Bimetallic Metal Sites in Metal-Organic Frameworks Facilitate the Production of 1-Butene from Electrosynthesized Ethylene.

Converting CO2 to synthetic hydrocarbon fuels is of increasing interest. In light of progress in electrified CO2 to ethylene, we explored routes to dimerize to 1-butene, an olefin that can serve as a building block to ethylene longer-chain alkanes. With goal of selective and active dimerization, we investigate a series of metal-organic frameworks having bimetallic catalytic sites. We find that the tunable pore structure enables optimization of selectivity and that periodic pore channels enhance activity. In a tandem system for the conversion of CO2 to 1-C4H8, wherein the outlet cathodic gas from a CO2-to-C2H4 electrolyzer is fed directly (via a dehumidification stage) into the C2H4 dimerizer, we study the highest-performing MOF found herein: M' = Ru and M″ = Ni in the bimetallic two-dimensional M'2(OAc)4M″(CN)4 MOF. We report a 1-C4H8 production rate of 1.3 mol gcat-1 h-1 and a C2H4 conversion of 97%. From these experimental data, we project an estimated cradle-to-gate carbon intensity of -2.1 kg-CO2e/kg-1-C4H8 when CO2 is supplied from direct air capture and when the required energy is supplied by electricity having the carbon intensity of wind.

Phenotypic targeting using magnetic nanoparticles for rapid characterization of cellular proliferation regulators.

Genome-wide CRISPR screens have provided a systematic way to identify essential genetic regulators of a phenotype of interest with single-cell resolution. However, most screens use live/dead readout of viability to identify factors of interest. Here, we describe an approach that converts cell proliferation into the degree of magnetization, enabling downstream microfluidic magnetic sorting to be performed. We performed a head-to-head comparison and verified that the magnetic workflow can identify the same hits from a traditional screen while reducing the screening period from 4 weeks to 1 week. Taking advantage of parallelization and performance, we screened multiple mesenchymal cancer cell lines for their dependency on cell proliferation. We found and validated pan- and cell-specific potential therapeutic targets. The method presented provides a nanoparticle-enabled approach means to increase the breadth of data collected in CRISPR screens, enabling the rapid discovery of drug targets for treatment.

Improved charge extraction in inverted perovskite solar cells with dual-site-binding ligands.

Inverted (pin) perovskite solar cells (PSCs) afford improved operating stability in comparison to their nip counterparts but have lagged in power conversion efficiency (PCE). The energetic losses responsible for this PCE deficit in pin PSCs occur primarily at the interfaces between the perovskite and the charge-transport layers. Additive and surface treatments that use passivating ligands usually bind to a single active binding site: This dense packing of electrically resistive passivants perpendicular to the surface may limit the fill factor in pin PSCs. We identified ligands that bind two neighboring lead(II) ion (Pb2+) defect sites in a planar ligand orientation on the perovskite. We fabricated pin PSCs and report a certified quasi-steady state PCE of 26.15 and 24.74% for 0.05- and 1.04-square centimeter illuminated areas, respectively. The devices retain 95% of their initial PCE after 1200 hours of continuous 1 sun maximum power point operation at 65°C.

Nickel Oxide Hole Injection Layers for Balanced Charge Injection in Quantum Dot Light-Emitting Diodes.

Quantum dot (QD) light-emitting diodes (QLEDs) are promising for next-generation displays, but suffer from carrier imbalance arising from lower hole injection compared to electron injection. A defect engineering strategy is reported to tackle transport limitations in nickel oxide-based inorganic hole-injection layers (HILs) and find that hole injection is able to enhance in high-performance InP QLEDs using the newly designed material. Through optoelectronic simulations, how the electronic properties of NiOx affect hole injection efficiency into an InP QD layer, finding that efficient hole injection depends on lowering the hole injection barrier and enhancing the acceptor density of NiOx is explored. Li doping and oxygen enriching are identified as effective strategies to control intrinsic and extrinsic defects in NiOx, thereby increasing acceptor density, as evidenced by density functional theory calculations and experimental validation. With fine-tuned inorganic HIL, InP QLEDs exhibit a luminance of 45 200 cd m-2 and an external quantum efficiency of 19.9%, surpassing previous inorganic HIL-based QLEDs. This study provides a path to designing inorganic materials for more efficient and sustainable lighting and display technologies.

