Convergent Active Site Evolution in Platinum Single Atom Catalysts for Acetylene Hydrochlorination and Implications for Toxicity Minimization.

Platinum single atoms anchored onto activated carbon enable highly stable Hg-free synthesis of vinyl chloride (VCM) via acetylene hydrochlorination. Compared to gold-based alternatives, platinum catalysts are in initial phases of development. Most synthetic approaches rely on chloroplatinic acid, presenting opportunities to explore other precursors and their impact on catalyst structure, reactivity, and toxicity aspects.

Metastable CoCuO Nanocrystals from Combustion-Aerosols for Molecular Sensing and Catalysis.

Metastable nanostructures are kinetically trapped in local energy minima featuring intriguing surface and material properties. To unleash their potential, there is a need for non-equilibrium processes capable of stabilizing a large range of crystal phases outside thermodynamic equilibrium conditions by closely and flexibly controlling atomic reactant composition, spatial temperature distribution and residence time. Here, the capture of metastable pseudo-binary metal oxides at room temperature is demonstrated with scalable combustion-aerosol processes.

Mechanochemically-derived iron atoms on defective boron nitride for stable propylene production.

Single-atom catalysts (SACs), possessing a uniform metal site structure, are a promising class of materials for selective oxidations of hydrocarbons. However, their design for targeted applications requires careful choice of metal-host combinations and suitable synthetic techniques. Here, we report iron atoms stabilised on defective hexagonal boron nitride (h-BN) mechanochemical activation in a ball mill as an effective catalyst for propylene production NO-mediated oxidative propane dehydrogenation (NO-ODHP), reaching 95% selectivity at 6% propane conversion and maintaining stable performance for 40 h on stream.

A Dye-Sensitized Sensor for Oxygen Detection under Visible Light.

Sensors that can accurately assess oxygen (O) concentrations in real time are crucial for a wide range of applications spanning personal health monitoring, environmental protection, and industrial process development. Here a high-performance chemiresistive sensor that allows for the rapid detection of O at room temperature under visible light illumination is described. Inspired by the operating principles of dye-sensitized solar cells, the chemiresistor is based on a single-walled carbon nanotube-titania hybrid (SWCNT-TiO) bearing a molecular Re-based photosensitizer [(bpy)(CO)ReBr] (bpy = 4,4'-[P(O)(OH)]-2,2'-bipyridine).

Triphenylphosphine Oxide: A Versatile Covalent Functionality for Carbon Nanotubes.

Broadening the scope of functionalities that can be covalently bound to single-walled carbon nanotubes (SWCNTs) is crucial for enhancing the versatility of this promising nanomaterial class in applied settings. Here we report the covalent linkage of triphenylphosphine oxide [PhP(O)] to SWCNTs, a hitherto overlooked surface functionality. We detail the synthesis and structural characterization of a new family of phosphine oxide-functionalized diaryliodonium salts that can facilitate direct PhP(O) transfer and afford novel SWCNTs with tunable PhP(O) content (SWCNT-P).

Low-nuclearity CuZn ensembles on ZnZrO catalyze methanol synthesis from CO.

Metal promotion could unlock high performance in zinc-zirconium catalysts, ZnZrO, for CO hydrogenation to methanol. Still, with most efforts devoted to costly palladium, the optimal metal choice and necessary atomic-level architecture remain unclear. Herein, we investigate the promotion of ZnZrO catalysts with small amounts (0.

Lattice-Stabilized Chromium Atoms on Ceria for NO Synthesis.

The development of selective catalysts for direct conversion of ammonia into nitrous oxide, NO, will circumvent the conventional five-step manufacturing process and enable its wider utilization in oxidation catalysis. Deviating from commonly accepted catalyst design principles for this reaction, reliant on manganese oxide, we herein report an efficient system comprised of isolated chromium atoms (1 wt %) stabilized in the ceria lattice by coprecipitation. The latter, in contrast to a simple impregnation approach, ensures firm metal anchoring and results in stable and selective NO production over 100 h on stream up to 79% NO selectivity at full NH conversion.

Evidence of bifunctionality of carbons and metal atoms in catalyzed acetylene hydrochlorination.

Carbon supports are ubiquitous components of heterogeneous catalysts for acetylene hydrochlorination to vinyl chloride, from commercial mercury-based systems to more sustainable metal single-atom alternatives. Their potential co-catalytic role has long been postulated but never unequivocally demonstrated. Herein, we evidence the bifunctionality of carbons and metal sites in the acetylene hydrochlorination catalytic cycle.

