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Fabrication of heterostructures by merging two or more materials in a single object. The domains at the nanoscale represent a viable strategy to purposely address materials’ properties for applications in several fields such as catalysis, biomedicine, and energy conversion. In this case, solution-phase seeded growth and the hot-injection method are ingeniously combined to fabricate TiO2/PbS heterostructures. The interest in such hybrid nanostructures arises from their absorption properties that make them advantageous candidates as solar cell materials for more efficient solar light harvesting and improved light conversion. Due to the strong lattice mismatch between TiO2 and PbS, the yield of the hybrid structure and the control over its properties are challenging. In this study, a systematic investigation of the heterostructure synthesis as a function of the experimental conditions (such as seeds’ surface chemistry, reaction temperature, and precursor concentration), its topology, structural properties, and optical properties are carried out. The morphological and chemical characterizations confirm the formation of small dots of PbS by decorating the oleylamine surface capped TiO2 nanocrystals under temperature control. Remarkably, structural characterization points out that the formation of heterostructures is accompanied by modification of the crystallinity of the TiO2 domain, which is mainly ascribed to lattice distortion. This result is also confirmed by photoluminescence spectroscopy, which shows intense emission in the visible range. This originated from self-trapped excitons, defects, and trap emissive states.

An innovative colloidal approach is proposed here to carry out the customized functionalization of TEMPO-Oxidized Cellulose Nanofibers (CNF) incorporating non-noble inorganic nanoparticles. A heterocoagulation process is applied between the delignified CNF and as-synthetized CuO nanoparticles (CuO NPs) to formulate mixtures which are used in the preparation of aerogels with antibacterial effect, which could be used to manufacture membranes, filters, foams, etc. The involved components of formulated blending, CNF and CuO NPs, were individually obtained by using a biorefinery strategy for agricultural waste valorization, together with an optimized chemical precipitation, assisted by ultrasounds. The optimization of synthesis parameters for CuO NPs has avoided the presence of undesirable species, which usually requires later thermal treatment with associated costs. The aerogels-based structure, obtained by conventional freeze-drying, acted as 3D support for CuO NPs, providing a good dispersion within the cross-linked structure of the nanocellulose and facilitating direct contact of the antibacterial phase against undesirable microorganisms. All samples showed a positive response against Escherichia coli and Staphylococcus aureus. An increase of the antibacterial response of the aerogels, measured by agar disk diffusion test, has been observed with the increase of CuO NPs incorporated, obtaining the width of the antimicrobial “halo” (nwhalo) from 0 to 0.6 and 0.35 for S. aureus and E. coli, respectively. Furthermore, the aerogels have been able to deactivate S. aureus and E. coli in less than 5 h when the antibacterial assays have been analyzed by a broth dilution method. From CNF-50CuO samples, an overlap in the nanoparticle effect produced a decrease of the antimicrobial kinetic.

Colloidal quantum wells, also known as colloidal nanoplatelets (NPLs), have emerged as a promising class of materials for light‐emitting devices (LEDs). However, the most widely studied core/shell NPLs, which rely on cadmium‐based shell layers, face challenges due to toxicity concerns and improper charge confinement. To address these limitations, a new synthetic approach is presented that enables the controlled growth of zinc chalcogenide‐based shell layers on NPLs. The synthesized CdSe/ZnSe core/shell NPLs exhibit emission between 615 and 630 nm, with a moderate photoluminescence quantum yield (PL‐QY) of 40–50%. It is also demonstrated that the lateral dimensions of the CdSe core NPLs significantly affect the optical properties of the core/shell heterostructures, with smaller lateral dimensions resulting in narrower emission linewidths as low as 20 nm. Further passivation of these core/shell NPLs with an additional ZnS shell layer significantly increases the PL‐QY up to 80–90%. Finally, the device performance of these two core/shell NPLs is investigated by fabricating solution‐processed LEDs. With LEDs incorporating CdSe/ZnSe/ZnS core/multi‐shell NPLs as the active light‐emitting layer, an external quantum efficiency (EQE) of 3.82% and a maximum brightness of 6477 cd m−2 is obtained. These findings underscore the significant potential of zinc chalcogenide‐based shell layers in advancing colloidal NPLs toward high‐performance light‐emitting devices. A new synthetic route is developed for the synthesis of CdSe/ZnSe/ZnS multi‐shell nanoplatelets (NPLs) with emissions between 615 and 630 nm and photoluminescence quantum yields up to 90%. Control over the lateral size of the starting CdSe core enabled the narrowing of the emission linewidth to 20 nm. These high‐performance core/multishell NPLs hold strong promise for next‐generation light‐emitting applications.

