Prospects of Nanoscience with Nanocrystals: 2025 Edition.

Nanocrystals (NCs) of various compositions have made important contributions to science and technology, with their impact recognized by the 2023 Nobel Prize in Chemistry for the discovery and synthesis of semiconductor quantum dots (QDs). Over four decades of research into NCs has led to numerous advancements in diverse fields, such as optoelectronics, catalysis, energy, medicine, and recently, quantum information and computing. The last 10 years since the predecessor perspective "Prospect of Nanoscience with Nanocrystals" was published in ACS Nano have seen NC research continuously evolve, yielding critical advances in fundamental understanding and practical applications.

Oxidant-assisted methane pyrolysis.

Methane pyrolysis has been proposed as a cost-competitive route to produce low-CO-emissions hydrogen that can utilize today's infrastructure to supply feedstock and manage waste, and thereby be rapidly scalable. However, this process faces challenges such as catalyst deactivation and carbon build-up that hinder its large-scale implementation. Pyrolysis is usually conducted in the absence of oxidizers to avoid combustion products such as CO.

Long-Range Metal-Sorbent Interactions Determine CO Capture and Conversion in Dual-Function Materials.

Carbon capture and utilization involve multiple energy- and cost-intensive steps. Dual-function materials (DFMs) can reduce these demands by coupling CO adsorption and conversion into a single material with two functionalities: a sorbent phase and a metal for catalytic CO conversion. The role of metal catalysts in the conversion process seems salient from previous work, but the underlying mechanisms remain elusive and deserve deeper investigation to achieve maximum utilization of the two phases.

A General Approach for Metal Nanoparticle Encapsulation Within Porous Oxides.

Encapsulation of metal nanoparticles within oxide materials has been shown as an effective strategy to improve activity, selectivity, and stability in several catalytic applications. Several approaches have been proposed to encapsulate nanoparticles, such as forming core-shell structures, growing ordered structures (zeolites or metal-organic frameworks) on nanoparticles, or directly depositing support materials on nanoparticles. Here, a general nanocasting method is demonstrated that can produce diverse encapsulated metal@oxide structures with different compositions (Pt, Pd, Rh) and multiple types of oxides (AlO, AlO-CeO, ZrO, ZnZrO, InO, MnO, TiO) while controlling the size and dispersion of nanoparticles and the porous structure of the oxide.

Unveiling the Stability of Encapsulated Pt Catalysts Using Nanocrystals and Atomic Layer Deposition.

Platinum exhibits desirable catalytic properties, but it is scarce and expensive. Optimizing its use in key applications such as emission control catalysis is important to reduce our reliance on such a rare element. Supported Pt nanoparticles (NPs) used in emission control systems deactivate over time because of particle growth in sintering processes.

Steam-Assisted Selective CO Hydrogenation to Ethanol over Ru-In Catalysts.

Multicomponent catalysts can be designed to synergistically combine reaction intermediates at interfacial active sites, but restructuring makes systematic control and understanding of such dynamics challenging. We here unveil how reducibility and mobility of indium oxide species in Ru-based catalysts crucially control the direct, selective conversion of CO to ethanol. When uncontrolled, reduced indium oxide species occupy the Ru surface, leading to deactivation.

Understanding and Harnessing Nanoscale Immiscibility in Ru-In Alloys for Selective CO Hydrogenation.

Bimetallic alloys made from immiscible elements are characterized by their tendency to segregate on the macroscopic scale, but their behavior is known to change at the nanoscale. Here, we demonstrate that in the Ru-In system, In atoms preferentially decorate the surface of 6 nm Ru nanoparticles, forming Ru-In superficial immiscible alloys. This surface decoration dramatically affects the catalytic performance of the system, even at small atomic fractions of In added to Ru.

Palladium Catalysts for Methane Oxidation: Old Materials, New Challenges.

ConspectusMethane complete oxidation is an important reaction that is part of the general scheme used for removing pollutants contained in emissions from internal combustion engines and, more generally, combustion processes. It has also recently attracted interest as an option for the removal of atmospheric methane in the context of negative emission technologies. Methane, a powerful greenhouse gas, can be converted to carbon dioxide and water via its complete oxidation.

Controlling the Strong Metal-Support Interaction Overlayer Structure in Pt/TiO Catalysts Prevents Particle Evaporation.

Platinum nanoparticles (NPs) supported by titania exhibit a strong metal-support interaction (SMSI) that can induce overlayer formation and encapsulation of the NP's with a thin layer of support material. This encapsulation modifies the catalyst's properties, such as increasing its chemoselectivity and stabilizing it against sintering. Encapsulation is typically induced during high-temperature reductive activation and can be reversed through oxidative treatments.

Selective Catalytic Behavior Induced by Crystal-Phase Transformation in Well-Defined Bimetallic Pt-Sn Nanocrystals.

The Pt-Sn bimetallic system is a much studied and commercially used catalyst for propane dehydrogenation. The traditionally prepared catalyst, however, suffers from inhomogeneity and phase separation of the active Pt-Sn phase. Colloidal chemistry offers a route for the synthesis of Pt-Sn bimetallic nanoparticles (NPs) in a systematic, well-defined, tailored fashion over conventional methods.

Templated encapsulation of platinum-based catalysts promotes high-temperature stability to 1,100 °C.

Stable catalysts are essential to address energy and environmental challenges, especially for applications in harsh environments (for example, high temperature, oxidizing atmosphere and steam). In such conditions, supported metal catalysts deactivate due to sintering-a process where initially small nanoparticles grow into larger ones with reduced active surface area-but strategies to stabilize them can lead to decreased performance. Here we report stable catalysts prepared through the encapsulation of platinum nanoparticles inside an alumina framework, which was formed by depositing an alumina precursor within a separately prepared porous organic framework impregnated with platinum nanoparticles.

