Search

M-cresol, one of phenolics, is highly toxic, refractory, and threatens human health and ecological safety. The study on the efficient m-cresol degradation technologies is crucial and helpful to restrain its discharge into water body. A composite of MnO-doped red mud (RM) to activate peroxymonosulfate (PMS) for the m-cresol degradation was fabricated and employed, favorable to the recycling and utilization of RM. Considering the catalytic activity and cost, 0.1 M/RM@G exhibited an excellent degradation capacity attributing to strong Fe3O4 and MnO synergy and was considered as the best catalyst among the investigative catalysts. 100 % of m-cresol and 71.4 % of COD could be degraded within 90 min under 2 g/L catalyst, 10 mM of PMS, 3-8 of initial pH and 50 mg/L m-cresol in the 0.1 M/RM@G/PMS system. The reaction rate constant (0.045 min−1) of 0.1 M/RM@G was much larger than RM@G (0.012 min−1), ARM (0.0048 min−1) and WRM (0.0028 min−1). Main Mn and Fe active components and abundant mesoporous structures on the catalyst surface could efficiently drove electron transfers, and further accelerated the redox cycles of Mn(III)Mn(II) and Fe(III)Fe(II) for activating PMS. 1O2 played a crucial role in degrading m-cresol. Based on the experiment data, the generation mechanism of radicals and the possible pathways of m-cresol degradation were proposed in the 0.1 M/RM@G/PMS system. This finding provides a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of m-cresol wastewater.

Developing a photocatalysis-based system is an effective strategy for removing antibiotics. Herein, La-doped NiAl-layered double hydroxides (LaNiAl-LDH) photocatalyst was synthesized using a chemical co-precipitation-hydrothermal method. The prepared samples were characterized by various advanced analyses and investigated for the photocatalytic degradation of tetracycline (TC). The crystalline phase and functional groups of the synthesized samples were successfully confirmed by XRD and FTIR analyses. By doping La into NiAl-LDH structure, the band gap was reduced from 3.01 eV to 2.57 eV, indicating higher photocatalytic activity of 1% LaNiAl-LDH. The surface morphology of the synthesized samples shows the formation of nanosheets in the structure of LDH. Under the optimum status ([TC] 0 = 10 mg/L, [1% LaNiAl-LDH] = 0.2 g/L, and pH = 6), the photocatalytic activity of 1% LaNiAl-LDH (84.85%) was higher than NiAl-LDH (71.52%) within 90 min reaction. This difference can be attributed to the presence of La sites in 1% LaNiAl-LDH which act as electron-transfer mediators, leading to a significant improvement in the separation of photogenerated charge carriers. The effect of the addition of various scavengers was evaluated. Moreover, using the o-phenylenediamine (OPD), and photoluminescence (PL) analysis, the formation of •OH radicals was supported. The higher charge-transfer efficiency of 1% LaNiAl-LDH was confirmed by photoelectrochemical analysis. Furthermore, the reusability, stability, and degradation pathway of the as-synthesized nanocomposite were systematically examined. This work presents guidance for applying doped LDH-based materials in photocatalysis and promising applications in wastewater remediation. [Display omitted] • La-doped NiAl-LDH prepared via co-precipitation-hydrothermal method. • La-doped NiAl-LDH improves the separation of charge carriers. • A possible mechanism for enhanced photocatalytic activity was proposed. • The photocatalytic system was successfully validated in matrices of real samples. • Possible intermediates were identified during the photocatalytic degradation of TC. [ABSTRACT FROM AUTHOR]

