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Magnéli phase titanium suboxides (M‐TSOs) belong to a type of sub‐stoichiometric titanium oxides based on the crystal structure of rutile TiO2. They possess a unique shear structure, granting them exceptional electrical conductivity and corrosion resistance. These two advantages are crucial for electrode materials in electrochemistry, hence the significant interest from numerous researchers. However, the preparation of M‐TSOs is uneconomic due to high temperature reduction and other complex synthesis process, thus limiting their practical application in electrochemical fields. This review delves into the crystal structure, properties, and synthesis methods of M‐TSOs, and touches on their applications as electrocatalysts in wastewater treatment and electrochemical water splitting. Furthermore, it highlights the research challenges and potential future research directions in M‐TSOs. [ABSTRACT FROM AUTHOR]

Exploring an appropriate support material for Cu‐based electrocatalyst is conducive for stably producing multi‐carbon chemicals from electroreduction of carbon monoxide. However, the insufficient metal‐support adaptability and low conductivity of the support would hinder the C−C coupling capacity and energy efficiency. Herein, non‐stoichiometric Ti4O7 was incorporated into Cu electrocatalysts (Cu−Ti4O7), and served as a highly conductive and stable support for highly energy‐efficient electrochemical conversion of CO. The abundant oxygen vacancies originated from ordered lattice defects in Ti4O7 facilitate the water dissociation and the CO adsorption to accelerate the hydrogenation to *COH. The highly adaptable metal‐support interface of Cu−Ti4O7 enables a direct asymmetrical C−C coupling between *CO on Cu and *COH on Ti4O7, which significantly lowers the reaction energy barrier for C2+ products formation. Additionally, the excellent electroconductivity of Ti4O7 benefits the reaction charge transfer through robust Cu/Ti4O7 interface for minimizing the energy loss. Thus, the optimized 20Cu−Ti4O7 catalyst exhibits an impressive selectivity of 96.4 % and ultrahigh energy efficiency of 45.1 % for multi‐carbon products, along with a remarkable partial current density of 432.6 mA cm−2. Our study underscores a novel C−C coupling strategy between Cu and the support material, advancing the development of Cu‐supported catalysts for highly efficient electroreduction of carbon monoxide. [ABSTRACT FROM AUTHOR]

In this paper, the PANI/PDA-Ti4O7 composite coating was prepared on 316L by constant current deposition with a current density of 2.8 mA·cm−2, in which the Ti4O7 powders were modified by PDA (polydopamine). The open-circuit potential of the obtained PANI/PDA-Ti4O7 composite coating is about 365 mVAg/AgCl, which is more positive than that of the bare 316L. During immersion in 1 M H2SO4 + 2 ppm HF for 200 h, the high stable corrosion potential and the lower Rf indicate that the composite coating has long-term corrosion resistance. [ABSTRACT FROM AUTHOR]

In this paper, a dense and well‐adherent polydopamine‐Ti4O7/epoxy resin (PDA‐Ti4O7/EP) composite coating is successfully prepared. The modified grafting of Ti4O7 by polydopamine (PDA) is achieved through the coordination complexation of unstable catechol groups in PDA with coordination unsaturated Ti atoms in Ti4O7. The potentiodynamic polarization curve and electrochemical impedance spectroscopy test results show that the performance of the composite coating is improved compared with that of the pure epoxy coating, and the composite coating slows down the penetration of electrolytes and aggressive ions and improves the corrosion resistance. The composite coating with 2 wt.% PDA‐Ti4O7 filler shows the best corrosion resistance, and its |Z|0.01 Hz remains above 1011 Ω cm2 after 30 days of immersion in 3.5 wt% NaCl solution. This can be attributed to the good barrier property of PDA‐Ti4O7 filler, which carries NH2 and OH reactive groups, interacting with the resin and matrix to improve the dispersion of the filler and the adhesion of the composite coating. The NH2 group reacts with the epoxy group in the epoxy resin in a ring‐opening reaction, which avoids the agglomeration of the filler and the uniformly dispersed filler fills the pores in the coating due to curing to improve the denseness of the coating and give full play to the barrier property of the filler. At the same time, the hydrogen bonding between the filler and the OH group in the resin and the substrate increases the adhesion of the coating. In addition, the unstable catechol group in PDA chelates with iron ions to further improve the overall corrosion resistance of the coating. Highlights: A dense and well‐adherent PDA‐Ti4O7/EP coating is successfully prepared.PDA connect with Ti4O7 through coordination of catechol groups and Ti atom.PDA‐Ti4O7 are chemically bonded to the EP through a ring‐opening reaction.PDA‐Ti4O7 improves the crosslinking density and barrier ability of the coating. [ABSTRACT FROM AUTHOR]

In this paper, a dense and well‐adherent polydopamine‐Ti4O7/epoxy resin (PDA‐Ti4O7/EP) composite coating is successfully prepared. The modified grafting of Ti4O7 by polydopamine (PDA) is achieved through the coordination complexation of unstable catechol groups in PDA with coordination unsaturated Ti atoms in Ti4O7. The potentiodynamic polarization curve and electrochemical impedance spectroscopy test results show that the performance of the composite coating is improved compared with that of the pure epoxy coating, and the composite coating slows down the penetration of electrolytes and aggressive ions and improves the corrosion resistance. The composite coating with 2 wt.% PDA‐Ti4O7 filler shows the best corrosion resistance, and its |Z|0.01 Hz remains above 1011 Ω cm2 after 30 days of immersion in 3.5 wt% NaCl solution. This can be attributed to the good barrier property of PDA‐Ti4O7 filler, which carries NH2 and OH reactive groups, interacting with the resin and matrix to improve the dispersion of the filler and the adhesion of the composite coating. The NH2 group reacts with the epoxy group in the epoxy resin in a ring‐opening reaction, which avoids the agglomeration of the filler and the uniformly dispersed filler fills the pores in the coating due to curing to improve the denseness of the coating and give full play to the barrier property of the filler. At the same time, the hydrogen bonding between the filler and the OH group in the resin and the substrate increases the adhesion of the coating. In addition, the unstable catechol group in PDA chelates with iron ions to further improve the overall corrosion resistance of the coating. Highlights: A dense and well‐adherent PDA‐Ti4O7/EP coating is successfully prepared.PDA connect with Ti4O7 through coordination of catechol groups and Ti atom.PDA‐Ti4O7 are chemically bonded to the EP through a ring‐opening reaction.PDA‐Ti4O7 improves the crosslinking density and barrier ability of the coating. [ABSTRACT FROM AUTHOR]

