N-doped TiO2 Research Articles

Optimized MFS Stack With N-Doped TiO2 Channel and La-Doped HfO2 Ferroelectric Layer for Highly Stable FeFETs

Optimized MFS Stack With N-Doped TiO₂ Channel and La-Doped HfO₂ Ferroelectric Layer for Highly Stable FeFETs

Electrospun PVDF/PVP Fibrous Membrane with Photocatalytic and Superhydrophilic Properties.

Membrane separation technology is used to treat environmental wastewater, but during the treatment process, the occurrence of membrane fouling greatly affects the treatment efficiency. To address this phenomenon, improve membrane antipollution capabilities, and treat organic wastewater, photocatalysis and membrane separation technology have been coupled, forming a suitable and promising treatment method. Here, we propose a simple strategy to prepare a polyvinylidene fluoride/polyvinyl pyrrolidone nitrogen-doped titanium dioxide fibrous membrane (PVDF/PVP N-doped TiO2 fibrous membrane). The experimental results showed that PVDF and PVP mixed spinning made the fibrous membrane have a unique microstructure, and the superhydrophobic PVDF fibrous membrane was changed into superhydrophilic. In addition, electrospraying technology was used to attach TiO2 nanoparticles (NPs) to the fiber, and nitrogen (N) was doped in this process to improve the photocatalytic activity of the fibrous membrane. Finally, methyl blue solution was used as the target organic pollutant. Under the irradiation of a xenon lamp, 90.05% of methyl blue was removed within 90 min, indicating that the membrane had good photocatalytic performance. In a water contact angle test, the PVDF/PVP N-doped TiO2 fibrous membrane showed superhydrophilicity. The design of a fibrous membrane with high photocatalytic activity and superhydrophilicity properties has great potential for practical application in the purification of industrial wastewater.

Interstitial N-Doped TiO2 for Photocatalytic Methylene Blue Degradation under Visible Light Irradiation

Photocatalysis is a promising method for methylene blue (MB) degradation due to its effectiveness and environmental compatibility. Among the photocatalysts, titanium dioxide (TiO2) has been widely used for MB degradation due to its exceptional photocatalytic activity. However, the wide bandgap limits the degradation efficiency of TiO2 under visible light. Here, an interstitial nitrogen-doped TiO2 (5%NT/TiO2) used thiourea as the N source was fabricated for visible light-derived MB degradation. The 5%NT/TiO2 exhibited an extended absorption range of visible light. Moreover, photoelectrochemical measurements showed an improvement in the photocurrent response and charge transfer behavior on N/TiO2. Thus, 5%NT/TiO2 had enhanced photocatalytic activity compared with pristine TiO2 and substitutive N-doped TiO2 (5%NAB/TiO2). The accelerated photocatalytic MB degradation process on N/TiO2 could be mainly attributed to the interstitial N doping, which caused the appearance of new energy states and extended optical properties. Through comparing the impact of interstitial and substitutive in TiO2 activity, our work proposes a suitable form of element doping to enhance the optical properties and photocatalytic activity of TiO2 and even other semiconductors, providing guidance for future work.

Enhanced degradation of diclofenac via H2O2-assisted photocatalysis in a submerged membrane reactor using N-doped TiO2

Enhanced degradation of diclofenac via H2O2-assisted photocatalysis in a submerged membrane reactor using N-doped TiO2

N-doped titania nanoparticles containing Mo6 bromide and iodide clusters: Activity in photodegradation of rhodamine B and tetracycline

Contamination of water sources is a major environmental problem with far-reaching consequences for humanity. Organic substances are among the most widespread and persistent pollutants. Advanced oxidation processes, especially photocatalysis, have been considered as one of the most promising technologies for organic pollution control. In this study, hybrid photocatalysts based on N-doped TiO2, which exhibits activity in the visible region of the spectrum, and different content of octahedral Mo6 bromide and iodide cluster complexes were synthesized to achieve the highest efficiency of the formed S-scheme photocatalytic system under white light irradiation. According to the data obtained, the resulting materials are nanoparticles with a diameter of ∼10 nm exhibiting absorption up to ∼550 nm. Photocatalytic studies were performed using model organic molecules – the more colored rhodamine B (RhB) and the less colored antibiotic tetracycline (TET). The most active samples showed high efficiencies against both pollutants with keff ∼0.3–0.4 and 0.4–0.5 min−1, respectively, while the activity of iodide complexes was ∼1.3 times higher than that of bromide complexes. The stability of the catalysts is preserved for up to 5 cycles of TET photodegradation.