Pyrochlore-Type Iron Hydroxy Fluorides as Low-Cost Lithium-Ion Cathode Materials for Stationary Energy Storage.

Pyrochlore-type iron (III) hydroxy fluorides (Pyr-IHF) are appealing low-cost stationary energy storage materials due to the virtually unlimited supply of their constituent elements, their high energy densities, and fast Li-ion diffusion. However, the prohibitively high costs of synthesis and cathode architecture currently prevent their commercial use in low-cost Li-ion batteries. Herein, a facile and cost-effective dissolution-precipitation synthesis of Pyr-IHF from soluble iron (III) fluoride precursors is presented.

Low-Valent Manganese Atoms Stabilized on Ceria for Nitrous Oxide Synthesis.

Nitrous oxide, N O, exhibits unique reactivity in oxidation catalysis, but the high manufacturing costs limit its prospective uses. Direct oxidation of ammonia, NH , to N O can ameliorate this issue but its implementation is thwarted by suboptimal catalyst selectivity and stability, and the lack of established structure-performance relationships. Systematic and controlled material nanostructuring offers an innovative approach for advancement in catalyst design.

Thermal synthesis of conversion-type bismuth fluoride cathodes for high-energy-density Li-ion batteries.

Towards enhancement of the energy density of Li-ion batteries, BiF has recently attracted considerable attention as a compelling conversion-type cathode material due to its high theoretical capacity of 302 mAh g, average discharge voltage of ca. 3.0 V vs.

Confinement-Tunable Transition Dipole Moment Orientation in Perovskite Nanoplatelet Solids and Binary Blends.

Tuning the transition dipole moment (TDM) orientation in low-dimensional semiconductors is of fundamental and practical interest, as it enables high-efficiency nanophotonics and light-emitting diodes. However, despite recent progress in nanomaterials physics and chemistry, material systems that allow continuous tuning of the TDM orientation remain rare. Here, combining -space photoluminescence spectroscopy and multiscale modeling, we demonstrate that the TDM orientation in lead halide perovskite (LHP) nanoplatelet (NPL) solids is largely confinement-tunable through the NPL geometry that regulates the anisotropy of Bloch states, dielectric confinement, and exciton fine structure.

Platinum-Iron(II) Oxide Sites Directly Responsible for Preferential Carbon Monoxide Oxidation at Ambient Temperature: An Operando X-ray Absorption Spectroscopy Study.

Operando X-ray absorption spectroscopy identified that the concentration of Fe species in the working state-of-the-art Pt-FeO catalysts quantitatively correlates to their preferential carbon monoxide oxidation steady-state reaction rate at ambient temperature. Deactivation of such catalysts with time on stream originates from irreversible oxidation of active Fe sites. The active Fe species are presumably Fe O clusters in contact with platinum nanoparticles; they coexist with spectator trivalent oxidic iron (Fe ) and metallic iron (Fe ) partially alloyed with platinum.

Operando Laboratory-Based Multi-Edge X-Ray Absorption Near-Edge Spectroscopy of Solid Catalysts.

Laboratory-based X-ray absorption spectroscopy (XAS) and especially X-ray absorption near-edge structure (XANES) offers new opportunities in catalyst characterization and presents not only an alternative, but also a complementary approach to precious beamtime at synchrotron facilities. We successfully designed a laboratory-based setup for performing operando, quasi-simultaneous XANES analysis at multiple K-edges, more specifically, operando XANES of mono-, bi-, and trimetallic CO hydrogenation catalysts containing Ni, Fe, and Cu. Detailed operando XANES studies of the multielement solid catalysts revealed metal-dependent differences in the reducibility and re-oxidation behavior and their influence on the catalytic performance in CO hydrogenation.

Performance descriptors of nanostructured metal catalysts for acetylene hydrochlorination.

Controlling the precise atomic architecture of supported metals is central to optimizing their catalytic performance, as recently exemplified for nanostructured platinum and ruthenium systems in acetylene hydrochlorination, a key process for vinyl chloride production. This opens the possibility of building on historically established activity correlations. In this study, we derived quantitative activity, selectivity and stability descriptors that account for the metal-dependent speciation and host effects observed in acetylene hydrochlorination.

Anisotropic nanocrystal superlattices overcoming intrinsic light outcoupling efficiency limit in perovskite quantum dot light-emitting diodes.