Electrooxidation is commonly used in wastewater treatment but faces challenges with recalcitrant pollutants like tetrabromobisphenol A (TBBPA). Understanding the role of direct electron transfer (DET) and secondary free radicals in forming intermediate products can not only reveal halogenated phenols' electrooxidation mechanism but also aid in electrode design. Coupling triple quadrupole mass spectrometer and quadrupole time-of-flight mass spectrometer, the transformation products (TPs) and their dynamics were investigated during electrooxidation treatments of TBBPA. Furthermore, electrophilic addition and ring-opening mechanisms were simulated by density functional theory (DFT), and toxic changes of TPs were assessed by quantitative structural-activity relationship. The results demonstrate that the steady-state concentration of hydroxyl radicals (•OH) significantly influences the oxidation kinetics before reaching the mass transfer limit. In addition, DET occurs at low potentials (Ep ≈ +0.35 to +0.45 V vs SHE), accompanied with the process of film formation. Six novel intermediates of TBBPA were discovered in electrooxidation process, revealing the ring-opening mechanisms of TBBPA regulated by the steady-state density of hydroxyl radicals. The toxicity of intermediates towards fish and daphnia decreased significantly than that of TBBPA. Our findings offer valuable insights into the electrooxidation process of brominated phenols including their transformation and toxicity changes. [ABSTRACT FROM AUTHOR]

The construction of high‐efficiency self‐supported ceramic photoelectrode based on ideal semiconductor materials is essential for achieving effective degradation of pollutants by photoelectrocatalysis (PEC) technology. Herein, a Ti4O7/h‐BN composite ceramic photoelectrode with a unique microstructure was fabricated by a step‐by‐step calcination process and used in PEC water pollution remediation. The PEC activity of Ti4O7 ceramic photoelectrode could be enhanced by introducing hexagonal boron nitride (h‐BN) nanoparticles on the surface. The most optimized Ti4O7/h‐BN photoelectrode exhibited the decolorization rate of active brilliant blue KN‐R at about 97.79% in 30 min. The PEC activities could remain stable during five degradation cycles. The excellent photoelectrocatalytic performance of Ti4O7/h‐BN ceramic photoelectrode could be attributed to the low Tafel slope, low charge transfer resistance, large electrochemical active area, and excellent photo‐generated carrier separation efficiency. A type‐II heterojunction was formed between the Ti4O7 and h‐BN, which caused more effective carrier separation and enhanced the generation of dominant active species •O2− and h+. This work provided a mature synthesis strategy of Ti4O7/h‐BN self‐supported ceramic photoelectrodes with excellent practical application prospects to achieve superior PEC performance for water purification. [ABSTRACT FROM AUTHOR]

Elemental doping is a promising way for enhancing the electrocatalytic activity of metal oxides. Herein, we fabricate Ti/ Ti4O7-CB-Ce anode materials by the modification means of carbon black and cerium co-doped Ti4O7, and this shift effectively improves the interfacial charge transfer rate of Ti4O7 and •OH yield in the electrocatalytic process. Remarkably, the Ti4O7-CB-Ce anode exhibits excellent efficiency of minocycline (MNC) wastewater treatment (100% removal within 20 min), and the removal rate reduces from 100 to 98.5% after five cycles, which is comparable to BDD electrode. •OH and 1O2 are identified as the active species in the reaction. Meanwhile, it is discovered that Ti/ Ti4O7-CB-Ce anodes can effectively improve the biochemical properties of the non-biodegradable pharmaceutical wastewater (B/C values from 0.25 to 0.44) and significantly reduce the toxicity of the wastewater (luminescent bacteria inhibition rate from 100 to 26.6%). This work paves an effective strategy for designing superior metal oxides electrocatalysts. [ABSTRACT FROM AUTHOR]

Black titania, a conductive ceramic material class, has garnered significant interest due to its unique optical and electrochemical properties. However, synthesising and properly characterising these structures pose a considerable challenge. This diverse material family comprises various titanium oxide phases, many of them non-stoichiometric. The term "black TiO2" was first introduced in 2011 by Xiaobo Chen, but Arne Magneli's groundbreaking discovery and in-depth investigation of black titania in 1957 laid the foundation for our understanding of this material. The non-stoichiometric black titanium oxides were then called the Magneli phases. Since then, the science of black titania has advanced, leading to numerous applications in photocatalysis, electrocatalysis, supercapacitor electrodes, batteries, gas sensors, fuel cells, and microwave absorption. Yet, the literature is rife with conflicting reports, primarily due to the inadequate analysis of black titania materials. This review aims to provide an overview of black titania nanostructures synthesis and the proper characterisation of the most common and applicable black titania phases. [ABSTRACT FROM AUTHOR]

[Introduction] An environmentally friendly technology that harnesses green renewable solar energy to generate thermal energy for seawater desalination is proposed and the design of a novel fibrous membrane evaporator with full-spectrum absorption capability is introduced, aiming to address global challenges such as environmental pollution and freshwater scarcity. [Method] The proposed technological process began with the preparation of nano-scale C@TiO2 fibrous membranes using the electrospinning process. These membranes then underwent in-situ carbothermal reduction at 800 ℃ for 2 hours, resulting in the production of carbon-based ceramic C@Ti4O7 photothermal conversion materials with a dark color. [Result] The results show that the C@Ti4O7 fibrous membrane exhibits a band gap much lower than that of W-TiO2 and excellent solar light absorption capability across a wide range of wavelengths from 200 to 2500 nm, due to the doping of C elements and Ti3+ and the presence of oxygen vacancy defects. Under a light intensity of 1 kW/m2, the surface temperature of the C@Ti4O7 fibrous membrane, floating at the air-seawater interface, can quickly rise to 74.55 °C. Consequently, the evaporation rate of seawater increases to 1.55 kg/(m2·h), resulting in a photothermal conversion efficiency as high as 90.68%. With a light intensity of 5 kW/m2, the evaporator can generate electrical signals of up to 460 mV. In addition, it is proven workable continuously for 30 days in the simulated seawater with NaCl mass fraction of 10%, without salt deposition on the surface. [Conclusion] Therefore, the adoption of carbon-based ceramic C@Ti4O7 as the photothermal conversion material for the solar-driven interfacial evaporator offers not only high efficiency in photothermal conversion, but also great potential for large-scale applications, demonstrating a broad application prospect in the field of seawater desalination.