Modulating d-p-band electron coupling by N-doping for promoting CuSAs-N/TiO2 photocatalytic hydrogen evolution

Doping can effectively improve the light absorption of single-atoms photocatalysts, but the metal-support interaction (MSI) and surface electronic structure will change due to doping, which needs further study. Herein, we report a nano-TiO2 co-modified with internal doping of N and surface loading of Cu single atoms (CuSAs-N/TiO2) for photocatalytic water-splitting hydrogen evolution. Experimental and theoretical studies confirm that the internal doped N can interact strongly with the surface-loaded CuSAs by modulating the d-p-band electronic coupling. The enhancement of d-p-band electronic coupling enhances the strong electron interaction between CuSA and support of N-doped TiO2. Especially, it significantly affects the d-p-band electronic structure of the catalyst surface lattice and causes electron redistribution in the local structure of surface CuSAs, which can optimize the surface hydrogen evolution kinetics and promote hydrogen production. Consequently, the photocatalytic hydrogen evolution activity, photoelectric response rate and light energy utilization of CuSAs-N/TiO2 are significantly improved. This work reveals the fundamental necessity of d-p-band electron coupling in MSI and catalyst surface electronic structure for driving solar water splitting. It provides valuable insights for the rational design of metal single-atom photocatalysts with high activity and efficient light energy utilization.

Heterophase homojunction construction by amorphous TiOx and N–TiO2 photoanode for oxygen evolution reaction kinetics and charge carriers’ transportation enhancement

Photoelectrochemical (PEC) water splitting by TiO2 photoanode for clean hydrogen production is limited by the poor charge separation and inert oxygen evolution reaction (OER) kinetics issues for now. In this work, a band-matched heterophase homojunction (TiOx/N–TiO2) by amorphous TiOx and N-doped TiO2 nanotube arrays is constructed by two-step anodic oxidation and impregnation. The photocurrent density of TiOx/N–TiO2 reaches 0.69 mA/cm2 at 1.23 V vs. RHE, which is 1.86 folds than bare TiO2. The enhanced charge carriers' injection/separation efficiency, smaller Tafel slope (37.79 mF dec−1) and larger electrochemical active surface area (ECSA) (1.98 mF cm−2) of TiOx/N–TiO2 indicate that N doping and heterophase homojunction with amorphous TiOx effectively facilitate the surface OER kinetics and charge carriers' transportation. TiOx/N–TiO2 is annealed with a transformation of the surface amorphous TiOx layer into anatase TiO2 (a-TiOx/N–TiO2) to study the role of amorphous TiO2 in PEC water splitting. The photocurrent density and applied bias photon-to-current efficiency (ABPE) for a-TiOx/N–TiO2 decrease, even lower than the pristine TiO2. This is due to the reduction of surface oxygen vacancies, which causes the slowdown of OER kinetics and the weakening of charge carrier transportation ability. That is favorable for a better understanding of the OER kinetics and charge carriers’ transportation enhancement mechanism by the surficial modification on the semiconductor during the PEC water splitting.

