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.

Cation Exchange in Colloidal Transition Metal Nitride Nanocrystals.

Transition metal nitride (TMN)-based nanostructures have emerged as promising materials for diverse applications in electronics, photonics, energy storage, and catalysis due to their highly desirable physicochemical properties. However, synthesizing TMN-based nanostructures with designed compositions and morphologies poses challenges, especially in the solution phase. The cation exchange reaction (CER) stands out as a versatile postsynthetic strategy for preparing nanostructures that are otherwise inaccessible through direct synthesis. Nevertheless, exploration of the CER in TMNs lags behind that in metal chalcogenides and metal phosphides. Here, we demonstrate cation exchange in colloidal metal nitride nanocrystals, employing Cu3N nanocrystals as starting materials to synthesize Ni4N and CoN nanocrystals. By controlling the reaction conditions, Cu3N@Ni4N and Cu3N@CoN core@shell heterostructures with tunable compositions can also be obtained. The Ni4N and CoN nanocrystals are evaluated as catalysts for the electrochemical oxygen evolution reaction (OER). Remarkably, CoN nanocrystals demonstrate superior OER performance with a low overpotential of 286 mV at 10 mA·cm-2, a small Tafel slope of 89 mV·dec-1, and long-term stability. Our CER approach in colloidal TMNs offers a new strategy for preparing other metal nitride nanocrystals and their heterostructures, paving the way for prospective applications.

Photochemical tuning of dynamic defects for high-performance atomically dispersed catalysts.

Developing active and stable atomically dispersed catalysts is challenging because of weak non-specific interactions between catalytically active metal atoms and supports. Here we demonstrate a general method for synthesizing atomically dispersed catalysts via photochemical defect tuning for controlling oxygen-vacancy dynamics, which can induce specific metal-support interactions. The developed synthesis method offers metal-dynamically stabilized atomic catalysts, and it can be applied to reducible metal oxides, including TiO2, ZnO and CeO2, containing various catalytically active transition metals, including Pt, Ir and Cu. The optimized Pt-DSA/TiO2 shows unprecedentedly high photocatalytic hydrogen evolution activity, producing 164 mmol g-1 h-1 with a turnover frequency of 1.27 s-1. Furthermore, it generates 42.2 mmol gsub-1 of hydrogen via a non-recyclable-plastic-photoreforming process, achieving a total conversion of 98%; this offers a promising solution for mitigating plastic waste and simultaneously producing valuable energy sources.

Clinicopathological significances of cribriform pattern in lung adenocarcinoma.

The present study aimed to investigate the clinicopathological and prognostic implications of the cribriform pattern in lung adenocarcinoma through a meta-analysis. The estimated rates of cribriform pattern in lung adenocarcinomas were investigated. The correlations between cribriform pattern and clinicopathological characteristics, including genetic alterations and prognosis were evaluated. The estimated rate of cribriform pattern was 0.150 (95% confidence interval [CI], 0.101-0.218) in lung adenocarcinoma. The estimated rates of cribriform pattern in the 5% and 10% criteria were 0.230 (95% CI 0.125-0.386) and 0.130 (95% CI 0.062-0.252), respectively. The presence of cribriform pattern was significantly correlated with larger tumor size (> 30 mm), spread through air spaces, and lymph node metastasis (P < 0.001, P < 0.001, and P = 0.007, respectively, in the meta-regression test). There were no significant differences between cribriform pattern, smoking history, and vascular and lymphatic invasion. In lung adenocarcinoma with cribriform pattern, the estimated rates of ALK rearrangement, KRAS, and EGFR mutations were 0.407 (95% CI 0.165-0.704), 0.330 (95% CI 0.117-0.646), and 0.249 (95% CI 0.125-0.437), respectively. ALK rearrangement was significantly more frequent in lung adenocarcinomas with cribriform pattern than in those without. The overall survival rate was significantly worse in lung adenocarcinomas with a cribriform pattern than in those without (hazard ratio 2.051, 95% CI 1.369-3.075). In conclusion, the presence of a cribriform pattern can be a useful predictor of the clinicopathological characteristics and prognosis of patients with lung adenocarcinoma.

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.

Effect of Fluorination Position on the Crystalline Structure and Stretchability of Intrinsically Stretchable Polymer Semiconductors.