Ligand-modified nanoparticle surfaces influence CO electroreduction selectivity.

Improving the kinetics and selectivity of CO2/CO electroreduction to valuable multi-carbon products is a challenge for science and is a requirement for practical relevance. Here we develop a thiol-modified surface ligand strategy that promotes electrochemical CO-to-acetate. We explore a picture wherein nucleophilic interaction between the lone pairs of sulfur and the empty orbitals of reaction intermediates contributes to making the acetate pathway more energetically accessible. Density functional theory calculations and Raman spectroscopy suggest a mechanism where the nucleophilic interaction increases the sp2 hybridization of CO(ad), facilitating the rate-determining step, CO* to (CHO)*. We find that the ligands stabilize the (HOOC-CH2)* intermediate, a key intermediate in the acetate pathway. In-situ Raman spectroscopy shows shifts in C-O, Cu-C, and C-S vibrational frequencies that agree with a picture of surface ligand-intermediate interactions. A Faradaic efficiency of 70% is obtained on optimized thiol-capped Cu catalysts, with onset potentials 100 mV lower than in the case of reference Cu catalysts.

Selective Electrified Propylene-to-Propylene Glycol Oxidation on Activated Rh-Doped Pd.

Renewable-energy-powered electrosynthesis has the potential to contribute to decarbonizing the production of propylene glycol, a chemical that is used currently in the manufacture of polyesters and antifreeze and has a high carbon intensity. Unfortunately, to date, the electrooxidation of propylene under ambient conditions has suffered from a wide product distribution, leading to a low faradic efficiency toward the desired propylene glycol. We undertook mechanistic investigations and found that the reconstruction of Pd to PdO occurs, followed by hydroxide formation under anodic bias. The formation of this metastable hydroxide layer arrests the progressive dissolution of Pd in a locally acidic environment, increases the activity, and steers the reaction pathway toward propylene glycol. Rh-doped Pd further improves propylene glycol selectivity. Density functional theory (DFT) suggests that the Rh dopant lowers the energy associated with the production of the final intermediate in propylene glycol formation and renders the desorption step spontaneous, a concept consistent with experimental studies. We report a 75% faradic efficiency toward propylene glycol maintained over 100 h of operation.

CO2 Electrolyzers.

CO2 electrolyzers have progressed rapidly in energy efficiency and catalyst selectivity toward valuable chemical feedstocks and fuels, such as syngas, ethylene, ethanol, and methane. However, each component within these complex systems influences the overall performance, and the further advances needed to realize commercialization will require an approach that considers the whole process, with the electrochemical cell at the center. Beyond the cell boundaries, the electrolyzer must integrate with upstream CO2 feeds and downstream separation processes in a way that minimizes overall product energy intensity and presents viable use cases. Here we begin by describing upstream CO2 sources, their energy intensities, and impurities. We then focus on the cell, the most common CO2 electrolyzer system architectures, and each component within these systems. We evaluate the energy savings and the feasibility of alternative approaches including integration with CO2 capture, direct conversion of flue gas and two-step conversion via carbon monoxide. We evaluate pathways that minimize downstream separations and produce concentrated streams compatible with existing sectors. Applying this comprehensive upstream-to-downstream approach, we highlight the most promising routes, and outlook, for electrochemical CO2 reduction.

Engineering colloidal semiconductor nanocrystals for quantum information processing.

Quantum information processing-which relies on spin defects or single-photon emission-has shown quantum advantage in proof-of-principle experiments including microscopic imaging of electromagnetic fields, strain and temperature in applications ranging from battery research to neuroscience. However, critical gaps remain on the path to wider applications, including a need for improved functionalization, deterministic placement, size homogeneity and greater programmability of multifunctional properties. Colloidal semiconductor nanocrystals can close these gaps in numerous application areas, following years of rapid advances in synthesis and functionalization. In this Review, we specifically focus on three key topics: optical interfaces to long-lived spin states, deterministic placement and delivery for sensing beyond the standard quantum limit, and extensions to multifunctional colloidal quantum circuits.

The dynamic adsorption affinity of ligands is a surrogate for the passivation of surface defects.

