Selective photocatalytic oxidation of NO to nitrate (NO 3 – ) over toxic NO 2 remains challenging due to low selectivity and inefficient charge migration in existing systems. This study introduces Fe 3+ as an electron acceptor beneath a Bi 4 TaO 8 Cl/Bi 2 O 2 CO 3 heterojunction to precisely regulate electron pathways and promote targeted hydroxyl radical ( • OH) generation. Combined experimental and DFT analyses reveal Fe 3+ ’s dual role: enhancing interfacial electron transfer and activating H 2 O at surface sites to form • OH. The optimized heterojunction achieves 68.19 % NO conversion with minimal NO 2 selectivity (10.98 %). ESR and ROS quenching confirm Fe 3+ -driven electron migration enriches surface holes, boosting H 2 O adsorption and • OH production (2.76-fold increase). The strong oxidation capacity of • OH suppresses NO 2 formation, favoring complete NO oxidation to NO 3 – . This work provides a strategic approach for selective NO removal by electron-pathway engineering, advancing the design of eco-friendly photocatalysts for air pollution control.
Sen Guo,Cong Shen,Yao Gui,Huiming Li,Jinhong Lü,Jianfa Li
Biochar (BC) and ferrihydrite (Fh) were used together in activation of H 2 O 2 for removal of sulfamethazine (SMZ), a refractory antibiotic pollutant. The results show a complementary effect between biochar and ferrihydrite on activation of H 2 O 2 , namely biochar accelerated Fe(Ⅲ)/Fe(Ⅱ) cycle through electron donation/transfer, while ferrihydrite enhanced the yield of • OH through a sustainable release of dissolved Fe. Thus several times more • OH was produced in the co-activated system (BC + Fh/H 2 O 2 ) than either in the ferrihydrite-catalyzed Fenton-like system (Fh/H 2 O 2 ) or in the biochar-activated system (BC/H 2 O 2 ). Consequently, a more efficient oxidation of SMZ was observed in BC + Fh/H 2 O 2 , in which the reaction rate constant ( k obs ) is 30.7 times in Fh/H 2 O 2 and 6.08 times in BC/H 2 O 2 , respectively. This research provides a simple and sustainable strategy for enhancing the efficiency of Fenton-like oxidation of pollutants.
A novel bifunctional MOF(2Fe/Co)/CA cathode with a high surface possessing area, and good electrocatalytic and photocatalytic activity, was proposed for the solar photo–electro–Fenton (SPEF) process. The optimal nFe: nCo ratio was 2:1 for successfully introducing MOF(2Fe/Co) on the surface of CA, which is due to the specific interaction affinity of FeOOH between MOF(2Fe/Co) and CA. Continuous on–site generation of H 2 O 2 through an oxygen reduction reaction (ORR) was achieved over the CA cathode. The electron transfer number (n) of the ORR with CA was 2.5 in the selected potential range. Moreover, the addition of MOF can behave as the active sites for enhancing the ORR activity and hence can increase the yield of the H 2 O 2 . Simultaneously, the photoinduced electron (e cb − ) of MOF(2Fe/Co) efficiently in–situ decomposed H 2 O 2 to form hydroxyl radicals ( OH). The observation indicated that the e cb − is an efficient and new Fenton–like catalysts that is pH–independent. Efficient photo–electro–catalytic performance was exhibited when applied to degrade Rhodamine B (RhB) and dimethyl phthalate (DMP). Almost 100% RhB removal and 85% DMP removal were reached in 45 min and 120 min, respectively. The MOF(Fe/Co)/CA presented very low iron and cobalt leaching (<0.5 ppm) even in an acidic media, and it retained an efficient degradation efficiency in the wide pH range of 3–9.
Fengyue Zhao,Juan Xiao,Shipeng Geng,Yi Wang,Panagiotis Tsiakaras,Shuqin Song
Fe 3+ /Fe 2+ interconversion is one of the key factors for heterogeneous electro-Fenton degradation of organic pollutants. In this study, MIL-101Fe-derived carbon wrapping Fe 7 S 8 nanocomposite (Fe 7 S 8 /C-1-600) exhibits outstanding rhodamine B (RhB) degradation ability with extremely low iron leaching and high recyclable degradability within 60 min in a wide pH range. Moreover, Fe 7 S 8 /C-1-600 presents a much higher activity for RhB degradation than Fe 3 O 4 counterpart without sulfidation, which could be mainly attributed to the accelerated Fe 3+ /Fe 2+ cycling by iron with both multiple valences (Fe 0 , Fe 2+ , and Fe 3+ ) and sulfur species (S 2− and S 2 2− ) of the catalyst. The enhancement of H 2 O 2 adsorption and activation into OH on Fe 7 S 8 surface is confirmed by density functional theory calculations with respect to that on Fe 3 O 4 . Interestingly, SO 4 · − can be generated by reacting S 2 2− with dissolved O 2 and subsequently converted into ·OH, which further facilitates RhB degradation. These findings may shed a new insight into the potential application of metal sulfides for wastewater treatment.
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