Control of CD1d-restricted antigen presentation and inflammation by sphingomyelin.

Invariant natural killer T (iNKT) cells recognize activating self and microbial lipids presented by CD1d. CD1d can also bind non-activating lipids, such as sphingomyelin. We hypothesized that these serve as endogenous regulators and investigated humans and mice deficient in acid sphingomyelinase (ASM), an enzyme that degrades sphingomyelin. We show that ASM absence in mice leads to diminished CD1d-restricted antigen presentation and iNKT cell selection in the thymus, resulting in decreased iNKT cell levels and resistance to iNKT cell-mediated inflammatory conditions. Defective antigen presentation and decreased iNKT cells are also observed in ASM-deficient humans with Niemann-Pick disease, and ASM activity in healthy humans correlates with iNKT cell phenotype. Pharmacological ASM administration facilitates antigen presentation and restores the levels of iNKT cells in ASM-deficient mice. Together, these results demonstrate that control of non-agonistic CD1d-associated lipids is critical for iNKT cell development and function in vivo and represents a tight link between cellular sphingolipid metabolism and immunity.

Loss of the ceramide synthase HYL-2 from Caenorhabditis elegans impairs stress responses and alters sphingolipid composition.

Sphingolipids, essential membrane components and signaling molecules in cells, have ceramides at the core of their metabolic pathways. Initially termed as "longevity assurance genes", the encoding genes of ceramide synthases are closely associated with individual aging and stress responses, although the mechanisms remain unclear. This study aims to explore the alterations and underlying mechanisms of three ceramide synthases, HYL-1, HYL-2, and LAGR-1, in the aging and stress responses of Caenorhabditis elegans. Our results showed the knockdown of HYL-1 extends the lifespan and enhance stress resistance in worms, whereas the loss of HYL-2 function significantly impairs tolerances to heat, oxidation, and ultraviolet stress. Stress intolerance induced by HYL-2 deficiency may result from intracellular mitochondrial dysfunction, accumulation of reactive oxygen species, and abnormal nuclear translocation of DAF-16 under stress conditions. Loss of HYL-2 led to a significant reduction of predominant ceramides (d17:1/C20∼C23) as well as corresponding complex sphingolipids. Furthermore, the N-acyl chain length composition of sphingolipids underwent dramatic modifications, characterized by a decrease in C22 sphingolipids and an increase in C24 sphingolipids. Extra d18:1-ceramides resulted in diminished stress resilience in wild-type worms, while supplementation of d18:1/C16 ceramide to HYL-2-deficient worms marginally improved stress tolerance to heat and oxidation. These findings indicate the importance of appropriate ceramide content and composition in maintaining subcellular homeostasis and nuclear-cytoplasmic signal transduction during healthy aging and stress responses.

Cryo-EM structure of human HCN3 channel and its regulation by cAMP.

HCN channels are important for regulating heart rhythm and nerve activity and have been studied as potential drug targets for treating depression, arrhythmia, nerve pain, and epilepsy. Despite possessing unique pharmacological properties, HCN channels share common characteristics in that they are activated by hyperpolarization and modulated by cAMP and other membrane lipids. However, the mechanisms of how these ligands bind and modulate HCN channels are unclear. In this study, we solved structures of full-length human HCN3 using cryo-EM and captured two different states, including a state without any ligand bound and a state with cAMP bound. Our structures reveal the novel binding sites for cholesteryl hemisuccinate in apo state and show how cholesteryl hemisuccinate and cAMP binding cause conformational changes in different states. These findings explain how these small modulators are sensed in mammals at the molecular level. The results of our study could help to design more potent and specific compounds to influence HCN channel activity and offer new therapeutic possibilities for diseases that lack effective treatment.

Metal-Organic Framework (MOF)-Based Clean Energy Conversion: Recent Advances in Unlocking its Underlying Mechanisms.

