Bismuth vanadate (BiVO4) has been widely investigated as a photoanode material for photoelectrochemical (PEC) water splitting because it has a suitable bandgap and strong visible-light absorption. However, its performance is highly dependent on film thickness, as there is a trade-off between light absorption and charge transport. In this study, BiVO4 thin films with thicknesses of 200, 300, and 400 nm were deposited on FTO substrates via RF magnetron sputtering to systematically investigate the thickness-dependent PEC performance. X-ray diffraction and field-emission scanning electron microscopy confirmed the formation of uniform and crystalline BiVO4 thin films. UV–vis spectroscopy revealed that light absorption increased with film thickness. PEC measurements showed that the 300 nm BiVO4 photoanode delivered the highest photocurrent density of 1.91 mA cm-2 at 1.23 V vs. RHE, along with a maximum HC-STH efficiency of 0.309 %. Electrochemical impedance spectroscopy indicated that the 300 nm film exhibited the lowest charge transfer resistance, suggesting reduced charge recombination. Furthermore, the optimized photoanode maintained stable photocurrent for over 5 hours. These results highlight that precise thickness control via RF magnetron sputtering is critical for optimizing the PEC performance of BiVO4 photoanodes.

Abstract
1. 서 론
2. 실험 방법
    2.1. BiVO4 박막 제작
    2.2. 특성평가
    2.3. PEC 특성평가를 위해 사용된 공식
3. 결과 및 고찰
4. 결 론
Acknowledgement
References
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• 정수인(전남대학교 신소재공학과) | Suin Jeong (Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 박유성(전남대학교 신소재공학과) | Youseong Park (Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 김영록(전남대학교 신소재공학과) | Youngrog Kim (Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 황성하(전남대학교 신소재공학과) | Seong Ha Hwang (Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea)
• 김진혁(전남대학교 신소재공학과) | Jin Hyeok Kim (Department of Materials Science and Engineering, Chonnam National University, Gwangju 61186, Republic of Korea) Corresponding author