原位表征技术揭示析氢电催化剂活性中心

文章简介课题组以导电碳布上生长的氢氧化镍纳米片为模板,通过与对苯二硫酚配体反应,成功合成出具有平面Ni（SR）4配位结构的镍—硫醇配位聚合物纳米片,并发现该材料在碱性析氢测试中,催化活性随测试时间逐渐加存在明显诱导期的现象。在保持20m A/cm2的电流密度条件下,析氢所需过电位逐渐降低,约10小时后该

Ultrastable Atomic Copper Nanosheets for Selective Electrochemical Reduction of Carbon Dioxide

金属铜表面很容易被空气氧化，因此铜纳米材料在空气中极不稳定，如何制备原子级厚度的二维铜纳米片一直是纳米材料领域的一个挑战性难题。厦门大学化学化工学院郑南峰教授课题组发展了一种制备稳定超薄二维铜基纳米材料的有效方法，并将这类材料应用于二氧化碳的选择性电催化还原。该项研究还发现所合成的复合纳米材料能够将二氧化碳和水选择性地电化学还原为组成可调的合成气（一氧化碳和氢气混合气），在较低的还原电位下可高选择性地将二氧化碳还原成一氧化碳(其法拉第效率高达92%)。铜基纳米材料在二氧化碳电化学还原中具有优异的性能，但产物异常多样，选择性控制的难度很大。该项工作利用简单的表面配位修饰大幅改善电催化选择性的策略为二氧化碳还原电催化剂的设计提供了新思路。 该工作是在郑南峰教授指导下，并与傅钢教授课题组、加拿大Dalhousie大学张鹏教授合作完成，第一作者为化学化工学院博士生代磊，硕士生钦青、博士生汪佩、赵小静等参与了该工作。【Abstract】The electrochemical conversion of CO2 and H2O into syngas using renewably generated electricity is an attractive approach to simultaneously achieve chemical fixation of CO2 and storage of renewable energy. Developing cost-effective catalysts for selective electroreduction of CO2 into CO is essential to the practical applications of the approach. We report a simple synthetic strategy for the preparation of ultrathin Cu/Ni(OH)2 nanosheets as an excellent cost-effective catalyst for the electrochemical conversion of CO2 and H2O into tunable syngas under low overpotentials. These hybrid nanosheets with Cu(0)-enriched surface behave like noble metal nanocatalysts in both air stability and catalysis. Uniquely, Cu(0) within the nanosheets is stable against air oxidation for months because of the presence of formate on their surface. With the presence of atomically thick ultrastable Cu nanosheets, the hybrid Cu/Ni(OH)2 nanosheets display both excellent activity and selectivity in the electroreduction of CO2 to CO. At a low overpotential of 0.39 V, the nanosheets provide a current density of 4.3 mA/cm2 with a CO faradaic efficiency of 92%. No decay in the current is observed for more than 22 hours. The catalysts developed in this work are promising for building low-cost CO2 electrolyzers to produce CO.We thank the beamline BL14W1 (Shanghai Synchrotron Radiation Facility) for providing the beam time. the Ministry of Science and Technology of China (2017YFA0207302 and 2015CB93230)and the National Natural Science Foundation of China (21731005, 21420102001, 21333008). 研究工作得到了科技部和国家自然科学基金委的资助，X-射线吸收光谱测试在上海光源BL14W1线站完成

Visual nesting system for irregular cutting-stock problem based on rubber band packing algorithm

This article deals with the packing problem of irregular items allocated into a rectangular sheet to minimize the waste. Conventional solution is not visual during the packing process. It obtains a reasonable and relatively satisfactory solution between the nesting time and nesting solution. This article adopts a physical method that uses rubber band packing algorithm to simulate a rubber band wrapping those packing irregular items. The simulation shows a visual and fast packing process. The resultant rubber band force is applied in the packing items to translate, rotate, and slide them to make the area decrease and obtain a high packing density. An improved analogy QuickHull algorithm is presented to obtain extreme points of rubber band convex hull. An adaptive module could set a variable rubber band force and a variable time step to make a proper convergence and no intersection. A quick convex decomposition method is used to solve the problem of concave polygon. A plural vector expression approach is adopted to calculate the resultant vector of the rubber band force. Several cases are compared with the benchmark problems to prove rubber band packing algorithm performance