Carbon neutrality is an important goal for humanity . As an eco-friendly technology, electrocatalytic clean energy conversion technology has emerged in the 21st century. Currently, metal-organic framework (MOF)-based electrocatalysis, including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), hydrogen evolution reaction (HER), hydrogen oxidation reaction (HOR), carbon dioxide reduction reaction (CO2RR), nitrogen reduction reaction (NRR), are the mainstream energy catalytic reactions, which are driven by electrocatalysis. In this paper, the current advanced characterizations for the analyses of MOF-based electrocatalytic energy reactions have been described in details, such as density function theory (DFT), machine learning, operando/in situ characterization, which provide in-depth analyses of the reaction mechanisms related to the above reactions reported in the past years. The practical applications that have been developed for some of the responses that are of application values, such as fuel cells, metal-air batteries, and water splitting have also been demonstrated. This paper aims to maximize the potential of MOF-based electrocatalysts in the field of energy catalysis, and to shed light on the development of current intense energy situations.

Metal-organic framework-derived two-dimensional in-plane Janus catalysts promoting oxygen electroreduction to hydrogen peroxide.

We use MOFs material as precursor to synthesize carbon based two-dimensional (2D) materials loaded with In2 S3 -In2 O3 (In-S-O) nanoparticles. The In-S-O nanoparticles have exhibited Janus architecture composed of two compounds with different crystal structures that are combined in-plane on 2D carbon material surface. The excellent properties of this in-plane Janus material include 2D nanoarchitecture and its Janus properties formed by combining two different crystal structures. It has exhibited excellent electrochemical performances due to its abundant electrochemical active sites and large specific surface area. According to experiments, the electron transfer number of the material for two-electron oxygen reduction is about 2.4, and the hydrogen peroxide yield is 32 mg/h cm2 . In the further test of liquid flow electrolytic cell, the yield can reach up to 172 mg/h cm2 .

Chemotherapy re-use versus anti-angiogenic monotherapy as the third-line treatment of patients with metastatic colorectal cancer: a real-world cohort study.

BACKGROUND: There are various recommendations for third-line treatment in mCRC, however, there is no consensus on who is more suitable for particular strategy. Chemotherapy re-use in third-line setting is a common option in clinical practice. This study aimed to investigate the efficacy of third-line chemotherapy re-use by the comparison with that of anti-angiogenic monotherapy, and further find the population more suitable for third-line chemotherapy. METHODS: Using electronic medical records of patients with mCRC, a retrospective cohort study was conducted. A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting as control group were retrospectively collected. Baseline characteristics were analyzed using the χ² test or the Fisher's exact test. ROC curve and surv_cutpoint function of 'survminer' package in R software were used to calculate the cut-off value. Survival curves were plotted with the Kaplan-Meier method and were compared using the log-rank test. The Cox proportional hazard regression model was used to analyze the potential risk factors. RESULTS: A total of 143 patients receiving chemotherapy and 40 patients receiving anti-angiogenic monotherapy in third-line setting were retrospectively collected. Chemotherapy rechallenge was recorded in 93 patients (93/143, 65.0%), and the remaining patients chose new chemotherapeutic drugs that had not been previously used, including irinotecan-based (22/50), oxaliplatin-based (9/50), raltitrexed (9/50), gemcitabine (5/50) and other agents (5/50). The ORR and DCR of third-line chemotherapy reached 8.8%, 61.3%, respectively (anti-angiogenic monotherapy group: ORR 2.6%, DCR 47.4%). The mPFS and mOS of patients receiving chemotherapy were 4.9 and 12.0 m, respectively (anti-angiogenic monotherapy group: mPFS 2.7 m, mOS 5.2 m). Subgroup analyses found that patients with RAS/RAF mutation, longer PFS (greater than 10.6 m) in front-line treatment or larger tumor burden had better prognosis with third-line chemotherapy rather than anti-angiogenic monotherapy. CONCLUSIONS: Third-line chemotherapy re-use was effective in mCRC. Those with more aggressive characteristics (RAS/RAF mutant, larger tumor burden) or better efficacy of previous chemotherapy (longer PFS) were more appropriate for third-line chemotherapy, rather than anti-angiogenic monotherapy.

Combined score based on plasma fibrinogen and platelet-lymphocyte ratio as a prognostic biomarker in esophageal squamous cell carcinoma.

