Superionic fluoride gate dielectrics with low diffusion barrier for two-dimensional electronics.

Exploration of new dielectrics with a large capacitive coupling is an essential topic in modern electronics when conventional dielectrics suffer from the leakage issue near the breakdown limit. Here, to address this looming challenge, we demonstrate that rare-earth metal fluorides with extremely low ion migration barriers can generally exhibit an excellent capacitive coupling over 20 µF cm-2 (with an equivalent oxide thickness of ~0.15 nm and a large effective dielectric constant near 30) and great compatibility with scalable device manufacturing processes. Such a static dielectric capability of superionic fluorides is exemplified by MoS2 transistors exhibiting high on/off current ratios over 108, ultralow subthreshold swing of 65 mV dec-1 and ultralow leakage current density of ~10-6 A cm-2. Therefore, the fluoride-gated logic inverters can achieve notably higher static voltage gain values (surpassing ~167) compared with a conventional dielectric. Furthermore, the application of fluoride gating enables the demonstration of NAND, NOR, AND and OR logic circuits with low static energy consumption. In particular, the superconductor-insulator transition at the clean-limit Bi2Sr2CaCu2O8+δ can also be realized through fluoride gating. Our findings highlight fluoride dielectrics as a pioneering platform for advanced electronic applications and for tailoring emergent electronic states in condensed matter.

Quantum spin driven Yu-Shiba-Rusinov multiplets and fermion-parity-preserving phase transition in K3C60.

Magnetic impurities in superconductors are of increasing interest due to emergent Yu-Shiba-Rusinov (YSR) states and Majorana zero modes for fault-tolerant quantum computation. However, a direct relationship between the YSR multiple states and magnetic anisotropy splitting of quantum impurity spins remains poorly characterized. By using scanning tunneling microscopy, we systematically resolve individual transition-metal (Fe, Cr, and Ni) impurities induced YSR multiplets as well as their Zeeman effects in the K3C60 superconductor. The YSR multiplets show identical d orbital-like wave functions that are symmetry-mismatched to the threefold K3C60(1 1 1) host surface, breaking point-group symmetries of the spatial distribution of YSR bound states in real space. Remarkably, we identify an unprecedented fermion-parity-preserving quantum phase transition between ground states with opposite signs of the uniaxial magnetic anisotropy that can be manipulated by an external magnetic field. These findings can be readily understood in terms of anisotropy splitting of quantum impurity spins, and thus elucidate the intricate interplay between the magnetic anisotropy and YSR multiplets.

Electronic inhomogeneity and phase fluctuation in one-unit-cell FeSe films.

One-unit-cell FeSe films on SrTiO3 substrates are of great interest owing to significantly enlarged pairing gaps characterized by two coherence peaks at ±10 meV and ±20 meV. In-situ transport measurement is desired to reveal novel properties. Here, we performed in-situ microscale electrical transport and combined scanning tunneling microscopy measurements on continuous one-unit-cell FeSe films with twin boundaries. We observed two spatially coexisting superconducting phases in domains and on boundaries, characterized by distinct superconducting gaps ( Δ 1 ~15 meV vs. Δ 2 ~10 meV) and pairing temperatures (Tp1~52.0 K vs. Tp2~37.3 K), and correspondingly two-step nonlinear V ~ I α behavior but a concurrent Berezinskii-Kosterlitz-Thouless (BKT)-like transition occurring at T BKT ~28.7 K. Moreover, the onset transition temperature T c onset ~54 K and zero-resistivity temperature T c zero ~31 K are consistent with Tp1 and T BKT , respectively. Our results indicate the broadened superconducting transition in FeSe/SrTiO3 is related to intrinsic electronic inhomogeneity due to distinct two-gap features and phase fluctuations of two-dimensional superconductivity.

Perioperative corticosteroids for reducing postoperative complications following esophagectomy: an updated systematic review and meta-analysis.

