Promoted PhotocatalyticH₂ Production of0<i>D</i>/2D CeO₂ Nanoparticles and N‑DefectsGraphitic Carbon Nitride S‑Scheme Heterojunction

Incorporating two-phase heterojunctions with matching band structures represents a promising strategy for developing photocatalysts with enhanced efficiency. This work prefers a novel approach that employs a template-assisted strategy based on a porous structured UCCN@CeO₂ 0<i>D</i>/2D S-scheme heterojunction. The proposed method aims to improve photocatalytic activity by harnessing the synergistic effects of monodispersed CeO₂ nanoparticles and ultrathin N-defect CN nanosheets. The catalyst demonstrates a remarkable photocatalytic hydrogen evolution rate, reaching an impressive value of 5.59 mmol h^–1 g^–1 when subjected to simulated sunlight irradiation. Furthermore, the photocatalyst maintains a substantial activity level, yielding 2.35 mmol h^–1 g^–1 under visible light (≥400 nm). The significant improvement in the photocatalytic performance of the UCCN@CeO₂ catalyst is attributed to the unique structural design and effective charge separation facilitated by the S-scheme mechanism. Kelvin probe force microscopy, theoretical calculations, and femtosecond transient absorption spectroscopy affirm the efficient charge transportation across the catalyst interface. Additionally, electron spin resonance spectroscopy measurements further support the charge transfer pathway in the S-scheme. This research presents an innovative approach for designing and developing CN-based catalysts featuring S-scheme heterojunctions, aiming to improve their efficiency and practical use in photocatalytic applications.