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Substoichiometric titanium oxides i.e. Magneli phase (MP) TiOx are attractive due to their conductive nature. However, their synthesis is challenging. In this work, Anisotropic MP- Ti4O7 nanoparticles and Au doped nanocomposites were synthesized using β- cyclodextrin as template. The MP nanomaterials were 20-30 nm in size. The synthesis conditions were mild. These MP- TiOx nanomaterials show efficient charge separation upon light excitation i.e. they (i) act as efficient photocatalysts; (ii) they can be sensitized by a fluorescent dye; (iii) finite element method (FEM) simulations indicate substantial interfacial plasmonic charge generation at the metal-semiconductor interface in the doped nanocomposites.

Developing stable and highly selective two‐electron oxygen reduction reaction (2e− ORR) electrocatalysts for producing hydrogen peroxide (H2O2) is considered a major challenge to replace the anthraquinone process and achieve a sustainable green economy. Here, we doped Sn into Ti4O7 (D−Sn−Ti4O7) by simple polymerization post‐calcination method as a high‐efficiency 2e− ORR electrocatalyst. In addition, we also applied plain calcination after the grinding method to load Sn on Ti4O7 (L−Sn−Ti4O7) as a comparison. However, the performance of L−Sn−Ti4O7 is far inferior to that of the D−Sn−Ti4O7. D−Sn−Ti4O7 exhibits a starting potential of 0.769 V (versus the reversible hydrogen electrode, RHE) and a high H2O2 selectivity of 95.7 %. Excitingly, the catalyst can maintain a stable current density of 2.43 mA ⋅ cm−2 for 3600 s in our self‐made H‐type cell, and the cumulative H2O2 production reaches 359.2 mg ⋅ L−1 within 50,000 s at 0.3 V. The performance of D−Sn−Ti4O7 is better than that of the non‐noble metal 2e− ORR catalysts reported so far. The doping of Sn not only improves the conductivity but also leads to the lattice distortion of Ti4O7, further forming more oxygen vacancies and Ti3+, which greatly improves its 2e− ORR performance compared with the original Ti4O7. In contrast, since the Sn on the surface of L−Sn−Ti4O7 displays a synergistic effect with Tin+ (3≤n≤4) of Ti4O7, the active center Tin+ dissociates the O=O bond, making it more inclined to 4e− ORR. [ABSTRACT FROM AUTHOR]

Possessing high electronic conductivity and the nature of chemical inertness, the Magnéli phase titanium oxide Ti4O7 is a promising material for various electrochemical applications. Herein, the Ti4O7 electrode in aqueous Li2SO4 electrolyte is characterized for its supercapacitor applications. The oxide electrode exhibits pseudocapacitive behavior over a wide potential range of ±1.0 V (vs. Ag/AgCl), showing a specific capacitance of 105 F g−1, equivalent to 85 µF cm−2–oxide, along with outstanding high-rate performance and cycle stability (96 % capacitance retention after 5000 cycles). In situ X-ray absorption near-edge spectroscopy analysis on the Ti K-edge absorption reveals that the pseudocapacitance does not involve the redox reaction of the oxide electrode material. A pseudocapacitance mechanism attributed to the reversible redox reactions of the hydrogen and oxygen atoms adsorbed on the oxide surface is proposed.

Magnéli phases are an important class of transition metal oxides widely utilized in fields such as batteries, electrocatalysis, and photocatalysis. However, there are no reports on the use of Magnéli phases as additives in ceramic sintering. In order to explore the impact of the Magnéli phase as an additive on the sintering process, self-made Magnéli phase Ti 4 O 7 powder was added to the graded mixture of titanium dioxide (TiO 2) coarse powder and nanopowder, and sintered under atmospheric conditions in this study. The sintering characteristics, microstructure, and mechanical properties of TiO 2 ceramics with different content of Ti 4 O 7 were characterized. The results revealed that the addition of Ti 4 O 7 contributed to the reduction of the densification temperature of TiO 2 ceramics. Compared to the undoped sample, the addition of 1 wt% Ti 4 O 7 powder significantly improved the flexural strength and Vickers hardness of TiO 2 ceramics by 13.5% and 24.8%. According to the results of thermal analysis, UV–Vis–NIR, and XPS, the mechanism of Ti 4 O 7 in the sintering process of TiO 2 ceramics under atmospheric conditions was systematically discussed. This work not only obtained TiO 2 ceramics with improved performance but also showed the tremendous potential of Magnéli phases in the field of ceramic sintering. [ABSTRACT FROM AUTHOR]

Electro catalysts play a vital role in facilitating the reaction process in the oxygen reduction reaction (ORR) of fuel cells. In methanol fuel cells, methanol easily penetrates the diaphragm rendering the ORR catalyst inactive. Although commercial platinum exhibits excellent ORR catalytic activity, its poor methanol resistance and long-time durability severely restrict its sustainable development and application. This work synthesized Ti4O7/CNT nanocomposite electrocatalysts by using the sol-gel method followed by high-temperature carbothermal reduction. The obtained catalysts exhibit a large electrochemically active surface area (347.89 cm2) and low interfacial charge transfer resistance (64.5 Ω). The reduction potential (0.73 V), onset potential (0.93 V), half-wave potential (0.73 V), and electron transfer number (3.7) of this electrocatalyst are all close to those of the Pt/C electrocatalysts in alkaline medium. Simultaneously, it also possesses remarkable methanol tolerance and long-term durability, whose relative current density can maintain above 74% after cycling for 24 h. [ABSTRACT FROM AUTHOR]

Although Magnéli phase Ti 4 O 7 has been recognized as one of the most promising anode materials for electrochemical advanced oxidation process (EAOP), the current density is still not uniformly distributed on the large-sized Ti 4 O 7 bulk electrode due to its relatively poor conductivity, which leads to rapid deterioration and damage of the electrode. Therefore, the development of Ti 4 O 7 coated metal electrode on a large scale with low cost is of great significance for its industrial applications. Here we report for the first time that Ti 4 O 7 -coated Ti electrode is successfully prepared by sintering the brushed TiO 2 coating on Ti substrate. The microstructure and electrochemical behavior of the electrode were also investigated. Results show that the continuous and porous Magnéli phase Ti 4 O 7 coating well bonded with the substrate can be fabricated by sintering the pre-coated TiO 2 with the thickness of 78–200 μm on Ti substrate at 1000 °C for 1 h under a flowing argon atmosphere. The electrochemical stability window of the Ti 4 O 7 -coated Ti electrode in 1 M NaCl solution is more than 4.2 V. Additionally, the refractory organic ethylene glycol butyl ether is effectively degraded on the Ti 4 O 7 -coated Ti electrode. The COD cr decreases from 18000 mg L−1 to 82 mg L−1 and the removal rate of COD cr reaches 99.54% after electrolysis for 24 h. [ABSTRACT FROM AUTHOR]