BACKGROUND: This updated systematic review and meta-analysis aims to evaluate the efficacy and safety of perioperative corticosteroid administration versus placebo for esophageal cancer patients following scheduled esophagectomy. METHODS: We searched databases through June 30, 2023. We included articles on randomized controlled trials (RCTs) comparing perioperative corticosteroid administration with placebo in esophageal cancer patients with esophagectomy. The outcomes were the death rate during hospitalization, length of hospital stay, and short-term complications. Risk ratios (RRs) and corresponding 95% confidence interval (CIs) for each estimated effect size were applied for dichotomous outcomes, and the mean difference (MD) and corresponding 95% CIs for each estimated effect size were applied for continuous outcomes. We used GRADE to evaluate the quality of each of the outcome and the level of recommendations. RESULTS: Nine RCTs with 508 participants were included in this study. Severe outcomes, including the length of hospital stay, leakage, mortality during the hospitalization period in the corticosteroid group was comparable to that in the control group, but positive effects of corticosteroid administration were observed on the length of intensive care unit stay (MD -3.1, 95% CI - 5.43 to - 0.77), cardiovascular disorders (RR 0.44, 95% CI 0.21-0.94) and other general complications (RR 0.49, 95% CI 0.29-0.85). CONCLUSIONS: Peri-operative intravenous corticosteroid administration may reduce cardiovascular disorders, other general complications and the length of ICU stay without carrying severe outcomes. More high quality RCTs are warranted to further investigate the effects of corticosteroids on postoperative mortality and complications for esophageal cancer patients with esophagectomy. SYSTEMATIC REVIEW REGISTRATION: Cochrane, registration number: 196.

Significantly enhanced superconductivity in monolayer FeSe films on SrTiO3(001) via metallic δ-doping.

Superconductivity transition temperature (Tc) marks the inception of a macroscopic quantum phase-coherent paired state in fermionic systems. For 2D superconductivity, the paired electrons condense into a coherent superfluid state at Tc, which is usually lower than the pairing temperature, between which intrinsic physics including Berezinskii-Kosterlitz-Thouless transition and pseudogap state are hotly debated. In the case of monolayer FeSe superconducting films on SrTiO3(001), although the pairing temperature (Tp) is revealed to be 65-83 K by using spectroscopy characterization, the measured zero-resistance temperature ([Formula: see text]) is limited to 20 K. Here, we report significantly enhanced superconductivity in monolayer FeSe films by δ-doping of Eu or Al on SrTiO3(001) surface, in which [Formula: see text] is enhanced by 12 K with a narrowed transition width ΔTc ∼ 8 K, compared with non-doped samples. Using scanning tunneling microscopy/spectroscopy measurements, we demonstrate lowered work function of the δ-doped SrTiO3(001) surface and enlarged superconducting gaps in the monolayer FeSe with improved morphology/electronic homogeneity. Our work provides a practical route to enhance 2D superconductivity by using interface engineering.

Quantized anomalous Hall resistivity achieved in molecular beam epitaxy-grown MnBi2Te4 thin films.

The intrinsic magnetic topological insulator MnBi2Te4 provides a feasible pathway to the high-temperature quantum anomalous Hall (QAH) effect as well as various novel topological quantum phases. Although quantized transport properties have been observed in exfoliated MnBi2Te4 thin flakes, it remains a big challenge to achieve molecular beam epitaxy (MBE)-grown MnBi2Te4 thin films even close to the quantized regime. In this work, we report the realization of quantized anomalous Hall resistivity in MBE-grown MnBi2Te4 thin films with the chemical potential tuned by both controlled in situ oxygen exposure and top gating. We find that elongated post-annealing obviously elevates the temperature to achieve quantization of the Hall resistivity, but also increases the residual longitudinal resistivity, indicating a picture of high-quality QAH puddles weakly coupled by tunnel barriers. These results help to clarify the puzzles in previous experimental studies on MnBi2Te4 and to find a way out of the big difficulty in obtaining MnBi2Te4 samples showing quantized transport properties.

Clinical study of camrelizumab combined with docetaxel and carboplatin as a neoadjuvant treatment for locally advanced oesophageal squamous cell carcinoma.

