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<p>This study demonstrates, for the first time, the successful consolidation of a TiO<sub>2</sub>-Fe<sub>3</sub>O<sub>4</sub>-reduced graphene oxide (rGO) ternary photocatalyst into a dense, adherent coating using room-temperature aerosol deposition (AD) without requiring any post-deposition thermal treatment. While TiO<sub>2</sub>-Fe<sub>3</sub>O<sub>4</sub>-graphene composites have been widely reported in powder suspension systems, their direct consolidation into functional coatings via AD has not previously been achieved due to challenges associated with heterogeneous particle size, density mismatch, and differential impact behavior. In this work, composite powders comprising nanoscale Fe<sub>3</sub>O<sub>4</sub>, micrometer-scale TiO<sub>2</sub>, and layered rGO were synthesized and deposited without post-annealing or binders. Systematic optimization of deposition parameters (2&#xa0;Torr chamber pressure, single pass, 10&#xa0;SLM gas flow, and 4&#xa0;mm/s substrate translation speed) enabled stable impact consolidation of this multi-component system into coatings approximately 5-7&#xa0;μm thick, as confirmed by surface profilometry and cross-sectional analysis. Phase integrity was preserved after deposition, demonstrating that AD can be extended beyond single-oxide systems to complex ternary photocatalysts. Compared to aerosol-deposited pure TiO<sub>2</sub> coatings fabricated under comparable conditions, the ternary composite exhibited significantly enhanced methylene blue degradation under both UV and natural sunlight irradiation. Normalized photocatalytic efficiency per unit mass was consistently higher for the composite, reflecting synergistic interactions among TiO<sub>2</sub> (photoactive phase), Fe<sub>3</sub>O<sub>4</sub> (redox mediator and charge-transfer facilitator), and rGO (electron-transport network and visible-light sensitizer). Electrochemical impedance spectroscopy further revealed reduced charge-transfer resistance in the composite coating, directly correlating improved electrical conductivity with photocatalytic performance. These results establish aerosol deposition as a viable room-temperature route for immobilizing complex multi-component photocatalysts into dense functional coatings, overcoming limitations associated with powder-based systems. The demonstrated feasibility of ternary composite consolidation significantly broadens the application scope of AD for advanced environmental remediation coatings.</p>

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Novel Room-Temperature Aerosol-Deposited TiO2-Fe3O4-rGO Coatings with Enhanced Photocatalytic Activity for Water Purification

  • 期刊论文

  • 发表日期：

    2026年5月5日

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  • Azadeh Vahedi,
  • Thomas W. Coyle,
  • Javad Mostaghimi,
  • Zhenying Yang

摘要

This study demonstrates, for the first time, the successful consolidation of a TiO2-Fe3O4-reduced graphene oxide (rGO) ternary photocatalyst into a dense, adherent coating using room-temperature aerosol deposition (AD) without requiring any post-deposition thermal treatment. While TiO2-Fe3O4-graphene composites have been widely reported in powder suspension systems, their direct consolidation into functional coatings via AD has not previously been achieved due to challenges associated with heterogeneous particle size, density mismatch, and differential impact behavior. In this work, composite powders comprising nanoscale Fe3O4, micrometer-scale TiO2, and layered rGO were synthesized and deposited without post-annealing or binders. Systematic optimization of deposition parameters (2 Torr chamber pressure, single pass, 10 SLM gas flow, and 4 mm/s substrate translation speed) enabled stable impact consolidation of this multi-component system into coatings approximately 5-7 μm thick, as confirmed by surface profilometry and cross-sectional analysis. Phase integrity was preserved after deposition, demonstrating that AD can be extended beyond single-oxide systems to complex ternary photocatalysts. Compared to aerosol-deposited pure TiO2 coatings fabricated under comparable conditions, the ternary composite exhibited significantly enhanced methylene blue degradation under both UV and natural sunlight irradiation. Normalized photocatalytic efficiency per unit mass was consistently higher for the composite, reflecting synergistic interactions among TiO2 (photoactive phase), Fe3O4 (redox mediator and charge-transfer facilitator), and rGO (electron-transport network and visible-light sensitizer). Electrochemical impedance spectroscopy further revealed reduced charge-transfer resistance in the composite coating, directly correlating improved electrical conductivity with photocatalytic performance. These results establish aerosol deposition as a viable room-temperature route for immobilizing complex multi-component photocatalysts into dense functional coatings, overcoming limitations associated with powder-based systems. The demonstrated feasibility of ternary composite consolidation significantly broadens the application scope of AD for advanced environmental remediation coatings.