BACKGROUND: Increasing evidence has showed that inflammatory biomarkers, including neutrophil to lymphocyte ratio (NLR), platelet to lymphocyte ratio (PLR) and fibrinogen can be used as predictors in the prognosis of esophageal squamous cell carcinoma (ESCC). The aim of this study was to explore prognostic value of these biomarkers and evaluate the clinicopathological and prognostic significance of combined score based on plasma fibrinogen and platelet-lymphocyte ratio (F-PLR score). METHODS: A total of 506 patients with ESCC were enrolled in this study. Harrell's concordance index (c-index) was used to determine the optimal cut-off values of these markers and evaluate their prognostic significance. The relationship between factors with survival rates (including overall survival [OS] and disease-free survival [DFS]) was explored by Kaplan-Meier curve, univariate analysis and multivariate cox hazard analysis. RESULTS: Our result indicated that high F-PLR score was significantly associated with longer tumor length and deeper depth of tumor invasion (p < 0.01). The result of Cox multivariable analysis showed that F-PLR score was an independent prognostic factor for OS (p = 0.002) and DFS (p = 0.003). In addition, F-PLR score presented the greater c-index values for OS and DFS compared with NLR, PLR and fibrinogen level. Our result also showed that the c-index values for OS and DFS were both greater in TNM + F-PLR than those in TNM stage alone. CONCLUSIONS: In conclusion, F-PLR score is a predictive biomarker for prognosis in patients with ESCC.

Functional genomics reveals that tumors with activating phosphoinositide 3-kinase mutations are dependent on accelerated protein turnover.

Activating mutations in the phosphoinositide 3-kinase (PI3K) signaling pathway are frequently identified in cancer. To identify pathways that support PI3K oncogenesis, we performed a genome-wide RNAi screen in isogenic cell lines harboring wild-type or mutant PIK3CA to search for PI3K synthetic-lethal (SL) genes. A combined analysis of these results with a meta-analysis of two other large-scale RNAi screening data sets in PI3K mutant cancer cell lines converged on ribosomal protein translation and proteasomal protein degradation as critical nononcogene dependencies for PI3K-driven tumors. Genetic or pharmacologic inhibition of either pathway alone, but not together, selectively killed PI3K mutant tumor cells in an mTOR-dependent manner. The expression of ribosomal and proteasomal components was significantly up-regulated in primary human colorectal tumors harboring PI3K pathway activation. Importantly, a PI3K SL gene signature containing the top hits of the SL genes identified in our meta-analysis robustly predicted overall patient survival in colorectal cancer, especially among patients with tumors with an activated PI3K pathway. These results suggest that disruption of protein turnover homeostasis via ribosome or proteasome inhibition may be a novel treatment strategy for PI3K mutant human tumors.

Treatment of nitrogen and phosphorus from sewage tailwater in paddy rice wetlands: concept and environmental benefits.

Domestic sewage tailwater (DSTW) reuse for crop irrigation is considered a promising practice to reduce water demand, mitigate water pollution, and substitute chemical fertilization. The level of the above environmental benefits of this water reuse strategy, especially when applied to paddy wetlands, remains unclear. In this study, soil column experiments were conducted to investigate the nitrogen and phosphorus fate in paddy wetlands subjected to different tailwater irrigation and drainage strategies, specifically, (i) TW1 and TW2 for regular or enhanced irrigation-drainage without N fertilization, (ii) TW3 and TW4 for regular irrigation with base or tillering N fertilizer, (iii) conventional fertilization N210, and (iv) no-fertilization controls N0. The results showed that the total nitrogen (TN), nitrate (NO3-), and total phosphorus (TP) removal rates from the paddies irrigated by DSTW ranged between 51.92 and 59.34%, 68.1 and 83.42%, and 85.69 and 86.98% respectively. Ammonia emissions from the DSTW-irrigated treatments were reduced by 14.6~47.2% compared to those paddies subjected to conventional fertilization (N210), similarly for TN emissions, with the exception of the TW2 treatment. Overall, it is established that the paddy wetland could effectively remove residual N and P from surface water runoffs, while the partial substitution of chemical fertilization by DSTW could be confirmed. The outcome of this study demonstrates that DSTW irrigation is a promising strategy for sustainable rice production with a minimized environmental impact.

Entropy-Driven Direct Air Electrofixation.

