2023 New's Items

Congratulations to the 2023 Kavli ENSI Fellowship Recipients!

August 1, 2023

Energy Funneling in a Noninteger Two-Dimensional Perovskite

Oddo A
Yang P
2023

Energy funneling is a phenomenon that has been exploited in optoelectronic devices based on low-dimensional materials to improve their performance. Here, we introduce a new class of two-dimensional semiconductor, characterized by multiple regions of varying thickness in a single confined nanostructure with homogeneous composition. This “noninteger 2D semiconductor” was prepared via the structural transformation of two-octahedron-layer-thick (n = 2) 2D cesium lead bromide perovskite nanosheets; it consisted of a central n = 2 region surrounded by edge-lying...

Operando methods: A new era of electrochemistry

Yang Y
Yang P
2023

One of the grand challenges facing electrochemistry is to directly resolve the complex nature of (electro)catalyst active sites and capture real-time “movies” of reaction dynamics, i.e. “watching chemistry in action”. The need for such fundamental understanding has stimulated the development of operando/in situ methods, which have greatly enhanced our ability to identify activity descriptors of electrocatalysts and establish structure–property relationships of energy materials. This review summarizes the frontiers of operando electrochemical liquid-cell scanning transmission electron...

Operando High-Energy-Resolution X-ray Spectroscopy of Evolving Cu Nanoparticle Electrocatalysts for CO2 Reduction

Feijóo J
Yang P
2023

Advances in electrocatalysis research rely heavily on building a thorough mechanistic understanding of catalyst active sites under realistic operating conditions. Only recently have techniques emerged that enable sensitive spectroscopic data collection to distinguish catalytically relevant surface sites from the underlying bulk material under applied potential in the presence of an electrolyte layer. Here, we demonstrate that operando high-energy-resolution fluorescence detected X-ray absorption spectroscopy (HERFD-XAS) is a powerful spectroscopic method which offers...

High-Photovoltage Silicon Nanowire for Biological Cofactor Production

Lineberry E
Yang P
2023

Photocathodic conversion of NAD+ to NADH cofactor is a promising platform for activating redox biological catalysts and enzymatic synthesis using renewable solar energy. However, many photocathodes suffer from low photovoltage, consequently requiring a high cathodic bias for NADH production. Here, we report an n+p-type silicon nanowire (n+p-SiNW) photocathode having a photovoltage of 435 mV to drive energy-efficient NADH production. The enhanced band bending at the n+/p interface accounts for the high photovoltage, which conduces to a...

Synthesis of Carbohydrates from Methanol Using Electrochemical Partial Oxidation over Palladium with the Integrated Formose Reaction

Soland N
Yang P
2023

Electrochemically derived multicarbon products are a golden target for valorization of captured carbon dioxide due to the potential of turning a waste product into useful commodity chemicals with renewable energy sources. As a tantalizing approach toward their synthesis, the formose reaction utilizes catalytic condensation of formaldehyde to generate carbohydrates. While a sustainable approach to artificial carbohydrate production through electrochemical generation of formaldehyde is desirable, to date, it has not been fully realized. Here, we study the electrocatalytic conversion of...

High-entropy halide perovskite single crystals stabilized by mild chemistry

Folgueras MC
Yang P
2023

Although high-entropy materials are excellent candidates for a range of functional materials, their formation traditionally requires high-temperature synthetic procedures of over 1,000 °C and complex processing techniques such as hot rolling1,...

Understanding the Structural Evolution of IrFeCoNiCu High-Entropy Alloy Nanoparticles under the Acidic Oxygen Evolution Reaction

Maulana AL
Yang P
2023

High-entropy alloy (HEA) nanoparticles are promising catalyst candidates for the acidic oxygen evolution reaction (OER). Herein, we report the synthesis of IrFeCoNiCu-HEA nanoparticles on a carbon paper substrate via a microwave-assisted shock synthesis method. Under OER conditions in 0.1 M HClO4, the HEA nanoparticles exhibit excellent activity with an overpotential of ∼302 mV measured at 10 mA cm–2 and improved stability over 12 h of operation compared to the monometallic Ir counterpart. Importantly, an active Ir-rich shell layer...

Quantification of strain and its impact on the phase stabilization of all-inorganic cesium lead iodide perovskites

Le HKD
Yang P
2023

The high-temperature perovskite γ-phase of CsPbI3 readily undergoes phase transition at ambient conditions to a low-temperature non-perovskite δ-phase with a poorer optoelectronic performance, thus hindering commercialization of these materials in photovoltaics. Here, we present the epitaxial growth of CsPbI3 nanoplates on muscovite mica single-crystal substrates and demonstrate that the high-temperature phase stability of these nanoplates is enhanced by a strained interface. Strain is measured as a function of nanoplate thickness...

Photochemical Diodes for Simultaneous Bias-Free Glycerol Valorization and Hydrogen Evolution

Lin JA
Roh I
Yang P
2023

Artificial photosynthesis offers a route to producing clean fuel energy. However, the large thermodynamic requirement for water splitting along with the corresponding sluggish kinetics for the oxygen evolution reaction (OER) limits its current practical application. Here, we offer an alternative approach by replacing the OER with the glycerol oxidation reaction (GOR) for value-added chemicals. By using a Si photoanode, a low GOR onset potential of −0.05 V vs RHE and a photocurrent density of 10 mA/cm2 at 0.5 V vs RHE can be reached. Coupled with a Si...