Chinese Journal of Catalysis

Chinese Journal of Catalysis ›› 2027, Vol. 92: 274-284.DOI: 10.1016/S1872-2067(26)65278-3

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Regulating carrier dynamics in CdS via controlled sulfur vacancy engineering: Insights from femtosecond transient absorption spectroscopy

Zheng Menga, Chenbin Aia, Jianjun Zhanga, Bowen Hea, Liuyang Zhanga,*(), Zhen Wub,*(), Serguei Filatovc, Dmitry Selishchevd,*(), Jahan B. Ghasemie,*(), Jiaguo Yua,*()   

  1. a Laboratory of Solar Fuel, Faculty of Materials Science and Chemistry, China University of Geosciences, Wuhan 430078, Hubei, China
    b Department of Chemical Engineering, Ordos Institute of Technology, Ordos 017000, Inner Mongolia, China
    c Heat and Mass Transfer Institute, National Academy of Sciences of Belarus, P. Brovka, 15, ITMO, Minsk 220072, Belarus
    d Department of Unconventional Catalytic Processes, Boreskov Institute of Catalysis SB RAS, Lavrentieva Ave. 5, Novosibirsk 630090, Russia
    e Faculty of Chemistry, School of Sciences, University of Tehran, Tehran 1417614335, Iran
  • Received:2026-05-09 Accepted:2026-06-25 Online:2027-01-02 Published:2026-10-30
  • Contact: *E-mail: zhangliuyang@cug.edu.cn (L. Zhang),
    wuzhen@oit.edu.cn (Z. Wu),
    selishev@catalysis.ru (D. Selishchev),
    jahan.ghasemi@ut.ac.ir (J. B. Ghasemi),
    yujiaguo93@cug.edu.cn (J. Yu).
  • Supported by:
    National Natural Science Foundation of China(52322214);National Natural Science Foundation of China(22278383);National Natural Science Foundation of China(22409181);National Natural Science Foundation of China(22469001);National Natural Science Foundation of China(22361132529);National Science Foundation of Hubei Province(2023AFA088)

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Abstract:

Severe electron-hole recombination remains a fundamental bottleneck limiting the efficiency of semiconductor photocatalysts. Engineering defect states, particularly sulfur vacancies (Sv), offers an effective strategy to tailor local electronic structures and regulate charge carrier dynamics. Herein, CdS hollow spheres with tunable Sv concentrations were constructed through thermal treatment, yielding a non-monotonic (volcano-type) dependence of defect density. Ultrafast femtosecond transient absorption spectroscopy reveals that a moderate Sv concentration introduces shallow electron-trapping states, thereby prolonging the lifetime of photogenerated electrons (up to 1112.0 ps in acetonitrile) and suppressing recombination. In contrast, excessive Sv accumulation generates recombination centers, resulting in accelerated carrier decay. Kelvin probe force microscopy further demonstrates that the optimally engineered sample exhibits the lowest surface photovoltage (77 mV), indicative of efficient electron accumulation at surface active sites. More importantly, this work identifies a concentration-dependent dual role of sulfur vacancies—evolving from charge-separation promoters to recombination centers—and elucidates the interplay between defect-mediated carrier trapping and surface reaction kinetics in aqueous environments. These findings establish a refined mechanistic framework for defect engineering and provide strategic guidance for the rational design of high-performance CdS-based photocatalysts.

Key words: CdS, Sulfur vacancy, Femtosecond transient absorption spectroscopy, Carrier dynamics, Surface photovoltage