Ti 4 O 7 is a kind of conductive ceramic material with a high electrical conductivity and excellent electrochemical performance, rendering it a potential candidate for electrode applications. Here, for the first time, we report the successful preparation of Ti 4 O 7 electrodes with different porosities by adding a pore-forming agent. The results showed that the as-prepared Ti 4 O 7 electrodes contained both mesoporous and macroporous structures. In addition, with an increase in the porosity of the electrodes, the electrochemical oxidation degradation of high-concentration methyl orange (MO) solution first increased, until reaching a critical point, and then decreased. The Ti 4 O 7 electrode with a porosity of 34.9% and an electrical conductivity of 336.1 S cm-1 exhibited the highest electrochemical oxidation ability. The electrochemical oxidation rate constants for MO and chemical oxygen demand (COD) of the porous Ti 4 O 7 electrode were 1.7 times those of the dense Ti 4 O 7 electrode. Compared to commercial stainless steel, graphite, and Ti/RuO 2 electrodes, the Ti 4 O 7 porous electrode showed superior electrochemical oxidation performance under the same experimental conditions. The result of this study provide new directions for the application of Ti 4 O 7 electrode materials. [ABSTRACT FROM AUTHOR]

Linear substituents, despite their simpler structures compared to heterocyclic ones, exhibit distinct chemical behaviors. Using sulfacetamide (SAM) and sulfaguanidine (SGD) as model compounds, we assessed the impact of these substituents on degradation efficiency, active species identification, reaction pathways, and intermediate toxicity during electrooxidation in water. Through density functional theory, we elucidated the mechanisms, focusing on electronic structural changes and interactions with active species. Notably, the acetyl group in SAM (0.1016) acquired more electrons than the guanidyl group in SGD (0.0281), resulting in SAM having a higher free energy change (Δ G = 15. 06 kcal/mol) compared to SGD (Δ G = 9. 59 kcal/mol). This difference makes SAM less likely to undergo direct electron transfer and less reactive towards hydroxyl radical addition, leading to slower degradation rates. The applied potential notably increased SAM's sensitivity to hydroxyl radicals. Both the highest occupied molecular orbital (HOMO) and lowest unoccupied molecular orbital (LUMO) were contributed by the parent fragment, facilitating electrophilic reactions mainly on the aniline part. Seventeen intermediate products and three major transformation pathways were identified, emphasizing aniline group destruction before discharge. This research enhances understanding of the degradation and environmental fate of sulfonamides, providing valuable insights for optimizing pollutant degradation and discharge reduction. [Display omitted] • Experimental efficiency variations of linear substituents in typical water conditions align with predicted differences in free energy mechanisms. • High-resolution mass spectrometry coupled with free energy calculations reveals 17 structurally precise intermediate products. • Linear substituents induce benzene ring-opening as a primary pathway post-sulfonamide substitution, effectively reducing toxicity. • Strong correlation found between reaction pathway variances induced by linear substituents and changes in electronic structure post-substitution. [ABSTRACT FROM AUTHOR]

[Display omitted] Transition metal catalysts for replacing noble metals have been extensively studied, but the deficiencies in intrinsic activity and stability limit their application in electrocatalysis. Here, we present CoNi alloy nanoparticles loaded on Ti 4 O 7 supports and embedded in N, S doped carbon nanofibers by electrospinning method. The prepared CoNi/Ti 4 O 7 @NS-CNFs exhibits satisfactory ORR and OER activities with a low potential gap of 0.664 V and shows a high stability over long periods of testing, which are superior to most of the transition metal catalysts reported so far. Accordingly, the Zn-air battery constructed with the prepared catalyst demonstrates a maximum power density of 165.7 mW cm−2 and a specific capacity of 788.4 mA h g Z n - 1 (1.61 and 1.14 times higher than that of Pt/C + IrO 2 , respectively). The addition of S element and corrosion-resistant Ti 4 O 7 plays a significant part in the morphology and activity of the prepared catalyst, which optimizes the distribution and electronic structure of active centers, and improves the stability of the catalyst. This effort provides a possible approach to exploring the efficient performance of the other transition metals. [ABSTRACT FROM AUTHOR]

Here we report for the first time that Magnéli phase Ti 4 O 7 electrode with super performance is successfully prepared by hot-pressed sintering of single-phase submicron Ti 4 O 7 powders. The microstructure, mechanical properties, electrical conductivity and electrochemical performance of the Ti 4 O 7 electrodes were also investigated. Results show that the compact and homogeneous bulk Ti 4 O 7 without evident defects such as pores and cracks is achieved when the submicron Ti 4 O 7 powder was sintered at 1200 °C for 0.5 h. As a result, the bulk density of the Ti 4 O 7 reaches its theoretical value (4.323 g cm−3). Additionally, it has excellent physical and chemical properties, including the mean values of hardness and Young's modulus of 15.20 ± 0.42 and 247.40 ± 6.70 GPa, respectively, the Vickers-hardness of 1165.5 ± 9.5 HV, the highest known conductivity of 1252.5 S cm−1, and the widest known electrochemical stability window of 4.19 V in 1 M NaCl solution. [ABSTRACT FROM AUTHOR]

[Display omitted] • The R ct value of Ti 4 O 7 -C 3 N 4 (5.445 Ω·cm2) was reduced by 66.05 % compared with Ti 4 O 7. • The degradation ratio of IMD with Ti 4 O 7 -C 3 N 4 was as high as 99.18 % in 1.256 min. • The removal of IMD in the actural Wanjiang water with Ti 4 O 7 -C 3 N 4 was up to 81.12 %. Imidacloprid (IMD) is a kind of neonicotinoid insecticide, which is widely used in the agricultural production. There are few reports on electrocatalytic degradation of IMD with the low concentration. In this study Ti 4 O 7 -C 3 N 4 electrode was employed for the first time to electrocatalytically degrade low concentration IMD. Compared with pure Ti 4 O 7 electrode, the oxygen evolution potential was increased from 1.84 V to 2.50 V, the charge transfer resistance (R ct) was reduced by 66.05 %, and the oxygen vacancies were increased by 2.5 times compared to the original Ti 4 O 7. Especially, the R ct for Ti 4 O 7 (5.45 Ω·cm2) was only 1/7 of that for boron-doped diamond (BDD) (38.89 Ω·cm2). IMD degradation ratio was up to 98 % in only 1.256 min (75.360 s) using a Ti 4 O 7 -C 3 N 4. When SongShan Lake water, Wanjiang water, and secondary effluent were treated, the degradation radios of IMD were 70.30 %, 72.33 % and 81.12 %, respectively. In the presence of Cl− coexisting ions, no disinfection by-product of ClO 4 − was detected, which is an advantage for Ti 4 O 7 -C 3 N 4 compared with BDD. The first and 48th degradation ratios were 99 % and 97 %, respectively, indicating the good stability of Ti 4 O 7 -C 3 N 4. The development of Ti 4 O 7 -C 3 N 4 provides a stable, low energy consumptions and no secondary pollution anode for the treatment of actual wastewater. [ABSTRACT FROM AUTHOR]