Novel dual-photoelectrode Z-scheme PEC system for efficient TBBPA removal and debromination: Performance and promoting mechanism

Herein, a novel dual-photoelectrode Z-scheme photoelectrocatalytic system is created to achieve efficient synergistic anodic oxidation and cathodic reduction for TBBPA degradation and debromination. Based on the polydopamine-modified N-doped TiO2 nanotubes (PN-TNTs) photoanode and polydopamine-modified Cu2O nanowires (PC-CNWs) photocathode, the degradation, debromination and mineralization were 99.4%, 77.7% and 52.1% at 0.7 V under visible light for 2 h. The introduction of PDA enhances the visible light absorption by the TiO2 photoanode and protects the Cu2O photocathode from photocorrosion. The main active species identified by electron paramagnetic resonance (EPR) and scavenger experiments as •OH and e− were found to promote the degradation and debromination of TBBPA by oxidation and reduction, respectively. The degradation pathway of TBBPA was determined by Density Functional Theory (DFT) calculations and HPLC-MS analyses. Comparing the intermediates of single and dual chambers, it demonstrated that the photocathode was able to achieve the continuous debromination of TBBPA and intermediates, which reduced the toxicity. Finally, the stability, reusability and energy consumption were evaluated, confirming the feasibility of the system.

Effective sonophotocatalytic degradation of tetracycline in water: Optimization, kinetic modeling, and degradation pathways

Hybrid advanced oxidation processes (AOPs) are gaining interest in degradation of variety of recalcitrant compounds for water and wastewater treatment, due to possible synergistic effects. The present study systematically evaluated the degradation of tetracycline (TC) with a sonophotocatalytic process combining acoustic cavitation (sonocavitation) and photocatalysis based on N-doped TiO2 catalyst. The TC degradation rate constant was 2.4 × 10−2 min−1, i.e., much higher than individual sonocatalytic (0.5 × 10−2 min−1) and photocatalysis (0.6 × 10−2 min−1) processes at the optimized conditions. The synergy index was 2.14, which reveals a significant improvement in the process performance. Maximum TC degradations of 55.5 ± 1.8 % for photocatalysis, 66.4 ± 1.8 % for sonocatalysis, and 79.5 ± 0.3 % for sonophotocatalysis were observed for 10 mg L−1 initial TC concentration after 90 min of treatment. The photocatalytic experiments were extended further to 210 min to achieve a maximum degradation of 78.9 ± 0.2 % at the optimized condition. Scavenging experiments confirmed that hydroxyl radicals (•OH), electron holes (h+), and superoxide radical anions (O2−•) played a significant role in the degradation of TC. Further, the degradation intermediates for each process were identified and degradation pathways were proposed. Empirical kinetic models based on operational parameters were also developed and validated.

Sucrose-based reticulated vitreous carbon modified with N-doped TiO2 as an adsorbent and photocatalyst: Enhanced removal of methyl orange from aqueous solutions

A novel and low-cost 3D reticulated vitreous carbon (RVC) was synthesized and modified with (N-TiO2) to obtain an RVC/N-TiO2 composite, which was employed to remove methyl orange in an aqueous solution. This material was synthesized using the sacrificial template method and impregnated with an environmentally friendly sucrose resin, followed by N-TiO2 impregnation by dip-coating technique. SEM-EDS characterization confirmed the uniform covering of the TiO2, and XRD, Raman, and XPS evinced the presence of anatase and rutile polymorphs in the film and the N-doping, respectively. N-TiO2 coating onto RVC provides a higher specific surface area and electrochemical active area, boosting the wettability and the adsorption capacity. Additionally, this film favoured the photoelectrochemical response of the composite and the generation of •OH radicals. The adsorption, desorption, and photocatalytic studies demonstrated that >95 % decolorization of MO was achieved in 30 min without light irradiation and that >95.5 % degradation was attained in 120 min under visible light. The foam demonstrated reusability for over five cycles of adsorption/desorption of MO, with a capacity to recover up to 99 % of the dye after the first cycle and up to 94.07 % after the fifth cycle. Meanwhile, the minimal desorption of the dye (2.5 %) after illumination confirmed the photocatalytic degradation. This indicates that the process was not merely adsorption but also photocatalytic degradation.

