Single-Atom Iron Anchored Tubular g-C3 N4 Catalysts for Ultrafast Fenton-Like Reaction: Roles of High-Valency Iron-Oxo Species and Organic Radicals.

Single-atom catalysts have emerged as an efficient oxidant activator for eliminating organic pollutants in Fenton-like systems. However, the complex preparation, single active site, lack of understanding of the fundamental mechanism, and harsh pH conditions currently limit their practical applications. In this work, single-atom iron anchored nitrogen-rich g-C3 N4 nanotubes (FeCNs) are designed and synthesized by a facile approach, and eco-friendly peracetic acid (PAA) is selected as the oxidant for Fenton-like reactions. The constructed heterogenous system achieves an enhanced degradation of various organic contaminants over a wide pH range of 3.0-9.0, exhibiting an ultrahigh and stable catalytic activity, outperforming equivalent quantities of pristine g-C3 N4 by 75 times. The 18 O isotope-labeling technique, probe method, and theoretical calculations demonstrate that the efficient catalytic activity relies on the high-valency iron-oxo species coupled with organic radicals generated by PAA. An increase in electron transport from the contaminant to the formed "metastable PAA/FeCN catalyst surface complex" is detected. A double driving mechanism for the tubular g-C3 N4 regulated by a single Fe site and PAA activation is proposed. This work opens an avenue for developing novel catalysts with the coexistence of multiple active units and providing opportunities for significantly improving catalytic efficiency.

Quantitative Coassembly for Precise Synthesis of Mesoporous Nanospheres with Pore Structure-Dependent Catalytic Performance.

Precise synthesis of porous materials is essential for their applications. Self-assembly is a widely used strategy for synthesizing porous materials, but quantitative control of the assembly process still remains a great challenge. Here, a quantitative coassembly approach is developed for synthesizing resin/silica composite and its derived porous spheres. The assembly behaviors of the carbon and silica precursors are regulated without surfactants and the growth kinetics of the composite spheres are quantitatively controlled. This assembly approach enables the precise control of the size and pore structures of the derived carbon spheres. These carbon spheres provide a good platform to explore the structure-performance relationships of porous materials, and demonstrate their pore structure-dependent performance in catalytic water decontamination. This work provides a simple and robust approach for precise synthesis of porous spheres and brings insights into function-oriented design of porous materials.

Hierarchically porous nanosheets-constructed 3D carbon network for ultrahigh-capacity supercapacitor and battery anode.

An advanced hierarchically porous nanosheets-constructed three-dimensional (3D) carbon material (HPNSC) is prepared by using low-cost agricultural waste-nelumbium seed-pods as the precursor, and potassium hydroxide (KOH) as the activator. The as-prepared HPNSC material has a hierarchically porous nanosheets-constructed structure with 3D carbon nanosheet network morphology, which can enable fast and efficient transfer of Li+/Na+/H+ during charge-discharge process. The assembled HPNSC//HPNSC symmetric supercapacitors exhibit an improved energy density of 41.3 W h kg-1 with a power density of 180 W kg-1 in 1 mol l-1 Na2SO4 electrolyte. The energy density can still be maintained at 16.3 W h kg-1 even if the power density is increased to 9000 W kg-1. When acting as the reversible electrode for lithium ion batteries, this HPNSC material can achieve a high specific capacity of 1246 mA h g-1 at 0.1 A g-1. Moreover, sodium ion battery with HPNSC electrode exhibits excellent cycling performance of 161.8 mA h g-1 maintained even after being cycled 3350 times. The electrochemical performances clearly indicate that the HPNSC developed in this work is a very promising energy storage electrode material, and can further provide new insights for designing and developing highly porous materials for energy storage in other fields.