Electrochemical nitrate reduction (NITRR) offers a promising alternative toward nitrogen recycling and ammonia production under ambient conditions, for which highly active and selective electrocatalyst is desired. In this study, metallic cobalt nanoarrays as facilely prepared from the electrochemical reduction of Co(OH)2 nanoarrays (NAs) are demonstrated to exhibit unprecedented NH3 producing capability from catalyzing NITRR. Benefitting from the high intrinsic activity of Co0, intimate contact between active species and conductive substrate and the nanostructure which exposes large number of active sites, the Co‐NAs electrode exhibits current density of −2.2 A cm−2 and NH3 production rate of 10.4 mmol h−1 cm−2 at −0.24 V versus RHE under alkaline condition and significantly surpasses reported counterparts. Moreover, the close‐to‐unity (≥96%) Faradaic efficiency (FE) toward NH3 is achieved over wide application range (potential, NO3− concentration and pH). Density function theory calculation reveals the optimized adsorption energy of NITRR intermediates on Co surface over Co(OH)2. Furthermore, it is proposed that despite the sluggish kinetics of Volmer step (H2O → *H + *OH) which provides protons in conventional hydrogenation mechanism, the proton‐supplying water dissociation process on Co surface is drastically facilitated following a concerted water dissociation–hydrogenation pathway.

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Developing high-efficiency and low-cost catalysts for the hydrogen evolution reaction (HER) and hydrogen generation from chemical hydrogen storage materials are both significant and critical for the exploitation and utilization of hydrogen energy. Herein, we reported a ruthenium−cobalt alloy (Ru, 1.8 wt %) enriched in hollow carbon spheres (denoted RuCo@HCSs) synthesized through a wet vacuum impregnation method followed by pyrolysis treatment. RuCo alloys are obtained by direct reduction of Ru and Co chloride precursors, avoiding hydrothermal and washing processes, and the Ru/Co ratio of the alloy can be precisely controlled. The RuCo@HCS catalyst not only displays outstanding HER performance with a low overpotential (η 10 ) and Tafel slope (21 mV and 32 mV dec −1 in 1.0 M KOH, 57 mV and 48 mV dec −1 in 0.5 M H 2 SO 4 , and 49 mV and 59 mV dec −1 in 1.0 M phosphate-buffered saline) within a wide pH range but also offers a high turnover frequency (TOF) value of 784 mol H2 min −1 mol cat −1 for the hydrolysis of ammonia borane under ambient conditions. The excellent catalytic performance of RuCo@HCSs is attributed to the special hollow embedded configuration and collaborative effect between carbon shells and RuCo alloys. Density functional theory calculations reveal that the excellent catalytic performance of RuCo@HCSs originates from the carbon shells activated by the electron transferred from the embedded metal nanoparticles. This work provides a convenient route for preparing highly active and inexpensive metal/carbon composite bifunctional catalysts.

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Background/Aims: Hepatic artery stenosis (HAS) is a potentially life-threatening complication of liver transplantation because the associated mortality and morbidity rates are high. Surgical reconstruction was recommended as first choice of treatment and interventional radiologic techniques have been introduced recently. However, the mid- or long-term outcomes of HAS were unclear. The purpose of this study was to evaluate the efficacy of interventional therapy and clinical outcomes of HAS following liver transplantation. Methods: A retrospective analysis was performed for 20 cases of HAS documented by angiography from October 2003 to August 2007 at the authors’ institution. All patients underwent transluminal interventional therapy including percutaneous transluminal angioplasty and endovascular stent placement. The technical results, hepatic artery patency and clinical outcome were reviewed. Results: All patients were treated with interventional management. Technical and immediate success was 100%. Of 8 patients with early HAS (within 1 month of transplantation), 1 underwent retransplantation due to deterioration of liver function. One died of acute liver failure waiting for retransplantation. Of 12 patients with late HAS (after 1 month of liver transplantation), 1 died of severe sepsis 38 days after transplantation. Five patients underwent late retransplantation due to ischemic-type biliary strictures or recurrent attacks of cholangitis. One of these patients died 11 days after retransplantation. The median follow-up of all 20 patients was 14.4 months after liver transplantation. The Kaplan-Meier curve of patency showed that cumulated primary patency of hepatic artery interventional treatment at 3, 6 and 12 months was 94, 87 and 79%, respectively. Two patients died of causes unrelated to HAS. Three patients developed recurrent HAS and were successfully treated with second interventional therapy. Eight patients (40%) developed ischemic-type biliary strictures and 7 underwent endoscopic treatment or percutaneous transhepatic cholangiodrainage. Graft function in 5 patients improved. The Kaplan-Meier curve of survival showed that the 1- and 2-year cumulated survival rates of early and late HAS were 87.5 and 43.8% and 81.5 and 61.1%, respectively. There was no significant difference in 1- and 2-year survival rates between early and late HAS (log-rank test, p = 0.928). Conclusion: Interventional therapy is an effective treatment for both early and late HAS with excellent short- and mid-term outcomes, while without irreversible graft dysfunction resulted from HAS. However, the patients have a high incidence of ischemic-type biliary lesions.