Exploring the spatially resolved charge transfer mechanism in the Al-doped SrTiO3/C3N5 S-scheme heterojunction for boosted solar-driven photocatalytic hydrogen evolution

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🔬研究者:Provides spatially resolved evidence of S-scheme charge transfer, useful for designing efficient heterojunction photocatalysts.

🏢実務担当者:Offers a promising photocatalyst material for green hydrogen production, potentially relevant for renewable energy companies.

🏛政策担当者:Supports the feasibility of solar-driven hydrogen as a clean energy source, informing renewable energy policy.

Developing highly efficient and low-cost C3N5-based photocatalysts for hydrogen production is of great significance. However, research on the surface potential distribution of photogenerated charges in the C3N5-based S-scheme heterojunction from a spatial perspective with nanoscale precision is still lacking. In this work, using Al-doped SrTiO3 (ASTO) with strong oxidation ability and C3N5 nanosheets with high reduction ability, a novel S-scheme heterojunction was created. The ASTO/C3N5 S-scheme heterojunction was synthesized via a hydrothermal method. It reveals that the polyhedral ASTO particles are in intimate contact with C3N5 nanosheets, with a clear and distinct interface observed between them. The optimal 5%-ASTO/C3N5 S-scheme heterojunction exhibits a high hydrogen production rate under simulated solar light, surpassing pristine C3N5 and ASTO by factors of 2.5 and 37.4, respectively. Light-assisted Kelvin-probe force microscopy (KPFM) was employed to uncover the spatially resolved features of the kinetics of charge transfer in the ASTO/C3N5 S-scheme heterojunction. It reveals that photogenerated electrons gather on the surface of C3N5 as a reduction photocatalyst (RP) in the heterojunction, resulting in a reduced surface photovoltage (SPV) compared to pure C3N5, whereas holes accumulate on the surface of ASTO as an oxidation photocatalyst (OP) in the heterojunction, providing higher SPV than pure ASTO. Moreover, the large work function difference (0.41 eV) between ASTO and C3N5 induces a robust interfacial electric field (IEF). This strong IEF facilitates the photogenerated electrons in ASTO’s conduction band (CB) recombine with holes in C3N5’s valence band (VB), preserving high redox potentials. Furthermore, active free radical measurement confirms the enhanced •O2− and •OH signals for the 5%-ASTO/C3N5 heterojunction, confirming the S-scheme mechanism and excluding the type-II mechanism, which is also demonstrated by in-situ X-ray photoelectron spectra (XPS). Overall, this work offers some evidence regarding the spatially resolved characteristics of the kinetics of charge transfer in the S-scheme heterojunction.

• scidb https://doi.org/10.57760/sciencedb.cjcatal.00044first seen 2026-08-11 05:35:38 · last seen 2026-08-13 05:59:16