Herein, we aimed to evaluate the efficacy and safety of camrelizumab combined with docetaxel and carboplatin as a neoadjuvant treatment for locally advanced oesophageal squamous cell carcinoma (OSCC). Fifty-one patients with OSCC, treated from July 2020 to October 2022, were analyzed. Of them, 41 patients underwent surgery 4-8 weeks after undergoing two cycles of camrelizumab (200 mg IV Q3W) combined with docetaxel (75 mg/m2 IV Q3W) and carboplatin (area under the curve = 5-6 IV Q3W). The primary endpoint was the pathological complete response rate. All 51 patients (100%) experienced treatment-related grades 1-2 adverse events, and 2 patients (3.9%) experienced grade 4 events (including elevated alanine transaminase/aspartate transferase levels and Guillain-Barre syndrome). Fifty patients were evaluated for the treatment efficacy. Of them, 13 achieved complete response, and the objective response rate was 74%. Only 41 patients underwent surgical treatment. The pathological complete response rate was 17.1%, the major pathological response rate was 63.4%, and the R0 resection rate was 100%. Approximately 22% of the patients had tumor regression grades 0. Eight patients (19.5%) developed surgery-related complications. The median follow-up time was 18 months (range: 3-29 months). Four patients experienced disease progression, while four died. The median disease-free survival and overall survival were not reached. Camrelizumab combined with docetaxel and carboplatin is an effective and safe neoadjuvant treatment for locally advanced OSCC. This regimen may afford a potential strategy to treat patients with locally advanced OSCC.

Successful treatment of epidermodysplasia verruciformis with a combination of 5-aminolevulinic acid photodynamic therapy and surgery.

Epidermodysplasia verruciformis (EV) is a rare inherited immune disease characterized by pityriasis versicolor-like macules, hyperpigmented or hypopigmented warty papules and irregular reddish-brown plaques, mainly on the face, neck and extremities. Some therapeutic options include medications, lifestyle changes, ALA-PDT, surgery and so on. But there is no cure for EV and thus the clinical management is challenging. We report a case of EV that was refractory to multiple therapies and achieved an encouraging result with a combination therapy of surgery and 5-aminolevulinic acid photodynamic therapy (ALA-PDT).

PHLDA1 is a P53 target gene involved in P53-mediated cell apoptosis.

Pleckstrin homeolike domain, family A, member 1 (PHLDA1) is a multifunctional protein that plays diverse roles in A variety of biological processes, including cell death, and hence its altered expression has been found in different types of cancer. Although studies have shown a regulatory relationship between p53 and PHLDA1, the molecular mechanism is still unclear. Especially, the role of PHLDA1 in the process of apoptosis is still controversial. In this study, we found that the expression of PHLDA1 in human cervical cancer cell lines was correlated with the up-expression of p53 after treatment with apoptosis-inducing factors. Subsequently, the binding site and the binding effect of p53 on the promoter region of PHLDA1 were verified by our bioinformatics data analysis and luciferase reporter assay. Indeed, we used CRISPR-Cas9 to knockout the p53 gene in HeLa cells and further confirmed that p53 can bind to the promoter region of PHLDA1 gene, and then directly regulate the expression of PHLDA1 by recruiting P300 and CBP to change the acetylation and methylation levels in the promoter region. Finally, a series of gain-of-function experiments further confirmed that p53 re-expression in HeLap53-/- cell can up-regulate the reduction of PHLDA1 caused by p53 knockout, and affect cell apoptosis and proliferation. Our study is the first to explore the regulatory mechanism of p53 on PHLDA1 by using the p53 gene knockout cell model, which further proves that PHLDA1 is a target-gene in p53-mediated apoptosis, and reveals the important role of PHLDA1 in cell fate determination.

Hierarchical nanofibrous and recyclable membrane with unidirectional water-transport effect for efficient solar-driven interfacial evaporation.

Solar-driven interfacial evaporation technology has attracted significant attention for water purification. However, design and fabrication of solar-driven evaporator with cost-effective, excellent capability and large-scale production remains challenging. In this study, inspired by plant transpiration, a tri-layered hierarchical nanofibrous photothermal membrane (HNPM) with a unidirectional water transport effect was designed and prepared via electrospinning for efficient solar-driven interfacial evaporation. The synergistic effect of the hierarchical hydrophilic-hydrophobic structure and the self-pumping effect endowed the HNPM with unidirectional water transport properties. The HNPM could unidirectionally drive water from the hydrophobic layer to the hydrophilic layer within 2.5 s and prevent reverse water penetration. With this unique property, the HNPM was coupled with a water supply component and thermal insulator to assemble a self-floating evaporator for water desalination. Under 1 sun illumination, the water evaporation rates of the designed evaporator with HNPM in pure water and dyed wastewater reached 1.44 and 1.78 kg·m-2·h-1, respectively. The evaporator could achieve evaporation of 11.04 kg·m-2 in 10 h under outdoor solar conditions. Moreover, the tri-layered HNPM exhibited outstanding flexibility and recyclability. Our bionic hydrophobic-to-hydrophilic structure endowed the solar-driven evaporator with capillary wicking and transpiration effects, which provides a rational design and optimization for efficient solar-driven applications.

