Fe- and Mg-modified binder-free Cu₂O thin films for solid-state symmetric supercapacitors: composition-dependent structure-electrochemical property relationships.
- 1Department of Physics, Abdul Wali Khan University Mardan Mardan 23200 Pakistan [email protected].
- 2Department of Chemistry, College of Science, Princess Nourah bint Abdulrahman University P.O. Box 84428 Riyadh 11671 Saudi Arabia.
Abstract
Binder-free cuprous oxide (Cu₂O) thin films were grown directly on copper foil by successive ionic layer adsorption and reaction (SILAR) using nominal Fe or Mg additions of 1, 3 and 5 at% relative to Cu. The films are denoted by modifier and nominal loading as Fe1, Fe3 and Fe5, and Mg1, Mg3 and Mg5, with the unmodified film written as pristine Cu₂O. Composition-matched electrodes were assembled into symmetric devices with a poly(vinylidene fluoride) (PVDF)-based LiCl/KOH gel electrolyte. X-ray diffraction shows a cuprite-dominant Cu₂O phase throughout both series, together with a composition-dependent shift of the (111) reflection and a corresponding change in coherent-domain size. Field-emission scanning electron microscopy shows compact granular Fe-modified films, whereas Mg modification produces a stronger evolution of particle size and surface architecture, culminating in an open agglomerated texture at Mg5. At 0.5 mA cm⁻², Fe1 and Mg1 deliver device areal capacitances of 129 and 80 mF cm⁻² against 12 mF cm⁻² for pristine Cu₂O, with fitted charge-transfer resistances of 759 and 18.5 Ω against (3.9 ± 0.7) × 10⁴ Ω for the unmodified film. The lowest charge-transfer resistances of the series belong to Mg1 and Fe5 rather than to the two highest-capacitance devices, and the Warburg coefficient falls by four orders of magnitude on modification. After 10 000 cycles all seven devices retain 95-99% of their capacitance, while coulombic efficiency remains strongly composition-dependent, from 61% for Mg1 to 97% for Fe5 and Mg3. Scan-rate current deconvolution assigns 59-94% of the stored charge to the surface-controlled term. Low-level Fe and Mg modification therefore tunes Cu₂O through distinct, non-monotonic combinations of interfacial kinetics, ion transport, redox accessibility and film morphology, and no single descriptor ranks the seven compositions in the same order.
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BibTeX
@article{javed2026mgmodified,
title = {{Fe- and Mg-modified binder-free Cu₂O thin films for solid-state symmetric supercapacitors: composition-dependent structure-electrochemical property relationships.}},
author = {Zikra Javed and Maria Bibi and Yousra Noor and Inam Ullah and Haseeb Jamal and Farooq Khan and Rahat Shah and Tarfah Al-Warhi and Baseena Sardar and Majid Khan},
journal = {RSC advances},
year = {2026},
month = oct,
doi = {10.1039/d6ra08981j},
url = {https://europepmc.org/article/MED/42840527},
note = {CC BY-NC},
}
RIS
TY - JOUR
TI - Fe- and Mg-modified binder-free Cu₂O thin films for solid-state symmetric supercapacitors: composition-dependent structure-electrochemical property relationships.
AU - Zikra Javed
AU - Maria Bibi
AU - Yousra Noor
AU - Inam Ullah
AU - Haseeb Jamal
AU - Farooq Khan
AU - Rahat Shah
AU - Tarfah Al-Warhi
AU - Baseena Sardar
AU - Majid Khan
PY - 2026
DA - 2026/10/06
JO - RSC advances
DO - 10.1039/d6ra08981j
UR - https://europepmc.org/article/MED/42840527
AB - Binder-free cuprous oxide (Cu₂O) thin films were grown directly on copper foil by successive ionic layer adsorption and reaction (SILAR) using nominal Fe or Mg additions of 1, 3 and 5 at% relative to Cu. The films are denoted by modifier and nominal loading as Fe1, Fe3 and Fe5, and Mg1, Mg3 and Mg5, with the unmodified film written as pristine Cu₂O. Composition-matched electrodes were assembled into symmetric devices with a poly(vinylidene fluoride) (PVDF)-based LiCl/KOH gel electrolyte. X-ray diffraction shows a cuprite-dominant Cu₂O phase throughout both series, together with a composition-dependent shift of the (111) reflection and a corresponding change in coherent-domain size. Field-emission scanning electron microscopy shows compact granular Fe-modified films, whereas Mg modification produces a stronger evolution of particle size and surface architecture, culminating in an open agglomerated texture at Mg5. At 0.5 mA cm⁻², Fe1 and Mg1 deliver device areal capacitances of 129 and 80 mF cm⁻² against 12 mF cm⁻² for pristine Cu₂O, with fitted charge-transfer resistances of 759 and 18.5 Ω against (3.9 ± 0.7) × 10⁴ Ω for the unmodified film. The lowest charge-transfer resistances of the series belong to Mg1 and Fe5 rather than to the two highest-capacitance devices, and the Warburg coefficient falls by four orders of magnitude on modification. After 10 000 cycles all seven devices retain 95-99% of their capacitance, while coulombic efficiency remains strongly composition-dependent, from 61% for Mg1 to 97% for Fe5 and Mg3. Scan-rate current deconvolution assigns 59-94% of the stored charge to the surface-controlled term. Low-level Fe and Mg modification therefore tunes Cu₂O through distinct, non-monotonic combinations of interfacial kinetics, ion transport, redox accessibility and film morphology, and no single descriptor ranks the seven compositions in the same order.
SN - 2046-2069
ER -