According to the principles of chemical thermodynamics, the catalytic activation of small molecules (like N2 in air and CO2 in flue gas) generally exhibits a negative activity dependence on O2 owning to the competitive oxygen reduction reaction (ORR). Nevertheless, some catalysts can show positive activity dependence for N2 electrofixation, an important route to produce ammonia under ambient condition. Here we report that the positive activity dependence on O2 of (Ni0.20Co0.20Fe0.20Mn0.19Mo0.21)3S4 catalyst arises from high-entropy mechanism. Through experimental and theoretical studies, we demonstrate that under the reaction condition in the mixed N2/O2, the adsorption of O2 on high-entropy catalyst contributes to activating N2 molecules characteristic of elongated N≡N bond lengths. As comparison to the low- and medium-entropy counterparts, high entropy can play the second role of attenuating competitive ORR by displaying a negative exponential entropy-ORR activity relationship. Accordingly, benefiting from the O2, the system for direct air electrofixation has demonstrated an ammonia yield rate of 47.70 µg h-1 cm-2, which is even 1.5 times of pure N2 feedstock (31.92 µg h-1 cm-2), overtaking all previous reports for this reaction. We expect the present finding providing an additional dimension to high entropy that leverages systems beyond the constraint of traditional rules.

Cryo-EM structure of mouse TRPML2 in lipid nanodiscs.

In mammalians, transient receptor potential mucolipin ion channels (TRPMLs) exhibit variable permeability to cations such as Ca2+, Fe2+, Zn2+, and Na+ and can be activated by the phosphoinositide PI(3,5)P2 in the endolysosomal system. Loss or dysfunction of TRPMLs has been implicated in lysosomal storage disorders, infectious diseases, and metabolic diseases. TRPML2 has recently been identified as a mechanosensitive and hypotonicity-sensitive channel in endolysosomal organelles, which distinguishes it from TRPML1 and TRPML3. However, the molecular and gating mechanism of TRPML2 remains elusive. Here, we present the cryo-EM structure of the full-length mouse TRPML2 in lipid nanodiscs at 3.14 Å resolution. The TRPML2 homotetramer structure at pH 7.4 in the apo state reveals an inactive conformation and some unique features of the extracytosolic/luminal domain and voltage sensor-like domain that have implications for the ion-conducting pathway. This structure enables new comparisons between the different subgroups of TRPML channels with available structures and provides structural insights into the conservation and diversity of TRPML channels. These comparisons have broad implications for understanding a variety of molecular mechanisms of TRPMLs in different pH conditions, including with and without bound agonists and antagonists.

Less-Coordinated Atomic Copper-Dimer Boosted Carbon-Carbon Coupling During Electrochemical CO2 Reduction.

This work reports a metal-organic framework (MOF) with less-coordinated copper dimers, which displays excellent electrochemical CO2 reduction (eCO2 RR) performance with an advantageous current density of 0.9 A cm-2 and a high Faradaic efficiency of 71% to C2 products. In comparison with MOF with Cu monomers that are present as Cu1 O4 with a coordination number of 3.8 ± 0.2, Cu dimers exist as O3 Cu1 ···Cu2 O2 with a coordination number of 2.8 ± 0.1. In situ characterizations together with theoretical calculations reveal that two *CO intermediates are stably adsorbed on each site of less-coordinated Cu dimers, which favors later dimerization via a key intermediate of *CH2 CHO. The highly unsaturated dual-atomic Cu provides large-quantity and high-quality actives sites for carbon-carbon coupling, achieving the optimal trade-off between activity and selectivity of eCO2 RR to C2 products.

Structure-Based Discovery and Structural Basis of a Novel Broad-Spectrum Natural Product against the Main Protease of Coronavirus.

