Engineering vacancy and hydrophobicity of two-dimensional TaTe2 for efficient and stable electrocatalytic N2 reduction

Demand for ammonia continues to increase to sustain the growing global population. The direct electrochemical N2 reduction reaction (NRR) powered by renewable electricity offers a promising carbon-neutral and sustainable strategy for manufacturing NH3, yet achieving this remains a grand challenge. Here, we report a synergistic strategy to promote ambient NRR for ammonia production by tuning the Te vacancies (VTe) and surface hydrophobicity of two-dimensional TaTe2 nanosheets. Remarkable NH3 faradic efficiency of up to 32.2% is attained at a mild overpotential, which is largely maintained even after 100 h of consecutive electrolysis. Isotopic labeling validates that the N atoms of formed NH4+ originate from N2. In situ X-ray diffraction indicates preservation of the crystalline structure of TaTe2 during NRR. Further density functional theory calculations reveal that the potential-determining step (PDS) is ∗NH2 + (H+ + e–) → NH3 on VTe-TaTe2 compared with that of ∗ + N2 + (H+ + e–) → ∗N–NH on TaTe2. We identify that the edge plane of TaTe2 and VTe serve as the main active sites for NRR. The free energy change at PDS on VTe-TaTe2 is comparable with the values at the top of the NRR volcano plots on various transition metal surfaces

Single-atom cadmium-N4 sites for rechargeable Li–CO2 batteries with high capacity and ultra-long lifetime

The rechargeable Li–CO2 battery shows great potential in civil, military, and aerospace fields due to its high theoretical energy density and CO2 capture capability. To facilitate the practical application of Li–CO2 battery, the design of efficient, low-cost, and robust non-noble metal cathodes to boost CO2 reduction/evolution kinetics is highly desirable yet remains a challenge. Herein, single-atom cadmium is reported with a Cd-N4 coordination structure enable rapid kinetics of both the discharge and recharge process when employed as a cathode catalyst, and thus facilitates exceptional rate performance in a Li–CO2 battery, even up to 10 A g−1, and remains stable at a high current density (100 A g−1). An unprecedented discharge capacity of 160045 mAh g−1 is attained at 500 mA g−1. Excellent cycling stability is maintained for 1685 and 669 cycles at 1 A g−1 and capacities of 0.5 and 1 Ah g−1, respectively. Density functional theory calculations reveal low energy barriers for both Li2CO3 formation and decomposition reactions during the respective discharge and recharge process, evidencing the high catalytic activity of single Cd sites. This study provides a simple and effective avenue for developing highly active and stable single-atom non-precious metal cathode catalysts for advanced Li–CO2 batteries

Tuning the Pd-catalyzed electroreduction of CO2 to CO with reduced overpotential

Developing selective and efficient catalysts is highly desirable for electrochemical CO2 reduction (ECR) to fuels and chemicals. Pd can strongly bind *COOH but weakly bind *CO, thus resulting in CO as a product. However, proton reduction also occurs severely on the surface of Pd, leading to low CO selectivity. Here we found that the ECR to CO can be greatly enhanced by controlling the Pd–ceria interface and doping with tellurium atoms. Notably, a very high mass activity of 92 mA mgPd−1 (at 1.0 V vs. reversible hydrogen electrode) for CO formation was achieved, significantly surpassing previously reported Pd catalysts (35 mA mgPd−1 at −1.0 V). The Pd catalysts comprising CeOx displayed more positive onset potentials than the Pd catalysts in the absence of CeOx, enabling ECR to CO at −0.6 V (vs. RHE). The modified Pd catalyst also afforded an unprecedented CO faradaic efficiency of over 84% at a low Pd loading (<3 wt%). Density functional theory calculations revealed that the Pd atoms located between the Te dopant and CeO2 promoted CO formation, thus improving CO2 conversion efficiency

Endoscopic Submucosal Dissection for Recurrent or Residual Superficial Esophageal Cancer after Chemoradiotherapy: Two Cases

