ABSTRACT
Solar rechargeable zinc-air battery is a promising approach for capturing and storing intermittent solar energy through photoelectrochemical reactions. However, unassisted photo-charging of zinc-air batteries is challenging due to suboptimal carrier accumulation on photoelectrodes, resulting in sluggish reaction kinetics. Here, unassisted photo-charging of zinc-air battery is achieved by investigating anisotropic photogenerated charge separation on a series of representative semiconductors (ZnIn2 S4 , TiO2 , and In2 O3 ), among which the exceptional anisotropic charge separation on a ZnIn2 S4 photoelectrode is revealed based on anisotropic charge diffusion capabilities. The charge separation is facet-dependent, which is observed using Kelvin probe force microscopy, verifying a cause-and-effect relationship between the photo-charge accumulation on photoelectrodes and their photo-charging performance in zinc-air batteries. This work achieves an unassisted photo-charging current density of 1.9 mA cm-2 with a light-to-chemical energy conversion efficiency of 1.45%, highlighting the importance of anisotropic semiconductors for unassisted photo-charging of zinc-air batteries via efficient photogenerated charge separation.
ABSTRACT
The application of Li-S batteries has been hindered by the shuttling behavior and sluggish reaction kinetics of polysulfides. Here an effective polysulfide immobilizer and catalytic promoter is developed by proposing oxygen-vacancy-rich Tin O2 n -1 quantum dots (OV-Tn QDs) decorated on porous carbon nanosheets (PCN), which are modulated using Ti3 C2 Tx MXene as starting materials. The Tn QDs not only confine polysulfides through strong chemisorption but also promote polysulfide conversion via redox-active catalysis. The introduction of oxygen vacancies further boosts the immobilization and conversion of polysulfides by lowering the adsorption energy and shortening the bond lengths. The PCN provides a physical polysulfide confinement as well as a flexible substrate preventing OV-Tn QDs from aggregation. Moreover, the two building blocks are conductive, thereby effectively improving the electron/charge transfer. Finally, the ultrasmall size of QDs along with the porous structure endows OV-Tn QDs@PCN with large specific surface area and pore volume, affording adequate space for S loading and volume expansion. Therefore, the OV-Tn QDs@PCN/S delivers a high S loading (79.1 wt%), good rate capability (672 mA h g-1 at 2 C), and excellent long-term cyclability (88% capacity retention over 1000 cycles at 2 C). It also exhibits good Li+ storage under high S-mass loading and lean electrolyte.
ABSTRACT
The genus Zachobiella Banks, 1920 is reviewed and a new species Zachobiellayunanica sp. n. described from China. All species found in China are redescribed, and Zachobiellasubmarginata Esben-Petersen, 1929 is recorded from China for the first time. A key to the adults of Zachobiella is provided.
ABSTRACT
Two new species of Neuronema McLachlan are described from China: Neuronemaypsilum sp. nov., which was found in Beijing and Shaanxi provinces, and Neuronema maculosum sp. nov., which was found in Chongqing and Gansu provinces. Keys are given to identify the species of Neuronema in China.
