Coordination and interface engineering to boost catalytic property of two-dimensional ZIFs for wearable Zn-air batteries

Metal organic frameworks(MOFs) have been considered as compelling precursor for miscellaneous applications. However, their unsatisfied electrocatalytic performance limits their direct application as electrocatalyst. Herein, by incorporating the cobalt-oxide bonds and polyaniline(PANI) with two-dimension zeolitic imidazolate frameworks(ZIFs), a novel bifunctional catalyst(Co-O-ZIF/PANI) for Zn-air battery was designed based on a facile and eco-friendly method. This Co-O-ZIF/PANI with optimized surface adsorption effect and suitable Co^(3+)/Co^(2+)ratio, exhibits eminent electrocatalytic activity toward both oxygen reduction and evolution reaction. The as-assembled liquid ZABs based on Co-O-ZIF/PANI achieves a remarkable maximum power density of 123.1 m W cm^(-2) and low discharge-charge voltage gap of 0.81 V at 5 m A cm^(-2) for over 300 cycles. Operando Raman spectroscopy reveals that the excellent performance origins from the optimized surface chemisorption property of O_(2) and H_(2)O brought by Co–O bonds and PANI. This work provides a novel prospect to develop efficient MOF derived bifunctional electrocatalysts by optimizing surface chemisorption properties.

A review of hard carbon anode: Rational design and advanced characterization in potassium ion batteries

K-ion batteries(KIBs)have attracted tremendous attention and seen significant development because of their low price,high operating voltage,and properties similar to those of Li-ion batteries.In the field of development of full batteries,exploring high-performing and low-cost anode materials for K-ion storage is a crucial challenge.Owing to their excellent cost effectiveness,abundant precursors,and environmental benignancy,hard carbons(HCs)are considered promising anode materials for KIBs.As a result,researchers have devoted much effort to quantify the properties and to understand the underlying mechanisms of HC-based anodes.In this review,we mainly introduce the electrochemical reaction mechanism of HCs in KIBs,and summarize approaches to further improve the electrochemical performance in HC-based materials for K-ion storage.In addition,we also highlight some advanced in situ characterization methods for understanding the evolutionary process underlying the potassiation–depotassiation process,which is essential for the directional electrochemical performance optimization of KIBs.Finally,we raise some challenges in developing smart-structured HC anode materials for KIBs,and propose rational design principles and perspectives serving as the guidance for the targeted optimization of HC-based KIBs.

Colloidal Virus Particles with Hierarchical Nanomorphology and Facile Biosurface Modification

Aiming to the enormous requirement for the epidemic defense researches,we designed and constructed a spherical colloidal virus particle(CVP)to mimic nature virus in morphology,physical,chemical and biological characteristics,via coating spiky protein on col-loidal nanoparticles(CNPs)core with bulge hierarchical nanomorphology.The novel virus-like surface nanoparticles can easily be synthesized.The physical,chemical nature and the formation mechanism of the prepared CVPs were characterized and discussed.The synthesized CVPs are similar in size and envelope thickness to common natural viruses.It was demonstrated that the diameter of CVPs is about 238±12 nm,including an 8 nm thickness protein crown with bulges of 33 nm in average width.The CVPs with an isoelectric point of 4.5,meets the native virus property of negative charge under neutral condition.The protein crown enhances the roughness remarkably from 10 nm(CNPs)to 22 nm(CVPs)determined by atomic force microscopy.Thanks to the biomimetic rough morphology,the CVPs show greatly superior cellular uptake performance compared to CNPs,ovalbumin(OVA)and smoothed col-loidal particles(SCPs).The formation mechanism of protein crown with specific thickness can be attributed to the electrostatic in-teraction,protein's flexible structure and specific wettability.These results indicate that the as-prepared artificial virions mimic na-ture viruses in multi-dimension,in terms of size,surface rough morphology,surface negative charge and glycoprotein envelope composition.The synthetic colloidal virus particles pave a facile way toward engineering virus particles substitute for virus-related diseases prevention,diagnostics and cellular delivery vectors.