Understanding the effects of electrode meso-macropore structure and solvent polarity on electric double layer capacitors based on a continuum model

The structures of electrode meso-macropore and the solvent polarity are the crucial factors dominating the performance of the electric double layer capacitors(EDLCs),but their impacts are usually tangled and difficult to decouple and quantitate.Here the effects of electrode meso-macropore structure and solvent polarity on the specific capacitance of an EDLC are quantitatively investigated using a steady-state continuum model.The simulation results indicate the specific capacitances are significantly affected by the meso-macropore surface structure.The specific capacitances significantly decrease for both convex surface structures but obviously increase for both concave surface structures,with the increase of curvature radius from 1 to 20 nm.As for solvents,the polar solvent with high saturated dielectric permittivity improves the capacitance performance.Moreover,the electrode meso-macropore structure is of more concern compared with solvent polarity when aiming at enhancing the specific capacitance.These results provide fundamentals for the rational design of porous electrodes and polar electrolytes for EDLCs.

3D-Printed Flat-Bone-Mimetic Bioceramic Scaffolds for Cranial Restoration

The limitations of autologous bone grafts necessitate the development of advanced biomimetic biomaterials for efficient cranial defect restoration.The cranial bones are typical flat bones with sandwich structures,consisting of a diploe in the middle region and 2 outer compact tables.In this study,we originally developed 2 types of flat-bone-mimeticβ-tricalcium phosphate bioceramic scaffolds(Gyr-Comp and Gyr-Tub)by high-precision vat-photopolymerization-based 3-dimensional printing.Both scaffolds had 2 outer layers and an inner layer with gyroid pores mimicking the diploe structure.The outer layers of Gyr-Comp scaffolds simulated the low porosity of outer tables,while those of Gyr-Tub scaffolds mimicked the tubular pore structure in the tables of flat bones.The Gyr-Comp and Gyr-Tub scaffolds possessed higher compressive strength and noticeably promoted in vitro cell proliferation,osteogenic differentiation,and angiogenic activities compared with conventional scaffolds with cross-hatch structures.After implantation into rabbit cranial defects for 12 weeks,Gyr-Tub achieved the best repairing effects by accelerating the generation of bone tissues and blood vessels.This work provides an advanced strategy to prepare biomimetic biomaterials that fit the structural and functional needs of efficacious bone regeneration.

铂–镍双原子分散在具有新型(NiPt)-N_(4)C_(2)构型的氮掺杂碳纳米结构上用于协同电催化析氢反应

单原子催化剂具有原子利用率高、活性中心明确、催化中心原子配位数低等优点,有望提高电催化性能.具有相邻杂原子的双原子催化剂(DAC)有望发挥两个原子的协同作用,从而进一步提高活性.在本文中,我们报道了一种PtNi-NC催化剂,该催化剂由固定在氮掺杂碳基底上的PtNi双原子构成,该基底采用原子层沉积技术合成.X射线吸收光谱证实了Pt–Ni双原子的存在.所制备的PtNi-NC催化剂具有优异的催化活性,在10 m A cm^(-2)的电流密度下,酸性介质中析氢反应(HER)的过电位为30 m V,与市售20 wt%Pt/C相当.特别值得注意的是,PtNi-NC具有比20 wt%Pt/C更高的质量活性,约为其21倍.密度泛函理论计算表明,Pt–Ni双原子通过调节局部电子结构和优化电荷分布产生协同效应,有助于优化吸附性能和增强电催化性能.这项工作为DAC的制备提供了新途径,揭示了它们在电催化HER等领域的应用潜力.

Interfacial high-concentration electrolyte for stable lithium metal anode:Theory,design,and demonstration

Lithium metal anodes hold great potential for high-energy-density secondary batteries.However,the uncontrollable lithium dendrite growth causes poor cycling efficiency and severe safety concerns,hindering lithium metal anode from practical application.Electrolyte components play important roles in suppressing lithium dendrite growth and improving the electrochemical performance of long-life lithium metal anode,and it is still challenging to effectively compromise the advantages of the conventional electrolyte(1 mol·L^(−1)salts)and high-concentration electrolyte(>3 mol·L^(−1)salts)for the optimizing electrochemical performance.Herein,we propose and design an interfacial high-concentration electrolyte induced by the nitrogen-and oxygen-doped carbon nanosheets(NO-CNS)for stable Li metal anodes.The NO-CNS with abundant surface negative charges not only creates an interfacial high-concentration of lithium ions near the electrode surface to promote chargetransfer kinetics but also enables a high ionic conductivity in the bulk electrolyte to improve ionic mass-transfer.Benefitting from the interfacial high-concentration electrolyte,the NO-CNS@Ni foam host presents outstanding electrochemical cycling performances over 600 cycles at 1 mA·cm^(−2) and an improved cycling lifespan of 1,500 h for symmetric cells.