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Metal vacancies in semiconductor oxides enhance hole mobility for efficient photoelectrochemical water splitting

Nature Catalysis volume 8, pages 229–238 (2025)Cite this article

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Abstract

Achieving efficient carrier separation in transition-metal-oxide semiconductors is crucial for their applications in optoelectronic and catalytic devices. However, the substantial disparity in mobility between holes and electrons heavily limits device performance. Here we develop a general strategy for enhancing hole mobility via reducing their effective mass through metal vacancy (VM) management. The introduction of VM yields remarkable improvements in hole mobility: 430% for WO3, 350% for TiO2 and 270% for Bi2O3. To illustrate the importance of this finding, we applied the VM concept to photoelectrochemical water splitting, where efficient carrier separation is highly coveted. In particular, VM-WO3 achieves a 4.4-fold enhancement in photo-to-current efficiency, yielding a performance of 4.8 mA cm−2 for both small- and large-scale photoelectrodes with exceptional stability for over 120 h.

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Fig. 1: Theoretical calculation of the energy band structures.
Fig. 2: Material characterizations of WO3 samples.
Fig. 3: Hole mobility measurement by the SCLC method.
Fig. 4: Enhanced hole mobility for fast carrier transfer.
Fig. 5: PEC water-splitting characterization.
Fig. 6: General VM engineering induced hole mobility enhancement.

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Data availability

The data that support the findings of this study are available from the corresponding authors upon reasonable request.

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Acknowledgements

We thank the Foundation for Innovative Research Groups of the National Natural Science Foundation of China (grant no. 52121004), National Natural Science Foundation of China (grant nos. 22376222, 52372253, 22002189 and 52202125), the Science and Technology lnnovation Program of Hunan Province (grant no. 2023RC1012), Central South University Research Programme of Advanced Interdisciplinary Studies (grant no. 2023QYJC012), Central South University Innovation-Driven Research Programme (grant no. 2023CXQD042) and China Postdoctoral Science Foundation (grant nos. 2022M723547, 2022M713548 and 2023T160735). We also acknowledge the funding and support from the Deutsche Forschungsgemeinschaft (DFG) under Germany’s Excellence Strategy EXC 2089/1-390776260, the Bavarian Program Solar Technologies Go Hybrid (SolTech), the Center for NanoScience (CeNS) and the European Commission through the ERC grants CATALIGHT and SURFLIGHT. Y.K. and E.C. acknowledge the DFG excellence research cluster e-conversion for financing via the students exchange program the 4-month reseach stay of Y.K. from LMU to CSU. We are grateful for resources from the High Performance Computing Center of Central South University. We acknowledge the help from Beam Lines BL01C1 in the National Synchrotron Radiation Research Center (Hsinchu, Taiwan) for various synchrotron-based measurements.

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Author notes

  1. These authors contributed equally: Jun Wang, Kang Liu, Wanru Liao.

Authors and Affiliations

  1. Hunan Joint International Research Center for Carbon Dioxide Resource Utilization, State Key Laboratory of Powder Metallurgy, School of Physics, Central South University, Changsha, P. R. China

    Jun Wang, Kang Liu, Wanru Liao, Yingkang Chen, Qiyou Wang, Tao Luo, Hongmei Li, Junwei Fu & Min Liu

  2. School of Chemistry and Chemical Engineering, Changsha University of Science and Technology, Changsha, P. R. China

    Jun Wang & Wanru Liao

  3. Nanoinstitut München, Fakultät für Physik, Ludwig-Maximilians-Universität München, Munich, Germany

    Yicui Kang, Evangelina Pensa & Emiliano Cortés

  4. School of Metallurgy and Environment, Central South University, Changsha, P. R. China

    Hanrui Xiao, Jiawei Chen, Liyuan Chai, Fangyang Liu, Liangxing Jiang & Min Liu

  5. National Synchrotron Radiation Research Center, Hsinchu, Taiwan

    Ting-Shan Chan

  6. College of Chemistry and Chemical Engineering, Central South University, Changsha, P. R. China

    Shanyong Chen

  7. Centre for Metamaterial Research and Innovation, Department of Engineering, University of Exeter, Exeter, UK

    Changxu Liu

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Contributions

M.L. and E.C. supervised the whole project. J.W. and W.L. conceived the research and designed the experiments. K.L. carried out the DFT calculations and wrote the corresponding section. J.W., W.L., Y.K., H.X., Y.C., Q.W., T.L. and J.C. synthesized the samples, performed the electrochemical experiments and catalyst characterizations, and analysed the results. H.L., S.C., E.P., F.L., L.J., C.L., L.C. and J.F. contributed to the manuscript editing and revising. T.-S.C. conducted the XAS measurements. J.W. and H.X. performed the SCLC measurements. All authors read and commented on the manuscript.

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Correspondence to Emiliano Cortés or Min Liu.

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Supplementary Information

Supplementary Figs. 1–56, Discussion and Tables 1–8.

Supplementary Data 1

Atomic coordinates of DFT calculation.

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Wang, J., Liu, K., Liao, W. et al. Metal vacancies in semiconductor oxides enhance hole mobility for efficient photoelectrochemical water splitting. Nat Catal 8, 229–238 (2025). https://doi.org/10.1038/s41929-025-01300-1

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