A clear understanding of the structure-property relationship of intrinsically stretchable polymer semiconductors (ISPSs) is essential for developing high-performance polymer-based electronics. Herein, we investigate the effect of the fluorination position on the crystalline structure, charge-carrier mobility, and stretchability of polymer semiconductors based on a benzodithiophene-co-benzotriazole configuration. Although four different polymer semiconductors showed similar field-effect mobilities for holes (µ ≈ 0.1 cm2 V-1 s-1), polymer semiconductors with nonfluorinated backbones exhibited improved thin-film stretchability confirmed with crack onset strain (εc ≈ 20%-50%) over those of fluorinated counterparts (εc ≤ 10%). The enhanced stretchability of polymer semiconductors with a nonfluorinated backbone is presumably due to the higher face-on crystallite ratio and π-π stacking distance in the out-of-plane direction than those of the other polymer semiconductors. These results provide new insights into how the thin-film stretchability of polymer semiconductors can be improved by using precise molecular tailoring without deteriorating electrical properties.

Orthogonal Dual Photocatalysis of Single Atoms on Carbon Nitrides for One-Pot Relay Organic Transformation.

Single-atom photocatalysis has shown potential in various single-step organic transformations, but its use in multistep organic transformations in one reaction systems has rarely been achieved. Herein, we demonstrate atomic site orthogonality in the M1/C3N4 system (where M = Pd or Ni), enabling a cascade photoredox reaction involving oxidative and reductive reactions in a single system. The system utilizes visible-light-generated holes and electrons from C3N4, driving redox reactions (e.g., oxidation and fluorination) at the surface of C3N4 and facilitating cross-coupling reactions (e.g., C-C and C-O bond formation) at the metal site. The concept is generalized to different systems of Pd and Ni, thus making the catalytic site-orthogonal M1/C3N4 system an ideal photocatalyst for improving the efficiency and selectivity of multistep organic transformations.

Highly Efficient Nitrogen-Fixing Microbial Hydrogel Device for Sustainable Solar Hydrogen Production.

Conversion of sunlight and organic carbon substrates to sustainable energy sources through microbial metabolism has great potential for the renewable energy industry. Despite recent progress in microbial photosynthesis, the development of microbial platforms that warrant efficient and scalable fuel production remains in its infancy. Efficient transfer and retrieval of gaseous reactants and products to and from microbes are particular hurdles. Here, inspired by water lily leaves floating on water, a microbial device designed to operate at the air-water interface and facilitate concomitant supply of gaseous reactants, smooth capture of gaseous products, and efficient sunlight delivery is presented. The floatable device carrying Rhodopseudomonas parapalustris, of which nitrogen fixation activity is first determined through this study, exhibits a hydrogen production rate of 104 mmol h-1  m-2 , which is 53 times higher than that of a conventional device placed at a depth of 2 cm in the medium. Furthermore, a scaled-up device with an area of 144 cm2 generates hydrogen at a high rate of 1.52 L h-1  m-2 . Efficient nitrogen fixation and hydrogen generation, low fabrication cost, and mechanical durability corroborate the potential of the floatable microbial device toward practical and sustainable solar energy conversion.

A Semi-Crystalline Polymer Semiconductor with Thin Film Stretchability Exceeding 200.

Despite the emerging scientific interest in polymer-based stretchable electronics, the trade-off between the crystallinity and stretchability of intrinsically stretchable polymer semiconductors-charge-carrier mobility increases as crystallinity increases while stretchability decreases-hinders the development of high-performance stretchable electronics. Herein, a highly stretchable polymer semiconductor is reported that shows concurrently improved thin film crystallinity and stretchability upon thermal annealing. The polymer thin films annealed at temperatures higher than their crystallization temperatures exhibit substantially improved thin film stretchability (> 200%) and hole mobility (≥ 0.2 cm2  V-1  s-1 ). The simultaneous enhancement of the crystallinity and stretchability is attributed to the thermally-assisted structural phase transition that allows the formation of edge-on crystallites and reinforces interchain noncovalent interactions. These results provide new insights into how the current crystallinity-stretchability limitation can be overcome. Furthermore, the results will facilitate the design of high-mobility stretchable polymer semiconductors for high-performance stretchable electronics.

Floatable photocatalytic hydrogel nanocomposites for large-scale solar hydrogen production.