Quantum dot (QD) light-emitting diodes (LEDs) are emerging as one of the most promising candidates for next-generation displays. However, their intrinsic light outcoupling efficiency remains considerably lower than the organic counterpart, because it is not yet possible to control the transition-dipole-moment (TDM) orientation in QD solids at device level. Here, using the colloidal lead halide perovskite anisotropic nanocrystals (ANCs) as a model system, we report a directed self-assembly approach to form the anisotropic nanocrystal superlattices (ANSLs).

Reconfigurable halide perovskite nanocrystal memristors for neuromorphic computing.

Many in-memory computing frameworks demand electronic devices with specific switching characteristics to achieve the desired level of computational complexity. Existing memristive devices cannot be reconfigured to meet the diverse volatile and non-volatile switching requirements, and hence rely on tailored material designs specific to the targeted application, limiting their universality. "Reconfigurable memristors" that combine both ionic diffusive and drift mechanisms could address these limitations, but they remain elusive.

Remarkable stability of a molecular ruthenium complex in PEM water electrolysis.

The dinuclear Ru diazadiene olefin complex, [Ru(OTf)(μ-H)(Medad)(dbcot)], is an active catalyst for hydrogen evolution in a Polymer Exchange Membrane (PEM) water electrolyser. When supported on high surface area carbon black and at 80 °C, [Ru(OTf)(μ-H)(Medad)(dbcot)]@C evolves hydrogen at the cathode of a PEM electrolysis cell (400 mA cm, 1.9 V).

Stabilization of Lead-Reduced Metal Halide Perovskite Nanocrystals by High-Entropy Alloying.

Colloidal metal halide perovskite (MHP) nanocrystals (NCs) are an emerging class of fluorescent quantum dots (QDs) for next-generation optoelectronics. A great hurdle hindering practical applications, however, is their high lead content, where most attempts addressing the challenge in the literature compromised the material's optical performance or colloidal stability. Here, we present a postsynthetic approach that stabilizes the lead-reduced MHP NCs through high-entropy alloying.

Controlled Formation of Dimers and Spatially Isolated Atoms in Bimetallic Au-Ru Catalysts via Carbon-Host Functionalization.

The introduction of a foreign metal atom in the coordination environment of single-atom catalysts constitutes an exciting frontier of active-site engineering, generating bimetallic low-nuclearity catalysts often exhibiting unique catalytic synergies. To date, the exploration of their full scope is thwarted by (i) the lack of synthetic techniques with control over intermetallic coordination, and (ii) the challenging characterization of these materials. Herein, carbon-host functionalization is presented as a strategy to selectively generate Au-Ru dimers and isolated sites by simple incipient wetness impregnation, as corroborated by careful X-ray absorption spectroscopy analysis.

Ceria-Supported Gold Nanoparticles as a Superior Catalyst for Nitrous Oxide Production via Ammonia Oxidation.

The production of nitrous oxide, N O, via NH oxidation is not on a practical scale due to the lack of a suitable catalyst. Instead, it is produced via thermal decomposition of NH NO , rendering N O too costly and limiting its prospective uses. Herein, we report CeO -supported Au nanoparticles (2-3 nm) as a highly selective catalyst for low-temperature NH oxidation to N O, exhibiting two orders of magnitude higher space-time yield than the state-of-the-art Mn-Bi/α-Al O and remarkable stability over 70 h on stream.

Design of carbon supports for metal-catalyzed acetylene hydrochlorination.

For decades, carbons have been the support of choice in acetylene hydrochlorination, a key industrial process for polyvinyl chloride manufacture. However, no unequivocal design criteria could be established to date, due to the complex interplay between the carbon host and the metal nanostructure. Herein, we disentangle the roles of carbon in determining activity and stability of platinum-, ruthenium-, and gold-based hydrochlorination catalysts and derive descriptors for optimal host design, by systematically varying the porous properties and surface functionalization of carbon, while preserving the active metal sites.

Sparse ab initio x-ray transmission spectrotomography for nanoscopic compositional analysis of functional materials.

The performance of functional materials is either driven or limited by nanoscopic heterogeneities distributed throughout the material's volume. To better our understanding of these materials, we need characterization tools that allow us to determine the nature and distribution of these heterogeneities in their native geometry in 3D. Here, we introduce a method based on x-ray near-edge spectroscopy, ptychographic x-ray computed nanotomography, and sparsity techniques.