Morphology-Dependent Excited-State Dynamics in Hollow Sphere Poly(Heptazine Imide) Photocatalysts
15 affiliations
- 1Institute of Electrochemistry Ulm University Albert-Einstein-Allee 47
- 2Institute for Technical Chemistry and Environmental Chemistry, Faculty of Chemistry and Earth Sciences
- 3Friedrich Schiller University Jena Philosophenweg
- 4Institute for Physical Chemistry
- 5Schiller University Jena Helmholtzweg
- 6Department Functional Interfaces Leibniz Institute of Photonic Technology (Leibniz-IPHT
- 7Albert-Einstein-Straße
- 8Institute of Organic Chemistry and Macromolecular Chemistry (IOMC
- 9Friedrich Schiller University Jena Lessingstraße
- 10Center for Energy and Environmental Chemistry Jena (CEEC Jena
- 11Jena Center for Soft Matter Friedrich Schiller University Jena Philosophenweg
- 12Institute of Inorganic and Analytical Chemistry Friedrich-Schiller-University Jena Humboldtstraße
- 13Helmholtz Institute for Polymers in Energy Applications Jena (HIPOLE Jena, Lessingstraße 12–14, Jena, Germany, 07743
- 14Leibniz Institute of Surface Engineering (Leibniz-IOM, Permoserstraße 15, Leipzig, Germany, 04318
- 15Felix-Bloch-Institute of Solid State Physics University Leipzig Linnéstraße
Abstract
Photocatalytic oxygen reduction to hydrogen peroxide (H2O2) over stable, earthabundant materials is attractive for solar energy conversion. The question how photocatalyst morphology governs photocatalytic performance remains, however, poorly understood, as the contributions of surface area and charge-carrier dynamics are convoluted. Herein, we investigate a series of hard-templated hollow potassium poly(heptazine imide) (PHI) spheres (KPHIS) with varying shell thickness and porosity. The photocatalytic H2O2 production is benchmarked against bulk KPHI and correlated with excited-state dynamics probed by steadystate and time-resolved photoluminescence and femtosecond transient absorption spectroscopy under quencher-free and donor-containing conditions. Notably, whilst all KPHIS outperform bulk KPHI, the activity varies non-monotonically with shell thickness and excitation wavelength, whereby the thickest-shelled sphere ‒ not the one with the highest specific surface area and pore volume ‒ is most active at 365 and 406 nm, with apparent quantum yields up to ~3.9%. These experiments reveal that the activity is governed not by porosity alone but by the kinetic competition between donor-mediated hole extraction (least efficient in the most porous sample at low wavelength irradiation) and stabilization of long-lived reduced states that drive O2 reduction. Shell thickness should be co-optimized with light penetration depth and donorconditioned charge dynamics, rather than maximizing porosity alone.
Related
- Triaryl-Heptazine Photocatalysts for the Oxidation of C–H and C–C Bonds in Nitrogen-Containing Molecules
- Comprehensive spectroscopic analysis of energy inversion of the lowest singlet and triplet excited states in the heptazine HzTFEX2
- A Lewis-acidic anion enhances energy transfer from excited cationic photocatalysts to basic substrates.
- Constrained Nuclear-Electronic Orbital Time-Dependent Density Functional Theory for Excited-State Dynamics with Nuclear Quantum Effects
- Cation-Dependent Ion Dynamics and Morphology in Metal-Contaminated Nafion Membranes
BibTeX
@misc{lange2026morphologydependent,
title = {{Morphology-Dependent Excited-State Dynamics in Hollow Sphere Poly(Heptazine Imide) Photocatalysts}},
author = {Alexander Lange and Lingli Ni and Arindam Konar and Andreas Stihl and Dariusz Mitoraj and Marius Hermesdorf and Desirée Leistenschneider and Andrea Pannwitz and Felix H. Schacher and Benjamin Dietzek-Ivanšić and Radim Beranek and Martin Oschatz},
howpublished = {ChemRxiv},
year = {2026},
month = sep,
doi = {10.26434/chemrxiv.15008563/v1},
url = {https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008563/v1},
note = {CC BY},
}
RIS
TY - UNPB
TI - Morphology-Dependent Excited-State Dynamics in Hollow Sphere Poly(Heptazine Imide) Photocatalysts
AU - Alexander Lange
AU - Lingli Ni
AU - Arindam Konar
AU - Andreas Stihl
AU - Dariusz Mitoraj
AU - Marius Hermesdorf
AU - Desirée Leistenschneider
AU - Andrea Pannwitz
AU - Felix H. Schacher
AU - Benjamin Dietzek-Ivanšić
AU - Radim Beranek
AU - Martin Oschatz
PY - 2026
DA - 2026/09/09
PB - ChemRxiv
DO - 10.26434/chemrxiv.15008563/v1
UR - https://chemrxiv.org/doi/full/10.26434/chemrxiv.15008563/v1
AB - Photocatalytic oxygen reduction to hydrogen peroxide (H2O2) over stable, earthabundant materials is attractive for solar energy conversion. The question how photocatalyst morphology governs photocatalytic performance remains, however, poorly understood, as the contributions of surface area and charge-carrier dynamics are convoluted. Herein, we investigate a series of hard-templated hollow potassium poly(heptazine imide) (PHI) spheres (KPHIS) with varying shell thickness and porosity. The photocatalytic H2O2 production is benchmarked against bulk KPHI and correlated with excited-state dynamics probed by steadystate and time-resolved photoluminescence and femtosecond transient absorption spectroscopy under quencher-free and donor-containing conditions. Notably, whilst all KPHIS outperform bulk KPHI, the activity varies non-monotonically with shell thickness and excitation wavelength, whereby the thickest-shelled sphere ‒ not the one with the highest specific surface area and pore volume ‒ is most active at 365 and 406 nm, with apparent quantum yields up to ~3.9%. These experiments reveal that the activity is governed not by porosity alone but by the kinetic competition between donor-mediated hole extraction (least efficient in the most porous sample at low wavelength irradiation) and stabilization of long-lived reduced states that drive O2 reduction. Shell thickness should be co-optimized with light penetration depth and donorconditioned charge dynamics, rather than maximizing porosity alone.
ER -