Enhanced hydrogen evolution activity of CsPbBr3 nanocrystals achieved by dimensionality change

Halide Perovskite Photocatalysts for Clean Fuel Production and Organic Synthesis: Opportunities and Challenges

The need to constrain the use of fossil fuels causing global warming is motivating the development of a variety of photocatalysts for solar-to-fuel generation and chemical synthesis. In particular, semiconductor-based photocatalysts have been extensively exploited in solar-driven organic synthesis, carbon dioxide (CO2) conversion into value-added products, and hydrogen (H2) generation from water (H2O) splitting. Recently, metal halide perovskites (MHPs) have emerged as an important class of semiconductors for heterogeneous photocatalysis owing to their interesting properties. Despite key issues with long-term stability and degradation in polar solvents due to their ionic character, there has been significant progress in halide perovskite-based photocatalysts with improving their stability and performance in the gas and liquid phases. This review discusses the state-of-the-art for using halide perovskite-based photocatalysts and photoelectrocatalysis in hydrogen production from water and halogen acid solutions, CO2 reduction into value-added chemicals, and various organic chemical transformations. The different types of halide perovskites used, design strategies to overcome the instability issues in polar solvents, and the efficiencies achieved are discussed. Furthermore, the outstanding challenges associated with the use of polar electrolytes and how the stability and performance can be improved are discussed.

Promoting Charge-Carriers Dynamics by Relaxed Lattice Strain in A-site-Doped Halide Perovskite for Photocatalytic H2 Evolution

Because of the unique and superior optoelectronic properties, metal halide perovskites (MHPs) have attracted great interest in photocatalysis. Element doping strategy is adopted to modify perovskite materials to improve their photocatalytic performance. However, the contribution of bare doping-site onto photocatalytic efficiency, and the correlation between doping locations and activity have not yet to be demonstrated. The unique properties of non-active alkali metals promoted us to systematically explore the potential of A-site-doped MHPs for photocatalysis. Herein, we dope potassium (K+) into CsPbBr3 via an anti-solvent precipitation method and first reveal that the occupied locations of K+ in CsPbBr3 is lattice incorporation rather than surface segregation, which would change from A-site substitution to interstitial site in lattice with the increase of K+ concentrations. Taking hydrogen (H2) evolution as a model reaction, photocatalytic activity of CsPbBr3 after K+ doping could be significantly improved ~11-fold with A-site substitution, which is superior to that of interstitial site doping. Moreover, other alkali metals including lithium (Li), sodium (Na), and rubidium (Rb) doping give the same results. The structure of photocatalysts during reaction confirmed the contribution of A-site doping onto enhanced photocatalytic activity. Mechanistic insights show it is a result of the relaxed lattice strain induced promoted charge-carriers dynamics and upward shifting of band after K+ A-site doping.

In-situ synthesized perovskite/polyhedral oligomeric silsesquioxane nanocomposites for robust X-ray imaging

Perovskites are extensively studied in scintillation detection due to their low cost, simple synthesis, high scintillation light yield, and rapid decay times. However, their instability to light and radiation leads to scintillation performance degradation. To address these stability concerns, this paper proposes a new perovskite nanocrystal (NC) synthesis method that employs aminopropyllsobutyl polyhedral oligomeric silsesquioxane (POSS) as a ligand and a coating layer to passivate the perovskite NCs, significantly enhancing their stability and photoluminescence efficiency. Furthermore, the resultant perovskite/aminopropyllsobutyl POSS nanocomposites exhibit remarkable capabilities in X-ray detection limits, imaging quality, and radiation hardness. These findings underscore the potential of enhanced perovskite in revolutionizing the field of scintillator materials, offering promising pathways for their future applications and development.

Defects of Metal Halide Perovskites in Photocatalytic Energy Conversion: Friend or Foe?

Photocatalytic solar-to-fuel conversion over metal halide perovskites (MHPs) has recently attracted much attention, while the roles of defects in MHPs are still under debate. Specifically, the mainstream viewpoint is that the defects are detrimental to photocatalytic performance, while some recent studies show that certain types of defects contribute to photoactivity enhancement. However, a systematic summary of why it is contradictory and how the defects in MHPs affect photocatalytic performance is still lacking. In this review, the innovative roles of defects in MHP photocatalysts are highlighted. First, the origins of defects in MHPs are elaborated, followed by clarifying certain benefits of defects in photocatalysts including optical absorption, charge dynamics, and surface reaction. Afterward, the recent progress on defect-related MHP photocatalysis, i.e., CO2 reduction, H2 generation, pollutant degradation, and organic synthesis is systematically discussed and critically appraised, putting emphasis on their beneficial effects. With defects offering peculiar sets of merits and demerits, the personal opinion on the ongoing challenges is concluded and outlining potentially promising opportunities for engineering defects on MHP photocatalysts. This critical review is anticipated to offer a better understanding of the MHP defects and spur some inspiration for designing efficient MHP photocatalysts.

All-inorganic lead halide perovskites for photocatalysis: a review

Nowadays, environmental pollution and the energy crisis are two significant concerns in the world, and photocatalysis is seen as a key solution to these issues. All-inorganic lead halide perovskites have been extensively utilized in photocatalysis and have become one of the most promising materials in recent years. The superior performance of all-inorganic lead halide perovskites distinguish them from other photocatalysts. Since pure lead halide perovskites typically have shortcomings, such as low stability, poor active sites, and ineffective carrier extraction, that restrict their use in photocatalytic reactions, it is crucial to enhance their photocatalytic activity and stability. Huge progress has been made to deal with these critical issues to enhance the effects of all-inorganic lead halide perovskites as efficient photocatalysts in a wide range of applications. In this manuscript, the synthesis methods of all-inorganic lead halide perovskites are discussed, and promising strategies are proposed for superior photocatalytic performance. Moreover, the research progress of photocatalysis applications are summarized; finally, the issues of all-inorganic lead halide perovskite photocatalytic materials at the current state and future research directions are also analyzed and discussed. We hope that this manuscript will provide novel insights to researchers to further promote the research on photocatalysis based on all-inorganic lead halide perovskites.