RESUMEN
Lead halide perovskite nanocrystals (LHP NCs) have garnered attention as promising light-harvesting materials for optoelectronics and photovoltaic devices, attributed to their impressive optoelectronic properties. However, their susceptibility to moisture-induced degradation has hindered their practical applications. Despite various encapsulation strategies, challenges persist in maintaining their stability and optoelectronic performance simultaneously. Here, a ligand exchange approach is proposed using (11-mercaptoundecyl)-N,N,N-trimethylammonium bromide (MUTAB) to enhance the stability and dispersibility of CsPbBr3 (CPB) NCs in aqueous environments. MUTAB enables effective surface passivation of the CPB NCs via robust Pb-S interactions at the S-terminal while concurrently directing water molecules through the unbound cationic N-terminal or vice versa, ensuring water dispersibility and stability. Spectroscopic analysis confirms retained structural and optical integrity post-ligand exchange. Crucially, MUTAB-bound CPB NCs exhibit sustained charge transfer properties, demonstrated by aqueous colloidal oxidation reactions. This ligand exchange strategy offers a promising pathway for advancing LHP NCs toward practical optoelectronic and photocatalytic applications.
RESUMEN
CsPbBr3 nanocrystals (NCs) employed as a photocatalyst resulted in efficient benzylamine oxidation under oxygen atmosphere. Improved reaction yields stem from favorable -NH2 functional group interactions on the NC surface, while additional interactions with -OMe or -SMe functional groups post-product formation result in lower yields. These insights into interfacial interactions and mechanistic aspects advance sustainable chemical transformations through cost-effective and recyclable CsPbBr3 NC-catalyzed primary amine oxidation.
RESUMEN
The remarkable catalytic potential of perovskite nanocrystals (NCs) remains underutilized due to their limited stability in polar media, resulting from the vulnerability of their structure to disruption by polar solvents. In this study, we address this challenge by employing the bolaamphiphilic NKE-12 ligand, which features multiple denticities to effectively shield the surface of CsPbBr3 NCs from polar solvent interactions without compromising their light-harvesting properties. Our research, utilizing electrochemical impedance and photocurrent response measurements, highlights efficient charge separation and charge transfer enabled by NKE-12 ligands, which feature multiple ionic groups and peptide bonds, compared to conventional oleylamine/oleic acid ligands on CsPbBr3 NCs. Through the utilization of purely ligand-derived water-dispersed CsPbBr3/NKE-12 NCs, we successfully showcased their photocatalytic activity for acrylamide polymerization. A series of control experiments unveil a radical-based reaction pathway and suggest the synergistic involvement of photogenerated electrons and holes in producing the O2·- and OH· free radicals, respectively. Our findings emphasize the crucial role of ligand engineering in stabilizing perovskites in water and harnessing their exceptional photocatalytic attributes. This study opens new avenues for applying perovskite NCs in various catalytic processes in polar media.
RESUMEN
The demand for a benign alternative to energy-intensive industrial chemical transformations is critical. Lead halide perovskites have emerged as promising candidates due to their unique optoelectronic properties, including high absorption coefficients in the visible region, tunable band gaps, and long charge carrier-diffusion lengths. In this study, we present a model reaction to showcase the photocatalytic utility of perovskite nanocrystals (NCs). Specifically, we demonstrate the synthesis of trichloroethylene (TCEt) from 1,1,2,2-tetrachloroethane (TCE) using CsPbBr3 NCs under white light illumination. The band-edge positions of the NCs and the redox potential of TCE enable efficient electron transfer for C-Cl bond activation. Furthermore, while ensuring operational stability, CsPbBr3 NCs undergo light-controlled modification, leading to the formation of mixed-halide perovskite (CsPbBrxCl3-x) NCs during the reaction. This procedure yields a mixed-halide perovskite that maintains stability while containing the desired halide content. Additionally, the reaction produces HBr as a byproduct, serving as a self-cleaning technique to eliminate excess Br- ions from the solution. Ultimately, we achieve nearly 100% conversion of CsPbBr3 to pure CsPbCl3 NCs, with a full width at half-maximum of approximately 11.2 nm. Our clean and efficient approach to synthesizing TCEt using perovskite NCs provides interesting insights into violet light-emitting diode (LED) fabrication and color patterning. This study highlights the promising potential of perovskite materials for sustainable chemical transformations and optoelectronic applications.