Raffaella Buonsanti

Related publications (127)

Copper Nanocrystal Morphology Determines the Viability of Molecular Surface Functionalization in Tuning Electrocatalytic Behavior in CO2 Reduction

Raffaella Buonsanti, Pranit Srinivas Iyengar, Valery Okatenko, James Richard Pankhurst

Molecular surface functionalization of metallic catalysts is emerging as an ever-developing approach to tuning their catalytic performance. Here, we report the synthesis of hybrid catalysts comprising copper nanocrystals (CuNCs) and an imidazolium ligand for the electrochemical CO2 reduction reaction (CO2RR). We show that this organic modifier steers the selectivity of cubic CuNCs toward liquid products. A comparison between cubic and spherical CuNCs reveals the impact of surface reconstruction on the viability of surface functionalization schemes. Indeed, the intrinsic instability of spherical CuNCs leads to ejection of the functionalized surface atoms. Finally, we also demonstrate that the more stable hybrid nanocrystal catalysts, which include cubic CuNCs, can be transferred into gas-flow CO2RR cells for testing under more industrially relevant conditions.

AMER CHEMICAL SOC2021

Copper, my precious!

Raffaella Buonsanti

To produce chemicals and fuels from CO2 and water while storing excess energy from renewable resources will play a big role in sustainability. Three decades ago, we learned that copper possesses the unique ability to break the stable CO2 bonds and to form C-C bonds, a key step towards higher-value products.

NATURE PORTFOLIO2021

Developing the Chemistry of Colloidal Cu Nanocrystals to Advance the CO2 Electrochemical Reduction

Raffaella Buonsanti

The ability to tailor make materials with atomic scale precision is crucial for understanding the sensitivities of their performance parameters and for achieving the design specification corresponding to optimal device operation. Herein, this topic is discussed in the context of catalysis. The electrochemical CO2 reduction reaction (CO2RR) holds the promise to close the carbon cycle by storing renewable energies in chemical feedstocks, yet it suffers from the lack of efficient and selective catalysts. This article highlights how colloidal chemistry can contribute to tackle this compelling issue by designing shape-controlled nanocatalysts. In particular, two case studies relative to copper nanocrystals are discussed.

SWISS CHEMICAL SOC2021

Emerging collaborations at the forefront of growth in electrochemical synthesis

Raffaella Buonsanti

CELL PRESS2021

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At the outermost surface of colloidal QDs are organic surface ligands which dynamically bind and release in solution to control the growth kinetics, control the size/shape of the crystals, passivate surface states, and provide colloidal stability through favorable interactions with the solvent. However, the dynamicity comes at the expense of the stability of the QD suspension. Here, we show that ligands can be permanently locked on the QD surface by a thin layer of an inert metal oxide which forms within the ligand shell, over the headgroup. By interrogating the surface chemistry with different spectroscopic methods, we prove the ligand locking on the QD surface. As a result, an exceptional stability of the coated QD inks is achieved in a wide concentration range, even in the presence of chemically competing surface ligands in solution. We anticipate that this critical breakthrough will benefit different areas related to colloidal QDs, spanning from single-particle studies to displays and solar cells and biological applications. Furthermore, the same chemistry could be easily translated to surface treatments of bulk materials and thin films.

2021

Hybrid materials constructed from the assembly of inorganic building blocks and organic linkers have shown unique properties and applications. Superstructures of semiconductor magic-sized nanoclusters linked by diamines now join this class of materials.

NATURE RESEARCH2021

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Engineering physicochemical properties of two-dimensional transition metal dichalcogenide (2D-TMD) materials by surface manipulation is essential to enabling their practical and large-scale application. This is especially challenging for colloidal 2D-TMDs that are plagued by the unintentional formation of structural defects during the synthetic procedure. However, the available methods to manage surface states of 2D-TMDs in solution phase are still limited, hampering the production of high-quality colloidal 2D-TMD inks. Here, we demonstrate an efficient solution-phase strategy to passivate surface defect states of colloidal WS2 nanoflakes with halide ligands, which results in the activation of their photoluminescence emission. Photophysical investigation and density functional theory calculations suggest that halide atoms enable the suppression of non-radiative recombination through the elimination of deep gap trap states and the introduction of localized states in the energy band structure from which excitons can efficiently recombine. Importantly, halide passivated WS2 nanoflakes retain colloidal stability and photoluminescence emission after several weeks of storage in ambient atmosphere, corroborating the potential of developed WS2 inks thereof.

2021

Shaping Copper Nanocatalysts to Steer Selectivity in the Electrochemical CO2 Reduction Reaction

Raffaella Buonsanti, Kevin Rossi

The carbon-neutral production of fuels and chemical feedstocks is one of the grand challenges for our society to solve. The electrochemical conversion of CO2 is emerging as a promising technology contributing to this goal. Despite the huge amount of progress made over the past decade, selectivity still remains a challenge. This Account presents an overview of recent progress in the design of selective catalysts by exploiting the structural sensitivity of the electrochemical CO2 reduction reaction (CO2RR). In particular, it shows that the accurate and precise control of the shape and size of Cu nanocatalysts is instrumental in understanding and in discovering the structure-selectivity relationships governing the reduction of CO2 to valuable hydrocarbons, such as methane and ethylene. It further illustrates the use of faceted Cu nanocatalysts to interrogate catalytic pathways and to increase selectivity toward oxygenates, such as ethanol, in the framework of tandem schemes. The last part of the Account highlights the role of well-defined nanocatalysts in identifying reconstruction mechanisms which might occur during operation. An outlook for the emerging paradigms which will empower the design of novel catalysts for CO2RR concludes the Account.

2021

The Inorganic Chemistry of Nanoparticles

Raffaella Buonsanti

2021

Theory-Guided Enhancement of CO2 Reduction to Ethanol on Ag-Cu Tandem Catalysts via Particle-Size Effects

Raffaella Buonsanti, Pranit Srinivas Iyengar, James Richard Pankhurst

In the CO2 reduction reaction, the design of electrocatalysts that selectively promote alcohols over hydrocarbons (e.g., ethanol over ethylene) hinges on the understanding of the pathways and specific sites that form alcohols. Herein, theoretical considerations guide state-of-the-art synthesis of well-defined catalysts to show that higher selectivity toward ethanol is achieved on Cu(110) edge sites compared to Cu(100) terraces. Specifically, we study the catalytic behavior of Cu nano-cubes (Cu-cub) of different sizes in the framework of tandem catalysis with CO-producing Ag nano-spheres. We predict and experimentally find that the smaller Cu-cub possess higher selectivity for ethanol in view of their larger edge-to-faces ratio and of the fact that ethylene is produced at terraces while ethanol is selectively produced at step edges. These results call for synthetic developments toward Cu nanostructures exposing only edge sites, such as hollow cubic nanocages, to further increase ethanol selectivity. More generally, this study encourages the application of well-defined nano catalysts as a bridge between theory and experiments in electrocatalysis.

AMER CHEMICAL SOC2021