[Display omitted] • CaO 2 -coated biochar is a suitable substrate material for pesticide remediation. • Successful CaO 2 coating on biochar decreased adsorption but largely improved overall removal efficiency. • CaO 2 in biochar activated in-situ advanced oxidation process at adsorption sites. • Cyclic transformation mechanisms of persistent free radicals were proposed. Biochar (pyrolyzed organic material) has been increasingly recognized for its catalytic role in facilitating the advanced oxidation of emerging organic pollutants. However, the inherent catalytic capacity remains highly uncontrollable, leading to considerable uncertainty when scaling up for real-world applications. This study explores the intensified catalytic role of biochar coated with CaO 2 in generating hydroxyl radicals (OH·) and facilitating advanced oxidation of tebuconazole, a prevalent fungicide, tebuconazole was selected as a representative pesticide in agricultural drainage. In addition to evaluating the potential for degradation by advanced oxidation processes (AOPs), the adsorption capabilities of two commercially available biochars, one derived from agricultural waste (ABC) and the other from spruce chips (SBC), as well as their CaO 2 -coated derivatives (ABC/CaO 2 and SBC/CaO 2), were also assessed. By taking advantage of the strong adsorption capacity of biochar, and activating AOPs at the adsorption sites by CaO 2 , this material enables more efficient and targeted removal of tebuconazole. The results indicate that CaO 2 coating on biochar promoted over tenfold increase in the generation of OH·, resulting in 99% tebuconazole removal within 10 min. Despite a decrease in adsorption capacity of 40–50% resulted by CaO 2 coating, the 10-minutes overall pesticide removal performance was significantly enhanced. The catalytic potential of biochar is closely related to its surface chemical properties, particularly the presence of persistent free radicals which can be regenerated. This research paves a new way for employing CaO 2 -enhanced intensified biochar in agricultural mitigation measures. [ABSTRACT FROM AUTHOR]

Mitochondria are structurally and functionally unique organelles in male gametes. Apparently, as the only organelles remaining in mature sperm, mitochondria not only produce adeno-sine triphosphate (ATP) through oxidative phosphorylation (OXPHOS) to support sperm mobility, but also play key roles in regulating reactive oxidation species (ROS) signaling, calcium homeostasis, steroid hormone biosynthesis, and apoptosis. Mitochondrial dysfunction is often associated with the aging process. Age-dependent alterations of the epididymis can cause alterations in sperm mitochondrial functioning. The resultant cellular defects in sperm have been implicated in male infertility. Among these, oxidative stress (OS) due to the overproduction of ROS in mitochondria may represent one of the major causes of these disorders. Excessive ROS can trigger DNA damage, disturb calcium homeostasis, impair OXPHOS, disrupt the integrity of the sperm lipid membrane, and induce apoptosis. Given these facts, scavenging ROS by antioxidants hold great potential in terms of finding promising therapeutic strategies to treat male infertility. Here, we summarize the progress made in understanding mitochondrial dysfunction, aging, and male infertility. The clinical potential of antioxidant interventions was also discussed. [ABSTRACT FROM AUTHOR]

• Magnetic p-n Bi 2 WO 6 /CuFe 2 O 4 for efficient photo-Fenton-like was fabricated. • Different ROS-dominated dark-and photo-Fenton-like reactions were explored. • Possible degradation pathways of TCH and products toxicity were analyzed. The extensive use of tetracycline hydrochloride (TCH) poses a threat to human health and the aquatic environment. Here, magnetic p-n Bi 2 WO 6 /CuFe 2 O 4 catalyst was fabricated to efficiently remove TCH. The obtained Bi 2 WO 6 /CuFe 2 O 4 exhibited 92.1% TCH degradation efficiency and 50.7% and 35.1% mineralization performance for TCH and raw secondary effluent from a wastewater treatment plant in a photo-Fenton-like system, respectively. The remarkable performance was attributed to the fact that photogenerated electrons accelerated the Fe(III)/Fe(II) and Cu(II)/Cu(I) conversion for the Fenton-like reaction between Fe(II)/Cu(I) and H 2 O 2 , thereby generating abundant •OH for pollutant oxidation. Various environmental factors including H 2 O 2 concentration, initial pH, catalyst dosage, TCH concentration and inorganic ions were explored. The reactive oxidation species (ROS) quenching results and electron spin resonance (ESR) spectra confirmed that •O 2 − and •OH were responsible for the dark and photo-Fenton-like systems, respectively. The degradation mechanisms and pathways of TCH were proposed, and the toxicity of products was evaluated. This work contributes a highly efficient and environmentally friendly catalyst and provides a clear mechanistic explanation for the removal of antibiotic pollutants in environmental remediation. [Display omitted] [ABSTRACT FROM AUTHOR]