High-Temperature Polymer Dielectrics Designed Using an Invertible Molecular Graph Generative Model.

Generating new molecules with the desired physical or chemical properties is the key challenge of computational material design. Deep learning techniques are being actively applied in the field of data-driven material informatics and provide a promising way to accelerate the discovery of innovative materials. In this work, we utilize an invertible graph generative model to generate hypothetical promising high-temperature polymer dielectrics. A molecular graph generative model based on the invertible normalizing flow is trained on a data set containing 250k polymer molecular graphs (mostly generated by an RNN-based generative model) to learn the invertible transformations between latent distributions and molecular graph structures. When generating molecular graphs, a sample vector is drawn from the latent space, and then an adjacency tensor and node attribute matrix are generated through two invertible flows in two steps and assembled into a molecular graph. The model has the merits of exact likelihood training and an efficient one-shot generation process. The learned latent space is used to generate polymers with a high glass-transition temperature (Tg) and a wide band gap (Eg) for the application of high-temperature energy storage film capacitors. This work contributes to the efficient design of high-temperature polymer dielectrics by using deep generative models.

Intrinsic surface p-wave superconductivity in layered AuSn4.

The search for topological superconductivity (TSC) is currently an exciting pursuit, since non-trivial topological superconducting phases could host exotic Majorana modes. However, the difficulty in fabricating proximity-induced TSC heterostructures, the sensitivity to disorder and stringent topological restrictions of intrinsic TSC place serious limitations and formidable challenges on the materials and related applications. Here, we report a new type of intrinsic TSC, namely intrinsic surface topological superconductivity (IS-TSC) and demonstrate it in layered AuSn4 with Tc of 2.4 K. Different in-plane and out-of-plane upper critical fields reflect a two-dimensional (2D) character of superconductivity. The two-fold symmetric angular dependences of both magneto-transport and the zero-bias conductance peak (ZBCP) in point-contact spectroscopy (PCS) in the superconducting regime indicate an unconventional pairing symmetry of AuSn4. The superconducting gap and surface multi-bands with Rashba splitting at the Fermi level (EF), in conjunction with first-principle calculations, strongly suggest that 2D unconventional SC in AuSn4 originates from the mixture of p-wave surface and s-wave bulk contributions, which leads to a two-fold symmetric superconductivity. Our results provide an exciting paradigm to realize TSC via Rashba effect on surface superconducting bands in layered materials.

Use of Deep-Learning Assisted Assessment of Cardiac Parameters in Zebrafish to Discover Cyanidin Chloride as a Novel Keap1 Inhibitor Against Doxorubicin-Induced Cardiotoxicity.

Doxorubicin-induced cardiomyopathy (DIC) brings tough clinical challenges as well as continued demand in developing agents for adjuvant cardioprotective therapies. Here, a zebrafish phenotypic screening with deep-learning assisted multiplex cardiac functional analysis using motion videos of larval hearts is established. Through training the model on a dataset of 2125 labeled ventricular images, ZVSegNet and HRNet exhibit superior performance over previous methods. As a result of high-content phenotypic screening, cyanidin chloride (CyCl) is identified as a potent suppressor of DIC. CyCl effectively rescues cardiac cell death and improves heart function in both in vitro and in vivo models of Doxorubicin (Dox) exposure. CyCl shows strong inhibitory effects on lipid peroxidation and mitochondrial damage and prevents ferroptosis and apoptosis-related cell death. Molecular docking and thermal shift assay further suggest a direct binding between CyCl and Keap1, which may compete for the Keap1-Nrf2 interaction, promote nuclear accumulation of Nrf2, and subsequentially transactivate Gpx4 and other antioxidant factors. Site-specific mutation of R415A in Keap1 significantly attenuates the protective effects of CyCl against Dox-induced cardiotoxicity. Taken together, the capability of deep-learning-assisted phenotypic screening in identifying promising lead compounds against DIC is exhibited, and new perspectives into drug discovery in the era of artificial intelligence are provided.

Prominent Josephson tunneling between twisted single copper oxide planes of Bi2Sr2-xLaxCuO6+y.

