Electrochemical reduction of carbon dioxide (CO) to value-added carbon products is a promising approach to reduce CO levels and mitigate the energy crisis. However, poor product selectivity is still a major obstacle to the development of CO reduction. Here we demonstrate exclusive Ni-N sites through a topo-chemical transformation strategy, bringing unprecedentedly high activity and selectivity for CO reduction. Topo-chemical transformation by carbon layer coating successfully ensures preservation of the Ni-N structure to a maximum extent and avoids the agglomeration of Ni atoms to particles, providing abundant active sites for the catalytic reaction. The Ni-N structure exhibits excellent activity for electrochemical reduction of CO with particularly high selectivity, achieving high faradaic efficiency over 90% for CO in the potential range from -0.5 to -0.9 V and gives a maximum faradaic efficiency of 99% at -0.81 V with a current density of 28.6 mA cm. We anticipate exclusive catalytic sites will shed new light on the design of high-efficiency electrocatalysts for CO reduction.

High-purity pyrrole-type FeN4 sites have been developed as a superior oxygen reduction catalyst for proton exchange membrane fuel cells.

Electrochemical conversion of CO to value-added chemicals using renewable electricity provides a promising way to mitigate both global warming and the energy crisis. Here, a facile ion-adsorption strategy is reported to construct highly active graphene-based catalysts for CO reduction to CO. The isolated transition metal cyclam-like moieties formed upon ion adsorption are found to contribute to the observed improvements. Free from the conventional harsh pyrolysis and acid-leaching procedures, this solution-chemistry strategy is easy to scale up and of general applicability, thus paving a rational avenue for the design of high-efficiency catalysts for CO reduction and beyond.

Background-Paroxysmal atrial fibrillation (PAF) can be eliminated with continuous circular lesions (CCLs) around the pulmonary veins (PVs), but it is unclear whether all PVs are completely isolated. Methods and Results-Forty-one patients with symptomatic PAF underwent 3D mapping, and all PV ostia were marked on the 3D map based on venography. Irrigated radiofrequency energy was applied at a distance from the PV ostia guided by 2 Lasso catheters placed within the ipsilateral superior and inferior PVs. The mean radiofrequency duration was 1550Ϯ511 seconds for left-sided PVs and 1512Ϯ506 seconds for right-sided PVs. After isolation, automatic activity was observed in the right-sided PVs in 87.8% and in the left-sided PVs in 80.5%. During the procedure, a spontaneous or induced PV tachycardia (PVT) with a cycle length of 189Ϯ29 ms was observed in 19 patients. During a mean follow-up of 6 months, atrial tachyarrhythmias recurred in 10 patients. Nine patients underwent a repeat procedure. Conduction gaps in the left CCL in 9 patients and in the right CCL in 2 patients were closed during the second procedure. A spontaneous PVT with a cycle length of 212Ϯ44 ms was demonstrated in 7 of 9 patients, even though no PVT had been observed in 6 of these 7 patients during the first procedure. No AF recurred in 39 patients after PV isolation during follow-up. Conclusions-Automatic activity and fast tachycardia within the PVs could reflect an arrhythmogenic substrate in patients with PAF, which could be eliminated by isolating all PVs with CCLs guided by 3D mapping and the double-Lasso technique in the majority of patients.

Ventricular arrhythmias are an important cause of morbidity and mortality and come in a variety of forms, from single premature ventricular complexes to sustained ventricular tachycardia and fibrillation. Rapid developments have taken place over the past decade in our understanding of these arrhythmias and in our ability to diagnose and treat them. The field of catheter ablation has progressed with the development of new methods and tools, and with the publication of large clinical trials. Therefore, global cardiac electrophysiology professional societies undertook to outline recommendations and best practices for these procedures in a document that will update and replace the 2009 EHRA/HRS Expert Consensus on Catheter Ablation of Ventricular Arrhythmias. An expert writing group, after reviewing and discussing the literature, including a systematic review and meta-analysis published in conjunction with this document, and drawing on their own experience, drafted and voted on recommendations and summarized current knowledge and practice in the field. Each recommendation is presented in knowledge byte format and is accompanied by supportive text and references. Further sections provide a practical synopsis of the various techniques and of the specific ventricular arrhythmia sites and substrates encountered in the electrophysiology lab. The purpose of this document is to help electrophysiologists around the world to appropriately select patients for catheter ablation, to perform procedures in a safe and efficacious manner, and to provide follow-up and adjunctive care in order to obtain the best possible outcomes for patients with ventricular arrhythmias.