Tuning oxygen vacancies via photoinduced defect engineering in plasma pre-treated TiO2 for efficient solar-light-driven oxidation of trace methane

Photocatalysis employing cost-effective commercial titanium dioxide offers an ideal solution for eliminating trace methane emissions from livestock and poultry farming. However, significant challenges such as the rapid recombination of photogenerated carriers, a limited light absorption spectrum, and weak adsorption capabilities considerably hinder the effectiveness of titanium dioxide in the photocatalytic treatment of trace methane. This study proposes a novel approach to activate plasma pre-treated N-doped commercial anatase TiO2 into dual-defect TiO2 (N-doped TiO2-x) featuring stable and controllable oxygen vacancies (OV) through photoinduced defect engineering. Characterizations of the photocatalyst confirm the successful creation of surface defects, further evaluated through solar-light-driven CH4 (ppm level) removal investigations. The yield of this N-doped TiO2-x in converting CH4 is 4.84 μmol h−1, 44 times greater than that of unmodified TiO2, significantly outperforming previous studies. UV–Vis diffuse reflection spectra, and photoluminescence indicate that the modified commercial anatase TiO2 possesses a narrower band gap, efficient photogenerated carrier separation, and enhanced charge transfer. Furthermore, density functional theory (DFT) calculations demonstrate that the synergistic effects of oxygen vacancies and N doping enhance the adsorption and activation of both O2 and CH4 in the rate-determining step of the reaction. This innovative strategy holds considerable promise for modifying various materials for more efficient photocatalytic applications.

A handy way for forming N-doped TiO2/carbon from pectin and d,l-serine hydrazide hydrochloride

N-doped TiO2/carbon composites (N-TiPC) have shown excellent photodegradation performances to the organic contaminants but are limited by the multistage preparation (i.e., preparation of porous carbon, preparation of N-doped TiO2, and loading of N-doped TiO2 on porous carbon). Here, we develop a handy way by combining the Pickering emulsion-gel template route and chelation reaction of polysaccharides. The N-TiPC is obtained by calcinating pectin/Dl-serine hydrazide hydrochloride (SHH)-Ti4+ chelate and is further described by modern characterization techniques. The results show that the N atom is successfully doped into the TiO2 lattice, and the bandgap value of N-TiPC is reduced to 2.3 eV. Moreover, the particle size of N-TiPC remains about 10 nm. The configurations of the composites are simulated using DFT calculation. The photocatalytic experiments show that N-TiPC has a high removal efficiency for methylene blue (MB) and oxytetracycline hydrochloride (OTC-HCL). The removal ratios of MB (20 mg/L, 50 mL) and OTC-HCL (30 mg/L, 50 mL) are 99.41 % and 78.29 %, respectively. The cyclic experiments show that the photocatalyst has good stability. Overall, this study provides a handy way to form N-TiPC with enhanced photodegradation performances. It can also be promoted to other macromolecules such as cellulose and its derivatives, sodium alginate, chitosan, lignin, etc.

Crystal and band structures of N-doped Ti3O5 coatings: Experiments and first-principles calculations

N-doped α-phase Ti3O5 has received limited attention in both theoretical and experimental studies compared to N-doped TiO2. This work focuses on the production and analysis of N-doped Ti3O5 coatings, which can be facilely produced using air-based sputtering. First-principles calculations were employed to investigate the crystal and band structures of N-doped Ti3O5. The results revealed that substitutional nitrogen doping within the investigated range preserved the orthorhombic structure of Ti3O5. As the N-doping concentrations increased, Ti3O5 exhibited a transition from metallic to semiconducting characteristics, confirmed by the density of states and refined band calculations. The calculated bandgaps in the semiconductor regime aligned well with the limited experimental results, demonstrating the pronounced narrowing effect of nitrogen doping. Integrating these calculations with experimental findings enhances the understanding of the crystalline and physical properties of N-doped Ti3O5 coatings.

