Regulating the Electronic Structure of Cu Single-Atom Catalysts toward Enhanced Electro-Fenton Degradation of Organic Contaminants via 1O2 and •OH.

Heterogeneous electro-Fenton degradation with 1O2 and •OH generated from O2 reduction is cost-effective for the removal of refractory organic pollutants from wastewater. As 1O2 is more tolerant to background constituents such as salt ions and a high pH value than •OH, tuning the production of 1O2 and •OH is important for efficient electro-Fenton degradation. However, it remains a great challenge to selectively produce 1O2 and improve the species yield. Herein, the electronic structure of atomically dispersed Cu-N4 sites was regulated by doping electron-deficient B into porous hollow carbon microspheres (CuBN-HCMs), which improved *O2 adsorption and significantly enhanced 1O2 selectivity in electro-Fenton degradation. Its 1O2 yield was 2.3 times higher than that of a Cu single-atom catalyst without B doping. Meanwhile, •OH was simultaneously generated as a minor species. The CuBN-HCMs were efficient for the electro-Fenton degradation of phenol, sulfamethoxazole, and bisphenol A with a high mineralization efficiency. Its kinetic constants showed insignificant changes under various anions and a wide pH range of 1-9. More importantly, it was energy-efficient for treating actual coking wastewater with a low energy consumption of 19.0 kWh kgCOD-1. The superior performance of the CuBN-HCMs was contributed from 1O2 and •OH and its high 1O2 selectivity.

A 2.5-Dimensional biomimetic dual-functional bifacial-evaporator for high efficient evaporation and water purification.

Nowadays, solar-driven interfacial steam generation (SISG) is a sustainable and green technology for mitigating the water shortage crisis. Nevertheless, SISG is suffering from the enrichment of volatile organic compounds in condensate water and non-volatile organic compounds in feed water in practical applications. Herein, taking inspiration from nature, a dual-functional bifacial-CuCoNi (Bi-CuCoNi) evaporator with a special biomimetic urchin-like microstructure was successfully prepared. The unique design with 2.5-Dimensional bifacial working sides and urchin-like light absorption microstructure provided the Bi-CuCoNi evaporator with remarkable evaporation performance (1.91 kg m-2 h-1 under 1 kW m-2). Significantly, due to the urchin-like microstructure, the adequately exposed catalytic active sites enabled the Bi-CuCoNi/peroxydisulfate (PDS) system to degrade non-volatile organic pollutants (removal rate of 99.3 % in feed water, close to 100 % in condensate water) and the volatile organic pollutants (removal rate of 99.1 % in feed water, 98.2 % in condensate water) simultaneously. Moreover, the Bi-CuCoNi evaporator achieved non-radical pathway degradation at whole-stages. The dual-functional evaporator successfully integrated advanced oxidation processes (AOPs) into SISG, providing a new idea for high-quality freshwater production from polluted wastewater. ENVIRONMENTAL IMPLICATION: Inspired by nature, a dual-functional bifacial CuCoNi evaporator with a special biomimetic urchin-like microstructure formed by CuCoNi oxide nanowires grown on nickel foam by the hydrothermal synthesis method was successfully prepared. The prepared Bi-CuCoNi evaporator can effectively degrade organic pollutants in feed water and condensate water simultaneously during SISG, thus generating high-quality fresh water. Meanwhile, the health risks associated with the accumulation of organic pollutants in water during traditional SISG were reduced via green and sustainable way. The spatial 2.5-Dimensional structural design of Bi-CuCoNi provided new insights for achieving efficient water evaporation and fresh water generation from various polluted wastewater.

Boosting peroxymonosulfate activation by iron-based dual active site for efficient sulfamethoxazole degradation: synergism of Fe and N-doped carbon.

Persulfate activation is emerged as an alternative applied in environment remediation, but it is still a great challenge to develop highly active catalysts for efficient degradation of organic pollutants. Herein, a heterogeneous iron-based catalyst with dual-active sites was synthesized by embedding Fe nanoparticles (FeNPs) onto the nitrogen-doped carbon, which was used to activate peroxymonosulfate (PMS) for antibiotics decomposition. The systematic investigation indicated the optimal catalyst exhibited a significant and stable degradation efficiency of sulfamethoxazole (SMX), in which the SMX can be completely removed in 30 min even after 5 cycle tests. Such satisfactory performance was mainly attributed to the successful construction of electron-deficient C centers and electron-rich Fe centers via the short C-Fe bonds. These short C-Fe bonds accelerated electrons to shuttle from SMX molecules to electron-rich Fe centers with a low transmission resistance and short transmission distance, enabling Fe (III) to receive electrons to promote the regeneration of Fe (II) for durable and efficient PMS activation during SMX degradation. Meanwhile, the N-doped defects in the carbon also provided reactive bridges that accelerated the electron transfer between FeNPs and PMS, ensuring the synergistic effects toward Fe (II)/Fe (III) cycle to some extent. The quenching tests and electron paramagnetic resonance (EPR) indicated O2·- and 1O2 were the dominant active species during the SMX decomposition. As a result, this work provides an innovative method to construct a high-performance catalyst to active sulfate for organic contaminant degradation.

Enhanced persulfate activation by nitrogen-doped mesoporous carbon for efficiently degrading organic matters.

Nitrogen-doped carbon materials (NMC) are widely used in peroxymonosulfate-based advanced oxidation processes (PMS-AOPs). Despite great efforts to improve the specific surface area of and the content of N atoms in catalysts for enhancing catalytic performance, this does not mean that the catalytic performance will improve with the increasing specific surface area and nitrogen content. Therefore, it is the key to optimize pore structure of NMC for maximizing the catalytic performance of nitrogen active sites. Herein, we synthesized the NMC as an efficient catalyst to activate PMS for the phenol removal. It can be found that the mesopore structure significantly accelerated the diffusion of reactants and might build the spatial confinement effect to improve the utilization of short life free radicals for further improving the removal efficiency. The removal efficiency of 1NMC750 (95%) with abundant mesopore channels was much higher than that of 1NMC750-0F127 (20%) with abundant micropore channels. Furthermore, the mechanism was confirmed to be radical (SO4•-, •OH) and non-radical (1O2, electron transfer) pathways. This study proposed a new insight for improving the catalytic performance of carbon materials by coordinating the pore structure.