In the effort to accelerate adsorption and catalytic conversion of lithium polysulfides (Li‐PSs) and suppress the shuttle effect of lithium‐sulfur batteries (LSBs), the Ti4O7 nanosheets/carbon material‐modified separator is successfully fabricated to reducing soluble Li‐PSs' crossover from cathode to anode. The catalyst of mesoporous Ti4O7 nanosheets with O−Ti−O units synthesized at low temperature shows both excellent conductivity and high surface area. The modified separator can serve as a diffusion barrier of Li‐PSs and catalyst for converting soluble low‐chain sulfides into insoluble ones and then remarkably enhance the sulfur utilization and electrochemical performance of the LSB. This work provides a feasible avenue in both design and synthesis of mesoporous catalyst materials for suppressing the shuttle effect of lithium‐sulfur batteries. [ABSTRACT FROM AUTHOR]

Applications of advanced cathode materials with well‐designed chemical components and/or optimized nanostructures promoting the sulfur redox kinetics and suppressing the shuttle effect of polysulfides are highly valued. However, in the case of actual lithium‐sulfur (Li−S) batteries under practical working conditions, one long‐term obstacle still exists, which is mainly due to the difficulties in massive synthesis of such nanomaterials with low cost and ease of control on the nanostructure. Herein, we develop a facile synthesis of carbon coated Ti4O7 hollow nanoparticles (C−Ti4O7) using spherical polymer electrolyte brush as soft template, which is scalable via utilizing a minipilot reactor. The C−Ti4O7 hollow nanoparticles provide strong chemical adsorption to polysulfides through the large polar surface and additional physical confinement by rich micro‐ & mesopores and have successfully been employed as an efficient sulfur host for multilayer pouch cells. Besides, the sluggish kinetics of the sulfur and lithium sulfide redox mechanism can be improved by the highly conductive Ti4O7 via catalyzation of the conversion of polysulfides. Consequently, the C−Ti4O7 based pouch cell endows a high discharge capacity of 1003 mAh g−1 at 0.05 C, a high‐capacity retention of 83.7 % after 100 cycles at 0.1 C, and a high Coulombic efficiency of 97.5 % at the 100th cycle. This work proposes an effective approach to transfer the synthesis of hollow Ti4O7 nanoparticles from lab‐ to large‐scale production, paving the way to explore a wide range of advanced nanomaterials for multilayer Li−S pouch cells. [ABSTRACT FROM AUTHOR]

In the last years, an increasing attention has been devoted to the utilization of anodic oxidation (AO) technologies for the treatment of wastewater polluted by recalcitrant organics. Recently, Ti4O7 was proposed as a promising anode for AO for the treatment of various organics. Here the potential utilization of commercial Ti4O7 anodes has been evaluated considering the electrochemical treatment of synthetic wastewater contaminated by three very different organic molecules (namely, oxalic acid, phenol and Acid Orange 7), all characterized by a very high resistance to AO. The performances of Ti4O7 were compared with that of two largely investigated anodes: Boron‐doped diamond (BDD), which is probably the most effective electrode for AO, and an Ir‐based anode which presents a relatively low cost. Moreover, the effect of various operative conditions (current density, mixing rate and initial concentration of the organic) was evaluated by both experimental studies and the adoption of a theoretical model previously developed for BDD anodes. It was shown that the performances of the process can be improved by a proper selection of operative conditions. Moreover, it was found that the proposed model can be effectively used to predict the effect of operative parameters at Ti4O7 anodes, thus helping the process optimization. [ABSTRACT FROM AUTHOR]

Tetratitanium heptoxide, Ti4O7, is known to exhibit a two-step phase transition from the charge-delocalized to charge-localized phase and the charge-disordered to charge-ordered phase around 150 K and 130 K, respectively. Herein, a nanoscopic effect of the Ti4O7 phase transition is studied. A one-step phase transition from the charge-delocalized to charge-localized phase is realized in Ti4O7 nanocrystals where the transition from the charge-disordered to charge-ordered phase is suppressed. Perturbation to the free energy by the surface energy can explain this anomalous phase transition. The present nanoscopic effect, which can control cooperativity in phase transitions, should contribute to develop advanced switching materials.

Preparation of the Magnéli Ti4O7 reactive electrochemical membrane (REM) with high purity is of great significance for its application in electrochemical advanced oxidation processes (EAOPs) for wastewater treatment. In this study, the Ti4O7 REM with high purity was synthesized by mechanical pressing of TiO2 powders followed by thermal reduction to Ti4O7 using the Ti powder as the reducing reagent, where the TiO2 monolith and Ti powder were separated from each other with the distance of about 5 cm in the vacuum furnace. When the temperature was elevated to 1333 K, the Magnéli phase Ti4O7 REM with the Ti4O7 content of 98.5% was obtained after thermal reduction for 4 h. Noticeably, the surface and interior of the obtained REM bulk sample has a homogeneous Ti4O7 content. Doping carbon black (0wt%-15wt%) could increase the porosity of the Ti4O7 REM (38–59%). Accordingly, the internal resistance of the electrode and electrolyte and the charge-transfer impedance increased slightly with the increasing carbon black content. The optimum electroactive surface area (1.1 m2) was obtained at a carbon black content of 5wt%, which increased by 1.3-fold in comparison with that without carbon black. The as-prepared Ti4O7 REMs show high oxygen evolution potential, approximately 2.7 V/SHE, indicating their appreciable electrocatalytic activity toward the production of •OH.