Surface defects in semiconducting materials, though they have been widely studied, remain a prominent source of loss in optoelectronic devices; here we sought a new angle of approach, looking into the dynamic roles played by surface defects under atmospheric stressors and their chemical passivants in the lifetime of optoelectronic materials. We find that surface defects possess properties distinct from those of bulk defects. ab initio molecular dynamics simulations reveal a previously overlooked reversible degradation mechanism mediated by hydrogen vacancies. We find that dynamic surface adsorption affinity (DAA) relative to surface treatment ligands is a surrogate for passivation efficacy, a more strongly-correlated feature than is the static binding strength emphasized in prior reports. This guides us to design targeted passivator ligands with high molecular polarity: for example, 4-aminobutylphosphonic acid exhibits strong DAA and provides defect passivation applicable to a range of perovskite compositions, including suppressed hydrogen vacancy formation, enhanced photovoltaic performances and operational stability in perovskite solar cells.

Reduction of 5-Hydroxymethylfurfural to 2,5-Bis(hydroxymethyl)Furan at High Current Density using a Ga-Doped AgCu:Cationomer Hybrid Electrocatalyst.

Hydrogenation of biomass-derived chemicals is of interest for the production of biofuels and valorized chemicals. Thermochemical processes for biomass reduction typically employ hydrogen as the reductant at elevated temperatures and pressures. Here, the authors investigate the direct electrified reduction of 5-hydroxymethylfurfural (HMF) to a precursor to bio-polymers, 2,5-bis(hydroxymethyl)furan (BHMF). Noting a limited current density in prior reports of this transformation, a hybrid catalyst consisting of ternary metal nanodendrites mixed with a cationic ionomer, the latter purposed to increase local pH and facilitate surface proton diffusion, is investigated. This approach, when implemented using Ga-doped Ag-Cu electrocatalysts designed for p-d orbital hybridization, steered selectivity to BHMF, achieving a faradaic efficiency (FE) of 58% at 100 mA cm-2 and a production rate of 1 mmol cm-2 h-1, the latter a doubling in rate compared to the best prior reports.

Asymmetric Triphenylethylene-Based Hole Transporting Materials for Highly Efficient Perovskite Solar Cells.

Molecular hole-transporting materials (HTMs) having triphenylethylene central core were designed, synthesized, and employed in perovskite solar cell (PSC) devices. The synthesized HTM derivatives were obtained in a two- or three-step synthetic procedure, and their characteristics were analyzed by various thermoanalytical, optical, photophysical, and photovoltaic techniques. The most efficient PSC device recorded a 23.43% power conversion efficiency. Furthermore, the longevity of the device employing V1509 HTM surpassed that of PSC with state-of-art spiro-OMeTAD as the reference HTM.

Site-selective protonation enables efficient carbon monoxide electroreduction to acetate.

Electrosynthesis of acetate from CO offers the prospect of a low-carbon-intensity route to this valuable chemical--but only once sufficient selectivity, reaction rate and stability are realized. It is a high priority to achieve the protonation of the relevant intermediates in a controlled fashion, and to achieve this while suppressing the competing hydrogen evolution reaction (HER) and while steering multicarbon (C2+) products to a single valuable product--an example of which is acetate. Here we report interface engineering to achieve solid/liquid/gas triple-phase interface regulation, and we find that it leads to site-selective protonation of intermediates and the preferential stabilization of the ketene intermediates: this, we find, leads to improved selectivity and energy efficiency toward acetate. Once we further tune the catalyst composition and also optimize for interfacial water management, we achieve a cadmium-copper catalyst that shows an acetate Faradaic efficiency (FE) of 75% with ultralow HER (<0.2% H2 FE) at 150 mA cm-2. We develop a high-pressure membrane electrode assembly system to increase CO coverage by controlling gas reactant distribution and achieve 86% acetate FE simultaneous with an acetate full-cell energy efficiency (EE) of 32%, the highest energy efficiency reported in direct acetate electrosynthesis.

Organic Polar Crystals, Second Harmonic Generation, and Piezoelectric Effects from Heteroadamantanes in the Space Group R3m.

Polar crystalline materials, a subset of the non-centrosymmetric materials, are highly sought after. Their symmetry properties make them pyroelectric and also piezoelectric and capable of second-harmonic generation (SHG). For SHG and piezoelectric applications, metal oxides are commonly used. The advantages of oxides are durability and hardness - downsides are the need for high-temperature synthesis/processing and often the need to include toxic metals. Organic polar crystals, on the other hand, can avoid toxic metals and can be amenable to solution-state processing. While the vast majority of polar organic molecules crystallize in non-polar space groups, we found that both 7-chloro-1,3,5-triazaadamantane, for short Cl-TAA, and also the related Br-TAA (but not I-TAA) form polar crystals in the space group R3m, easily obtained from dichloromethane solution. Measurements confirm piezoelectric and SHG properties for Cl-TAA and Br-TAA. When the two species are crystallized together, solid solutions form, suggesting that properties of future materials can be tuned continuously.

