Wenbin Xu

Ultrathin Bismuth Nanosheets as a Highly Efficient CO2 Reduction Electrocatalyst

Electrochemical reduction of CO2 to value-added products is an important and challenging reaction for sustainable energy study. Herein, bismuth nanosheets with thickness of around 10u2005nm were prepared through the electrochemical reduction of Bi3+ . Ultrathin Bi nanosheets with numerous low-coordination sites can efficiently reduce CO2 to formate in aqueous solution. Within the potential range of -0.9 to -1.2u2005V vs. reversible hydrogen electrode (RHE), the faradaic efficiency of formate is over 90u2009%, outperforming many Bi catalysts. At -0.7u2005V, the Bi nanosheets exhibit much higher current for formate generation than that of bulk Bi, attributed to a high surface area and also modified intrinsic electronic properties brought about by the ultrathin structure. DFT calculations demonstrate that Bi nanosheets have much higher density of states at the Fermi level compared to bulk Bi, favoring improved CO2 reduction on Bi nanosheets. At -1.0u2005V, Bi nanosheets exhibit high selectivity for formate and excellent stability during 5u2005h of electrolysis.

Selective Electrochemical Reduction of Carbon Dioxide Using Cu Based Metal Organic Framework for CO2 Capture

The conversion efficiency and product selectivity of the electroreduction of carbon dioxide have been largely limited by the low CO2 solubility in aqueous solution. To relieve this problem, Cu3(BTC)2 (Cu-MOF) as CO2 capture agent was introduced into a carbon paper based gas diffusion electrode (GDE) in this study. The faradaic efficiencies (FEs) of CH4 on GDE with Cu-MOF weight ratio in the range of 7.5-10% are 2-3-fold higher than that of GDE without Cu-MOF addition under negative potentials (-2.3 to -2.5 V vs SCE), and the FE of the competitive hydrogen evolution reaction (HER) is reduced to 30%. This work paves the way to develop GDE with high catalytic activity for ERC.

Negatively charged nanoporous membrane for a dendrite-free alkaline zinc-based flow battery with long cycle life

Alkaline zinc-based flow batteries are regarded to be among the best choices for electric energy storage. Nevertheless, application is challenged by the issue of zinc dendrite/accumulation. Here, we report a negatively charged nanoporous membrane for a dendrite-free alkaline zinc-based flow battery with long cycle life. Free of zinc dendrite/accumulation, stable performance is afforded for ∼240 cycles at current densities ranging from 80 to 160u2009mAu2009cm−2 using the negatively charged nanoporous membrane. Furthermore, 8u2009h and 7u2009h plating/stripping processes at 40u2009mAu2009cm−2 yield an average energy efficiency of 91.92% and an areal discharge capacity above 130u2009mAhu2009cm−2. A peak power density of 1056u2009mWu2009cm−2 is achieved at 1040u2009mAu2009cm−2. This study may provide an effective way to address the issue of zinc dendrite/accumulation for zinc-based batteries and accelerate the advancement of these batteries.Dendrite accumulation is a hindrance for alkaline zinc-based flow batteries. Here the authors design a negatively charged nanoporous membrane that mitigates zinc dendrite growth by repulsion of zincate anions, leading to a zinc-based flow battery with high power density and cycling stability.

The Effect of Organic Additives on the Activity and Selectivity of CO2 Electroreduction: The Role of Functional Groups

Electrochemical reduction of CO2 (ERC) to useful chemicals is an environmentally and technologically significant process. The process is confronted with significant challenges to simultaneously enhance the catalyst activity and product selectivity. In this paper, the effects of organic additives on the ERC process were systematically investigated by using DFT to screen additives with different functional groups for enhanced activity and selectivity. In particular, the additives with -NH3 + and -SO3 H groups had a remarkably positive effect on the ERC activity and hydrocarbon selectivity, which were predicted to impart a positive shift on onset potential of approximately 162 and 108u2005mV, respectively. Importantly, the additive can accelerate the electron transfer of the intermediate and tune the electronic structure of the catalyst surface, resulting in a clear deviation from transition-metal scaling lines. Combining bonding energy of crucial intermediates with partial atomic charge analysis, we rationalized the negative effect of high concentration additives and confirmed the proposed electron transfer model. Furthermore, additive molecules containing functional groups with positive charges and maximizing the deviation from transition-metal scaling lines are meaningful strategies to design and choose organic additives to enhance activity and selectivity of ERC.

A Long Cycle Life, Self‐Healing Zinc–Iodine Flow Battery with High Power Density

A zinc-iodine flow battery (ZIFB) with long cycle life, high energy, high power density, and self-healing behavior is prepared. The long cycle life was achieved by employing a low-cost porous polyolefin membrane and stable electrolytes. The pores in the membrane can be filled with a solution containing I3- that can react with zinc dendrite. Therefore, by consuming zinc dendrite, the battery can self-recover from micro-short-circuiting resulting from overcharging. By using KI, ZnBr2 , and KCl as electrolytes and a high ion-conductivity porous membrane, a very high power density can be achieved. As a result, a ZIFB exhibits an energy efficiency (EE) of 82u2009% at 80u2005mAu2009cm-2 , which is 8u2005times higher than the currently reported ZIFBs. Furthermore, a stack with an output of 700u2005W was assembled and continuously run for more than 300u2005cycles. We believe this ZIFB can lead the way to development of new-generation, high-performance flow batteries.