Recycling of Solvent Allows for Multiple Rounds of Reproducible Nanoparticle Synthesis.

Metal nanoparticles have superior properties for a variety of applications. In many cases, the improved performance of metal nanoparticles is tightly correlated with their size and atomic composition. To date, colloidal synthesis is the most commonly used technique to produce metal nanoparticles.

Sulfur-treated TiO shows improved alcohol dehydration activity and selectivity.

The dehydration of alcohols is an important class of reactions for the development of fossil-free fuel and chemical industries. Acid catalysts are well known to enhance the reactivity of alcohols following two main pathways of either dehydration to olefins or dehydrogenation to ketones/aldehydes. TiO surfaces have been well documented for primary and secondary alcohol dehydration with selectivity ranging from 1-100% towards dehydration products based on process conditions and catalyst structure.

Steering CO hydrogenation toward C-C coupling to hydrocarbons using porous organic polymer/metal interfaces.

The conversion of CO into fuels and chemicals is an attractive option for mitigating CO emissions. Controlling the selectivity of this process is beneficial to produce desirable liquid fuels, but C-C coupling is a limiting step in the reaction that requires high pressures. Here, we propose a strategy to favor C-C coupling on a supported Ru/TiO catalyst by encapsulating it within the polymer layers of an imine-based porous organic polymer that controls its selectivity.

Colloidal Platinum-Copper Nanocrystal Alloy Catalysts Surpass Platinum in Low-Temperature Propene Combustion.

Low-temperature removal of noxious environmental emissions plays a critical role in minimizing the harmful effects of hydrocarbon fuels. Emission-control catalysts typically consist of large quantities of rare, noble metals (e.g.

Voltage cycling process for the electroconversion of biomass-derived polyols.

Electrification of chemical reactions is crucial to fundamentally transform our society that is still heavily dependent on fossil resources and unsustainable practices. In addition, electrochemistry-based approaches offer a unique way of catalyzing reactions by the fast and continuous alteration of applied potentials, unlike traditional thermal processes. Here, we show how the continuous cyclic application of electrode potential allows Pt nanoparticles to electrooxidize biomass-derived polyols with turnover frequency improved by orders of magnitude compared with the usual rates at fixed potential conditions.

Atmospheric methane removal: a research agenda.

Atmospheric methane removal (e.g. methane oxidation to carbon dioxide) may be needed to offset continued methane release and limit the global warming contribution of this potent greenhouse gas.

Steam-created grain boundaries for methane C-H activation in palladium catalysts.

Defects may display high reactivity because the specific arrangement of atoms differs from crystalline surfaces. We demonstrate that high-temperature steam pretreatment of palladium catalysts provides a 12-fold increase in the mass-specific reaction rate for carbon-hydrogen (C–H) activation in methane oxidation compared with conventional pretreatments. Through a combination of experimental and theoretical methods, we demonstrate that an increase in the grain boundary density through crystal twinning is achieved during the steam pretreatment and oxidation and is responsible for the increased reactivity.

A General Approach for Monolayer Adsorption of High Weight Loadings of Uniform Nanocrystals on Oxide Supports.

Monodispersed metal and semiconductor nanocrystals have attracted great attention in fundamental and applied research due to their tunable size, morphology, and well-defined chemical composition. Utilizing these nanocrystals in a controllable way is highly desirable especially when using them as building blocks for the preparation of nanostructured materials. Their deposition onto oxide materials provide them with wide applicability in many areas, including catalysis.

Size-controlled nanocrystals reveal spatial dependence and severity of nanoparticle coalescence and Ostwald ripening in sintering phenomena.

A major aim in the synthesis of nanomaterials is the development of stable materials for high-temperature applications. Although the thermal coarsening of small and active nanocrystals into less active aggregates is universal in material deactivation, the atomic mechanisms governing nanocrystal growth remain elusive. By utilizing colloidally synthesized Pd/SiO2 powder nanocomposites with controlled nanocrystal sizes and spatial arrangements, we unravel the competing contributions of particle coalescence and atomic ripening processes in nanocrystal growth.

Design of Organic/Inorganic Hybrid Catalysts for Energy and Environmental Applications.

Controlling selectivity between competing reaction pathways is crucial in catalysis. Several approaches have been proposed to achieve this goal in traditional heterogeneous catalysts including tuning nanoparticle size, varying alloy composition, and controlling supporting material. A less explored and promising research area to control reaction selectivity is via the use of hybrid organic/inorganic catalysts.

Nanoscale Spatial Distribution of Supported Nanoparticles Controls Activity and Stability in Powder Catalysts for CO Oxidation and Photocatalytic H Evolution.

Supported metal nanoparticles are essential components of high-performing catalysts, and their structures are intensely researched. In comparison, nanoparticle spatial distribution in powder catalysts is conventionally not quantified, and the influence of this collective property on catalyst performance remains poorly investigated. Here, we demonstrate a general colloidal self-assembly method to control uniformity of nanoparticle spatial distribution on common industrial powder supports.

Readily Constructed Glass Piston Pump for Gas Recirculation.

The recirculation of gases in a sealed reactor system is a broadly useful method in catalytic and electrocatalytic studies. It is especially relevant when a reactant gas reacts slowly with respect to residence time in a catalytic reaction zone and when mass transport control through the reaction zone is necessary. This need is well illustrated in the field of electrocatalytic N reduction, where the need for recirculation of N has recently become more apparent.