Bacterial cellulose (BC) membranes with shape-memory properties allow the rapid preparation of artificial small-diameter blood vessels when combined with microfluidics-based patterning with multiple types of cells. Lyophilization of a wet multilayered rolled BC tube endows it with memory to recover its tubular shape after unrolling. The unrolling of the BC tube yields a flat membrane, and subsequent patterning with endothelial cells, smooth muscle cells, and fibroblast cells is carried out by microfluidics. The cell-laden BC membrane is then rerolled into a multilayered tube. The different cells constituting multiple layers on the tubular wall can imitate blood vessels in vitro. The BC tubes (2 mm) without cell modification, when implanted into the carotid artery of a rabbit, maintain thrombus-free patency 21 d after implantation. This study provides a novel strategy for the rapid construction of multilayered small-diameter BC tubes which may be further developed for potential applications as artificial blood vessels.
Perovskite solar cells (PSCs) using metal electrodes have been regarded as promising candidates for next‐generation photovoltaic devices because of their high efficiency, low fabrication temperature, and low cost potential. However, the complicated and rigorous thermal deposition process of metal contact electrodes remains a challenging issue for reducing the energy pay‐back period in commercial PSCs, as the ubiquitous one‐time use of a contact electrode wastes limited resources and pollutes the environment. Here, a nanoporous Au film electrode fabricated by a simple dry transfer process is introduced to replace the thermally evaporated Au electrode in PSCs. A high power conversion efficiency (PCE) of 19.0% is demonstrated in PSCs with the nanoporous Au film electrode. Moreover, the electrode is recycled more than 12 times to realize a further reduced fabrication cost of PSCs and noble metal materials consumption and to prevent environmental pollution. When the nanoporous Au electrode is applied to flexible PSCs, a PCE of 17.3% and superior bending durability of ≈98.5% after 1000 cycles of harsh bending tests are achieved. The nanoscale pores and the capability of the porous structure to impede crack generation and propagation enable the nanoporous Au electrode to be recycled and result in excellent bending durability.
Amorphous materials have great potential for storing energy owing to their porous structure, high stability, and fast charging rate. Also, ingeniously incorporating amorphous materials into crystalline materials through surface amorphization strategy can construct excellent electrodes for supercapattery. Herein, Ni−Co-layered double hydroxide/Ni−Co−borate (Ni−Co− LDH/Ni−Co−B i ) composite is synthesized by in situ formation of amorphous Ni−Co−borate on metal−organic frameworks (MOFs)-derived Ni−Co−LDH nanosheet array. The adherent amorphous Ni−Co−borate can modulate the crystalline and electronic structures of Ni−Co−LDH, which provide an effective path for electron transfer and boosts the kinetics of redox reaction. Consequently, the crystalline/amorphous Ni−Co−LDH/Ni−Co−B i composite shows a high specific capacity of 891 C/g at 1 A/g. When used as a battery-type electrode to assemble supercapattery, it displays a maximum energy density of 62.8 Wh/kg at a power density of 800 W/kg and fine stability (∼81% capacity retention after 5000 cycles). In addition, an all-solid-state supercapattery can lighten a white light-emitting diode (LED) for 60 s, demonstrating potential practical applications of Ni−Co− LDH/Ni−Co−B i . Hence, it is a very promising study to shed substantial light on inspiring crystalline/amorphous materials for energy storage.
To further improve the capacity, charge rate and cycling stability has become urgent issues to be solved for lithium-ion batteries (LIBs). In our study, we have synthesized nanoporous CoO nanowire clusters on three-dimensional (3D) porous graphene cloth (denoted as CoO-NW@GC) via a facile hydrothermal reaction and subsequent annealing process. The selfsupported graphene cloth is provided with large surface area, high porosity and superior electric conductivity, which can greatly contribute to the fast electron and ion transport. Due to the nanoporous CoO nanowire clusters uniformly in situ depositing on the robust 3D skeleton of GC substrate, the CoO-NW@GC hybrid as anode for LIBs achieves 1190 mAh/g and 429 mAh/g under the current densities of 0.2 A/g and 3.2 A/g, respectively. After more than 200 cycles at a current density of 0.5 A/g, the capacity still maintains 1100 mAh/g. The CoO-NW@GC illustrates high specific capacity, good stability as well as excellent rate performance.
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