Catalytic reduction of molecular dinitrogen (N2) to ammonia (NH3) is one of the most important and challenging industrial reactions.Electrochemical reduction is considered as an energy-saving technology for artificial ambient nitrogen fixation,which is emerging as an optimal potential sustainable strategy to substitute for the Haber-Bosch process.However,this process demands efficient catalysts for the N2 reduction reaction (NRR).Here,by means of first-principles calculations,we systematically explored the potential electrocatalytic performance of single transition metal atoms (Pd,Ag,Rh,Cu,Ti,Mo,Mn,Zn,Fe,Co,Ru,and Pt) embedded in monolayer defective boron phosphide (TMs/BP) monolayer with a phosphorus monovacancy for ambient NH3 production.Among them,the Mo/BP exhibits the best catalytic performance for ambient reduction of N2 through the typical enzymatic and consecutive reaction pathways with an activation barrier of 0.68 eV,indicating that Mo/BP is an efficient catalyst for N2 fixation.We believe that this work could provide a new avenue of ambient NH3 synthesis by using the designed single-atom electrocatalysts.
Abstract A creatively structure-function integrated C/C-SiC brake material, fabricated by chemical vapor infiltration (CVI) and liquid silicon infiltration (LSI), consisted of frictional function layer, stress relaxed layer and mechanical layer. The mechanical layer guaranteed high load-carrying capability, and the stress relaxed layer could effectively alleviate the thermal mismatch between the mechanical layer and the frictional function layer during the fabrication process. The frictional function layer exhibited excellent friction performance, mechanical and thermal properties. Due to the lower usage of carbon fibers as well as the elimination of “crusting” during the fabrication process, the production costs were effectively reduced. The fluctuation range of coefficient of friction (CoF) was as low as 0.03, and the mass and linear wear rate were less than 19.0 mg/cycle and 2.2 μm/(side·cycle) at 28 m/s, respectively. These results showed that the structure-function integrated C/C–SiC were promising candidates for high-performance and low-cost friction composites. Highlights • Structure-function integrated C/C-SiC exhibited stable friction performance. • Thermal mismatch was alleviated and delamination was not occurred during the fabrication process. • Phenomenon of “crusting” was not occurred during the CVI process. • Production costs were reduced for lower usage of carbon fibers and shortening of deposition period.