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Inheriting the energy storage mechanism of supercapacitors and rechargeable ion batteries, zinc ion capacitors (ZICs) greatly increase their energy density at high power without sacrificing their life span. However, sluggish kinetics and insufficient active sites for Zn 2+ storage induced by the significant mismatch of charge carriers with limited pore size hinder the efficient Zn 2+ storage and smooth application of carbonaceous cathode materials. Herein, a three-dimensional honeycomb-like porous carbon network (HPCN) was fabricated, which can reduce the diffusion barrier for fast kinetics, produce a high-density defect area, effectively increase active sites for charge storage, and generate a high nitrogen-doping content. Benefiting from these advantages, the optimized ZICs bring out a marvelous energy/power density (130 W h kg -1 /11.7 kW kg -1 ) with an ultrahigh reliable cyclability of 97.8% after 50 000 cycles at a high current density of 5 A g -1 . Importantly, systematic ex situ characterizations combined with theoretical calculations demonstrate that the outstanding Zn 2+ storage capacity is attributed to the synergistic effect of physical co-adsorption of cations and reversible chemisorption. This work presents an attractive strategy for developing advanced carbon cathodes with suitable pores and accelerates the exploration of charge storage mechanisms, which may open a new avenue for practical supercapacitors.

The designability of the porous structure of carbon material makes it a popular material for zinc-ion hybrid capacitors (ZIHCs). However, the micropore confinement effect leads to sluggish kinetics and is not well resolved yet. In this work, a pore-size controllable carbon material was designed to enhance ion accessibility. The experimental and calculated results revealed that suitable pore sizes and defects were beneficial to ion transfer/adsorption. Meanwhile, oxygen-containing functional groups could introduce a pseudocapacitance reaction. Its large specific surface area and interconnecting network structure could shorten the ion/electron transfer length to reach high ion adsorption capacity and fast kinetic behavior. When used as a zinc-ion hybrid capacitor cathode material, it showed 9.9 kW kg -1 power density and 100 W h kg -1 energy density. Even at 5 A g -1 , after 50 000 cycles, there was still 93% capacity retention. Systemic ex situ characterization and first-principles calculations indicated that the excellent electrochemical performance is attributed to the electric double layer capacitance (EDLC) - pseudocapacitance coupled mechanism via the introduction of an appropriate amount of oxygen-containing functional groups. This work provides a robust design for pore engineering and mechanistic insights into rapid zinc-ion storage in carbon materials.

A transition metal phosphide is an excellent candidate for supercapacitors due to its superior electrical conductivity and high theoretical capacity. In addition, compared with traditional 3D nano-materials, 2D nanosheets possess a greater specific surface area and shorter electron transport distance. In this study, a reasonable approach is proposed for the synthesis of ZIF-67 nanosheets on nickel foam with subsequent phosphorization by chemical vapor deposition (CVD) to obtain flake-like CoP combined with Ni2P (NCP/NF), in which nickel foam serves as the current collector as well as the resource of Ni to form Ni2P. Benefiting from the nanosheet array of CoP, the NCP/NF can improve the capacity of Ni2P from 0.57 C cm-2 to 1.43 C cm-2 at 1 mA cm-2. Furthermore, the NPC/NF/reduced graphene oxide (RGO) asymmetric supercapacitor (ASC) shows an energy density of 26.9 μW h cm-2 at a power density of 0.896 mW cm-2, and excellent cycling performance with a capacity retention of 93.75% after 5000 cycles at 10 mA cm-2.

This study reports the utilization of thiol-induced chemical etching of aggregation-induced emission (AIE)-active Au nanoclusters (NCs) for the facile, sensitive, and selective detection of cysteine. The AIE-active Au NCs were formed in an acidic solution containing excess Au(i)-thiolate complexes. At an acidic pH (2.0), the emission of these Au NCs was enhanced by cysteine at a concentratioin below 1 mM. However, the emission was quenched by cysteine at a high concentration, e.g., 500 mM, via the thiol-induced etching of gold, although the process occurred very slowly. Interestingly, in the absence of cysteine, increasing the solution pH enhanced the emission, while the presence of cysteine remarkably accelerated the etching-induced quenching process. The complete quenching of the emission by excess cysteine at pH 2.0 and the enhancement of the emission by the increasing pH in the absence of cysteine indicated that aurophilicity might not be involved in the AIE of the Au NCs prepared using glutathione (GSH) both as the reducing and protecting reagent. On the other hand, the etching process involved the penetration of cysteine molecules through the Au(i)-thiolate complexes, which could assemble or disassemble around the embedded Au NCs in response to the solution pH to get access to the innermost Au(0) cores. Therefore, a facile, sensitive, and selective method for the detection of cysteine was established. This method exhibited an extremely wide linear range as wide as nine orders of magnitude above the cysteine concentration, including two linear regions of the relative emission intensity of the Au NCs versus the logarithm of cysteine concentration, from 10 pM to 150 μM (correlation coefficient, 0.99851) and from 150 μM to 2 mM (correlation coefficient, 0.99866). An ultra-low limit of detection of 6.3 pM (S/N = 3) was also achieved. The developed method showed superior selectivity for cysteine relative to the 19 other natural amino acids and GSH. The method was applied for the analysis of human serum samples spiked with cysteine with satisfactory results. This study demonstrates the potential of the thiol-induced chemical etching approach as a powerful tool for studying luminescent metal NCs.

The cycling stability of Li-O 2 batteries has been impeded by the lack of high-efficiency, and durable oxygen cathodes for the oxygen-reduction reaction (ORR) and the oxygen-evolution reaction (OER). Herein we report a novel TiN nanorod array-based cathode, which was firstly prepared by growing a TiN nanorod array on carbon paper (CP), and then followed by depositing MnO 2 ultrathin sheets or Ir nanoparticles on the TiN nanorods to form well-ordered, three-dimensional (3D), and free-standing structured cathodes: TiN@MnO 2 /CP and TiN@Ir/CP. Both cathodes exhibited good specific capacity and excellent cycling stability. Their specific discharge capacities were up to 2637 and 2530 mA h g -1 , respectively. After 200 cycles for 2000 h at a current density of 100 mA g -1 , no obvious decays were observed for TiN@MnO 2 /CP and TiN@Ir/CP cathodes, while significant decreases were observed after the 80 th and 30 th cycles for the Pt/C and TiN/CP cathodes, respectively. Such high performance can be ascribed to the 3D array structure with enough microspace and high surface area, which facilitated the high dispersion of active components and prevented the formation of large/irreversible Li 2 O 2 .

A high-performance N-doped carbon catalyst with a fog-like, fluffy structure was prepared through pyrolyzing a mixture of polyacrylonitrile, melamine and iron chloride. The catalyst exhibits an excellent oxygen reduction reaction (ORR) performance, with a half-wave potential 27 mV more positive than that of a commercial Pt/C catalyst (-0.120 vs. -0.147 V) and a higher diffusion-limiting current density than that of Pt/C (5.60 vs. 5.33 mA cm(-2)) in an alkaline medium. Moreover, it also shows outstanding methanol tolerance, remarkable stability and nearly 100% selectivity for the four-electron ORR process. To our knowledge, it is one of the most active doped carbon ORR catalysts in alkaline media to date. By comparing catalysts derived from precursors containing different amounts of melamine, we found that the added melamine not only gives the catalyst a fluffy structure but also modifies the N content and the distribution of N species in the catalyst, which we believe to be the origins for the catalyst's excellent ORR performance.