M-cresol, one of phenolics, is highly toxic, refractory, and threatens human health and ecological safety. The study on the efficient m-cresol degradation technologies is crucial and helpful to restrain its discharge into water body. A composite of MnO-doped red mud (RM) to activate peroxymonosulfate (PMS) for the m-cresol degradation was fabricated and employed, favorable to the recycling and utilization of RM. Considering the catalytic activity and cost, 0.1 M/RM@G exhibited an excellent degradation capacity attributing to strong Fe 3 O 4 and MnO synergy and was considered as the best catalyst among the investigative catalysts. 100 % of m-cresol and 71.4 % of COD could be degraded within 90 min under 2 g/L catalyst, 10 mM of PMS, 3-8 of initial pH and 50 mg/L m-cresol in the 0.1 M/RM@G/PMS system. The reaction rate constant (0.045 min−1) of 0.1 M/RM@G was much larger than RM@G (0.012 min−1), ARM (0.0048 min−1) and WRM (0.0028 min−1). Main Mn and Fe active components and abundant mesoporous structures on the catalyst surface could efficiently drove electron transfers, and further accelerated the redox cycles of Mn(III) Mn(II) and Fe(III) Fe(II) for activating PMS. 1O 2 played a crucial role in degrading m-cresol. Based on the experiment data, the generation mechanism of radicals and the possible pathways of m-cresol degradation were proposed in the 0.1 M/RM@G/PMS system. This finding provides a new way for the synthesis of the efficient catalyst with RM and optimal operating strategies for the treatment of m-cresol wastewater. [ABSTRACT FROM AUTHOR]

[Display omitted] • ACF cathode exhibits excellent performance in PAA activation for SMX elimination. • ACF could maintain persistent catalytic ability under a cathodic electric field. • •OH generated from ACF cathode plays the dominant role in organics degradation. • Degradation intermediates of SMX are harmless to the aquatic ecology. Advanced oxidation processes (AOPs) based on peracetic acid (PAA) could generate various radicals with low by-product generation, making them a vital technology in the remediation of organic pollution. Maintaining the activity and continuous operation of catalytic systems in water treatment processes was a highly challenging research topic. Herein, the electrochemical process with an activated carbon fiber (E-ACF) cathode was devised to boost the activation of PAA (E-ACF-PAA) for persistent elimination of organics. Compared to other commonly used electrodes, the ACF cathode displayed superior PAA activation ability and higher sulfamethoxazole (SMX) removal. The applied cathodic electric field could protect ACF from PAA oxidation, maintaining its long-term catalytic ability over 50 cycles. Based on radical quenching studies, the EPR test, and the estimation of radical contribution, the E-ACF-PAA process was identified as a radical dominant system. Importantly, isolated chamber experiments proved that PAA was mainly decomposed on the cathode to produce hydroxyl radicals (OH) for SMX degradation, while the anode played a negligible role. According to toxicity prediction and algae growth tests, the degradation products were harmless to the aquatic ecology. Remarkably, continuous flow experiments over a 24 h and different water matrix tests have also proven applicability in practical scenarios. This work provided novel insights into the electrochemical activation of PAA and further expanded the potential applications of PAA-based AOPs in the remediation of organic pollution. [ABSTRACT FROM AUTHOR]

