Interfacial Engineering of Semicoherent Interface at Purified CsPbBr3 Quantum Dots/2D-PbSe for Optimal CO2 Photoreduction Performance

Recent advances in metal halide perovskite based photocatalysts for artificial photosynthesis and organic transformations

Metal halide perovskites (MHP) emerged as highly promising materials for photocatalysis, offering significant advancements in the degradation of soluble and airborne pollutants, as well as the transformation of functional organic compounds. This comprehensive review focuses on recent developments in MHP-based photocatalysts, specifically examining two major categories: lead-based (such as CsPbBr3) and lead-free variants (e.g. Cs2AgBiX6, Cs3Bi2Br9 and others). While the review briefly discusses the contributions of MHPs to hydrogen (H2) production and carbon dioxide (CO2) reduction, the main emphasis is on the design principles that determine the effectiveness of perovskites in facilitating organic reactions and degrading hazardous chemicals through oxidative transformations. Furthermore, the review addresses the key factors that influence the catalytic efficiency of perovskites, including charge recombination, reaction mechanisms involving free radicals, hydroxyl ions, and other ions, as well as phase transformation and solvent compatibility. By offering a comprehensive overview, this review aims to serve as a guide for the design of MHP-based photocatalysis and shed light on the common challenges faced by the scientific community in the domain of organic transformations.

Embedding CsPbBr3 Quantum Dots into an In2O3 Nanotube for Selective Photocatalytic CO2 Reduction to Hydrocarbon Fuels

Halide perovskite quantum dots (QDs) are one of the most prospective candidates for photocatalytic CO2 reduction, but their photocatalytic performances are far from satisfactory due to structural instability and severe charge recombination. In this study, we demonstrated a CsPbBr3 QDs/In2O3 hierarchical nanotube (CPB/IO) for efficient CO2 conversion, in which CsPbBr3 QDs were well-dispersed on the In-MOF-derived In2O3 nanotube by a facile self-assembly process. The optimized CPB/IO catalyst displayed an enhanced photocatalytic CO2 performance with a (CO + CH4) generation rate of 16.37 μmol·g-1·h-1 upon simulated solar illumination without a photosensitizer and sacrificial agent, which is 3.59 times stronger than that of pristine CsPbBr3 QDs (4.56 μmol·g-1·h-1). Besides, the modified CsPbBr3 QD catalyst exhibited an obvious increase of CH4 selectivity and excellent stability after four cycles. The unique zero-dimensional (0D)/one-dimensional (1D) heterostructure and matching band potentials between CsPbBr3 and In2O3 supply an intimate interfacial contact, numerous active sites, and effective charge transfer for CO2 photoreduction. This work can inspire the formation of novel halide-perovskite-involving photocatalysts for solar fuel formation.

In Situ Constructed Perovskite-Chalcogenide Heterojunction for Photocatalytic CO2 Reduction

Perovskite nanocrystals (PNCs) are promising candidates for solar-to-fuel conversions yet exhibit low photocatalytic activities mainly due to serious recombination of photogenerated charge carriers. Constructing heterojunction is regarded as an effective method to promote the separation of charge carriers in PNCs. However, the low interfacial quality and non-directional charge transfer in heterojunction lead to low charge transfer efficiency. Herein, a CsPbBr3 -CdZnS heterojunction is designed and prepared via an in situ hot-injection method for photocatalytic CO2 reduction. It is found that the high-quality interface in heterojunction and anisotropic charge transfer of CdZnS nanorods (NRs) enable efficient spatial separation of charge carriers in CsPbBr3 -CdZnS heterojunction. The CsPbBr3 -CdZnS heterojunction achieves a higher CO yield (55.8 µmol g-1  h-1 ) than that of the pristine CsPbBr3 NCs (13.9 µmol g-1  h-1 ). Furthermore, spectroscopic experiments and density functional theory (DFT) simulations further confirm that the suppressed recombination of charge carriers and lowered energy barrier for CO2 reduction contribute to the improved photocatalytic activity of the CsPbBr3 -CdZnS heterojunction. This work demonstrates a valid method to construct high-quality heterojunction with directional charge transfer for photocatalytic CO2 reduction. This study is expected to pave a new avenue to design perovskite-chalcogenide heterojunction.

Plasmonic Au Nanoparticle of a Au/TiO2-C3N4 Heterojunction Boosts up Photooxidation of Benzyl Alcohol Using LED Light

Plasmonic Au nanoparticles (NPs) employing localized surface plasmon resonance excitation have exhibited superior visible light absorption for many organic transformations. In this work, we prepared a ternary composite catalyst comprising plasmonic Au NPs and a 2D/2D TiO₂-C₃N₄ heterojunction via a photoreduction method of chloroauric acid in the presence of TiO₂-C₃N₄. The introduction of plasmonic nanogold particles embedded onto the TiO₂ surface of the TiO₂-C₃N₄ heterojunction can significantly improve the photocatalytic performance during photooxidation of benzyl alcohol to benzaldehyde under mild conditions (1 bar air, white LED irradiation at ambient temperature). The productivity over Au/TiO₂-C₃N₄ (0.25 mmol_reacted BA g_cat.^-1 h^-1) is found to be ∼5.6, 8.3, and 8.2-fold of these over the Au/TiO₂, TiO₂-C₃N₄, and C₃N₄-Au-TiO₂ heterojunctions, respectively. Trapping experiments and electron spin resonance (ESR) spectroscopy confirm that the superoxide (^·O₂^-) and hydroxyl radicals (^·OH) act as the reactive oxygen species during photooxidation. Furthermore, the experimental results combined with density functional theory calculations reveal that the chemisorbed benzyl alcohol population, surface oxygen vacancies, and lifetime of photoexcited electrons and holes are largely improved by plasmonic Au NPs. This study on nanogold composites provides some hints for developing new efficient and practical photocatalysts.