Separation Of Electron-hole Pairs Research Articles

Synthesis of MoS2@MoO3/(Cu+/g-C3N4) ternary composites with double S-scheme heterojunction for peroxymonosulfate activation exposing to visible light

The construction of semiconductor heterojunction is an effective way for charge separation in photocatalytic degradation of pollutants. In this study, a novel MoS2@MoO3/(Cu+/g-C3N4) ternary composites (MMCCN) was prepared via a simple calcination method. The as-prepared composites exhibited exceptional performance in activating peroxymonosulfate (PMS) for the degradation of rhodamine B (RhB). The activity testing results indicated that 99.41 % of RhB (10 mg·L−1, 10 mL) was effectively removed by the synergistic effect of composites photocatalyst (0.1 g·L−1) and PMS (0.1 g·L−1) under visible light irradiation for 40 min. Its reaction rate constant exceeded that of Cu+/g-C3N4, MoO3 and MoS2 by a factor of 3.56, 17.30 and 11.73 times, respectively. The crystal structure, band gap and density of states (DOS) of the semiconductors were calculated according to the density functional theory (DFT). Free radical trapping tests and electron spin resonance spectroscopy validated that 1O2, O2− and h+ are primary reactive species participating in the decomposition of RhB. The ternary composites demonstrated good stability and maintained excellent degradation efficiency even across four reaction cycles. Furthermore, the activation mechanism and the intermediates produced during the decomposition course of RhB by MMCCN/PMS/vis system were analyzed and elucidated. A double S-scheme heterojunctions was responsible for efficient separation of photo-induced electron-hole pairs. This work presents a novel method in the construction of double S-scheme heterojunctions for PMS activation which is expected to find wide applications in wastewater treatment and environmental remediation.

A Flower-like g-C3N4/CDs/Bi2WO6 Hierarchical Structure for Enhanced Photocatalytic Degradation of Tetracycline

Tetracycline (TC), as one of antibiotic emerging pollutants, has posed potential threats to ecological environment and human health because it is hardly biodegradable and prone to be accumulated in water. In this study, g-C3N4/CDs/Bi2WO6 S-scheme heterojunction with flower-like hierarchical structure was synthesized by hydrothermal method. The optimized composite demonstrates significantly enhanced photocatalytic activity with a TC degradation efficiency of 90.1% after 120 min of visible light irradiation and good reusability up to four consecutive cycles. This can be attributed to the improved light capture capability and efficient separation of photo-generated electron-hole pairs in the constructed S-scheme heterojunction. The introduced carbon dots (CDs) can be served as an efficient carrier transport highway, providing a superior photogenerated carrier separation efficiency and an expanded absorption spectrum. As a result, the strongest redox potentials of the CBCN and VBBWO can be retained for participating the photocatalytic reaction. Free radical capture and electron spin resonance experiments indicate that ·O2- and h+ are the principal active species in the g-C3N4/CDs/Bi2WO6 system. This work provides new strategy for the development of advanced materials in the field of photocatalytic treatment of wastewater.

Preparation of Cu-doped MIL-125(Ti)-derived carbon-based composites for the sonodynamic degradation of organic dyes

Sonocatalysis provides a green and sustainable strategy to remove industrial organic pollutants. Toward improving the sonocatalytic performance to remove the organic dyes, a new Cu-C@TiO2 catalyst was prepared via doping the Cu(II) ions into the MIL-125(Ti) and then carbonizing the resultant Cu-MIL-125(Ti) in this study. By the SEM, EDS and BET, the obtained Cu-C@TiO2 was a porous carbon-based hybrid with bimetallic centers, retaining a large amount of organic frameworks to supply adequate specific surface area for the adsorption; By the XPS and UV–vis DRS, the band gap of Cu-C@TiO2 was reduced to significantly broaden the light absorption region and facilitate the separation of electron-hole pairs; By the fluorescence spectra, the graphite-like structure and Cu particles produced on the catalyst surface served as an electron trap to inhibit the recombination of charge carriers. The Cu-C@TiO2 showed an excellent sonocatalytic performance to organic dyes, and under the ultrasound irradiation (35 KHz, 150 W), it could remove more than 95 % of rhodamine B (5.00 mg/L) and methylene blue (5.00 mg/L) within 10 min. By the kinetic analysis, it was found that the dye removal obeyed the first-order kinetic model, and the scavenging studies of free radicals (OH and O2−) verified the Cu-C@TiO2-mediated sonodynamic degradation was in the dye removal. In the end, a Cu-C@TiO2-mediated adsorption/sonodynamic degradation mechanism was proposed to thermodynamically expound the removal process of organic dyes.

