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Open research questions in TiO2 Photocatalysis and Solar Cells

61 unresolved questions extracted from the limitations and future-work sections of 519 TiO2 Photocatalysis and Solar Cells papers in our library. Each links back to the study that raised it.

What the literature leaves open

  • Interfacial recombination losses of photogenerated electron-hole pairs. Limited visible-light absorption of TiO2 nanoparticles. Electrostatic repulsion and reduced Cr(VI) adsorption at neutral to mildly acidic conditions.

    Visible-light-driven photocatalytic reduction of Cr(VI) over EDTA–TiO2 through surface complexation and ligand-to-metal charge transfer · 2026 · DOI

  • The development of environmentally friendly synthesis routes for photocatalytic materials is a growing area of research. The scalability and cost-effectiveness of the synthesis route are crucial factors for industrial applications. The stability and durability of the developed nanoparticles under various environmental conditions need to be evaluated.

    Sustainable Fabrication of Ag2O-Doped Anatase TiO2 Nanoparticles via Green Synthesis for Enhanced Photocatalysis · 2026 · DOI

  • High water consumption and release of substantial pollutants in the dairy sector. Lack of sustainable treatment methods for cheese wastewater. Significant environmental hazards associated with cheese wastewater.

    Doped and Codoped TiO2: Synthesis, Characterization and Application on Cheese Effluents Treatment · 2026 · DOI

  • Agglomeration of TiO2 QDs due to high surface energy. Difficulty in achieving stoichiometric purity. Limited resolution of SEM and AFM images due to sample preparation methods.

    Optimized sample preparation for reliable SEM and AFM analysis: A case-study of sol-gel synthesized TiO2 quantum dots · 2026 · DOI

  • Existing treatment technologies may not be efficient or sustainable. There is a need for the development of novel treatment technologies for industrial wastewater.

    Modeling and AI optimization of visible-light-driven acid orange 25 degradation using an Ag/N/ TiO2/persulfate system · 2026 · DOI

  • The decomposition of doxycycline is a complex process. The use of photocatalysts can be limited by their stability and activity.

    Decomposition Characteristics of Doxycycline by Visible-Light-Active Tb/Mg-Doped TiO₂ Photocatalyst Prepared using Liquid-Phase Plasma Synthesis Method · 2026 · DOI

  • However, the fundamental understanding of their structural kinetics evolution remains elusive.

    Spatial Reorganization of High‐Aspect‐Ratio Mesoporous TiO <sub>2</sub> Nanowires for High‐Efficiency Photocatalyst · 2026 · DOI

  • This review critically examines the evolution of porphyrin sensitizers in dye sensitized solar cells using a loss aware framework, revealing that efficiency plateaus in metallopor- phyrin based DSSCs are predominantly structural rather than incidental. Metal coordi- nation, while beneficial for tuning optical absorption, introduces coordination induced recombination pathways, aggregation tendencies, and voltage losses that fundamen- tally constrain device performance. In contrast, metal free porphyrins offer a uniquely controllable molecular platform in which steric insulation, π-extension, anchoring geometry, and interfacial energetics can be independently optimized. Recent advances demonstrate that systematic reduction of energy losses rather than aggressive absorp- tion enhancement alone underpins the most efficient additive free porphyrin DSSCs. Notably, architectures emphasizing optimized spacer length, multi point anchoring, and controlled supramolecular organization achieve lower Eloss, higher voltage extraction, and improved operational stability, even with simpler molecular constructs. Despite Bhuse et al. Discover Chemistry (2026) 3:132 Page 29 of 36 this progress, several challenges remain. The limited near infrared absorption of cur- rent metal free porphyrins constrains photocurrent generation, underscoring the need for rational extension of Q-band absorption without reintroducing aggregation driven losses. Furthermore, long term stability under full solar irradiance and thermal stress remains insufficient for commercial deployment, necessitating deeper understanding of interfacial degradation mechanisms and the development of compatible redox mediators and solid state hole transport systems.Looking forward, future breakthroughs are likely to arise from integrated design strategies that couple loss minimized porphyrin archi- tectures with tailored electrolytes, alternative anchoring chemistries, and controlled co- sensitization schemes. Rather than pursuing complexity for marginal gains, the field is poised to benefit from simpler, modular, and energetically disciplined sensitizer designs that prioritize voltage preservation and recombination suppression. Within this para- digm, metal free porphyrins stand out not merely as alternatives to metalloporphyrins, but as a rational pathway toward scalable, stable, and high efficiency DSSCs.

    Critical review of metalloporphyrin drawbacks and additive adverse effects in porphyrin DSSCs toward high efficiency metal free porphyrin sensitizers · 2026 · DOI

  • Further studies are needed to investigate the size-dependent bioactivity of TiO2 NPs. Recommendations for TEM and DLS analyses were added for accurate size and distribution measurements.

    Sol-gel Synthesis and Characterization of Titanium Dioxide Nanoparticles at 400 <sup>o</sup>C and Their Biological Applications · 2026 · DOI

  • The size-dependent bioactivity of TiO2 NPs has been poorly documented. There is a need for a comprehensive study on the size-dependant properties and bioapplications of TiO2 NPs.

    Sol-gel Synthesis and Characterization of Titanium Dioxide Nanoparticles at 400 <sup>o</sup>C and Their Biological Applications · 2026 · DOI

  • Further investigation of the effect of electron-withdrawing units on charge separation and interfacial recombination. Development of more efficient co-sensitization strategies for DSSCs. Exploration of the potential of diphenylamine-based co-sensitizers for other photovoltaic applications.