Partially-etched V 2 Al 1- x CT z ceramic with the average particle of ∼400 nm was synthesized by etching submicro-sized V 2 AlC with 40 wt% HF at room temperature (RT) for 48 h and 72 h, respectively. V 2 Al 1- x CT z etched for 72 h has exhibited higher charge-discharge property, with an average reversible discharge capacity of 349.2 mAh·g-1 at 0.1 A g-1 in the 120 cycles for lithium-ion batteries. The electrochemical performances of V 2 Al 1- x CT z could be improved by the addition of carbon nanotubes (CNTs), graphene (GF) and titanium suboxides (Ti 4 O 7) conductive additives, among which CNTs exhibit the best effectiveness with a capacity of ∼460 mAh·g-1 at 0.1 A g-1 in the 140 cycles and a capacity retention of ∼72% at 0.5 A g-1 after 400 cycles. [ABSTRACT FROM AUTHOR]

The large-scale manufacturing of lithium sulfur (Li-S) battery has been long hampered by the rapid capacity degradation and short cycle life, which is primarily attributed to the soluble polysulfides and subsequent continuing shuttling effect. The separator modification as a simple and effective technique has been extensively applied in Li-S batteries to solve inherent defects. Herein, the composite of Ketjen black (KB) and Ti4O7 was synthetized by carbothermal reduction and made into KB/Ti4O7-modified separator. The multifunctional layer can improve utilization of active substances and restrain shuttling effect by forming synergistic effect of physical obstruct and chemisorption for polysulides. The cell using KB/Ti4O7 separator exhibits enhanced electrochemical properties reflecting in higher specific capacity (1074 mAh g-1 at 1C) and longer cycling life (836 mAh g-1 after 100 cycles). The above results indicate that the composite of carbon and metallic oxide modified separator is pretty suitable for advanced Li-S battery. [ABSTRACT FROM AUTHOR]

A novelly modified Ti/PbO2 electrode was synthesized with Ti4O7 particles through electrochemical deposition method (marked as PbO2‐Ti4O7). The properties of the as‐prepared electrodes were characterized by scanning electron microscopy (SEM), X‐ray diffraction (XRD), linear sweep voltammetry (LSV), electrochemical impedance spectroscopy (EIS), hydroxyl radical concentration, accelerated life test, etc. Azophloxine was chosen as the model pollutant for electro‐catalytic oxidation to evaluate electrochemical activity of the electrode. The experimental results indicated that Ti4O7 modification could prominently improve the properties of the electrodes, especially, improve the surface morphology, enhance the current response, and reduce the impedance. However, the predominant phases of PbO2 electrodes were unchanged, which were completely pure β‐PbO2. During the electrochemical oxidation process, the PbO2‐Ti4O7(1.0) electrode showed the best performance on degradation of AR1 (i.e., the highest removal efficiency and the lowest energy consumption), which could be attributed to its high oxygen evolution potential (OEP) and strong capability of HO· generation. Moreover, the accelerated service lifetime of PbO2‐Ti4O7(1.0) electrode was 175 hr, 1.65 times longer than that of PbO2 electrode (105.5 hr). Practitioner points: PbO2/Ti4O7 composite anode was fabricated through electrochemical co‐deposition.Four concentration gradients of Ti4O7 particle were tested.PbO2‐Ti4O7(1.0) showed optimal electrocatalytic ability due to its high OEP and HO· productivity. [ABSTRACT FROM AUTHOR]

Tetratitanium heptoxide, Ti4O7, is known to exhibit a two-step phase transition from the charge-delocalized to charge-localized phase and the charge-disordered to charge-ordered phase around 150 K and 130 K, respectively. Herein, a nanoscopic effect of the Ti4O7 phase transition is studied. A one-step phase transition from the charge-delocalized to charge-localized phase is realized in Ti4O7 nanocrystals where the transition from the charge-disordered to charge-ordered phase is suppressed. Perturbation to the free energy by the surface energy can explain this anomalous phase transition. The present nanoscopic effect, which can control cooperativity in phase transitions, should contribute to develop advanced switching materials. Ti4O7 nanocrystal exhibits a one-step phase transition from a charge-delocalized to a charge-localized phase. This anomalous phase transition can be understood by the nanoscopic effect contributed by the surface energy. [ABSTRACT FROM AUTHOR]

In this paper, we report a facile approach to synthesize pure Magnéli phase Ti4O7 nanostructures via solvothermal processing and subsequent thermal treatment. The one-dimensional nanostructure of Ti4O7 nanorods (1D Ti4O7 NRs) was characterized by powder X-ray diffraction (XRD), scanning electron microscope (SEM) and high-resolution transmission electron microscopy (HRTEM). The as-obtained Ti4O7 NRs, with an average diameter of 150 nm, were used as sulfur host to prepare Ti4O7 NRs/sulfur cathode for lithium-sulfur (Li-S) batteries. Electrochemical measurements showed that the as-synthesized Ti4O7 NRs can improve the electrochemical reaction kinetics during the charge-discharge processes. The initial discharge capacity of the Ti4O7 NRs/sulfur cathode was 930 mAh g−1, and the remaining capacity was 490 mAh g−1 after 500 cycles at 1C, much higher than that of acetylene black/sulfur cathode. Electrochemical impedance spectroscopy (EIS) demonstrated Ti4O7 NRs/sulfur decreases the charge transfer resistance. Moreover, Ti4O7 NRs/sulfur composite exhibits low electrode polarization accompanied by a high lithium ion diffusion coefficient. [ABSTRACT FROM AUTHOR]

Solar steam generation (SSG) via interfacial photothermal conversion has emerged in sustainable seawater desalination and sewage purification. One of the grand challenges is that low light absorption generally limits photothermal materials on water evaporation rates and insufficient on-board performance for real practice. Herein, we propose a "molecular/phase dual-locking" strategy to homogeneously composite Magnéli phases like Ti 4 O 7 nanoparticles and poly(vinyl alcohol) (PVA) by chemical-physical bi-crosslinking. As-obtained Ti 4 O 7 -PVA nanocomposite hydrogels (TPNHs) exhibit a narrow bandgap (~0.81 eV) for highly efficient sunlight absorption all through UV–vis–NIR full-spectrum wavelengths (up to ~99.56 %) and enable a record high evaporation rate of ∼4.45 kg m−2 h−1 with outstanding energy efficiency (~90.69 %) under one sun irradiation. A 20−day continuous test in real seawater manifests excellent long-term performance stability of TPNHs without salt accumulation. We further demonstrate the SSG efficacy of such hydrogels by applying them for efficient desalination/purification of varying seawater and sewage samples with low-to-high salinity, strong acids/bases, heavy metal ions, and organic dyes. This "molecular/phase dual-locking" design strategy and resultant Ti 4 O 7 -PVA nanocomposite hydrogels present a promising methodology to boost practical applications for seawater desalination and sewage purification. • Design Ti 4 O 7 -PVA nanocomposite hydrogel via molecular/phase dual-lock strategy. • A record-high evaporation rate of ~4.45 kg m−1 h−1 • Narrow bandgap (~ 0.81 eV) and superior solar absorption (~ 99.56 %) • Superior long-term stability with 20-day continuous tests in simulated seawater • The purified water can meet the drinking requirements of WHO. [ABSTRACT FROM AUTHOR]