Epitaxial heterostructures of colloidal lead halide perovskite nanocrystals (NCs) with other semiconductors, especially the technologically important metal chalcogenides, can offer an unprecedented level of control in wavefunction design and exciton/charge carrier engineering. These NC heterostructures are ideal material platforms for efficient optoelectronics and other applications. Existing methods, however, can only yield heterostructures with random connections and distributions of the two components. The lack of epitaxial relation and uniform geometry hinders the structure–function correlation and impedes the electronic coupling at the heterointerface. This work reports the synthesis of uniform, epitaxially grown CsPbBr3/CdS Janus NC heterostructures with ultrafast charge separation across the electronically coupled interface. Each Janus NC contains a CdS domain that grows exclusively on a single 220 facet of CsPbBr3 NCs. Varying reaction parameters allows for precise control in the sizes of each domain and readily modulates the optical properties of Janus NCs. Transient absorption measurements and modeling results reveal a type II band alignment, where photoexcited electrons rapidly transfer (within ≈9 picoseconds) from CsPbBr3 to CdS. The promoted charge separation and extraction in epitaxial Janus NCs leads to photoconductors with drastically improved (approximately three orders of magnitude) responsivity and detectivity, which is promising for ultrasensitive photodetection. CsPbBr3/CdS Janus nanocrystals with evident epitaxial relation and adjustable sizes, previously inaccessible for perovskite/metal chalcogenide nanocrystal heterostructures, are synthesized. The strongly coupled, type II alignment enables the ultrafast transfer of photoexcited electrons (within ≈9 ps) from CsPbBr3 to CdS domain, leading to over three orders of magnitude increases in photoconducting behaviors.

Solar-to-H 2 conversion is attracting much research attention as a potential approach to meet global renewable energy demands. Although significant advances have been made using metal-tipped colloidal cadmium chalcogenide zero-dimensional (0D) quantum dots and one-dimensional (1D) nanorod heterostructures in solar-to-H 2 conversion, their efficiency may be further enhanced using an emerging class of colloidal cadmium chalcogenide nanocrystals, namely two-dimensional (2D) nanoplatelets (NPLs), because of their unique properties. In this review, we summarize the recent advances on exciton dissociation dynamics and light-driven H 2 generation performance of colloidal nanoplatelet heterostructures. Following an introduction on the electronic structure of 2D NPLs, we discuss the dynamics of exciton dissociation by electron transfer to molecular acceptors. The exciton quenching dynamics of CdS NPL-Pt and CdSe NPL-Pt heterostructures are compared to highlight the effect of material properties on the relative contributions of the energy-transfer and electron-transfer pathways. Representative solar-to-H 2 conversion performances of 2D NPL-metal heterostructures are discussed and compared with those of 1D nanorod-metal heterostructures. Finally, we discuss the challenges in further improving the solar-to-fuel conversion efficiencies of these systems.

Colloidal semiconductor nanocrystals (NCs) have been extensively studied for their tunable bandgap energy and outstanding optical properties. This research focuses on the synthesis of CdSe/CdSeS heterostructure nanocrystals (HNCs) with precisely controlled spherical morphologies. The synthesis process involved forming a CdSe core and subsequently coating it with a CdSeS shell through the gradual injection of sulfur (S) precursors, allowing the shell thickness to be finely adjusted between two and six monolayers. As the shell thickness increases, both the emission and absorption spectra systematically shift to lower-energy regions, thereby modifying the optical properties of the HNCs. A strong correlation is observed between the interfacial strain at the CdSe/CdSeS boundary and the shell thickness, which significantly affects the efficiency of HNCs. Temperature-dependent analyses reveal variations in emission energy with temperature, offering insights into the thermal behavior and resilience of these crystals. Anomalies in the temperature-dependent photoluminescence linewidth are attributed to carrier relaxation into local energy minima caused by interfacial strain. Compared with bare NCs, core-shell HNCs demonstrate enhanced coupling between excitons and both longitudinal optical phonons and acoustic phonons. This study highlights the critical role of shell thickness in fine-tuning the optical and thermal properties of CdSe/CdSeS HNCs, offering valuable insights for their potential applications in advanced technologies.