Josephson tunneling in twisted cuprate junctions provides a litmus test for the pairing symmetry, which is fundamental for understanding the microscopic mechanism of high temperature superconductivity. This issue is rekindled by experimental advances in van der Waals stacking and the proposal of an emergent d+id-wave. So far, all experiments have been carried out on Bi2Sr2CaCu2O8+x (Bi-2212) with double CuO2 planes but show controversial results. Here, we investigate junctions made of Bi2Sr2-xLaxCuO6+y (Bi-2201) with single CuO2 planes. Our on-site cold stacking technique ensures uncompromised crystalline quality and stoichiometry at the interface. Junctions with carefully calibrated twist angles around 45° show strong Josephson tunneling and conventional temperature dependence. Furthermore, we observe standard Fraunhofer diffraction patterns and integer Fiske steps in a junction with a twist angle of 45.0±0.2°. Together, these results pose strong constraints on the d or d+id-wave pairing and suggest an indispensable isotropic pairing component.

Identifying s-wave pairing symmetry in single-layer FeSe from topologically trivial edge states.

Determining the pairing symmetry of single-layer FeSe on SrTiO3 is the key to understanding the enhanced pairing mechanism. It also guides the search for superconductors with high transition temperatures. Despite considerable efforts, it remains controversial whether the symmetry is the sign-preserving s- or the sign-changing s±-wave. Here, we investigate the pairing symmetry of single-layer FeSe from a topological point of view. Using low-temperature scanning tunneling microscopy/spectroscopy, we systematically characterize the superconducting states at edges and corners of single-layer FeSe. The tunneling spectra collected at edges and corners show a full energy gap and a substantial dip, respectively, suggesting the absence of topologically non-trivial edge and corner modes. According to our theoretical calculations, these spectroscopic features can be considered as strong evidence for the sign-preserving s-wave pairing in single-layer FeSe.

Oscillation of Electronic-Band-Gap Size Induced by Crystalline Symmetry Change in Ultrathin PbTe Films.

For the semiconductors of atomic length scales, even one atom layer difference could modify crystal symmetry and lead to a significant change in electronic structure, which is essential for modern electronics. However, the experimental exploration of such effect has not been achieved due to challenges in sample fabrication and characterization with atomic-scale precision. Here, we report the discovery of crystal symmetry alternation induced band-gap oscillation in atomically thin PbTe films by scanning tunneling microscopy. As the thickness of PbTe films is reduced from an 18- to 2-atomic layer, the band-gap size not only expands from 0.19 eV to 1.06 eV by 5.6 fold, but also exhibits an even-odd-layer oscillation, which is attributed to the alternating crystal symmetries between P4/mmm and P4/nmm. Our work sheds new light on electronic structure engineering of semiconductors at atomic scale for next-generation nanoelectronics.

A Bilayer High-Temperature Dielectric Film with Superior Breakdown Strength and Energy Storage Density.

The further electrification of various fields in production and daily life makes it a topic worthy of exploration to improve the performance of capacitors for a long time, including thin-film capacitors. The discharge energy density of thin-film capacitors that serves as one of the important types directly depends on electric field strength and the dielectric constant of the insulation material. However, it has long been a great challenge to improve the breakdown strength and dielectric constant simultaneously. Considering that boron nitride nanosheets (BNNS) possess superior insulation and thermal conductivity owing to wide band gap and 2-dimensional structure, a bilayer polymer film is prepared via coating BNNS by solution casting on surface of polyethylene terephthalate (PET) films. By revealing the bandgap and insulating behavior with UV absorption spectrum, leakage current, and finite element calculation, it is manifested that nanocoating contributes to enhance the bandgap of polymer films, thereby suppressing the charge injection by redirecting their transport from electrodes. Worthy to note that an ultrahigh breakdown field strength (~ 736 MV m-1), an excellent discharge energy density (~ 8.77 J cm-3) and a prominent charge-discharge efficiency (~ 96.51%) are achieved concurrently, which is ascribed to the contribution of BNNS ultrathin layer. In addition, the modified PET films also have superior comprehensive performance at high temperatures (~ 120 °C). The materials and methods here selected are easily accessible and facile, which are suitable for large-scale roll-to-roll process production, and are of certain significance to explore the methods about film modification suitable for commercial promotion.

