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<p>CeO<sub>2</sub> nanorod photocatalysts with systematically tuned oxygen vacancy concentrations were synthesized via a one-step NaBH<sub>4</sub>-assisted hydrothermal method to elucidate the role of defect engineering in photocatalytic water splitting. A series of reduced samples (Ce1–Ce5) and pristine CeO<sub>2</sub> were thoroughly characterized. Increasing NaBH<sub>4</sub> dosage induced XRD peak broadening with crystallite size reduction (5.37–4.44&#xa0;nm) and a UV–Vis DRS red shift with bandgap narrowing (2.89–2.72&#xa0;eV). Urbach energy increased (0.36–0.41&#xa0;eV), reflecting mid-gap state formation. Raman, FTIR, and EPR (g ≈ 2.002) confirmed rising oxygen vacancy and Ce<sup>3+</sup> content, consistent with XPS, which revealed enhanced oxygen vacancy-related O 1s contribution (16.7–43%) and Ce<sup>3+</sup> fraction. Valence-band XPS and secondary electron cut-off showed band-edge shifts and reduced work function, promoting charge transfer. PL and TCSPC indicated prolonged carrier lifetimes in Ce3 (τ<sub>i</sub> − τ<sub>a</sub> = 1.1087 ns), while Ce4–Ce5 exhibited deep traps. CDB and S-parameter analyses identified Ce3 as optimal, balancing shallow and deep traps for efficient carrier dynamics. BET and BJH confirmed Ce3’s highest surface area (~ 1465 m<sup>2</sup>/g) and mesoporosity. Morphological analysis showed smooth rods (Ce, Ce1) evolving to porous, defect-rich rods (Ce2–Ce3) and partial amorphization (Ce4–Ce5). Ce3 delivered the highest H<sub>2</sub> evolution under visible light without sacrificial agents, highlighting the critical role of controlled oxygen vacancy engineering in advancing CeO<sub>2</sub>-based solar hydrogen production.</p>

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Tunable oxygen vacancies in CeO2 nanorods via one-step NaBH4-assisted synthesis for enhanced visible-light photocatalytic water splitting

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  • 发表日期：

    2026年3月7日

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  • Srinath Ranjan Tripathy,
  • Saroj Sundar Baral

摘要

CeO2 nanorod photocatalysts with systematically tuned oxygen vacancy concentrations were synthesized via a one-step NaBH4-assisted hydrothermal method to elucidate the role of defect engineering in photocatalytic water splitting. A series of reduced samples (Ce1–Ce5) and pristine CeO2 were thoroughly characterized. Increasing NaBH4 dosage induced XRD peak broadening with crystallite size reduction (5.37–4.44 nm) and a UV–Vis DRS red shift with bandgap narrowing (2.89–2.72 eV). Urbach energy increased (0.36–0.41 eV), reflecting mid-gap state formation. Raman, FTIR, and EPR (g ≈ 2.002) confirmed rising oxygen vacancy and Ce3+ content, consistent with XPS, which revealed enhanced oxygen vacancy-related O 1s contribution (16.7–43%) and Ce3+ fraction. Valence-band XPS and secondary electron cut-off showed band-edge shifts and reduced work function, promoting charge transfer. PL and TCSPC indicated prolonged carrier lifetimes in Ce3 (τi − τa = 1.1087 ns), while Ce4–Ce5 exhibited deep traps. CDB and S-parameter analyses identified Ce3 as optimal, balancing shallow and deep traps for efficient carrier dynamics. BET and BJH confirmed Ce3’s highest surface area (~ 1465 m2/g) and mesoporosity. Morphological analysis showed smooth rods (Ce, Ce1) evolving to porous, defect-rich rods (Ce2–Ce3) and partial amorphization (Ce4–Ce5). Ce3 delivered the highest H2 evolution under visible light without sacrificial agents, highlighting the critical role of controlled oxygen vacancy engineering in advancing CeO2-based solar hydrogen production.