Dual-ionic imidazolium salts to promote synthesis of cyclic carbonates at atmospheric pressure

Novel dual-ionic imidazolium salts are shown to display excellent catalytic activity for cycloaddition of carbon dioxide and epoxides under room temperature and atmospheric pressure(0.1 MPa)without any solvent and co-catalyst leading to 96.1%product yield.It can be reused five times to keep the product yield over 90%.These intriguing results are attributed to a new reaction mechanism,which is supported by theoretical calculations along with the measurements of ^(13)C NMR spectrum and Fourier transform infrared spectroscopy(FT-IR).The excellent catalytic activity can be traced to a CO_(2)-philic group along with an electrophilic hydrogen atom.Our work shows that incorporation of CO_(2)-philic group is an feasible pathway to develop the new efficient ionic liquids.

Efficient synthesis of cyclic carbonates under atmospheric CO_(2) by DMAP-based ionic liquids: the difference of inert hydrogen atom and active hydrogen atom in cation

The coupling reaction of carbon dioxide(CO_(2)) and epoxides is one of the most efficient pathways to achieve the carbon balance.However,to accomplish it under the mild conditions,especially under the atmospheric pressure,is still a perplexing problem.Three novel ionic liquids(ILs),[DMAPBrPC][TMGH],[DMAPBrPC][DBUH],and[DMAPBrPC][BTMA],are designed and synthesized.All of them display the excellent catalytic activity for the title reaction achieving the yield over 96.6% under the atmospheric CO_(2) pressure at 60℃.Interestingly,[DMAPBrPC][BTMA]with the inert hydrogen atom in cation exhibits the superior catalytic activity as compared to other two ILs with the protic hydrogen atom in cation along with the same anion.The active hydrogen atom in[DMAPBrPC][TMGH]and[DMAPBrPC][DBUH]would impede the–COO^(-)group to absorb CO 2,which is an unfavorable item for the reaction.Moreover,the strong hydrogen bond in[DMAPBrPC][TMGH]and[DMAPBrPC][DBUH]would lessen the nucleophilic ability of Br^(-) anion resulting in the inferior catalytic performance,which is further confirmed by the density functional theory(DFT)calculations.The cation without the active hydrogen atom could also be employed to design the ILs with the excellent catalytic feature when it is combined with the suitable anion.

Recent research progress for upconversion assisted dye-sensitized solar cells

Upconversion(UC)technology makes it possible to harvest infrared(IR)light from the sun and has increasingly been employed in recent years to improve the efficiency of solar cells.The progress in the area concerns both research on fundamental principles and processes of UC and technologies of device fabrication.Significant increase of important solar cell parameters,like short-circuit photocurrent density and open-circuit photovoltage as well as the total photon-to-current efficiency,has been accomplished.We here review the research published during the last few years in the area,in particular we consider the two most cherished techniques,namely the incorporation of upconverting nanophosphors directly into the photoanodes of the solar cells and the introduction of plasmonic metal nanoparticles co-existing with the UC particles.Other ways to achieve strong field enhancement,and the use of the non-linear nature of UC,is to apply microlenses,with or without assisting plasmonic excitation.Further enhanced UC action has been demonstrated by broad band and effective harvesting by organic IR antennas,with subsequent mediation by an intermediate nanoshell of the energy into the upconverting core.Codoping,nanohybrid and layer-by-layer technologies involving upconverting particles as well as the use of upconverting nanoparticles in hole-transport and electrolyte layers,tested in recent works,are also reviewed.While most of these technologies employ upconverting rare earth metals for sequential photon absorption,the main alternative technique,namely triplet-triplet annihilation UC using organic materials,is also reviewed.It is our belief that all these approaches will be further much researched in the near future,with potentially great impact on solar cell technology.