Fabrication of NiFe-LDH/MoS2 2D/2D material to construct direct Z-scheme heterojunction for enhanced CO2 photocatalytic reduction under visible light irradiation

In recent years, the utilization of solar energy for conversion of CO2 into fuels has emerged as a promising strategy for mitigating the Greenhouse effect. However, transport efficiency of photogenerated carriers plays a crucial role in determining the efficacy of CO2 photocatalytic reaction. In this paper, a 2D/2D composite material consisting of NiFe-LDH/MoS2, presenting high efficiency in separating photogenerated electron-hole pairs, has been successfully synthesized using a straightforward hydrothermal method. XRD, XPS, FTIR and other characterization results proved that the composite was successfully prepared, and its unique direct Z-scheme heterostructure improved the efficiency of CO2 photocatalytic reduction effectively. The composite material NiFe-LDH/MoS2 demonstrated enhanced rate of photo-induced electron-hole pair separation comparing with pure NiFe-LDH. Apart from this, the charge transfer resistance was reduced simultaneously, the composite material exhibited perfect photocatalytic activity. In photocatalytic reduction reaction experiment, CO yield of NiFe-LDH/MoS2 can reach 10.72 μmol/g, which is 3.93-fold and 4.17-fold that of bare NiFe-LDH and MoS2. The cyclic test also shows that the catalyst has good stability under visible light irradiation.

Construction of AgI/NH2-MIL-125(Ti) heterojunction: Efficient degradation of organic pollutants in water by visible light response

Photocatalytic technology is an effective means to convert clean solar energy into green chemical energy, which has broad application prospects. Metal-organic framework (MOFs) composites have been widely used to remove pollutants from water. In this paper, the photocatalytic effect of NH2-MIL-125(Ti)[NM125(Ti)] photocatalyst with different AgI content on pollutants in water under visible light irradiation were studied. The successful preparation of AgI/NH2-MIL-125(Ti) photocatalyst was proved by the characterization of the physical and chemical structure of the composite material. When the dosage of AgI is 0.5 mmol, the removal rate of TC by AgI/NH2-MIL-125(Ti) is the highest (82 %). In addition, the photoelectrochemical test also proved that AMNT-0.5 mmol photocatalyst has higher electron-hole separation efficiency. After five cycle tests, the composite photocatalyst of ANMT-0.5 mmol still has good stability. The enhancement of the performance of ANMT-0.5 mmol photocatalyst can be attributed to: (i) the introduction of AgI increases the absorption of visible light in the composite; (ii) The close relationship between AgI and NM125(Ti) accelerates the separation of electron-hole pairs, thus improving the photocatalytic performance.

Self-assembled perylene diimide decorated g-C3N4 heterojunction catalyst with strong interfacial charge transfer through π-π interaction for efficient boosted photocatalytic degradation of tetracycline