Membraneless and flowless zinc-bromine batteries (MLFL-ZBBs) have emerged as a compelling solution for energy storage due to their cost-effectiveness, high cell voltage, and high safety. However, challenges persist in maintaining long-term stability and efficiency, primarily attributed to the inadequate adsorption of carbon-based host materials in ZBBs to soluble polybromides. Here, we report a highly conductive, inherently polar Ti 4 O 7 as the host material and demonstrate how it improves MLFL-ZBBs stability. Density functional theory calculations suggest the electron densities of Br atoms within polybromides are significantly intertwined with Ti atoms in Ti 4 O 7 , resulting in the formation of robust Ti-Br bonding, which are absent as for carbon and bromine interactions. Visual discrimination, UV–Vis, and X-ray photoelectron spectroscopy collectively confirm the substantial adsorption capabilities of Ti 4 O 7 towards polybromides. The Coulombic efficiency of MLFL-ZBBs with Ti 4 O 7 as host materials remain 93.8% after 2,000 cycles, which is more than three times that with traditional carbon-based host. [Display omitted] Metallic polar Ti 4 O 7 forms the strong Ti-Br bonds with the polybromides. This robust chemisorption allows the polybromides to be anchored to the cathode and not react with the cathode metal Zn, resulting in a significant increase in the stability of the membraneless and flowless zinc-bromine battery compared to conventional carbon materials. [ABSTRACT FROM AUTHOR]

Precious metal catalysts are widely recognized for their excellent efficiency in OER and ORR, but high cost and stability limit further commercial expansion. Carbon-based catalysts with large specific surface area, although a potential alternative to noble metal catalysts in terms of price and performance, are notoriously weak in terms of corrosion resistance in extreme environments. Metal catalysts are able to solve the above problems and are gradually coming into the limelight, but the control of morphology is not as good as that of carbon-based catalysts. Therefore, in order to solve the above problems together, the development of bifunctional catalysts with high efficiency, stability, low cost and excellent morphology has become a bright research direction. In this study, a new catalyst consisting of phosphorus-doped self-supported nanostructured Ti 4 O 7 and nickel-gallium alloy particles was investigated using an electrostatic spinning process. Most of the previous studies have simply prepared Ti 4 O 7 nanofibers without in-depth investigation on how to better control their morphology. In contrast, this study presents a universal set of experimental parameters for the development of very fine Ti 4 O 7 nanospinning. With the help of this set of parameters, we develop a novel Ti 4 O 7 /C composite substrate nanofiber catalyst with an average diameter less than 297 nm. Its excellent morphology and corrosion resistance make it an inexpensive bifunctional catalyst with great potential. Relevant OER performed in 1 M KOH electrolyte shows that the catalyst has a low Tafel slope (80.77 mV dec−1), a small overpotential (282 mV at 10 mA cm−2), and excellent stability (up to 5000 cycles). In a strongly alkaline environment, the catalyst outperforms commercially available RuO 2 (299 mV and 105.79 mV dec−1). In addition, the catalyst demonstrates a half-wave potential of 0.86 V in 0.1 M KOH electrolyte, exhibiting excellent ORR performance. The maximum power density (161 mW cm−2) and energy density (813 mA h g Zn − 1 ) of the zinc-air battery assembled with this catalyst exceeds the performance of the air battery using the Pt/C catalyst with better stability. In summary, this study achieves significant methodological advances and develops a novel bifunctional catalyst, which is of interest to a wide range of researchers. The first synthesis of a new low-cost catalyst, NiGa/Ti 4 O 7 @PCNFs, which is a new self-supporting bifunctional catalyst with exceptional performances in oxygen electrocatalysis and Zn-air batteries. [Display omitted] • Parameters for the preparation of fine Ti 4 O 7 nanofibers are proposed. • Novel catalyst NiGa/Ti 4 O 7 @PCNFs is prepared. • Cheap novel catalysts have better performance than precious metal catalysts. [ABSTRACT FROM AUTHOR]

Graphical abstract Highlights • Ti 4 O 7 , NbO 2 and Nb x Ti 1−x O 2 thin films were prepared in a vacuum by PLD. • Nb x Ti 1−x O 2 shows both metallic and semiconducting light absorption behaviors. • Nb x Ti 1−x O 2 has a large and constant absorption coefficient at visible wavelength. Abstract We investigated the optical absorption properties of Nb x Ti 1−x O 2 thin films, a solid solution combining the reduced titanium and niobium oxide phases TiO 2 and NbO 2. The optical absorption properties of Nb x Ti 1−x O 2 thin films prepared by pulsed laser deposition at 600 °C were shown to be large in magnitude at an almost constant value of ≈17 µm−1. Because this large absorption coefficient is nearly independent of incident photon energy in the visible range (400–700 nm), the Nb x Ti 1−x O 2 thin films appear optically black. Flat and homogenous, optically black coatings like these are desirable for color isolation in flat panel displays. The origin of flat wavelength dispersion in Nb x Ti 1−x O 2 is the coexistence of semiconducting absorption and metallic light absorption mechanisms. Localized Nb-Nb dimers in the metallic Nb x Ti 1−x O 2 phase open an optical band gap which gives rise to semiconducting behavior. We show here that reduction results in strong visible light sensitization in normally transparent Nb-Ti oxides. [ABSTRACT FROM AUTHOR]

Graphical abstract The Ti 4 O 7 /carbon nanofibers (TCNFs) were successfully prepared by one step electrospinning and subsequent carbothermal reduction. When served as an interlayer, the CMK3-S cathode with TCNFs showed excellent cycling and high-rate performances. Highlights: • TCNFs were obtained easily-via electrospinning followed by in-situ carbonreduction. • The interlayer has both physical blocking and chemical adsorption effects for LiPSs. • Ti 4 O 7 chemical binding of LiPSs by Ti-S bonds greatly reduces LiPSs shuttle. • The 3D TCNFs make for lower interfacial resistance and faster redox reaction. • Li-S battery exhibits excellent electrochemical performances, even at high rates. Abstract In this work, a free-standing and flexible Ti 4 O 7 /C nanofibers (TCNFs) interlayer is prepared via one-step electrospinning. The TCNFs interlayer acts as both physical barrier and chemical adsorption agent for lithium polysulfides (LiPSs), in which the 3D CNFs network with large volume and high conductivity contributes to LiPSs conversion and electron transfer, while the ‘sulphiphilic’ Ti 4 O 7 with strong chemical bonding to the soluble long-chain LiPSs contributes to less LiPSs dissolution and higher coulombic efficiency. In a lithium-sulfur (Li-S) cell, CMK3/S cathode with TCNFs interlayer exhibits greatly enhanced electrochemical capability than CMK3/S with CNFs interlayer and without interlayer, and a capacity of 560 mAh g−1 after 1000 cycles is obtained under a high current density of 1 C. Even at 3 C, the capacity decay is merely 0.030% per cycle over 2500 cycles. Notably, the simple, affordable and scalable fabrication method to form a controllable free-standing interlayer that brings a novel horizon on material structure design and performance improvement in practical application of Li-S batteries. [ABSTRACT FROM AUTHOR]