We report two cases of endoscopic submucosal dissection (ESD) for recurrent or residual esophageal squamous cell carcinoma (ESCC) lesions after chemoradiotherapy for advanced esophageal cancer. Case 1 involved a 64-year-old man who had previously undergone chemoradiotherapy for advanced ESCC and achieved a complete response (CR) for 22 months, until metachronous recurrent superficial ESCC was detected on follow-up esophagogastroduodenoscopy (EGD). We performed ESD and found no evidence of recurrence for 24 months. Case 2 involved a 59-year-old man who had previously undergone chemoradiotherapy for advanced ESCC. He responded favorably to treatment, and most of the tumor had disappeared on follow-up EGD 4 months later. However, there were two residual superficial esophageal lugol-voiding lesions. We performed ESD, and he had a CR for 32 months thereafter. ESD can be considered a viable treatment option for recurrent or residual superficial ESCC after chemoradiotherapy for advanced esophageal cancer

Suppression of Hydrogen Evolution Reaction in Electrochemical N₂ Reduction Using Single-Atom Catalysts: A Computational Guideline

We studied electrochemical nitrogen reduction reactions (NRR) to ammonia on single atom catalysts (SACs) anchored on defective graphene derivatives by density functional calculations. We find significantly improved NRR selectivity on SACs compared to that on the existing bulk metal surface due to the great suppression of the hydrogen evolution reaction (HER) on SACs with the help of the ensemble effect. In addition, several SACs, including Ti@N₄ (0.69 eV) and V@N₄ (0.87 eV), are shown to exhibit lower free energy for NRR than that of the Ru(0001) stepped surface (0.98 eV) due to a strong back-bonding between the hybridized d-orbital metal atom in SAC and π* orbital in *N₂. Formation energies as a function of nitrogen chemical potential suggest that Ti@N₄ and V@N₄ are also synthesizable under experimental conditions

Safety and Effectiveness of Endoscopist-Directed Nurse-Administered Sedation during Gastric Endoscopic Submucosal Dissection

Background and Aims. Endoscopic submucosal dissection (ESD) is routinely performed in treating gastric neoplasia and requires long-term higher levels of sedation. Endoscopist-directed nurse-administered sedation (EDNAS) has not been well studied in ESD. This study aimed to evaluate the safety and effectiveness of EDNAS for ESD. Methods. Patients treated with ESD for gastric tumors between 2013 and 2015 were retrospectively collected. Patients were divided into a midazolam-treated group (M group) and a midazolam plus propofol-treated group (MP group). Clinical outcome, safety, effectiveness, adverse events of ESD, and adverse events of sedation were analyzed. Results. Of 209 collected patients, 83 were in the M group and 126 were in the MP group. Of all patients, 67 patients had the circulatory adverse event during the ESD procedure. Sedation method was the only significant risk factor (M versus MP: 2.17 (1.14–4.15), p=0.019). In analysis of MP subgroups, 47 patients suffered an adverse event from sedation, and current smoking was the only significant association factor for adverse event (0.15 (0.03–0.68), p=0.014). Conclusions. In performing ESD, the effect of sedation is reduced in smoking patients. EDNAS may be acceptable for ESD under careful monitoring of vital sign and oxygen saturation

Nitrogen fixation by Ru single-atom electrocatalytic reduction

Nitrogen fixation under ambient conditions remains a significant challenge. Here, we report nitrogen fixation by Ru single-atom electrocatalytic reduction at room temperature and pressure. In contrast to Ru nanoparticles, single Ru sites supported on N-doped porous carbon greatly promoted electroreduction of aqueous N2 selectively to NH3, affording an NH3 formation rate of 3.665 mgNH3h−1mg−1Ru at −0.21 V versus the reversible hydrogen electrode. Importantly, the addition of ZrO2 was found to significantly suppress the competitive hydrogen evolution reaction. An NH3 faradic efficiency of about 21% was achieved at a low overpotential (0.17 V), surpassing many other reported catalysts. Experiments combined with density functional theory calculations showed that the Ru sites with oxygen vacancies were major active centers that permitted stabilization of *NNH, destabilization of *H, and enhanced N2 adsorption. We envision that optimization of ZrO2 loading could further facilitate electroreduction of N2 at both high NH3 synthesis rate and faradic efficiency