Search

Summary: Ni electrode was modified with graphene by the electrodeposition (ED) method to prepare an anode (anode‐ED) for microbial fuel cell (MFC). Electrochemical and morphological characterizations of anode‐ED along with the effects of anode modification on the MFC performance were investigated. The graphene modification based on cyclic voltammetric electrodeposition resulted in the decrease of charge transfer resistance (Rct) and improved extracellular electron transfer efficiency of anode. The maximum power density obtained from the MFC equipped with anode‐ED was 25.83 and 17.86 times larger than those of MFCs equipped with bare Ni anode and anode modified with graphene by traditional hydrothermal treatment method (anode‐HT), respectively. The electrochemical impedance spectroscopy (EIS) analysis results indicated that the Rct of anode decreased significantly after inoculation during the MFC operation. The improvement in power density was attributed to the decreasing Rct and the biocompatibility of graphene modified on anode‐ED surface. This study presented an effective electrodeposition method to make graphene‐modified anodes, which could improve the MFC performance. [ABSTRACT FROM AUTHOR]

[Display omitted] • A sulfur-doped CoFe 2 O 4 (S-CoFe 2 O 4) was newly fabricated as the Fenton catalyst. • The sulfurization resulted in a significant enhancement of Fenton performance. • The increased charge density of S-CoFe 2 O 4 was favorable to the H 2 O 2 activation. • The mechanism of S-CoFe 2 O 4 as the Fenton catalyst for the pollutants removal was proposed. Herein, mesoporous sulfurized CoFe 2 O 4 (S-CoFe 2 O 4) was developed and applied as a new Fenton catalyst. As a result, the sulfurization for CoFe 2 O 4 could significantly improve the Fenton performance, compared with the non-sulfurized CoFe 2 O 4. The enhanced removal efficiencies of pollutants in Fenton process catalyzed by S-CoFe 2 O 4 was attributed to the elevated specific area and decreased electron transfer resistance of S-CoFe 2 O 4. The DFT calculations further confirmed that the increased charge densities of Fe S bond and Co S bond could contribute to the existences of species of Fe and Co in S-CoFe 2 O 4 with the low valence, which were more favorable to the H 2 O 2 activation. Furthermore, electron paramagnetic resonance (EPR) tests showed that the OH and O 2 − were the main generated radicals during the H 2 O 2 activation process. This work provided a new strategy for the synthesis and application of an efficient non-precious metal Fenton catalyst. [ABSTRACT FROM AUTHOR]

[Display omitted] • Mn@5-NPC-800 was applied in heterogeneous Fenton-like reaction (HTFR). • HTFR performance was enhanced via the synergistic adsorption and oxidation process. • P, N co-doping enhanced the specific surface area, yields of MnIII and graphitic-N. • N, P co-doped carbon matrix facilitated electron transfer between MnP and PMS. • O 2 •− and 1O 2 were the main generated ROS, contributing to the pollutant removal. The heterogeneous Fenton-like reactions (HTFR) have attracted considerable interest for their efficacy in degrading pollutants. However, the development of effective strategies for enhancing performance in HTFR remains a subject of ongoing research. Herein, a synergistic adsorption and oxidation-dominated process was developed to overcome the bottlenecks of peroxymonosulfate (PMS)-based HTFR in terms of mass transfer and catalyst reactivity. Heteroatom (P, N) co-doping for manganese (Mn) was employed to fabricate an efficient catalyst, Mn@5-NPC-800, which exhibited exceptional abilities of adsorption and PMS activation. The enhanced performance of HTFR was attributed to the increased specific surface area (SSA) and enhanced yields of graphitic-N/MnIII of the catalyst, which facilitated reactant enrichment and electron transfer in the delocalized conjugated area, respectively. The PMS-based HTFR induced by Mn@5-NPC-800 for pollutant removal was characterized by a synergistic adsorption and reactive oxygen species (ROS)-dominated oxidation process. DFT calculations revealed that the N, P co-doped carbon matrix (NPC) acted as a conductive bridge, significantly improving electron transfer between MnP and PMS molecule, which was identified as a key factor in governing the catalytic performance. The investigation presents a suggestive example of employing a doping strategy to create a synergistic effect of adsorption and oxidation, thereby strengthening the performance of Fenton-like reactions. [ABSTRACT FROM AUTHOR]

• Novel photocatalytic redox-mediator-free r GO-based Z-scheme composite was prepared. • Improved charge transfer between CdS and AgBr via r GO promoted photocatalysis. • Photocatalytic composite enhanced activity for Rhodamine B pollutant degradation. High-efficiency photocatalytic degradation of a harmful organic pollutant, i.e., Rhodamine B (RhB), was achieved using an r GO-mediated CdS/AgBr (CdS/AgBr- r GO) photocatalyst composed of AgBr, CdS and reduced graphene oxide (r GO). The batch experiments demonstrated that the first-order kinetic constants of as-synthesized photocatalyst prepared CdS/AgBr- r GO with a mass ratio of 10:1:0.005 was 0.051 min−1. The value was 1.96 and 5.67 times higher than those of CdS and AgBr alone for RhB degradation, respectively. Using benzoquinone (BZQ), isopropyl alcohol (ISA) and ethylenediamine tetraacetic acid disodium salt (Na 2 -EDTA) as scavengers, the results of quenching experiment indicated that O 2 −, OH and h + are the dominant reactive species for RhB decomposition. The electrochemical analysis demonstrated that CdS and AgBr formed a Z-scheme photocatalytic system via r GO at the interface of the two semiconductors acting as a solid electron shuttle where the photogenerated electron-hole pairs were efficiently separated through electron transfer. Furthermore, the photostability of CdS/AgBr- r GO heterojunction photocatalysts was investigated over four successive runs. [ABSTRACT FROM AUTHOR]

External addition of Fe2+ is commonly required for the sake of activating H 2 O 2 in electro-Fenton, which limits the reaction continuity and causes the potential secondary pollution. Herein, a novel bifunctional cathode (rGO/MIL-88A/CF) was fabricated for achieving the in-situ H 2 O 2 generation and activation simultaneously. The rotating disc electrode (RDE) test showed that the average electron transfer number was about 2.01, indicating that selective two-electron reduction of oxygen molecule (2e– ORR) occurred on the as-prepared cathode. The quenching experiments and EPR tests proved that the oxygen-containing reactive species such as OH• and O 2 •– could be efficiently generated on rGO/MIL-88A/CF cathode, which contributed to the pollutant degradation. The obtained rGO/MIL-88A/CF cathode not only obtained the improvement of its charge transfer rate owing to the modification by the reduced graphene (rGO), but also acted as a stable activator for the electro-generated H 2 O 2 without additional reagents. Moreover, rGO/MIL-88A/CF cathode effectively facilitated the circulation of Fe2+/Fe3+ through cathodic reduction, which consequently enhanced the performance of the electro-Fenton. Our current investigation presented a feasible example of a novel bifunctional cathode applied in electro-Fenton towards efficient pollutant removal without exogenous H 2 O 2 activator. [Display omitted] [ABSTRACT FROM AUTHOR]