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<p>Photoelectrochemical (PEC) water-splitting advancement relies on integrating highly efficient photocatalysts to enable sustainable hydrogen production. Hematite (<i>α</i>-Fe<sub>2</sub>O<sub>3</sub>) has gained significant attention due to its strong absorption in the visible spectrum, excellent chemical stability, and natural abundance. However, its practical use is constrained by inherent limitations such as poor electrical conductivity and sluggish oxidation kinetics. To mitigate these drawbacks, this study explores the modification of hematite photoanodes with carbon quantum dots (CQDs). The hematite photoanodes were synthesized using a hydrothermal approach, followed by CQD incorporation through a simple dipping process. CQDs substantially improve hematite’s visible light absorption capacity, enhance charge carrier separation and mobility, and reduce interfacial resistance between the photoelectrode and electrolyte. Furthermore, this modification leads to an expanded electrochemically active surface area compared to pristine <i>α</i>-Fe<sub>2</sub>O<sub>3</sub> photoanodes. The CQD-modified photoanodes achieve a remarkable photocurrent density of 1.31&#xa0;mA&#xa0;cm<sup>−2</sup> at 1.23&#xa0;V versus RHE, along with a photon-to-current efficiency (IPCE) enhancement of 30%. The improved PEC performance is thoroughly analyzed through electrochemical impedance spectroscopy (EIS), Mott–Schottky analysis, and energy band structure assessments. Results indicate that CQD modification accelerates charge–transfer dynamics and enhances water oxidation kinetics. Unlike prior studies, this work employs a green-synthesized CQD sensitization using a simple dipping method, offering a low-cost, eco-friendly, and scalable route to enhance hematite performance. This work presents an innovative and effective approach for boosting PEC water-splitting performance while underscoring the potential of CQDs in hydrogen energy applications.</p>

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Tailoring hematite photoanodes with carbon quantum dots for improved photoelectrochemical performance

  • 期刊论文

  • 发表日期：

    2025年7月9日

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  • Muzammil Mushtaq,
  • P. Uma Sathyakam

摘要

Photoelectrochemical (PEC) water-splitting advancement relies on integrating highly efficient photocatalysts to enable sustainable hydrogen production. Hematite (α-Fe2O3) has gained significant attention due to its strong absorption in the visible spectrum, excellent chemical stability, and natural abundance. However, its practical use is constrained by inherent limitations such as poor electrical conductivity and sluggish oxidation kinetics. To mitigate these drawbacks, this study explores the modification of hematite photoanodes with carbon quantum dots (CQDs). The hematite photoanodes were synthesized using a hydrothermal approach, followed by CQD incorporation through a simple dipping process. CQDs substantially improve hematite’s visible light absorption capacity, enhance charge carrier separation and mobility, and reduce interfacial resistance between the photoelectrode and electrolyte. Furthermore, this modification leads to an expanded electrochemically active surface area compared to pristine α-Fe2O3 photoanodes. The CQD-modified photoanodes achieve a remarkable photocurrent density of 1.31 mA cm−2 at 1.23 V versus RHE, along with a photon-to-current efficiency (IPCE) enhancement of 30%. The improved PEC performance is thoroughly analyzed through electrochemical impedance spectroscopy (EIS), Mott–Schottky analysis, and energy band structure assessments. Results indicate that CQD modification accelerates charge–transfer dynamics and enhances water oxidation kinetics. Unlike prior studies, this work employs a green-synthesized CQD sensitization using a simple dipping method, offering a low-cost, eco-friendly, and scalable route to enhance hematite performance. This work presents an innovative and effective approach for boosting PEC water-splitting performance while underscoring the potential of CQDs in hydrogen energy applications.