Wenming Liu

A quick and green approach to prepare [Rmim]OH and its application in hydrophilic ionic liquid synthesis

A quick and green process to prepare [Rmim]OH solutions is developed based on fast ion exchange between OH− and halide ions (halide = Cl− or Br−) in ethanol. Five ionic liquids were synthesized by neutralizing the obtained [Rmim]OH solution with acids to verify the feasibility of the whole process. The halogen content in the finally obtained ionic liquids and the experimental factors influencing the content are mainly discussed. Moreover, two other alcohols besides ethanol, propanol and iso-propanol, were further examined as solvents. The results show that this process, together with the alkylation and hydroxide anion route, is simple and efficient for preparing various ionic liquids, and that the process is a complementary synthetic route to existing strategies to prepare various ILs.

Vitamin E assisted polymer electrolyte fuel cells

Due to breathing O2 from the air, vertebrates can suffer from diseases originating from oxidative stress. These, however, can be relieved by various antioxidants. Similarly, proton exchange membrane fuel cells (PEMFCs) suffer from the major problem of limited lifetimes, caused by chemical attacks by reactive oxygen species (ROS). Inspired by vertebrates, we herein show that the incorporation of a natural antioxidant, α-tocopherol (α-TOH), the most abundant component of vitamin E, which acts as a free radical scavenger, enables a maintenance of performance for PEMFCs which is impossible to achieve for fuel cells in the absence of α-TOH. It is notable that oxidized α-TOH can in turn be reduced by permeated H2 during fuel cell operation, resulting in its regeneration. Such reversibility leads to a chemical circulation system, which not only ensures the effective recycling of α-TOH, but also permits efficient protection of proton exchange membranes (PEMs) and thus allows their long-term operation.

Design and synthesis of cation-functionalized ionic liquid for application as electrolyte in proton exchange membrane fuel cells

Functional design was conducted for ionic liquid (IL) by introducing –SO3H to the cation, and an IL of N,N,N-trimethyl butylsulphonate ammonium hydrosulfate ([N1114SO3H]HSO4) was synthesized as the electrolyte in a proton exchange membrane fuel cell (PEMFC). Subsequently, a series of single cell tests was carried out, and the results show high cell performance for the PEMFC with the designed IL as the electrolyte. A maximum power density (MPD) of 90 mW cm−2 was obtained with the functionalized IL of [N1114SO3H]HSO4, while the MPD for the fuel cell with a similar but not functionalized IL can only provide an MPD of approximately 60 mW cm−2. Possible mechanisms behind the elevation of the fuel cell performance were investigated and discussed. The results show that the proton diffusion coefficient elevation of the functionalized IL is one important explanation for the increased fuel cell performance. Finally, theoretical calculation for the potential barrier for proton transportation in the two ILs was conducted. The results show that the potential barrier for the functionalized IL was lowered. All of these results imply that introducing a functional group to the cation is a promising way for a high proton conductive IL to function as the electrolyte in a PEMFC.