Storing solar energy in chemical bonds aided by heterogeneous photocatalysis is desirable for sustainable energy conversion. Despite recent progress in designing highly active photocatalysts, inefficient solar energy and mass transfer, the instability of catalysts and reverse reactions impede their practical large-scale applications. Here we tackle these challenges by designing a floatable photocatalytic platform constructed from porous elastomer-hydrogel nanocomposites. The nanocomposites at the air-water interface feature efficient light delivery, facile supply of water and instantaneous gas separation. Consequently, a high hydrogen evolution rate of 163 mmol h-1 m-2 can be achieved using Pt/TiO2 cryoaerogel, even without forced convection. When fabricated in an area of 1 m2 and incorporated with economically feasible single-atom Cu/TiO2 photocatalysts, the nanocomposites produce 79.2 ml of hydrogen per day under natural sunlight. Furthermore, long-term stable hydrogen production in seawater and highly turbid water and photoreforming of polyethylene terephthalate demonstrate the potential of the nanocomposites as a commercially viable photocatalytic system.

Flexible Organic Photodetectors with Mechanically Robust Zinc Oxide Nanoparticle Thin Films.

Zinc oxide nanoparticle (ZnO-NP) thin films have been intensively used as electron transport layers (ETLs) in organic optoelectronic devices, but their moderate mechanical flexibility hinders their application to flexible electronic devices. This study reveals that the multivalent interaction between ZnO-NPs and multicharged conjugated electrolytes, such as diphenylfluorene pyridinium bromide derivative (DFPBr-6), can significantly improve the mechanical flexibility of ZnO-NP thin films. Intermixing ZnO-NPs and DFPBr-6 facilitates the coordination between bromide anions (from the DFPBr-6) and zinc cations on ZnO-NP surfaces, forming Zn2+-Br- bonds. Different from a conventional electrolyte (e.g., KBr), DFPBr-6 with six pyridinium ionic side chains holds the Br--chelated ZnO-NPs adjacent to DFP+ through Zn2+-Br--N+ bonds. Consequently, ZnO-NP:DFPBr-6 thin films exhibit improved mechanical flexibility with a critical bending radius as low as 1.5 mm under tensile bending conditions. Flexible organic photodetectors with ZnO-NP:DFPBr-6 thin films as ETLs demonstrate reliable device performances with high R (0.34 A/W) and D* (3.03 × 1012 Jones) even after 1000 times repetitive bending at a bending radius of 4.0 mm, whereas devices with ZnO-NP and ZnO-NP:KBr ETLs yield >85% reduction in R and D* under the same bending condition.

Protic Ionic Liquids for Intrinsically Stretchable Conductive Polymers.

Inspired by the classic hard-soft acid-base theory and intrigued by a theoretical prediction of spontaneous ion exchange between poly(3,4-ethylenedioxythiophene):poly(styrenesulfonate) (PEDOT:PSS) and hard-cation-soft-anion ionic liquid (IL), we treat PEDOT:PSS with a new IL composed of a protic (i.e., extremely hard) cation (3-methylimidazolium, p-MIM+) and an extremely soft anion (tetracyanoborate, TCB-). In fact, this protic IL (p-MIM:TCB) accomplishes the same levels of ion-exchange-mediated PEDOT-PSS separation, PEDOT-rich nanofibril formation, and electrical conductivity enhancement (∼2500 S/cm) as its aprotic counterpart (EMIM:TCB with 1-ethyl-3-methylimidazolium), the best IL used for this purpose so far. Furthermore, p-MIM:TCB significantly outperforms EMIM:TCB in terms of improving the stretchability (i.e., the highest tensile strain) of the PEDOT:PSS thin film. This enhancement is a result of the aromatic and protic cation p-MIM+, which acts as a molecular adhesive holding the exchanged ion pairs (PEDOT+:TCB----p-MIM+:PSS-) via ionic intercalation (at the surface of TCB--decorated PEDOT+ clusters) and hydrogen bonding (to PSS-), in which washing p-MIM+ out of the film degrades the stretchability while keeping the morphology. Our results offer molecular-level insight into the morphological, electrical, and mechanical properties of PEDOT:PSS and a molecular-interaction-based enhancement strategy that can be used for intrinsically stretchable conductive polymers.

Ni single atoms on carbon nitride for visible-light-promoted full heterogeneous dual catalysis.

Visible-light-driven organic transformations are of great interest in synthesizing valuable fine chemicals under mild conditions. The merger of heterogeneous photocatalysts and transition metal catalysts has recently drawn much attention due to its versatility for organic transformations. However, these semi-heterogenous systems suffered several drawbacks, such as transition metal agglomeration on the heterogeneous surface, hindering further applications. Here, we introduce heterogeneous single Ni atoms supported on carbon nitride (NiSAC/CN) for visible-light-driven C-N functionalization with a broad substrate scope. Compared to a semi-heterogeneous system, high activity and stability were observed due to metal-support interactions. Furthermore, through systematic experimental mechanistic studies, we demonstrate that the stabilized single Ni atoms on CN effectively change their redox states, leading to a complete photoredox cycle for C-N coupling.