    Molecular engineering of diphenylamine-based co-sensitizers for enhanced photovoltaic performance in DSSCs: Achieving a 33 percent improvement over N719 · 2026 · DOI

  • The development of novel sensitizers is crucial for improving the efficiency of DSSCs. Ru-based sensitizers have drawbacks, including toxicity and high cost, necessitating their modification.

    Molecular engineering of diphenylamine-based co-sensitizers for enhanced photovoltaic performance in DSSCs: Achieving a 33 percent improvement over N719 · 2026 · DOI

  • The need for innovative materials capable of accurately detecting and degrading pollutants. The lack of understanding of the synergistic relationships among gas sensing, photocatalysis, piezoelectric, and piezo-photocatalytic activities.

    Environmentally Responsive Ag/BaTiO <sub>3</sub> /TiO <sub>2</sub> Nanocomposite for Selective Gas Sensing and Advanced Piezo-Photocatalysis · 2026 · DOI

  • Further research is needed to investigate the stability and reusability of Ag-TiO2 photocatalysts. The potential for ion leaching from the Ag-TiO2 catalyst should be investigated. The development of effective photocatalysts for the degradation of persistent antiviral contaminants is an area for future research.

    Ag-TiO2 photocatalyst for the degradation of isoprinosine: influence of silver modification on solar photocatalytic activity · 2026 · DOI

  • There is a lack of understanding of the effects of silver incorporation on the photocatalytic activity of TiO2 for the degradation of antiviral pharmaceuticals. The interactions between the catalyst and the pollutant are not well understood, and further research is needed to develop effective photocatalysts.

    Ag-TiO2 photocatalyst for the degradation of isoprinosine: influence of silver modification on solar photocatalytic activity · 2026 · DOI

  • Future research can focus on the experimental synthesis and characterization of the copper complexes. Future research can also explore the use of other metal complexes as redox mediator electrolytes for DSSC application.

    Computational Studies of Pyridyl Imidazole Copper Complexes as Redox Mediator Electrolytes for Dye Sensitized Solar-Cell (DSSC) Application · 2026 · DOI

  • The paper identifies a gap in the study of pyridyl imidazole copper complexes as redox mediator electrolytes for DSSC application. The paper aims to fill this gap by providing a computational study of the redox potentials and VOC values of the complexes.

    Computational Studies of Pyridyl Imidazole Copper Complexes as Redox Mediator Electrolytes for Dye Sensitized Solar-Cell (DSSC) Application · 2026 · DOI

  • The need for efficient near-infrared photosensitizers. The lack of understanding of the relaxation processes of conjugated polymers in solution versus on TiO2 films.

    A conjugated polymer photosensitizer for energy conversion applications · 2026 · DOI

  • Conventional treatment methods often prove inadequate, exhibiting limitations in efficiency and cost effectiveness. There is a need for further research on scaling TiO2-based photocatalysis toward practical water treatment applications. The economic feasibility and environmental impact of this technology need to be evaluated.

    Recent advances in photocatalytic degradation of organic dye wastewater using titanium dioxide: a review · 2026 · DOI

  • The limited visible-light absorption of TiO2 nanoparticles constrains the overall efficiency and practical scalability of heterojunction systems. The interfacial recombination losses of photogenerated electron-hole pairs limit the efficiency of heterojunction systems.

    Visible-light-driven photocatalytic reduction of Cr(VI) over EDTA–TiO2 through surface complexation and ligand-to-metal charge transfer · 2026 · DOI

  • Investigating the long-term storage stability of CITNPs. Evaluating the reusability of CITNPs over a larger number of consecutive cycles. Exploring the application of CITNPs in various industrial fields.

    Development and Characterisation of TiO2 Nanoparticles Immobilised With Catalase via Functionalised Intermediates · 2026 · DOI

  • The limited practical applications of catalase due to its low stability and reusability. The need for a novel method to enhance the stability and reusability of catalase.

    Development and Characterisation of TiO2 Nanoparticles Immobilised With Catalase via Functionalised Intermediates · 2026 · DOI

  • The study identifies a gap in the understanding of the effects of acidic pH on the sol-gel synthesis of TiO2 nanoparticles. The study aims to investigate the impact of pH on the properties of TiO2 nanoparticles.

    Influence of pH on the Sol-Gel Synthesis of TiO2 Nanoparticles: Structural, Morphological, and Surface Properties · 2026 · DOI

  • The photocatalytic activity of titanium dioxide nanolayers needs to be improved. There is a lack of studies on the effect of doping with metallic elements on the photocatalytic efficiency and electro-optical properties of titanium dioxide nanolayers.

    Increasing the photocatalytic efficiency and electro-optical properties of titanium dioxide nanolayers doped with copper, silver and gold elements · 2026 · DOI

  • The need for environmentally benign and sustainable treatment strategies for dye pollution. The lack of efficient photocatalysts for the degradation of methylene blue.

    Magnetically recoverable AgFe2O4/TiO2 nanocomposites for enhanced photocatalytic degradation of methylene blue under UV light · 2026 · DOI

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61 open questions have been extracted from the limitations and future-work passages of 519 TiO2 Photocatalysis and Solar Cells papers in our library. Each one below links back to the study that raised it, so you can read the original claim in context.

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