An Automated Method of 3D Facial Soft Tissue Landmark Prediction Based on Object Detection and Deep Learning.

BACKGROUND: Three-dimensional facial soft tissue landmark prediction is an important tool in dentistry, for which several methods have been developed in recent years, including a deep learning algorithm which relies on converting 3D models into 2D maps, which results in the loss of information and precision. METHODS: This study proposes a neural network architecture capable of directly predicting landmarks from a 3D facial soft tissue model. Firstly, the range of each organ is obtained by an object detection network. Secondly, the prediction networks obtain landmarks from the 3D models of different organs. RESULTS: The mean error of this method in local experiments is 2.62±2.39, which is lower than that in other machine learning algorithms or geometric information algorithms. Additionally, over 72% of the mean error of test data falls within ±2.5 mm, and 100% falls within 3 mm. Moreover, this method can predict 32 landmarks, which is higher than any other machine learning-based algorithm. CONCLUSIONS: According to the results, the proposed method can precisely predict a large number of 3D facial soft tissue landmarks, which gives the feasibility of directly using 3D models for prediction.

3-dimensional analysis of hard- and soft-tissue symmetry in a Chinese population.

BACKGROUND: Facial symmetry severely affects appearance and function. Large numbers of patients seek orthodontic treatment to improve facial symmetry. However, the correlation between hard- and soft-tissue symmetry is still unclear. Our aim was to investigate the hard- and soft-tissue symmetry in subjects with different levels of menton deviation and sagittal skeletal classes with 3D digital analysis and to investigate the relationship between the entire and individual hard- and soft-tissues. METHODS: A total of 270 adults (135 males and 135 females) consisting of 45 subjects of each sex in each sagittal skeletal classification group. All subjects were further classified into relative symmetry (RS), moderate asymmetry (MA) and severe asymmetry (SA) groups based on the degree of menton deviation from the mid-sagittal plane (MSP). The 3D images were segmented into anatomical structures and mirrored across the MSP after establishing a coordinate system. Original and mirrored images were registered by a best-fit algorithm, and the corresponding root mean square (RMS) values and colormap were obtained. The Mann‒Whitney U test and Spearman correlation were conducted for statistical analysis. RESULTS: The RMS increased with greater deviations with regard to the deviation of the menton in most of anatomical structures. Asymmetry was represented in the same way regardless of sagittal skeletal pattern. The soft-tissue asymmetry had a significant correlation with dentition in the RS group (0.409), while in the SA group, it was related to the ramus (0.526) and corpus (0.417) in males and was related to the ramus in the MA (0.332) and SA (0.359) groups in females. CONCLUSIONS: The mirroring method combining CBCT and 3dMD provides a new approach for symmetry analysis. Asymmetry might not be influenced by sagittal skeletal patterns. Soft-tissue asymmetry might be reduced by improving the dentition in individuals with RS group, while among those with MA or SA, whose menton deviation was larger than 2 mm, orthognathic treatment should be considered.

Electrocatalyst Microenvironment Engineering for Enhanced Product Selectivity in Carbon Dioxide and Nitrogen Reduction Reactions.

Carbon and nitrogen fixation strategies are regarded as alternative routes to produce valuable chemicals used as energy carriers and fertilizers that are traditionally obtained from unsustainable and energy-intensive coal gasification (CO and CH4), Fischer-Tropsch (C2H4), and Haber-Bosch (NH3) processes. Recently, the electrocatalytic CO2 reduction reaction (CO2RR) and N2 reduction reaction (NRR) have received tremendous attention, with the merits of being both efficient strategies to store renewable electricity while providing alternative preparation routes to fossil-fuel-driven reactions. To date, the development of the CO2RR and NRR processes is primarily hindered by the competitive hydrogen evolution reaction (HER); however, the corresponding strategies for inhibiting this undesired side reaction are still quite limited. Considering such complex reactions involve three gas-liquid-solid phases and successive proton-coupled electron transfers, it appears meaningful to review the current strategies for improving product selectivity in light of their respective reaction mechanisms, kinetics, and thermodynamics. By examining the developments and understanding in catalyst design, electrolyte engineering, and three-phase interface modulation, we discuss three key strategies for improving product selectivity for the CO2RR and NRR: (i) targeting molecularly defined active sites, (ii) increasing the local reactant concentration at the active sites, and (iii) stabilizing and confining product intermediates.