Article Highlight | 9-Dec-2025

Porous microreactor chip for photocatalytic seawater splitting over 300 hours at atmospheric pressure

Shanghai Jiao Tong University Journal Center

Porous Microreactor Chip for Photocatalytic Seawater Splitting over 300 Hours at Atmospheric Pressure

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  • A film-type Ag3PO4/CdS photocatalyst in a porous substrate configuration is designed and prepared to avoid photocorrosion and ensure outstanding firmness.
  • Both the S and Ag vacancy-rich surface and the heterojunction within the space charge region are found to be the key for high solar-to-hydrogen efficiency and excellent stability in seawater over 300 h.
  • The first fully solar-driven hydrogen production prototype is constructed to work outdoors, exhibiting a high H2 evolution rate of 68.01 mmol h−1 m−2.
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Credit: Desheng Zhu, Zhipeng Dong, Chengmei Zhong, Junhong Zhang, Qi Chen, Ni Yin, Wencheng Jia, Xiong Zheng, Fengzai Lv*, Zhong Chen, Zhenchao Dong*, Wencai Huang*.

As green hydrogen production gains urgency, photocatalytic seawater splitting offers a sustainable path—but catalyst stability in saline conditions remains a bottleneck. Now, researchers from Xiamen University, USTC, and SINANO-CAS, led by Prof. Fengzai Lv and Prof. Zhenchao Dong, present a porous Ag3PO4/CdS microreactor chip that maintains 0.81 % solar-to-hydrogen efficiency for >300 h in natural seawater under ambient pressure and visible light, marking a 30× leap in durability over prior systems.

Why This Chip Matters

  • Catalytic Selectivity: Ag vacancies repel Cl⁻ ions; S vacancies anchor S-species and H2O, suppressing side reactions.
  • Space-Charge Engineering: 30 nm Ag3PO4/60 nm CdS heterojunction stays within the 354 nm space-charge region, enabling band-bending-tuned carrier transport without loss of redox strength.
  • Gas Separation: Layered geometry physically separates H2 and O2 evolution sites, cutting recombination.
  • Scalability: A 256 cm2 outdoor prototype delivers 68 mmol H2 h-1 m-2 under natural sunlight—no vacuum, no cooling, no forced convection.

Innovative Design & Features

  • Materials: Film-type Ag3PO4 (O2 site) and CdS (H2 site) co-deposited on porous Al2O3; 0.3 nm Pt atomic clusters decorate CdS.
  • Vacancy Control: O2 partial pressure during e-beam evaporation tunes Ag and S vacancy densities (EPR g = 2.003).
  • Structure: 1–10 µm surface pores enhance mass transfer; cross-sectional EDS confirms sharp, continuous heterointerface.
  • Characterization: KPFM visualizes 1.4 V contact-potential drop across the junction; thickness-dependent band bending verified by UPS, XPS, and EIS.

Performance & Outlook

  • Stability: 25-day cyclic test (300 h total) shows <16 % activity loss; no delamination after “double-85” test (85 °C/85 %RH).
  • Efficiency: 0.92 % peak STH (0.81 % average) in seawater; AQY 12.3 % at 420 nm; 18O-labeling confirms O2 from water oxidation.
  • Scalability: Modular 1 m2 panel projected to yield 0.54 mol H2 day-1; circular reactor designed for varied terrain.

Challenges & Next Steps

Vacancy oxidation remains the dominant decay pathway; the team is now exploring in-situ vacancy regeneration and anti-fouling coatings to push lifetime beyond 1 000 h.

This work provides a materials-by-design roadmap for saline-water splitting and demonstrates a ready-to-scale prototype that turns sunlight and seawater into fuel—no precious freshwater required.

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