Background-The high incidence of postprocedural atrial tachycardia reduces the absolute arrhythmia-free success rate of extensive ablation strategies to treat nonparoxysmal atrial fibrillation (NPAF). We hypothesized that a strategy of targeting low-voltage zones and sites with abnormal electrograms during sinus rhythm (SR-AEs) in the left atrium after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation in patients with NPAF is superior. Methods and Results-A total of 86 consecutive patients with NPAF were enrolled in study group. After circumferential pulmonary vein isolation, cavotricuspid isthmus ablation and cardioversion to SR, high-density mapping of left atrium was performed. Areas with low-voltage zone and SR-AE were targeted for further homogenization and elimination, respectively; 78 consecutive sex-and age-matched patients with NPAF who were treated with the stepwise approach served as the historical control group. In the study group, 92% (79/86) were successfully cardioverted after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation. Among the patients converted to SR, 70% (55/79) had lowvoltage zone and SR-AE and received additional ablation, whereas in 30% (24/79) without SR-AE or low-voltage zone, no further ablation was performed. During a follow-up period of >30 months, the Kaplan-Meier estimated probability to maintain SR at 24 months was 69.8% versus 51.3%. And after a single procedure, 3.5% (3/86) developed postprocedural atrial tachycardia in study group, compared with 30% (24/78) in control group (P=0.0003). Conclusions-A strategy of selective electrophysiologically guided atrial substrate modification in SR after circumferential pulmonary vein isolation and cavotricuspid isthmus ablation is clinically more effective than the stepwise approach for NPAF ablation. Clinical Trial Registration-URL: http://clinicaltrials.gov. Unique identifier: NCT01716143.(Circ Arrhythm Electrophysiol. 2016;9:e003382.

because of their high energy density and power density. [1][2][3] With expansion of the demand and applications, the price of lithium salt is increasing due to the limited lithium resources on earth, which prevents its application for large-scale application. Recently, Na-ion batteries (NIBs) and K-ion batteries (KIBs) have attracted increasing attention mainly because of the abundance of sodium and potassium in the Earth's crust. [4][5][6][7] Especially, the K + /K couple shows much lower redox potential (−2.93 V) in various carbonate-based electrolytes than that of the Na + /Na couple (−2.71 V), which offers widen electrochemical voltage windows and high energy density of full cell. [8] Thus, developing high-capacity and cost-effective rechargeable NIBs and KIBs is critical for both grid and transportation applications. Among different types of rechargeable batteries, room-temperature alkali metal-chalcogen batteries, such as sodium-sulfur (Na-S), potassium-sulfur (K-S), sodium-selenium (Na-Se), and potassium-selenium (K-Se) batteries, offer great potential because of their high energy density and low cost. [9][10][11][12][13] The inherent low electronic conductivity of S and soluble polysulfides shuttling in the ether-based electrolyte leads to the poor electrochemical performance of Na-S and K-S batteries. [10,11,14] Se possesses chemistry properties similar to sulfur (S) and has been considered to be an alternative cathode material for NIBs because of its high theoretical specific capacity (675 mA h g −1 ), high theoretical volumetric capacity (3253 mA h cm −3 ), and higher electronic conductivity (1 × 10 −3 S m −1 ) than that of S (5 × 10 −30 S m −1 ). [15][16][17] Among various metal-selenium batteries, including Li-Se, Na-Se, and K-Se batteries, Na-Se and K-Se batteries are especially attractive due to low material cost (rich abundance of Na and K in nature). Based on the reactions between Se and metal Li, Na or K: Se + 2M + + 2e − ↔ M 2 Se (M = Li, Na, K), these three Li-Se, Na-Se, and K-Se batteries possess the same theoretical specific capacity of 675 mA h g −1 . [17,18] The specific energy density of Na-Se batteries is smaller than that of Li-Se batteries but higher than that of K-Se batteries. [13,19,20] However, the Se cathode also suffers from short cycle life and low charging efficiency in NIBs Na-Se and K-Se batteries are attractive as a stationary energy storage system because of much abundant resources of Na and K in the Earth's crust. As the alloy-type Se has a severe pulverization issue, one critical challenge to develop advanced Na-Se and K-Se batteries is to explore a highly efficient and stable Se-based cathode. Herein, a flexible free-standing Se/carbon composite film is prepared by encapsulation of Se into a carbon nanotube (CNT) interwoven N,O dual-doped porous carbon nanosheet (Se@NOPC-CNT). The 3D interconnected CNT uniformly wrapped on the N,O dual-doped porous carbon skeletons improves the flexibility and offers an interconnected conductive pathway for rapid ionic/electronic transpo...

URL: http://www.clinicaltrials.gov. Unique identifier: NCT01761188.