles at 10 mA cm-2 under visible light.

Why Janus Dual-Atom Catalysis Matters
• Photo-Electro Synergy: Ni centers harvest holes for OER, Fe centers collect electrons for ORR, slashing recombination and raising photocurrent by 3×.
• Bipolar Doping: Coexisting n- and p-type domains widen the space-charge region, boosting carrier density 2.5-fold and shrinking charge-transfer resistance to 8.6 Ω.
• High-Current Stability: Light-assisted RZABs operate at 50 mA cm-2 for 300 cycles and 20 mA cm-2 for 1 600 cycles—an order-of-magnitude jump over prior photo-cathodes.

Innovative Design and Features
• Material System: Single-step hydrothermal co-assembly of hexaketocyclohexane, biphenylteramine, Fe/Ni acetates on carbon paper; 1.92 eV band-gap, atomically dispersed M-N4 verified by HAADF-STEM and XANES.
• Mechanistic Insight: In-situ Raman/XANES show Ni-OOH forms first at 1.3 V for OER while Fe-O₂H emerges at 0.85 V for ORR; DFT confirms 0.74 eV down-shift of Fe d-band center weakens *OH binding, lowering overpotentials to 170 mV (OER) and 350 mV (ORR).
• Device Architecture: Integrated directly as a freestanding air cathode—no binder, no conductive additive—yielding 267 mV photo-induced discharge gain and 0.53 V round-trip voltage gap at 1 mA cm-2.

Applications and Future Outlook
• Solar-Driven Storage: 2 × 2 cm2 pouch cells deliver 220 mW cm-2 peak power under 1 sun and maintain 80 % capacity after 500 deep cycles at 5 mA cm-2.
• Scalability: Precursor cost <$0.50 g-1, hydrothermal throughput >10 g L-1; roll-to-roll coating trials underway for 100 Wh module prototypes.
• Challenges & Next Steps: Long-term UV stability and rare-earth-free analogues (Cu/Co, Mn/Cr) are being explored; the team is also transferring the JDAC concept to photo-enhanced metal-sulfur and metal-N₂ batteries.

This work provides a universal blueprint for merging photocatalysis and electrocatalysis at the atomic limit, turning everyday sunlight into an extra voltage bonus for next-generation metal-air chemistries. Stay tuned for more light-harvesting battery breakthroughs from Prof. Zeng and Prof. Yu at Sun Yat-sen University!

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