[Display omitted] • Superior piezo-photocatalytic response BFO@SBBO heterojunction was successfully fabricated. • The polarization electric field across the p-n heterojunction remarkably improves the separation of photogenerated charge carriers. • Further addition of PS intensifies charge separation and visible light utilization. • 1O 2 dominate BPA removal in the piezo-photocatalytic reaction. • BFO@SBBO demonstrates excellent performance and high stability in remediating BPA and actual phenolic wastewater. Photoresponse piezoelectric materials have attracted tremendous interest as a new generation of photocatalysts for water purification. However, the development of durable and efficient piezo-photocatalyst remains to be a challenging task. Herein, a novel BiFeO 3 @SrBi 2 B 2 O 7 (BFO@SBBO) p-n heterojunction with ultrahigh piezo-photocatalytic ability was fabricated after adjustment of BFO outer layer thickness, and utilized to activate persulfate (PS) for efficient water decontamination. The synergistic effect between the internal electric field across the heterojunction and the PS greatly improves the separation of photogenerated charge carriers. In the presence of ultrasonic mechanical vibration, 10 mg/L bisphenol A (BPA) was completely removed within 20 min with the assistance of a low dosage of PS upon visible light irradiation, which outperform various piezo-photocatalysts. Transformation and contribution of reactive oxygen species (ROSs, i.e., OH, O 2 −, 1O 2 and SO 4 −) generated in the BFO@SBBO/US/Vis/PS system were evaluated and semi-quantified to understand the mechanism of BPA piezo-photocatalytic degradation. The stability and performance of BFO@SBBO piezo-photocatalysis toward typical organic pollutants and actual phenolic water remediation were evaluated, which confirmed the promising practical potential of BFO@SBBO in water remediation. This study offers a new insight into strategies for highly efficient piezo-photocatalyst for photocatalytic water remediation. [ABSTRACT FROM AUTHOR]

[Display omitted] • Z@GO-SOD was prepared via a green and fast way and used as Fenton-like photocatalyst. • Z@GO-SOD is highly photoactive for activating PS to produce ROSs. • Z@GO-SOD/PS/Vis system exhibits high efficiency in remediating ciprofloxacin. • Z@GO-SOD shows superior reactivity and high stability. The sluggish kinetics of Fe(II) regeneration and inactive Fe(III) sludge accumulation strongly hampers the scientific progress of Fenton-related reactions toward practical application. Herein, we developed a durable zero-valent iron super dispersed sodalite-graphene oxide hybrid (Z@GO-SOD) via reactive oxidation species (ROSs) route using industrial waste lithium silicon fume (LSF) as raw material, and first applied it as a visible-light-driven photocatalyst to initiate Fenton-like reaction for effective ciprofloxacin (CIP) remediation. The Z@GO-SOD featured a mesoporous structure with iron strongly interaction with GO hybrid zeolite, the GO hybrid zeolite acted as an efficient mediator, facilitating charge separation and transportation to expedite the iron redox cycle. The presence of persulfate could further act as an electron acceptor to boost photogenerated e−/h+ separation, resulting in more OH for fast CIP removal. Over 90 % of CIP was removed within 30 min in the Z@GO-SOD/Vis/PS system with the usage of merely 0.4 g/L catalyst, and as high as 71% CIP was completely mineralized, which outperformed most of the state-of-the-art photo-Fenton catalysts. Meanwhile, Z@GO-SOD also demonstrated excellent reusability and stability. This work indicated the feasibility of utilizing solar energy for both preparation of catalyst and remediation of wastewater, paying the way for a sustainable solution for environmental solid waste pollution and water scarcity issue. [ABSTRACT FROM AUTHOR]

Pyrite-mediated arsenopyrite oxidation is an important process affecting arsenic (As) mobility. The iron sulfides-induced reactive oxidation species (ROS) can exert significant influence on As transformation. However, the impact of pyrite-arsenopyrite association on ROS production and its contribution to As transformation were rarely estimated. Here, ROS formation and the redox conversion of As during the interaction between pyrite and arsenopyrite as function of O 2 , pH and pyrite surface oxidation were investigated. Pyrite promoted arsenopyrite oxidation and As(III) oxidation due to heterogeneous electron transfer. The electron transfer from arsenopyrite facilitated O 2 reduction on pyrite surface with increasing ROS formation. Hydroxyl radical (HO˙), superoxide (O 2 •)- and hydrogen peroxide (H 2 O 2) were the main reactive species for As(III) oxidation. Iron (hydr)oxides produced from pyrite surface oxidation provided fast electron transfer channels for efficient O 2 reduction as evidenced by electrochemical experiment, further verifying the promoted effect of surface-oxidized pyrite (SOP) on arsenopyrite dissolution. However, total As and As(V) obviously decreased during SOP-mediated arsenopyrite oxidation. Iron (hydr)oxides retained appreciable As through adsorption to limit its mobility, and decreased HO˙ production to inhibit As(III) oxidation via decomposing H 2 O 2. This work furthers our understanding of arsenic transformation in the environment which has important implications for mitigating arsenic pollution. [Display omitted] • Pyrite facilitated arsenopyrite oxidation and As(V) formation. • ROS was mainly responsible for As(III) oxidation. • Pyrite-mediated arsenopyrite oxidation by O 2 accelerated ROS formation. • Oxidation layer on pyrite affected arsenopyrite oxidation and As fate. [ABSTRACT FROM AUTHOR]