Effect of Bulky Atom Substitution on Backbone Coplanarity and Electrical Properties of Cyclopentadithiophene-Based Semiconducting Polymers.

The effect of atomic substitution on the optoelectronic properties of a coplanar donor-acceptor (D-A) semiconducting polymer (SPs), prepared using cyclopentadithiophene (CDT) and 2,1,3-benzothiadiazole (BT) moieties, is investigated. By substituting a carbon atom in the BT unit with CF or C-Cl, two random D-A SPs are prepared, and their optoelectronic properties are thoroughly investigated. Density functional theory calculations demonstrate that the fluorinated polymer has a slightly smaller dihedral angle (Ï´ = 0.6°) than the pristine polymer (Ï´ = 1.9°) in its lowest-energy conformation, implying efficient charge transport through the coplanar backbone of the fluorinated polymer. However, the chlorinated polymer shows the lowest energy at a relatively larger dihedral angle (Ï´ = 139°) due to the steric hindrance induced by bulky chlorine atoms in the backbone, thereby leading to thin-film morphology, which is unfavorable for charge transport. Consequently, the fluorinated polymer yields the highest field-effect mobility (µ) of 0.57 cm2 V-1 s-1 , slightly higher than that of the pristine polymer (µ = 0.33 cm2 V-1 s-1 ), and the extended device lifetime of organic field-effect transistors over 12 d without any encapsulation layers. The results of this study provide design guidelines for air-stable D-A SPs.

Oxygen-Vacancy-Driven Orbital Reconstruction at the Surface of TiO2 Core-Shell Nanostructures.

Oxygen vacancies and their correlation with the electronic structure are crucial to understanding the functionality of TiO2 nanocrystals in material design applications. Here, we report spectroscopic investigations of the electronic structure of anatase TiO2 nanocrystals by employing hard and soft X-ray absorption spectroscopy measurements along with the corresponding model calculations. We show that the oxygen vacancies significantly transform the Ti local symmetry by modulating the covalency of titanium-oxygen bonds. Our results suggest that the altered Ti local symmetry is similar to the C3v, which implies that the Ti exists in two local symmetries (D2d and C3v) at the surface. The findings also indicate that the Ti distortion is a short-range order effect and presumably confined up to the second nearest neighbors. Such distortions modulate the electronic structure and provide a promising approach to structural design of the TiO2 nanocrystals.

Designing Atomically Dispersed Au on Tensile-Strained Pd for Efficient CO2 Electroreduction to Formate.

Pd is one of the most effective catalysts for the electrochemical reduction of CO2 to formate, a valuable liquid product, at low overpotential. However, the intrinsically high CO affinity of Pd makes the surface vulnerable to CO poisoning, resulting in rapid catalyst deactivation during CO2 electroreduction. Herein, we utilize the interaction between metals and metal-organic frameworks to synthesize atomically dispersed Au on tensile-strained Pd nanoparticles showing significantly improved formate production activity, selectivity, and stability with high CO tolerance. We found that the tensile strain stabilizes all reaction intermediates on the Pd surface, whereas the atomically dispersed Au selectively destabilizes CO* without affecting other adsorbates. As a result, the conventional COOH* versus CO* scaling relation is broken, and our catalyst exhibits 26- and 31-fold enhancement in partial current density and mass activity toward electrocatalytic formate production with over 99% faradaic efficiency, compared to Pd/C at -0.25 V versus RHE.

9G TestTM Cancer/Lung: A Desirable Companion to LDCT for Lung Cancer Screening.

