Design of experiments unravels insights into selective ethylene or methane production on evaporated Cu catalysts

As a highly tempting technology to close the carbon cycle,electrochemical CO_(2)reduction calls for the development of highly efficient and durable electrocatalysts.In the current study,Design of Experiments utilizing the response surface method is exploited to predict the optimal process variables for preparing high-performance Cu catalysts,unraveling that the selectivity towards methane or ethylene can be simply modulated by varying the evaporation parameters,among which the Cu film thickness is the most pivotal factor to determine the product selectivity.The predicted optimal catalyst with a low Cu thickness affords a high methane Faradaic efficiency of 70.6%at the partial current density of 211.8 m A cm^(-2),whereas that of a high Cu thickness achieves a high ethylene selectivity of 66.8%at267.2 m A cm^(-2)in the flow cell.Further structure-performance correlation and in-situ electrospectroscopic measurements attribute the high methane selectivity to isolated Cu clusters with low packing density and monotonous lattice structure,and the high ethylene efficiency to coalesced Cu nanoparticles with rich grain boundaries and lattice defects.The high Cu packing density and crystallographic diversity is of essence to promoting C–C coupling by stabilizing*CO and suppressing*H coverage on the catalyst surface.This work highlights the implementation of scientific and mathematic methods to uncover optimal catalysts and mechanistic understandings toward selective electrochemical CO_(2)reduction.

Performance of novel overhead crane fume-collecting hood for pollutant removal

In industrial buildings,the presence of overhead cranes severely affects roof exhaust ventilation systems when capturing and discharging fumes,resulting in severe deterioration of the indoor plant environment.In this study,an overhead crane-based ventilation auxiliary device,called overhead crane fume-collecting hood(CFCH),is proposed to guide pollutants blocked by the overhead crane back to the roof exhaust hood.The airflow characteristics and pollutant distribution under the three modes of no overhead crane,overhead crane,and overhead crane+CFCH were compared using numerical simulations.Subsequently,the effects of the CFCH length(a),width(b),and height(h)on the pollutant capture performance were determined through orthogonal experiments and computational fluid dynamics.Finally,the pollutant capture efficiency(PCE)of the optimal CFCH was investigated considering different exhaust airflow rates.The results showed that the pollutants captured by the CFCH can be classified into directly and secondary captured pollutants,with the directly captured pollutants dominating.In addition,with the introduction of different sizes of CFCH around the overhead crane girders,the PCE significantly improved by 49.9%–74.6%.The length,width,and height of the CFCH on the PCE were statistically significant,and the priority of the three factors was as follows:h>b>a.The PCE decreased with increasing a,initially increased and then decreased with increasing b,and increased with h.Subsequently,when the optimal CFCH was used,the excessive exhaust air rate had no evident PCE improvement.This provides a new concept for the control of pollutants in industrial buildings and provides a theoretical basis for the design of CFCHs.

Synthesis of poly(silyl ether)s via copper-catalyzed dehydrocoupling polymerization

The development of efficient method to prepare poly(silyl ether)s(PSEs)is highly desirable.Herein,an environmentally sustainable copper-catalyzed dehydrocoupling polymerization was developed with good yields and high molecular weight(up to 48,400 of Mn and up to 97%yield).Monomers of different types(AB type or AA and BB type)are suitable to afford PSEs.The PSEs show good thermal stability and low glass-transition temperature.