Tungsten carbide as supports for Pt electrocatalysts with improved CO tolerance in methanol oxidation

One anti-CO-poisoning Pt-WC/C catalyst for methanol electro-oxidation is prepared in this work, through depositing platinum on tungsten carbide support using an intermittent microwave heating (IMH) method. The catalyst presents an improved methanol oxidation performance evidenced by a negative shift in onset potential, and increase of peak current density, compared with a commercial Pt/C one. CO stripping experiments indicate that the adsorbed CO is able to be oxidized and removed from the Pt-WC/C catalyst more easily, attesting the enhanced capability of anti-poisoning to CO-like species. Theoretical calculation further provides evidence that the surface electronic structure in Pt-WC/C and Pt/C catalysts is likely different. WC supports could lead to much stronger negative electronic property, which is beneficial for avoiding CO adsorption on the Pt-WC/C catalyst. In the mean time, the electron donating effect generated by WC supports also promotes the ability to oxidize the adsorbed CO-like species on catalysts. In good agreement with experimental results, the theoretical calculation proves the anti-CO-poisoning nature of the Pt-WC/C catalyst, and well explains the origin of the improvement in the electrochemical catalytic performance for effectively accelerating the oxidation of CO to CO₂ in methanol oxidation.     

大型挖掘机在国内矿山的应用

目前，国内各大矿山随着对生产工艺结构的不断优化，为达到采装、运输和选别设备能力的理想匹配，都在逐步对设备进行选型和更新，在采掘设备更新上更是各具特色，如大型挖掘机在矿山生产中的应用就尤其显得备受注目。     

铝合金双丝VP-GTAW增材构件组织和性能

以Al-6.3Cu和Al-5Mg为填丝材料进行铝合金双丝VP-GTAW增材制造试验。结果表明,采用双丝VP-GTAW制备试样可提高成形效率,且成形稳定;通过调节2种丝材的送丝速度可以获得不同主要合金元素含量的Al-Cu-Mg合金,合金组织主要由柱状晶和等轴枝晶组成,且呈非均匀分布特征,调节主要合金元素含量可实现对铝合金试样性能的控制。原始状态下铝合金试样的显微硬度(HV)为900~1000 MPa,抗拉、屈服强度分别可达286和183 MPa,但塑性较差,仅为4.5%。