Construction of self-supported TiO2 nanotube arrays with hybrid point defect engineering: A bifunctional anode for Li+/Na+ storage

Point defect engineering has garnered widespread application for enhancing the dynamic behavior of anode materials and improving electrochemical performance. Herein, a hybrid point defect strategy is proposed in Ti-based oxide materials to achieve N doping induced oxygen vacancies (OVs) and subsequently accelerated electron mobility and perform better diffusion kinetics. This methodology culminates in the fabrication of self-supported nanotube arrays comprising N-doped OVs-rich TiO2 (denoted as N-TNTs). Density functional theory (DFT) calculations and electrochemical characterizations validate that, hybrid point defects lead to high electron mobility and perform better diffusion kinetics, as well as higher Li+/Na+ ions adsorption energy barrier and diffusion energy barrier, which in turn improves the rate performance and cycling stability. This research provides a forward-looking and feasible strategy for the application of point defect engineering in anode materials.

Defects introducing and heterostructures engineering synergistically constructing active sites for achieving stable and fast ion transport in sodium-ion batteries

Bronze phase TiO2 (TiO2(B)) has attracted significant interest as potential anode materials for sodium-ion batteries (SIBs) due to its distinctive open tunnel structure, offering abundant insertion sites for Na+-ions. However, the practical application has been hindered by its poor electrical conductivity and insufficient Na+ diffusion kinetics. Herein, we propose a novel strategy that integrates defect introducing and heterostructures engineering to enhance the performance of TiO2(B) anode. Specifically, we aim to induce oxygen vacancies (OVs) into TiO2(B) through N-doping and in-situ growth on MXenes nanosheets, thereby fabricating N-doped TiO2(B)/MXenes (N-TiO-MX) heterostructures. This strategy leverages the synergistic effects of OVs and N-atoms, along with the formation of heterointerfaces, to effectively reduce the bandgap, increase the number of Na+-ion storage sites, and shorten ion diffusion distances. The robust coupling between TiO2(B) and MXenes ensures the structural integrity of N-TiO-MX heterostructures. Consequently, the N-TiO-MX exhibits a high specific capacity of 211.3 mAh g−1 at 0.1 A g−1 after 400 cycles and superior cycling stability with 163.1 mAh g−1 after 1000 cycles at 1.0 A g−1. The study provides unique insights for designing heterostructure materials to achieve high capacity and excellent fast-charging capability.

Constructing Direct Z-Scheme Y2TmSbO7/GdYBiNbO7 Heterojunction Photocatalyst with Enhanced Photocatalytic Degradation of Acetochlor under Visible Light Irradiation.

This study presents a pioneering synthesis of a direct Z-scheme Y2TmSbO7/GdYBiNbO7 heterojunction photocatalyst (YGHP) using an ultrasound-assisted hydrothermal synthesis technique. Additionally, novel photocatalytic nanomaterials, namely Y2TmSbO7 and GdYBiNbO7, were fabricated via the hydrothermal fabrication technique. A comprehensive range of characterization techniques, including X-ray diffractometry, Fourier-transform infrared spectroscopy, Raman spectroscopy, UV-visible spectrophotometry, X-ray photoelectron spectroscopy, transmission electron microscopy, X-ray energy-dispersive spectroscopy, fluorescence spectroscopy, photocurrent testing, electrochemical impedance spectroscopy, ultraviolet photoelectron spectroscopy, and electron paramagnetic resonance, was employed to thoroughly investigate the morphological features, composition, chemical, optical, and photoelectric properties of the fabricated samples. The photocatalytic performance of YGHP was assessed in the degradation of the pesticide acetochlor (AC) and the mineralization of total organic carbon (TOC) under visible light exposure, demonstrating eximious removal efficiencies. Specifically, AC and TOC exhibited removal rates of 99.75% and 97.90%, respectively. Comparative analysis revealed that YGHP showcased significantly higher removal efficiencies for AC compared to the Y2TmSbO7, GdYBiNbO7, or N-doped TiO2 photocatalyst, with removal rates being 1.12 times, 1.21 times, or 3.07 times higher, respectively. Similarly, YGHP demonstrated substantially higher removal efficiencies for TOC than the aforementioned photocatalysts, with removal rates 1.15 times, 1.28 times, or 3.51 times higher, respectively. These improvements could be attributed to the Z-scheme charge transfer configuration, which preserved the preferable redox capacities of Y2TmSbO7 and GdYBiNbO7. Furthermore, the stability and durability of YGHP were confirmed, affirming its potential for practical applications. Trapping experiments and electron spin resonance analyses identified active species generated by YGHP, namely •OH, •O2-, and h+, allowing for comprehensive analysis of the degradation mechanisms and pathways of AC. Overall, this investigation advances the development of efficient Z-scheme heterostructural materials and provides valuable insights into formulating sustainable remediation strategies for combatting AC contamination.