Dicarboxylic Acid-Assisted Surface Oxide Removal and Passivation of Indium Antimonide Colloidal Quantum Dots for Short-Wave Infrared Photodetectors.

Heavy-metal-free III-V colloidal quantum dots (CQDs) are promising materials for solution-processed short-wave infrared (SWIR) photodetectors. Recent progress in the synthesis of indium antimonide (InSb) CQDs with sizes smaller than the Bohr exciton radius enables quantum-size effect tuning of the band gap. However, it has been challenging to achieve uniform InSb CQDs with band gaps below 0.9 eV, as well as to control the surface chemistry of these large-diameter CQDs. This has, to date, limited the development of InSb CQD photodetectors that are sensitive to ≥ ${\ge }$ 1400 nm light. Here we adopt solvent engineering to facilitate a diffusion-limited growth regime, leading to uniform CQDs with a band gap of 0.89 eV. We then develop a CQD surface reconstruction strategy that employs a dicarboxylic acid to selectively remove the native In/Sb oxides, and enables a carboxylate-halide co-passivation with the subsequent halide ligand exchange. We find that this strategy reduces trap density by half compared to controls, and enables electronic coupling among CQDs. Photodetectors made using the tailored CQDs achieve an external quantum efficiency of 25 % at 1400 nm, the highest among III-V CQD photodetectors in this spectral region.

Retarding Ion Migration for Stable Blade-Coated Inverted Perovskite Solar Cells.

The fabrication of perovskite solar cells (PSCs) through blade coating is seen as one of the most viable paths toward commercialization. However, relative to the less scalable spin coating method, the blade coating process often results in more defective perovskite films with lower grain uniformity. Ion migration, facilitated by those elevated defect levels, is one of the main triggers of phase segregation and device instability. Here, a bifunctional molecule, p-aminobenzoic acid (PABA), which enhances the barrier to ion migration, induces grain growth along the (100) facet, and promotes the formation of homogeneous perovskite films with fewer defects, is reported. As a result, PSCs with PABA achieved impressive power conversion efficiencies (PCEs) of 23.32% and 22.23% for devices with active areas of 0.1 cm2 and 1 cm2 , respectively. Furthermore, these devices maintain 93.8% of their initial efficiencies after 1 000 h under 1-sun illumination, 75 °C, and 10% relative humidity conditions.

Identification of druggable regulators of cell secretion via a kinome-wide screen and high-throughput immunomagnetic cell sorting.

The identification of genetic regulators of cell secretions is challenging because it requires the sorting of a large number of cells according to their secretion patterns. Here we report the development and applicability of a high-throughput microfluidic method for the analysis of the secretion levels of large populations of immune cells. The method is linked with a kinome-wide loss-of-function CRISPR screen, immunomagnetically sorting the cells according to their secretion levels, and the sequencing of their genomes to identify key genetic modifiers of cell secretion. We used the method, which we validated against flow cytometry for cytokines secreted from primary mouse CD4+ (cluster of differentiation 4-positive) T cells, to discover a subgroup of highly co-expressed kinase-coding genes that regulate interferon-gamma secretion by these cells. We validated the function of the kinases identified using RNA interference, CRISPR knockouts and kinase inhibitors and confirmed the druggability of selected kinases via the administration of a kinase inhibitor in an animal model of colitis. The technique may facilitate the discovery of regulatory mechanisms for immune-cell activation and of therapeutic targets for autoimmune diseases.

Efficient multicarbon formation in acidic CO2 reduction via tandem electrocatalysis.

