Tancheng Dong,Yang Xiao,Wei Guo,Baojun Liu,Jincheng Mu
Biochar-induced interfacial defects modulate electronic structure of Mn Co spinel. • Complete IBU was removed in 5 min with an apparent reaction rate of 1.08 min −1 . • Interfacial structural defects accelerated redox cycles for boosted 1 O 2 generation. • The micropollutant was removed through a 1 O 2 dominated non-radical pathway. Spinel-based transition metal oxides are potential activators for peroxymonosulfate-based advanced oxidation processes (PMS-AOPs) in water purification, yet their sluggish redox cycling, stemming from poor conductivity, remains a critical limitation. In this work, a distiller's grain-derived porous biochar (BC)-decorated Mn Co spinel nanosheet catalyst (MnCoO x @BC) is developed and applied for PMS activation. The catalyst exhibits high efficacy in degrading ibuprofen (IBU), achieving complete removal within 5 min with an apparent reaction rate constant of 1.08 min −1 ([IBU] = 10 mg L −1 , [catalyst] = 200 mg L −1 , [PMS] = 200 mg L −1 ), which is 18 and 15 times for pristine BC and unsupported MnCoO x , respectively. Characterization and DFT calculation results indicate that the introduction of biochar could improve the conductivity and induce the formation of abundant oxygen defects, which accelerate the redox cycles of Co (III)/Co (II) and Mn (IV)/Mn (III) catalytic centers. This interfacial configuration facilitates the conversion of PMS into peroxysulfate radical (SO 5 • − ) and superoxide radical (O 2 • − ) species, and finally towards singlet oxygen ( 1 O 2 ), establishing a non-radical dominant pathway where 1 O 2 accounts for over 95% of the reactive species contribution. This work presents an effective strategy for developing defect-controlled catalytic interfaces to modulate the d-band center of metal sites and steer the interfacial electron transfer pathway, offering profound insights into non-radical-dominated mechanisms for the degradation of emerging micropollutants. Download: Download high-res image (312KB) Download: Download full-size image
The suitable proportion of diffusion contribution during the electrochemical process could influence the electrochemical performance of electrode materials. An effective method is that tuning the diffusion reaction contribution via doping heteroatom, introducing defects or surface modification. In this work, a unique core-shell structure material Cu-Mn-Co LDO-C is obtained. Benefitting from Cu pre-doped into Mn Co LDO, large amount of oxygen vacancies is introduced to enhance electrochemical performance; N-6 doped porous carbon shell protects Cu-Mn-Co LDO core and improves electrochemical performance of Cu-Mn-Co LDO-C further. In addition, doping Cu broadens potential window of Cu-Mn-Co LDO-C surprisingly. Cu-Mn-Co LDO-C presents 5028.7 mF cm −2 at a current density of 1 mA cm −2 with a facilely reached potential window of 0–0.65 V finally, and retains 73.4 % diffusion contribution at a scan rate of 1 mV s −1 , 18.3 % at 100 mV s −1 . After 10,000 cycles at 2 mA cm −2 , Cu-Mn-Co LDO-C keeps 90.3 % of initial capacitance. Using Cu-Mn-Co LDO-C as positive and Fe 3 O 4 -C as negative to fabricate a solid flexible asymmetrical supercapacitor (SAS), this SAS presents a considerable energy density that attribute to the high working potential of positive Cu-Mn-Co LDO-C. SAS could working stably at a potential window of 0–2.2 V, and presents the highest energy density 243.1 μWh cm −2 at a power density of 2.8 mW cm −2 , remains 203.0 μWh cm −2 at the highest power density of 55.4 mW cm −2 . A hand ring that was assembled by three SAS which contacted in series could light a highest rated voltage white LED more than 10 min. As a result, Cu-Mn-Co LDO-C is an ideal candidate for flexible positive electrode in the field of smart, portable energy storage.
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