Over the past 20 years, the severe acute respiratory syndrome coronavirus (SARS-CoV), Middle East respiratory syndrome CoV (MERS-CoV), and SARS-CoV-2 emerged, causing severe human respiratory diseases throughout the globe. Developing broad-spectrum drugs would be invaluable in responding to new, emerging coronaviruses and to address unmet urgent clinical needs. Main protease (Mpro; also known as 3CLpro) has a major role in the coronavirus life cycle and is one of the most important targets for anti-coronavirus agents. We show that a natural product, noncovalent inhibitor, shikonin, is a pan-main protease inhibitor of SARS-CoV-2, SARS-CoV, MERS-CoV, human coronavirus (HCoV)-HKU1, HCoV-NL63, and HCoV-229E with micromolar half maximal inhibitory concentration (IC50) values. Structures of the main protease of different coronavirus genus, SARS-CoV from the betacoronavirus genus and HCoV-NL63 from the alphacoronavirus genus, were determined by X-ray crystallography and revealed that the inhibitor interacts with key active site residues in a unique mode. The structure of the main protease inhibitor complex presents an opportunity to discover a novel series of broad-spectrum inhibitors. These data provide substantial evidence that shikonin and its derivatives may be effective against most coronaviruses as well as emerging coronaviruses of the future. Given the importance of the main protease for coronavirus therapeutic indication, insights from these studies should accelerate the development and design of safer and more effective antiviral agents. IMPORTANCE The current pandemic has created an urgent need for broad-spectrum inhibitors of SARS-CoV-2. The main protease is relatively conservative compared to the spike protein and, thus, is one of the most promising targets in developing anti-coronavirus agents. We solved the crystal structures of the main protease of SARS-CoV and HCoV-NL63 that bound to shikonin. The structures provide important insights, have broad implications for understanding the structural basis underlying enzyme activity, and can facilitate rational design of broad-spectrum anti-coronavirus ligands as new therapeutic agents.

Therapeutic targeting of hepatic ACSL4 ameliorates NASH in mice.

BACKGROUND AND AIMS: Globally, NAFLD is one of the most common liver disorders, with an estimated prevalence rate of more than 30% in men and 15% in women and an even higher prevalence in people with type 2 diabetes mellitus. Optimal pharmacologic therapeutic approaches for NAFLD are an urgent necessity. APPROACH AND RESULTS: In this study, we showed that compared with healthy controls, hepatic ACSL4 levels in patients with NAFLD were found to be elevated. Suppression of ACSL4 expression promoted mitochondrial respiration, thereby enhancing the capacity of hepatocytes to mediate ß-oxidation of fatty acids and to minimize lipid accumulation by up-regulating peroxisome proliferator-activated receptor coactivator-1 alpha. Moreover, we found that abemaciclib is a potent and selective ACSL4 inhibitor, and low dose of abemaciclib significantly ameliorated most of the NAFLD symptoms in multiple NAFLD mice models. CONCLUSIONS: Therefore, inhibition of ACSL4 is a potential alternative therapeutic approach for NAFLD.

Sintilimab Plus Apatinib and Chemotherapy as Second­/Third-Line treatment for Advanced Gastric or Gastroesophageal Junction Adenocarcinoma: a prospective, Single-Arm, phase II trial.

BACKGROUND: The prognosis of patients with previously treated advanced gastric or gastroesophageal junction (GEJ) cancer remains poor. Given the robust development of immunotherapy and targeted therapy during the last decades, we aimed to investigate if the combination of traditional second-line chemotherapy with sintilimab and apatinib could bring survival benefits for these patients. METHODS: In this single-center, single-arm, phase II trial, patients with previously treated advanced gastric or GEJ adenocarcinoma received specific dose level of intravenous paclitaxel or irinotecan (investigator's choice), 200 mg intravenous sintilimab on day 1, and 250 mg oral apatinib once daily continuously in each cycle until disease progression, intolerable toxicity, or withdrawal of consent. The primary endpoints were objective response rate and progression-free survival. The secondary endpoints were mainly overall survival and safety. RESULTS: From May 2019 to May 2021, 30 patients were enrolled. At the data cutoff date (March 19, 2022), the median follow-up duration was 12.3 months and 53.6% (95% CI, 33.9-72.5%) patients achieved objective response. The median progression-free survival and overall survival were 8.5 months (95% CI, 5.4-11.5) and 12.5 months (95% CI, 3.7-21.3), respectively. Grade 3-4 adverse events included hematological toxicities, elevated alanine aminotransferase, elevated aspartate aminotransferase, elevated alkaline phosphatase, elevated gamma-glutamyl transpeptidase, hyperbilirubinemia and proteinuria. The most frequent grade 3-4 adverse event was neutropenia (13.3%). No serious treatment-related adverse events or treatment-related deaths occurred. CONCLUSION: Sintilimab plus apatinib and chemotherapy demonstrates promising anti-tumor activity with manageable safety profile in patients with previously treated advanced gastric or GEJ cancer. TRIAL REGISTRATION: ClinicalTrials.gov: NCT05025033, 27/08/2021.