The electrochemical reduction of CO2 in acidic conditions enables high single-pass carbon efficiency. However, the competing hydrogen evolution reaction reduces selectivity in the electrochemical reduction of CO2, a reaction in which the formation of CO, and its ensuing coupling, are each essential to achieving multicarbon (C2+) product formation. These two reactions rely on distinct catalyst properties that are difficult to achieve in a single catalyst. Here we report decoupling the CO2-to-C2+ reaction into two steps, CO2-to-CO and CO-to-C2+, by deploying two distinct catalyst layers operating in tandem to achieve the desired transformation. The first catalyst, atomically dispersed cobalt phthalocyanine, reduces CO2 to CO with high selectivity. This process increases local CO availability to enhance the C-C coupling step implemented on the second catalyst layer, which is a Cu nanocatalyst with a Cu-ionomer interface. The optimized tandem electrodes achieve 61% C2H4 Faradaic efficiency and 82% C2+ Faradaic efficiency at 800 mA cm-2 at 25 °C. When optimized for single-pass utilization, the system reaches a single-pass carbon efficiency of 90 ± 3%, simultaneous with 55 ± 3% C2H4 Faradaic efficiency and a total C2+ Faradaic efficiency of 76 ± 2%, at 800 mA cm-2 with a CO2 flow rate of 2 ml min-1.

Arresting Ion Migration from the ETL Increases Stability in Infrared Light Detectors Based on III-V Colloidal Quantum Dots.

III-V colloidal quantum dots (CQDs) are of interest in infrared photodetection, and recent developments in CQDs synthesis and surface engineering have improved performance. Here this work investigates photodetector stability, finding that the diffusion of zinc ions from charge transport layers (CTLs) into the CQDs active layer increases trap density therein, leading to rapid and irreversible performance loss during operation. In an effort to prevent this, this work introduces organic blocking layers between the CQDs and ZnO layers; but these negatively impact device performance. The device is then, allowing to use a C60:BCP as top electron-transport layer (ETL) for good morphology and process compatibility, and selecting NiOX as the bottom hole-transport layer (HTL). The first round of NiOX -based devices show efficient light response but suffer from high leakage current and a low open-circuit voltage (Voc) due to pinholes. This work introduces poly[bis(4-phenyl) (2,4,6-trimethylphenyl)amine] (PTAA) with NiOX NC to form a hybrid HTL, an addition that reduces pinhole formation, interfacial trap density, and bimolecular recombination, enhancing carrier harvesting. The photodetectors achieve 53% external quantum efficiency (EQE) at 970 nm at 1 V applied bias, and they maintain 95% of initial performance after 19 h of continuous illuminated operation. The photodetectors retain over 80% of performance after 80 days of shelf storage.

Transient Measurements and Simulations Correlate Exchange Ligand Concentration and Trap States in Colloidal Quantum Dot Photodetectors.

Colloidal quantum dot (CQD) photodetectors (PDs) can detect wavelengths longer than the 1100 nm limit of silicon because of their highly tunable bandgaps. CQD PDs are acutely affected by the ligands that separate adjacent dots in a CQD-solid. Optimizing the exchange solution ligand concentration in the processing steps is crucial to achieving high photodetector performance. However, the complex mix of chemistry and optoelectronics involved in CQD PDs means that the effects of the exchange solution ligand concentration on device physics are poorly understood. Here we report direct correspondence between simulated and experimental transient photocurrent responses in CQD PDs. For both deficient and excess conditions, our model demonstrated the experimental changes to the transient photocurrent aligned with changes in trap state density. Combining transient photoluminescence, absorption, and photocurrent with this simulation model, we revealed that different mechanisms are responsible for the increased trap density induced by excess and deficient active layer ligand concentrations.

2D Hybrid Perovskites Employing an Organic Cation Paired with a Neutral Molecule.

Two-dimensional (2D) hybrid perovskites harness the chemical and structural versatility of organic compounds. Here, we explore 2D perovskites that incorporate both a first organic component, a primary ammonium cation, and a second neutral organic module. Through the experimental examination of 42 organic pairs with a range of functional groups and organic backbones, we identify five crystallization scenarios that occur upon mixing. Only one leads to the cointercalation of the organic modules with distinct and extended interlayer spacing, which is observed with the aid of X-ray diffraction (XRD) pattern analysis combined with cross-sectional transmission electron microscopy (TEM) and elemental analysis. We present a picture in which complementary pairs, capable of forming intermolecular bonds, cocrystallize with multiple structural arrangements. These arrangements are a function of the ratio of organic content, annealing temperature, and substrate surface characteristics. We highlight how noncovalent bonds, particularly hydrogen and halogen bonding, enable the influence over the organic sublattice in hybrid halide perovskites.