The objective of this work was to evaluate the efficiency of a solar TiO-assisted photocatalytic process on amoxicillin (AMX) degradation, an antibiotic widely used in human and veterinary medicine. Firstly, solar photolysis of AMX was compared with solar photocatalysis in a compound parabolic collectors pilot scale photoreactor to assess the amount of accumulated UV energy in the system ( Q) necessary to remove 20 mg L AMX from aqueous solution and mineralize the intermediary by-products. Another experiment was also carried out to accurately follow the antibacterial activity against Escherichia coli DSM 1103 and Staphylococcus aureus DSM 1104 and mineralization of AMX by tracing the contents of dissolved organic carbon (DOC), low molecular weight carboxylate anions, and inorganic anions. Finally, the influence of individual inorganic ions on AMX photocatalytic degradation efficiency and the involvement of some reactive oxygen species were also assessed. Photolysis was shown to be completely ineffective, while only 3.1 kJ L was sufficient to fully degrade 20 mg L AMX and remove 61 % of initial DOC content in the presence of the photocatalyst and sunlight. In the experiment with an initial AMX concentration of 40 mg L, antibacterial activity of the solution was considerably reduced after elimination of AMX to levels below the respective detection limit. After 11.7 kJ L, DOC decreased by 71 %; 30 % of the AMX nitrogen was converted into ammonium and all sulfur compounds were converted into sulfate. A large percentage of the remaining DOC was in the form of low molecular weight carboxylic acids. Presence of phosphate ions promoted the removal of AMX from solution, while no sizeable effects on the kinetics were found for other inorganic ions. Although the AMX degradation was mainly attributed to hydroxyl radicals, singlet oxygen also plays an important role in AMX self-photosensitization under UV/visible solar light. [ABSTRACT FROM AUTHOR]

The pathogenesis of metabolic-associated fatty liver disease (MAFLD) is complex and thought to be dependent on multiple parallel hits on a background of genetic susceptibility. The evidence suggests that MAFLD progression is a dynamic two-way process relating to repetitive bouts of metabolic stress and inflammation interspersed with endogenous anti-inflammatory reparative responses. In MAFLD, excessive hepatic lipid accumulation causes the production of lipotoxins that induce mitochondrial dysfunction, endoplasmic reticular stress, and over production of reactive oxygen species (ROS). Models of MAFLD show marked disruption of mitochondrial function and reduced oxidative capacitance with impact on cellular processes including mitophagy, oxidative phosphorylation, and mitochondrial biogenesis. In excess, ROS modify insulin and innate immune signaling and alter the expression and activity of essential enzymes involved in lipid homeostasis. ROS can also cause direct damage to intracellular structures causing hepatocyte injury and death. In select cases, the use of anti-oxidants and ROS scavengers have been shown to diminish the pro-apoptopic effects of fatty acids. Given this link, endogenous anti-oxidant pathways have been a target of interest, with Nrf2 activation showing a reduction in oxidative stress and inflammation in models of MAFLD. Thyroid hormone receptor β (THRβ) agonists and nuclear peroxisome proliferation-activated receptor (PPAR) family have also gained interest in reducing hepatic lipotoxicity and restoring hepatic function in models of MAFLD. Unfortunately, the true interplay between the clinical and molecular components of MAFLD progression remain only partly understood. Most recently, multiomics-based strategies are being adopted for hypothesis-free analysis of the molecular changes in MAFLD. Transcriptome profiling maps the unique genotype-phenotype associations in MAFLD and with various single-cell transcriptome-based projects underway, there is hope of novel physiological insights to MAFLD progression and uncover therapeutic targets., Competing Interests: The authors have no conflict of interests related to this publication., (© 2022 Authors.)

