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Optical phase change materials (O-PCMs) have attracted increasing attention and provide promising solutions for non-volatile reconfigurable photonics due to their large index contrast and non-volatile switching characteristics. In this work, we have explored the optical phase change properties of a dozen different O-PCMs and established the corresponding gene bank. Among these O-PCMs, Ge 1 Sb 2 Se 3 Te 1 (G1S2S3T1) films exhibit unprecedented low-loss, strong light modulation capability, and ultra-thermal stability capability, which are prepared by pulsed laser deposition. Meanwhile, we investigate the phase transition kinetic mechanism of G1S2S3T1 films by transmission electron microscope, temperature dependent transmission spectroscopy, and temperature dependent Raman spectroscopy. It is found that the wide bandgap (1.09 eV) in the amorphous state, the large bandgap variation (0.51 eV) between amorphous and crystalline states, the needle-like configuration of its crystalline state, and the special phase change process contribute to strong refractive index modulation. Moreover, we find that their ultra-thermal stability is from a strong Sb–Se bond. Through the simulation, we found that G1S2S3T1 can be applied to prepare ultra-low loss waveguide devices. The present work represents a significant step in the development of broadband nonvolatile photonics derived from O-PCMs. [ABSTRACT FROM AUTHOR]

Photosynthesis of hydrogen peroxide (H2O2) is regarded as an economically efficient and environmentally friendly synthesis method. However, the scalability of photocatalytic H2O2 production (PHP) is hindered by the sluggish reaction kinetics and rapid recombination of photogenerated charge carriers. In this study, an organic amine‐constrained ions intercalated carbon nitride/CdSe‐diethylenetriamine (K+/I−‐CN/CdSe‐D) S‐scheme heterojunction is synthesized using an organic–inorganic hybrid approach and employed for PHP for the first time. The optimization of the heterojunction interface by I− and K+ ions contributed to enhanced light absorption capabilities and reduced interlayer charge transfer distance. Concurrently, the synergy of C─Se bonds at interface effectively modulated the electron transfer pathways. The coordination environment and charge transfer mechanism are thoroughly investigated by extended X‐ray absorption fine structure and in situ irradiated X‐ray photoelectron spectroscopy. The H2O2 production rate of 40%K+/I−‐CN/CdSe‐D reached 2240.23 µmol h−1 g−1 in pure water. This study highlights the significance of dual tuning of interface chemical bonds and ionic intercalation as an effective strategy for enhancing the photocatalytic H2O2 , paving the way for further advancements in PHP technology. [ABSTRACT FROM AUTHOR]

The quick recombination of photogenerated carriers and the high surface reaction barrier are two important aspects influencing photocatalytic hydrogen generation. In this paper, a sulfur vacancy-modified two-dimensional (2D) fluorinated-TiO2 nanosheet/Mn0.2Cd0.8S (F-TiO2/MCS) S-scheme heterojunction was synthesized by a simple hydrothermal method to accelerate photogenerated electron transfer. The formation of an S-scheme heterojunction between MCS nanoflowers and 2D F-TiO2 enhances the efficacy of photocatalytic hydrogen generation by facilitating the separation of photogenerated electron–hole pairs. Meanwhile, the sulfur vacancies of F-TiO2/MCS change the local electronic structure of the heterojunction surface by capturing photogenerated electrons, resulting in a photocatalytic hydrogen evolution rate for F-TiO2/MCS of 3197 μmol g–1 h–1, which is 4.42 times greater than that of the pure MCS. Experimental measurements and density functional theory (DFT) calculations show that the mutual synergy between the S-scheme heterojunction and the sulfur vacancies not only provides abundant H2 adsorption active sites but also promotes interfacial charge separation and migration, which improves the photocatalytic performance of the F-TiO2/MCS composite. This work holds significance for the photocatalytic hydrogen production of sulfur vacancy-modified S-scheme heterojunctions. [ABSTRACT FROM AUTHOR]