The Ti4O7 modified Ti/PbO2 electrodes have been prepared by electrodeposition, and investigated systemically using scanning electron microscope (SEM), Energy dispersive X‐ray spectroscopy (EDS), powder X‐ray diffraction (XRD), photoluminescence spectroscopy (PL), and degradation of anthraquinone dye (reactive brilliant blue KN−R: C22H16N2Na2O11S3). It is found that the Ti4O7 modified Ti/PbO2 electrodes possessed smaller PbO2 crystal grains, good porous structure, enhanced oxygen evolution over‐potential and higher electrical conductivity, as compared to that of Ti/PbO2 electrode. Additionally, the Ti4O7 modified Ti/PbO2 electrode exhibited also longer accelerated lifetime, and higher photoelectrocatalytic activity for degradation of anthraquinone dye (reactive brilliant blue KN−R) than that of Ti/PbO2 electrode. The enhancement of the decolorization efficiency and stability for Ti4O7 modified Ti/PbO2 electrodes can be ascribed to the large electrochemical active areas, the presence of photoelectric synergism, rapid separation of photogenerated carriers, inhibition of oxygen precipitation, high current efficiency for formation of hydroxyl radicals, and the weakening of internal stress in PbO2 coatings. [ABSTRACT FROM AUTHOR]

The Ti4O7 modified Ti/PbO2 electrodes have been prepared by electrodeposition, and investigated systemically using scanning electron microscope (SEM), Energy dispersive X‐ray spectroscopy (EDS), powder X‐ray diffraction (XRD), photoluminescence spectroscopy (PL), and degradation of anthraquinone dye (reactive brilliant blue KN−R: C22H16N2Na2O11S3). It is found that the Ti4O7 modified Ti/PbO2 electrodes possessed smaller PbO2 crystal grains, good porous structure, enhanced oxygen evolution over‐potential and higher electrical conductivity, as compared to that of Ti/PbO2 electrode. Additionally, the Ti4O7 modified Ti/PbO2 electrode exhibited also longer accelerated lifetime, and higher photoelectrocatalytic activity for degradation of anthraquinone dye (reactive brilliant blue KN−R) than that of Ti/PbO2 electrode. The enhancement of the decolorization efficiency and stability for Ti4O7 modified Ti/PbO2 electrodes can be ascribed to the large electrochemical active areas, the presence of photoelectric synergism, rapid separation of photogenerated carriers, inhibition of oxygen precipitation, high current efficiency for formation of hydroxyl radicals, and the weakening of internal stress in PbO2 coatings. [ABSTRACT FROM AUTHOR]

Multifunctional Ti4O7 particles with interconnected-pore structure are designed and synthesized using porous poly(styrene- b-2-vinylpyridine) particles as a template. The particles can work efficiently as a sulfur-host material for lithium-sulfur batteries. Specifically, the well-defined porous Ti4O7 particles exhibit interconnected pores in the interior and have a high-surface area of 592 m2 g−1; this shows the advantage of mesopores for encapsulating of sulfur and provides a polar surface for chemical binding with polysulfides to suppress their dissolution. Moreover, in order to improve the conductivity of the electrode, a thin layer of carbon is coated on the Ti4O7 surface without destroying its porous structure. The porous Ti4O7 and carbon-coated Ti4O7 particles show significantly improved electrochemical performances as cathode materials for Li-S batteries as compared with those of TiO2 particles. [ABSTRACT FROM AUTHOR]

Recently, there are still some controversial mechanisms of the 3D electrocatalytic oxidation system, which would probably confound its industrial application. From the conventional viewpoint, the Ti 4 O 7 material may be the desired particle electrodes in the 3D system since its high oxygen evolution potential favors the production of •OH via H 2 O splitting reaction at the anode side of Ti 4 O 7 particle electrodes. In fact, the incorporation of Ti 4 O 7 particles showed phenol degradation of 88% and COD removal of 51% within 120 min, under the optimum conditions at energy consumption of 0.668 kWh g−1 COD, the performance of which was much lower than those in many previous literatures. In contrast, the prepared carbon black-polytetrafluoroethylene composite (CB-PTFE) particles with abundant oxygen-containing functional groups could yield considerable amounts of H 2 O 2 (200 mg L−1) in the 3D reactor and achieved a complete degradation of phenol and COD removal of 80% in the presence of Fe2+, accompanying a low energy consumption of only 0.080 kWh g−1 COD. It was estimated that only 20% of Ti 4 O 7 particles near the anode attained the potential over 2.73 V/SCE at 30 mA cm−2 based on the potential test and simulation, responsible for the low yield of •OH via the H 2 O splitting on Ti 4 O 7 (1.74 × 10−14 M), and the main role of Ti 4 O 7 particle electrodes in phenol degradation was through direct oxidation. For the CB-PTFE-based 3D system, current density of 10 mA cm−2 was sufficient for all the CB-PTFE particles to attain cathodic potential of −0.67 V/SCE, conducive to the high yield of H 2 O 2 and •OH (9.11 × 10−14 M) in the presence of Fe2+, and the •OH-mediated indirect oxidation was mainly responsible for the phenol degradation. Generally, this study can provide a deep insight into the 3D electrocatalytic oxidation technology and help to develop the high-efficiency and cost-efficient 3D technologies for industrial application. [Display omitted] • Mechanism of 3D electrocatalytic oxidation system with particles was clarified. • Only 20% of Ti 4 O 7 particles obtain sufficient induction potential for.•OH production. • Ti 4 O 7 particles used for phenol degradation was mainly via direct oxidation. • Carbon black-PTFE particles-based 3D system follows an electro-Fenton regime. • Carbon black-PTFE particles achieved a complete phenol degradation. [ABSTRACT FROM AUTHOR]