Degradation of conjugated estrogen in visible light-driven intimately coupled photocatalysis and biodegradation system

Visible light-driven intimately coupled photocatalysis and biodegradation (VDICPB) is an efficient technology for removing recalcitrant contaminants, but the degradation pathway on 17β-estradiol 3-Sulfate (E2-3S) is still not clear. In this study, VDICPB based on N-doped TiO2 as a photocatalyst was established to investigate the removal and transformation of E2-3S in synthetic wastewater. VDICPB showed a satisfactory removal efficiency of 97.8 ± 0.4 %, which was much higher than that of independent photocatalysis (84.0 ± 2.2 %) or biodegradation system (71.4 ± 1.8 %). Steroid C/D-rings of E2-3S was broken in VDICPB since the transformation process reached terminal central pathway. Primary metabolites did not accumulate in VDICPB, resulting in a low expression of functional genes. E2-3S was mainly removed by cooperative interaction of photocatalysis and co-metabolism of biofilm. Photocatalysis led to deconjugation and microbes acted to mineralization. This study provides technical reference and theoretical support for the removal of new pollutants.

Preparation and photoelectric properties of photoanode based on N-TiO2 deposited on copper electrode

Reducing the photoresistance of a photoanode is one of the key points to improving the electron transfer rate of dye-sensitive solar cells. With TiO2 sol acting as the titanium source and urea serving as the nitrogen source, the N-doped TiO2 composite electrode material was prepared by electrodeposition on the surface of copper foil. The results show that the N-TiO2/Cu electrode prepared by electrodeposition doping at a voltage of 1.0 V has a low photoresistance and bias of 0.25 V difference with the Cu electrode under visible light. The photocurrent is increased by 270 % in comparison with that of the TiO2/Cu electrode. The N-TiO2/Cu electrode shows good photoresponsivity and has a good potential application in dye-sensitive solar cells.

N-doped TiO2 for photocatalytic degradation of colorless and colored organic pollutants under visible light irradiation

N-doped TiO2 for photocatalytic degradation of colorless and colored organic pollutants under visible light irradiation

Direct Photocatalytic Methane Oxidation to Formaldehyde by N Doping Co-Decorated Mixed Crystal TiO2.

In this paper, N-doped TiO2 mixed crystals are prepared via direct calcination of TiN for highly selective oxidation of CH4 to HCHO at room temperature. The structures of the prepared TiO2 samples are characterized to be N-doped TiO2 of anatase and rutile mixed crystals. The crystal structures of TiO2 samples are determined by XRD spectra and Raman spectra, while N doping is demonstrated by TEM mapping, ONH inorganic element analysis, and high-resolution XPS results. Significantly, the production rate of HCHO is as high as 23.5 mmol·g-1·h-1 with a selectivity over 90%. Mechanism studies reveal that H2O is the main oxygen source and acts through the formation of ·OH. DFT calculations indicate that the construction of a mixed crystal structure and N-doping modification mainly act by increasing the adsorption capacity of H2O. An efficient photocatalyst was prepared by us to convert CH4 to HCHO with high yield and selectivity, greatly promoting the development of the photocatalytic CH4 conversion study.