[Display omitted] • Superior CIP removal was achieved in the E-PS using SnO 2 -Bi/Ti anode and FeCM cathode. • FeCM cathode outperforms various cathodes (Pt, Ti, graphite, and SS) in the E-PS. • 1O 2 was continuously generated and efficiently utilized for improved CIP removal. • E-FeCM-PS system shows superior reactivity and high stability. • E-FeCM-PS system exhibits high efficiency in remediating actual hospital effluent. In this work, electrochemical activation of persulfate (E-PS) for the energy efficient treatment of ciprofloxacin (CIP) was performed using a novel iron-decorated carbon membrane (FeCM) cathode and SnO 2 -Bi/Ti anode. Synergistic effect of electrochemical oxidation and PS activation resulted in superior CIP removal. The FeCM cathode outperforms various cathodes (Pt, Ti, graphite, and stainless steel), owing to the existence of C = O, Fe2+/Fe3+, and F on FeCM, which can facilitate 1O 2 generation and utilization in the E-PS system. Moreover, the continuous supply of negative charges endows rapid redox cycle of Fe2+/Fe3+ on FeCM cathode, which not only prevents iron leaching, but also reduces the consumption of active sites, and thus, enables FeCM with high stability over a wide pH range and improved cyclic performance. The potential of E-FeCM-PS for outdoor application were evaluated by removing various persistent organic pollutants, and treating actual hospital effluent. The CIP removal mechanism in the E-FeCM-PS process and the possible CIP degradation pathways were proposed. Overall, this work provides a plausible route for the continuous production of 1O 2 for effective abatement of organic contaminants via electro-activation of PS and gives an insight into the intrinsic role of iron-doped carbon membrane for persulfate cathodic activation. [ABSTRACT FROM AUTHOR]

Insufficient charge-carriers separation and deteriorated recycling are still bottlenecks limiting practical photocatalytic water purification. Herein, we developed a durable hollow core-shell TiO 2 @LaFeO 3 (TLFO) nanosphere via facile carbon-sphere-templated method and sol-gel process, and applied it as heterojunction photocatalyst coupled with peroxymonosulfate (PMS) for efficient atrazine (ATZ) removal via enhanced electron-transfer. The built-in electric field originated from the three-dimensional heterojunction between TiO 2 and LaFeO 3 , acting as charge transfer driving force, enhanced the charge separation rate. Meanwhile, PMS could function as electron acceptor to boost photogenerated charge separation and maximize reactive oxidant species (e.g., •OH, SO 4 •−, O 2 •− and 1O 2) production. Therefore, the fabricated TLFO heterojunction exhibited outstanding reusability, and superior ATZ removal efficiency without detectable metal ion leaching. This work successfully demonstrates the synergistic effect and superior hollow structure of TLFO heterojunction with promoted light utilization and PMS activation, which offers potential application for efficient abating environmental pollution using solar energy. [Display omitted] • A novel three-dimensional heterojunction TLFO was developed via a facile method. • The built-in electric field acts as driving force to improve electron transfer. • PMS addition further enhances charge separation rate, therefore maximum ROS production. • TLFO heterojunction shows long-term durability and maximum water treatment efficiency via synergistic effect. • TLFO exhibits 25-fold higher performance in ATZ removal than pure LFO, without metal ion leaching. [ABSTRACT FROM AUTHOR]

[Display omitted] • Introduce fundamentals of perovskite for photocatalytic water treatment. • Summarize state-of-art perovskite photocatalytic reactivity tuning strategies. • Overview progress of perovskite coupling with AOPs for improved water treatment. • Propose limitations and prospects of perovskites in practical water treatment. Perovskite oxides have been recognized as highly potent catalysts for photocatalytic water decontamination due to their potential to capture solar energy and drive catalytic reaction. However, pristine perovskite catalysts have inherent drawbacks such as low surface area, rapid recombination of photogenerated charge carriers and low solar light utilization efficiency, which limited their practical water treatment application. For the purpose of effective photocatalytic water purification, significant efforts have been emphasized on promoting perovskite reactivity in recent years. This review aims to summarize recent progress of tunning strategies and coupling Advanced oxidation processes (AOPs) methods for improving perovskite photocatalyst reactivity, destined for the decontamination of organic pollutants in wastewater. The general principles of designing perovskite photocatalysts for water decontamination are introduced for basic understanding of involved mechanism. Diverse perovskite regulating strategies such as hetero-substitution, decoration, as well as structure regulation have been discussed in detail to provide a comprehensive view of strategies that improve perovskite photocatalytic activity. In addition, recent rapid development of coupling various AOPs with perovskite for improved water remediation via collaborative effects are presented. Finally, the remaining challenges and possible future directions of practical perovskite photocatalytic water purification are also discussed. This review provides useful insight for efficient application of perovskite photocatalyst in water purification. [ABSTRACT FROM AUTHOR]