The optimal time of starting adjuvant chemotherapy after curative surgery in patients with colorectal cancer.

BACKGROUND: Postoperative adjuvant chemotherapy (AC) is now well-accepted as standard for high-risk stage II and stage III colorectal cancer (CRC) patients, however the optimal time to initiate AC remains elusive. METHODS: A comprehensive literature search was performed using the PubMed and Embase databases. The Hazard ratio (HR) with the corresponding 95% confidence interval (CI) was used as an effect measure to evaluate primary endpoints. All analyses were conducted using Stata software version 12.0 with the Random-effects model. RESULTS: A total of 30 studies were included in our study. Upon comparison on overall survival (OS), we identified that delaying the initiation of AC for > 8 weeks after operation was significantly associated with poor OS (HR: 1.37; 95% CI: 1.27-1.48; P < 0.01). The poor prognostic value of AC delay for > 8 weeks was not undermined by subgroup analysis based on region, tumor site, sample size and study quality. No obvious differences were observed in survival between AC within 5-8 weeks and ≤ 4 weeks (HR: 1.03; 95% CI: 0.96 -1.10; P = 0.46). Moreover, two studies both highlighted that the survival benefit of AC was still statistically significant when AC was applied 5-6 months after surgery compared with the non-chemotherapy group. CONCLUSIONS: Delaying the initiation of AC for > 8 weeks after surgery was significantly associated with poor OS. AC started within 8 weeks after surgery brought more benefits to CRC patients. There were no obvious differences in survival benefits between AC within 5-8 weeks and ≤ 4 weeks. Compared to patients not receiving AC after surgery, a delay of approximately 5-6 months was still useful to improve prognosis.

A novel effect of PDLIM5 in α7 nicotinic acetylcholine receptor upregulation and surface expression.

Nicotinic acetylcholine receptors (nAChRs) are widespread throughout the central nervous system. Signaling through nAChRs contributes to numerous higher-order functions, including memory and cognition, as well as abnormalities such as nicotine addiction and neurodegenerative disorders. Although recent studies indicate that the PDZ-containing proteins comprising PSD-95 family co-localize with nicotinic acetylcholine receptors and mediate downstream signaling in the neurons, the mechanisms by which α7nAChRs are regulated remain unclear. Here, we show that the PDZ-LIM domain family protein PDLIM5 binds to α7nAChRs and plays a role in nicotine-induced α7nAChRs upregulation and surface expression. We find that chronic exposure to 1 µM nicotine upregulated α7, ß2-contained nAChRs and PDLIM5 in cultured hippocampal neurons, and the upregulation of α7nAChRs and PDLIM5 is increased more on the cell membrane than the cytoplasm. Interestingly, in primary hippocampal neurons, α7nAChRs and ß2nAChRs display distinct patterns of expression, with α7nAChRs colocalized more with PDLIM5. Furthermore, PDLIM5 interacts with α7nAChRs, but not ß2nAChRs in native brain neurons. Knocking down of PDLIM5 in SH-SY5Y abolishes nicotine-induced upregulation of α7nAChRs. In primary hippocampal neurons, using shRNA against PDLIM5 decreased both surface clustering of α7nAChRs and α7nAChRs-mediated currents. Proteomics analysis and isothermal titration calorimetry (ITC) results show that PDLIM5 interacts with α7nAChRs through the PDZ domain, and the interaction between PDLIM5 and α7nAChRs can be promoted by nicotine. Collectively, our data suggest a novel cellular role of PDLIM5 in the regulation of α7nAChRs, which may be relevant to plastic changes in the nervous system.

Electrocatalytic CO2-to-C2+ with Ampere-Level Current on Heteroatom-Engineered Copper via Tuning *CO Intermediate Coverage.

