Liu Zheng,Qiu Zhipeng,Li Zhiyuan,Wei Tong,Fan Zhuangjun,Pang Huan
Due to the low cost, high theoretical capacity, and environmental friendliness, manganese-based cathodes are regarded as promising alternatives for aqueous zinc ion batteries (AZIBs). However, the practicality of the zinc-manganese system is faced with great challenges, such as the inevitable structural collapse of the cathode and controversial energy storage mechanisms. Herein, we propose a novel concept of spatial deposition mechanism through the addition of MnSO 4 additives in the MnO-pillared graphene blocks (G-MnO). The covalent interface between MnO nanoparticles and multilayered graphene nanosheets can construct an in-built micro-electric field, which is beneficial for consecutive electron transfer (in both horizontal and vertical directions). On this basis, the surficial activity of MnO confined in the interlayered nano-space is greatly enhanced and provides enough spatial deposition and subsequent reaction site for MnSO 4 additives, thus firstly extending the surficial controlled process to stereoscopic space, effectively improving the electrochemical performance of AZIBs. Therefore, the assembled Zn//G-MnO battery exhibits an excellent rate capability of 281.5 mAh g −1 at 0.1 A g −1 and 106 mAh g −1 at 20 A g −1 , and impressive cycling stability (93 mAh g −1 remaining after 5,000 cycles). This finding may provide a new opportunity for the rational design of surficial controlled energy storage and conversion devices.
Li Yiming,Yu Zhihao,Guo Mengyan,Zhang Ming,Xiong Jian,Qiao Yina,Zhang Rui,Lu Xuebin
Biomass-based carbon materials with hierarchical porous structures have attracted attention for their ability to provide more channels and shorten ion transport paths. Here, we developed a simple method based on confined nanospace deposition. During high-temperature treatment, the mesoporous silica layer wrapped around the outside of the crab shells acted as a closed nanospace and effectively suppressed the severe deformation of the crab shell structure by shrinking inward. The prepared carbon material has a layered porous structure with abundant and stable N and O co-doping (N 7.32%, O 3.69%). The specific capacitance of the three-electrode system was 134.3 F/g at a current density of 0.5 A/g in a 6 mol/L KOH electrolyte, and the assembled aqueous symmetric supercapacitors exhibited an excellent cycling stability of 98.81% even after 5000 cycles. Graphical abstract
Engineered surface-bound molecular gradients are of great importance for a range of biological applications. In this paper, we fabricated a polydopamine gradient on a hydrophobic surface. A microfluidic device was used to generate a covalently conjugated gradient of polydopamine (PDA), which changed the wettabilty and the surface energy of the substrate. The gradient was subsequently used to enable the spatial deposition of adhesive proteins on the surface. When seeded with human adipose mesenchymal stem cells, the PDA-graded surface induced a gradient of cell adhesion and spreading. The PDA gradient developed in this study is a promising tool for controlling cellular behavior and may be useful in various biological applications.
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