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Owing to their earth abundance, high atom utilization, and excellent activity, single iron atoms dispersed on nitrogen-doped carbons (Fe-N-C) have emerged as appealing alternatives to noble-metal platinum (Pt) for catalyzing the oxygen reduction reaction (ORR). However, the ORR activity of current Fe-N-C is seriously limited by the low density and inferior exposure of active Fe-Nx species. Here, a novel zinc-mediated template synthesis strategy is demonstrated for constructing densely exposed Fe-Nx moieties on hierarchically porous carbon (SA-Fe-NHPC). During the thermal treatment of 2,6-diaminopyridine/ZnFe/SiO2 complex, the zinc prevents the formation of iron carbide nanoparticles and the SiO2 template promotes the generation of hierarchically pores for substantially improving the accessibility of Fe-Nx moieties after subsequent leaching. As a result, the SA-Fe-NHPC electrocatalysts exhibit an unprecedentedly high ORR activity with a half-wave potential (E1/2 ) of 0.93 V in a 0.1 m KOH aqueous solution, which outperforms those for Pt/C catalyst and state-of-the-art noble metal-free electrocatalysts. As the air electrode in zinc-air batteries, the SA-Fe-NHPC demonstrates a large peak power density of 266.4 mW cm-2 and superior long-term stability. Therefore, the developed zinc-mediated template synthesis strategy for boosting the density and accessibility of Fe-Nx species paves a new avenue toward high-performance ORR electrocatalysts.

Graham Priest 2002 argues that all logical paradoxes that include set-theoretic paradoxes and semantic paradoxes share a common structure, the Inclosure Schema, so they should be treated as one family. Through a discussion of Berry's Paradox and the semantic notion ‘definable’, I argue that (i) the Inclosure Schema is not fine-grained enough to capture the essential features of semantic paradoxes, and (ii) the traditional separation of the two groups of logical paradoxes should be retained.

2D conjugated metal–organic frameworks (2D c‐MOFs) are emerging as electroactive materials for chemiresistive sensors, but selective sensing with fast response/recovery is a challenge. Phthalocyanine‐based Ni2[MPc(NH)8] 2D c‐MOF films are presented as active layers for polarity‐selective chemiresisitors toward water and volatile organic compounds (VOCs). Surface‐hydrophobic modification by grafting aliphatic alkyl chains on 2D c‐MOF films decreases diffused analytes into the MOF backbone, resulting in a considerably accelerated recovery progress (from ca. 50 to ca. 10 s) during humidity sensing. Toward VOCs, the sensors deliver a polarity‐selective response among alcohols but no signal for low‐polarity aprotic hydrocarbons. The octadecyltrimethoxysilane‐modified Ni2[MPc(NH)8] based sensor displays high‐performance methanol sensing with fast response (36 s)/recovery (13 s) and a detection limit as low as 10 ppm, surpassing reported room‐temperature chemiresistors., Surface‐modification of phthalocyanine‐based two‐dimensional conjugated metal‐organic framework (2D c‐MOF) films by grafting aliphatic alkyl chains is developed for achieving high‐performance polarity‐selective chemiresistive sensing toward humidity and polar alcohols.

Rechargeable sodium-iodine (Na-I2 ) batteries are attracting growing attention for grid-scale energy storage due to their abundant resources, low cost, environmental friendliness, high theoretical capacity (211 mAh g-1 ), and excellent electrochemical reversibility. Nevertheless, the practical application of Na-I2 batteries is severely hindered by their poor cycle stability owing to the serious dissolution of polyiodide in the electrolyte during charge/discharge processes. Herein, the atomic modulation of metal-bis(dihydroxy) species in a fully conjugated phthalocyanine copper metal-organic framework (MOF) for suppression of polyiodide dissolution toward long-time cycling Na-I2 batteries is demonstrated. The Fe2 [(2,3,9,10,16,17,23,24-octahydroxy phthalocyaninato)Cu] MOF composited with I2 (Fe2 -O8 -PcCu/I2 ) serves as a cathode for a Na-I2 battery exhibiting a stable specific capacity of 150 mAh g-1 after 3200 cycles and outperforming the state-of-the-art cathodes for Na-I2 batteries. Operando spectroelectrochemical and electrochemical kinetics analyses together with density functional theory calculations reveal that the square planar iron-bis(dihydroxy) (Fe-O4 ) species in Fe2 -O8 -PcCu are responsible for the binding of polyiodide to restrain its dissolution into electrolyte. Besides the monovalent Na-I2 batteries in organic electrolytes, the Fe2 -O8 -PcCu/I2 cathode also operates stably in other metal-I2 batteries like aqueous multivalent Zn-I2 batteries. Thus, this work offers a new strategy for designing stable cathode materials toward high-performance metal-iodine batteries.