• Reactive oxidation species for BBS were explored and clarified. • No OH radicals were produced for most BBS systems. • Holes may be more effective in photocatalytic oxidation for BBS. Bismuth-based semiconductors (BBS) are a group of promising candidates applied to visible light-induced photocatalysis. With deep positions of valence bands (2.34–4.04 eV), BBS exhibited excellent activity in oxidation processes. Fundamental studies on the reactive oxidation species primarily focused on TiO 2 under ultraviolet, and it was recognized that OH radicals were effective reactive oxidative species in photocatalytic oxidation processes. This verdict may not be applicable for all other photocatalytic systems. In this study, the reactive oxidation species for BBS in the photocatalytic decomposition of phenol were explored. BBS were prepared with Hierarchical structures and high crystallinity. It was found that OH radicals and superoxide radicals were negligibly produced in most BBS photocatalytic systems. Instead, separated holes on the valence band may directly react with adsorbed species including organics, and acted as the primary ROS. One of the possible explanations of this phenomenon may be due to the shorter lifetime of photogenerated charge carriers on most BBS (212.3–415.7 ms) compared to that of TiO 2 (1193.8 ms). Photocatalytic reaction pathways of degradation of phenol were also different between BBS and TiO 2 , which were proposed. This work shed light on the significance of addressing and clarifying the reactive oxidation species in BBS photocatalysis. [ABSTRACT FROM AUTHOR]

Silver/silver halides (Ag/AgX) are potential visible-light (VL) photocatalysts due to synergistic effects of surface plasmon resonance (SPR) and semiconductor photocatalysis. However, many contradictory opinions are found in published literature about the mechanism underlying photocatalytic oxidation (PCO) by Ag/AgX. In this study, Ag/AgBr particles were prepared by a simple one-pot synthesis method and used for degradation of Reactive Black 5 (RB5) as a model pollutant aiming to understand the effect of concentration of excess silver ions on SPR phenomenon, and to employ experimental and theoretical approaches to pinpoint the reactive oxidative species (ROS) responsible for RB5 degradation. 16.2% of initial 50 mg/L RB5 was degraded using 0.5 g/L AgBr (Ag+:AgBr = 0, i.e. no excess Ag+) under 60 min VL irradiation. Under identical experimental conditions, RB5 degradation increased to 86.5% using Ag/AgBr synthesized as Ag+:AgBr = 0.4, due to improved SPR effect. Experimental evidence supported by theoretical calculations revealed that superoxide radicals (•O 2) played a prime role in PCO followed by photo-generated holes, whereas the contribution of •OH was negligible. The presence of Ag0 on AgBr greatly influenced band energies and regulated the formation of ROS. With an increase in ratio Ag+:AgBr, the conductance and valence bands increasingly became more electro-negative and electro-positive, respectively, as compared to that at Ag+:AgBr = 0. The presence of Cl ̅ and SO 4 2− ions adversely affected RB5 degradation, whereas CO 3 2− did not cause any adverse impact. Ag/AgBr could be successfully immobilized over bacterial cellulose which, under identical conditions, provided 79.1% RB5 degradation in 60 min. The Ag/AgBr-BC could be reused five times. • A combined experimental-theoretical approach explains the mechanism of Ag/AgBr photocatalysis. • The presence of Ag0 on AgBr influences the Fermi level and regulates the formation of oxidation species. • Ag/AgBr was successfully immobilized on bacterial cellulose for the first time. • Ag/AgBr-BC is a potential and reusable photocatalyst. [ABSTRACT FROM AUTHOR]