The ability to control the active edge sites of transition metal dichalcogenides (TMDs) is crucial for modulating their chemical activity for various electrochemical applications, including hydrogen evolution reactions. In this study, we demonstrate a colloidal synthetic method to prepare core-shell-like heterostructures composed of MoSe2 and WSe2 via a two-step sequential growth. By overgrowing WSe2 on the surface of preexisting MoSe2 nanosheet edges, MoSe2-core/WSe2-shell heterostructures were successfully obtained. Systematic comparisons of the secondary growth time and sequential order of growth suggest that the low synthetic temperature conditions allow the stable overgrowth of shells rich in WSe2 on top of the core of MoSe2 with low Gibbs formation energy. The electrochemical analysis confirms that the catalytic activity correlates to the core-shell composition variation. Our results propose a new strategy to control the edge site activity of TMD materials prepared by colloidal synthesis, which is applicable to diverse electrochemical applications.

New advances in the sol–gel processing of ferroelectric ceramic powders and thin films and recently, scientific and technological interests in ferroelectric ceramics have been focused particularly on thin films. This is mainly due to their great potential applications in integrated electronics as passive components and as non-volatile ferroelectric memories, optoelectronic devices, etc. Special attention has been paid to the effects of the microstructure and composition on the piezoelectric properties of ferroelectric ceramic powders and thin films, and various characterization techniques are reported. This paper introduces the basic principles governing ferroelectricity and lists the various materials which exhibit these properties. The processing of ferroelectric ceramics and thin films in general and sol–gel processing in particular, with some examples are described. Finally, important applications of ferroelectric films and microstructure examination as well as powerful techniques are briefly discussed.

Structural control in metal/semiconductor multicomponent nanoparticles can lead to advanced functional properties, as optoelectronic processes and accessibility (e.g., by charge carriers or molecules) of the different components can be simultaneously tailored. In this study, the impact of surface‐adsorbed molecules (5‐amino‐2‐mercaptobenzimidazole ‐ AMBI) on the wet‐chemical deposition of cuprous oxide (Cu2O) shells on gold nanoprisms is investigated. It is shown that the otherwise excellent compatibility between gold and Cu2O, and hence the shell deposition, is profoundly influenced by the presence of AMBI. The time evolution of the optical and structural properties during the shell growth indicates that the inherent Volmer‐Weber characteristic of the Cu2O deposition process gets greatly amplified by the surface adsorption of AMBI. Measurements performed on individual nanoparticles show that this originates in the inhomogeneous, multi‐patch coverage of the particle surface. Under optimized synthetic conditions, the tips of the nanoprisms are effectively protected from Cu2O overgrowth and are left bare. Molecular patches created on the surface of gold nanoprisms enable the region‐selective growth of a Cu2O shell on the prisms, ensuring simultaneously the intimate contact between the metal and semiconductor phases and the accessibility of the high‐intensity plasmonic near‐field regions.

There have been tremendous efforts to develop new synthetic methods for creating novel nanoparticles (NPs) with enhanced and desired properties. Among the many synthetic approaches, NP synthesis through ion exchange is a versatile and powerful technique providing a new pathway to design complex structures as well as metastable NPs, which are not accessible by conventional syntheses. Herein, we introduce kinetic and thermodynamic factors controlling the ion exchange reactions in NPs to fully understand the fundamental mechanisms of the reactions. Additionally, many representative examples are summarized to find related advanced techniques and unique NPs constructed by ion exchange reactions. Cation exchange reactions mainly occur in chalcogenide compounds, while anion exchange reactions are mainly involved in halogen (e.g. perovskite) and metal-chalcogenide compounds. It is expected that NP syntheses through ion exchange reactions can be utilized to create new devices with the required properties by virtue of their versatility and ability to tune fine structures.