A complimentary biomarker test that can be used in combination with LDCT for lung cancer screening is highly desirable to improve the diagnostic capacity of LDCT and reduce the false-positive rates. Most importantly, the stage I lung cancer detection rate can be dramatically increased by the simultaneous use of a biomarker test with LDCT. The present study was conducted to evaluate 9G testTM Cancer/Lung's sensitivity and specificity in detecting Stage 0~IV lung cancer. The obtained results indicate that the 9G testTM Cancer/Lung can detect lung cancer with overall sensitivity and specificity of 75.0% (69.1~80.3) and 97.3% (95.0~98.8), respectively. The detection of stage I, stage II, stage III, and stage IV cancers with sensitivities of 77.5%, 78.1%, 67.4%, and 33.3%, respectively, at the specificity of 97.3% have never been reported before. The receiver operating characteristic curve analysis allowed us to determine the population-weighted AUC of 0.93 (95% CI, 0.91-0.95). These results indicate that the 9G testTM Cancer/Lung can be used in conjunction with LDCT to screen lung cancer. Furthermore, obtained results indicate that the use of 9G testTM Cancer/Lung with LDCT for lung cancer screening can increase stage I cancer detection, which is crucial to improve the currently low 5-year survival rates.

Opposite Polarity Surface Photovoltage of MoS2 Monolayers on Au Nanodot versus Nanohole Arrays.

We prepared MoS2 monolayers on Au nanodot (ND) and nanohole (NH) arrays. Both these sample arrays exhibited enhanced photoluminescence intensity compared with that of a bare SiO2/Si substrate. The reflectance spectra of MoS2/ND and MoS2/NH had clear features originating from excitation of localized surface plasmon and propagating surface plasmon polaritons. Notably, the surface photovoltages (SPV) of these hybrid plasmonic nanostructures had opposite polarities, indicating negative and positive charging at MoS2/ND and MoS2/NH, respectively. Surface potential maps, obtained by Kelvin probe force microscopy, suggested that the potential gradient led to a distinct spatial distribution of photo-generated charges in these two samples under illumination. Furthermore, the local density of photo-generated excitons, as predicted from optical simulations, explained the SPV spectra of MoS2/ND and MoS2/NH. We show that the geometric configuration of the plasmonic nanostructures modified the polarity of photo-generated excess charges in MoS2. These findings point to a useful means of optimizing optoelectronic characteristics and improving the performance of MoS2-based plasmonic devices.

Direct Synthesis of Intermetallic Platinum-Alloy Nanoparticles Highly Loaded on Carbon Supports for Efficient Electrocatalysis.

Compared to nanostructured platinum (Pt) catalysts, ordered Pt-based intermetallic nanoparticles supported on a carbon substrate exhibit much enhanced catalytic performance, especially in fuel cell electrocatalysis. However, direct synthesis of homogeneous intermetallic alloy nanocatalysts on carbonaceous supports with high loading is still challenging. Herein, we report a novel synthetic strategy to directly produce highly dispersed MPt alloy nanoparticles (M = Fe, Co, or Ni) on various carbon supports with high catalyst loading. Importantly, a unique bimetallic compound, composed of [M(bpy)3]2+ cation (bpy = 2,2'-bipyridine) and [PtCl6]2- anion, evenly decomposes on carbon surface and forms uniformly sized intermetallic nanoparticles with a nitrogen-doped carbon protection layer. The excellent oxygen reduction reaction (ORR) activity and stability of the representative reduced graphene oxide (rGO)-supported L10-FePt catalyst (37 wt %-FePt/rGO), exhibiting 18.8 times higher specific activity than commercial Pt/C catalyst without degradation over 20 000 cycles, well demonstrate the effectiveness of our synthetic approach toward uniformly alloyed nanoparticles with high homogeneity.

Operando Identification of the Chemical and Structural Origin of Li-Ion Battery Aging at Near-Ambient Temperature.

Integrated with heat-generating devices, a Li-ion battery (LIB) often operates at 20-40 °C higher than the ordinary working temperature. Although macroscopic investigation of the thermal contribution has shown a significant reduction in the LIB performance, the molecular level structural and chemical origin of battery aging in a mild thermal environment has not been elucidated. On the basis of the combined experiments of the electrochemical measurements, Cs-corrected electron microscopy, and in situ analyses, we herein provide operando structural and chemical insights on how a mild thermal environment affects the overall battery performance using anatase TiO2 as a model intercalation compound. Interestingly, a mild thermal condition induces excess lithium intercalation even at near-ambient temperature (45 °C), which does not occur at the ordinary working temperature. The anomalous intercalation enables excess lithium storage in the first few cycles but exerts severe intracrystal stress, consequently cracking the crystal that leads to battery aging. Importantly, this mild thermal effect is accumulated upon cycling, resulting in irreversible capacity loss even after the thermal condition is removed. Battery aging at a high working temperature is universal in nearly all intercalation compounds, and therefore, it is significant to understand how the thermal condition contributes to battery aging for designing intercalation compounds for advanced battery electrode materials.