An ampere-level current density of CO2 electrolysis is critical to realize the industrial production of multicarbon (C2+) fuels. However, under such a large current density, the poor CO intermediate (*CO) coverage on the catalyst surface induces the competitive hydrogen evolution reaction, which hinders CO2 reduction reaction (CO2RR). Herein, we report reliable ampere-level CO2-to-C2+ electrolysis by heteroatom engineering on Cu catalysts. The Cu-based compounds with heteroatom (N, P, S, O) are electrochemically reduced to heteroatom-derived Cu with significant structural reconstruction under CO2RR conditions. It is found that N-engineered Cu (N-Cu) catalyst exhibits the best CO2-to-C2+ productivity with a remarkable Faradaic efficiency of 73.7% under -1100 mA cm-2 and an energy efficiency of 37.2% under -900 mA cm-2. Particularly, it achieves a C2+ partial current density of -909 mA cm-2 at -1.15 V versus reversible hydrogen electrode, which outperforms most reported Cu-based catalysts. In situ spectroscopy indicates that heteroatom engineering adjusts *CO adsorption on Cu surface and alters the local H proton consumption in solution. Density functional theory studies confirm that the high adsorption strength of *CO on N-Cu results from the depressed HER and promoted *CO adsorption on both bridge and atop sites of Cu, which greatly reduces the energy barrier for C-C coupling.

Stabilizing Cu2+ Ions by Solid Solutions to Promote CO2 Electroreduction to Methane.

Copper is the only metal catalyst that can perform the electrocatalytic CO2 reduction reaction (CRR) to produce hydrocarbons and oxygenates. Its surface oxidation state determines the reaction pathway to various products. However, under the cathodic potential of CRR conditions, the chemical composition of most Cu-based catalysts inevitably undergoes electroreduction from Cu2+ to Cu0 or Cu1+ species, which is generally coupled with phase reconstruction and the formation of new active sites. Since the initial Cu2+ active sites are hard to retain, there have been few studies about Cu2+ catalysts for CRR. Herein we propose a solid-solution strategy to stabilize Cu2+ ions by incorporating them into a CeO2 matrix, which works as a self-sacrificing ingredient to protect Cu2+ active species. In situ spectroscopic characterization and density functional theory calculations reveal that compared with the conventionally derived Cu catalysts with Cu0 or Cu1+ active sites, the Cu2+ species in the solid solution (Cu-Ce-Ox) can significantly strengthen adsorption of the *CO intermediate, facilitating its further hydrogenation to produce CH4 instead of dimerization to give C2 products. As a result, different from most of the other Cu-based catalysts, Cu-Ce-Ox delivered a high Faradaic efficiency of 67.8% for CH4 and a low value of 3.6% for C2H4.

Battery-Driven N2 Electrolysis Enabled by High-Entropy Catalysts: From Theoretical Prediction to Prototype Model.

A small-scale standalone device of nitrogen (N2 ) splitting holds great promise for producing ammonia (NH3 ) in a decentralized manner as the compensation or replacement of centralized Haber-Bosch process. However, the design of such a device has been impeded by sluggish kinetics of its half reactions, i.e., cathodic N2 reduction reaction (NRR) and anodic oxygen evolution reaction (OER). Here, it is predicted from density function theory that high-entropy oxides (HEOs) are potential catalysts for promoting NRR and OER, and subsequently develop a facile procedure to synthesize HEOs in the morphology of sea urchin-shaped hollow nanospheres assembled from ultrathin nanosheets. The excellent electrocatalytic activities of HEOs for both NRR (NH3 yield rate: 47.58 µg h-1 mg-1 and Faradaic efficiency (FE): 10.74%) and OER (215 mV @10 mA cm-2 ) are demonstrated. Consequently, a prototype device of N2 electrolysis driven by commercial batteries is constructed, which can operate smoothly and deliver remarkable NH3 yield rate (41.11 µg h-1 mg-1 ) and FE (14.14%). Further mechanism study has attributed the excellent catalytic performances of HEOs to their unique electronic structures originated from multi-metal synergistic effects and entropy increase effects. The work will provide new clues for designing versatile catalysts and devices for large-scale industrialization.