Perylene diimide (PDI) organic material and its derivatives as photocatalysts possesses excellent charge separation efficiency and are renowned as among the top n-type organic semiconductors capable of absorbing visible light owing to their narrow band gap (∼1.69 eV). Heterojunction photocatalysts with efficient electron transfer and excellent photocatalytic performance are of great significance for the degradation of organic compounds in the environment. In this work, a series of heterojunction catalysts (CNPDI) with robust interfacial charge transfer via π-π interaction were prepared using g-C3N4 and different mass ratio of the self-assembled PDI as precursors, subsequently utilized as efficient visible-light-driven photocatalysts for the degradation of organic tetracycline. SEM and TEM results indicated that porous CN was completely wrapped around PDI nanorod structure formed by strong π-π interactions. In the presence of activating potassium peroxymonosulfate (PMS) substances, the kinetic rate constant of the CNPDI photocatalytic system clocked in at 0.026 min−1, marking 2.36 fold increase compared to the original CN (0.011 min−1). The bolstered degradation performance was attributed to the built-in potential formed by the self-assembled PDI and CN, promoting the separation of electron-hole pairs and redistribution of charge density in the interface region. This work presents a useful insight into the crafting of PDI-based heterojunction photocatalysts for degradation environmental pharmaceutical pollutants.

Construction of 0D Ti3C2Tx MXene nanoparticles sensitized 1D TiO2 nanotube arrays for enhanced photocatalytic and photoelectrochemical properties

Developing efficient photocatalysts with highly active facets and appropriate cocatalyst hybridization to form heterostructure is a valid way to expedite the separation of photoexcited electron-hole pairs. Herein, a novel 0D/1D Ti3C2Tx MXene/TiO2 photocatalyst was fabricated for photoelectrochemical (PEC) water splitting and tetracycline antibiotic photocatalytic degradation. Meanwhile, highly-exposed TiO2 nanotube arrays were prepared by electrochemical anodizing method, and Ti3C2Tx nanoparticles with mixed terminal group were uniformly grown on the surface of TiO2 through the hydrothermal and solvothermal process, respectively. Compared with pure TiO2, the Ti3C2Tx/TiO2 heterostructure exhibited different degrees of enhancement in PEC and photocatalytic degradation activities under simulated sunlight. The TNT/M-h sample yielded a photocurrent density of 1.77 mA cm−2 at 0 V (vs. SCE) and achieved a 95.57 % photocatalytic removal rate of tetracycline within 140 min. The excellent performance originated from the strong interfacial contact and work function discrepancy between the ordered tubular structure of TiO2 and 0D Ti3C2Tx nanoparticles, which realized the high-efficiency photogeneration and transfer of electron-hole pairs.

Up-conversion luminescence and Bi SPR effect promoted Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst for efficient photocatalytic hydrogen production with simultaneous degradation of malachite green

Photocatalytic hydrogen production with simultaneous degradation of organic pollutants by using solar energy provide a promising strategy to solve the energy and environmental issue in the future. However, for onefold wide band-gap semiconductor, the poor photocatalytic efficiency limits its application on a large scale due to its easy recombination of photo-generated electron-hole pairs and low solar energy utilization. Herein, a novel Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst is prepared via photo-assisted isoelectric point method. In this composite photocatalyst, up-convention luminescence material, NaYF4:Er,Yb,Tm, can offer more ultraviolet light and visible light to intensify the activations of BiOBr and metal Bi nanoparticles, respectively. Furthermore, the formation of Z-scheme BiVO4(040)-BiOBr photocatalystic sytem, the spatial separation of the BiVO4(040) and BiVO4(110) facets and the presence of metal Bi surface plasmon resonance effect are contributed to the high-efficiency separation of the photo-generated electron-hole pairs. The experimental results show that as-prepared Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst exhibits advanced photocatalytic hydrogen production amount (192.0 μm) and excellent degradation ratio of malachite green (88.51 %) under simulated sunlight irradiation for 5.0 h. The apparent quantum yield of the Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst at 420 nm reaches a specific value of 5.8 %. In addition, Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst also remains a high stability in the photocatalytic hydrogen production with simultaneous degradation of malachite green within six reuse. At last, the possible reaction mechanism and degradation pathways of malachite green caused by Z-scheme BiVO4(040)-Bi-(NaYF4:Er,Yb,Tm@BiOBr)/Bi photocatalyst under simulated sunlight irradiation are put forward.

Boosting the piezocatalytic performance of BaTiO3-based materials via phase boundary and defect co-engineering

Recently, piezocatalytic technology has been recognized as an efficient and viable strategy for the remediation of aquatic environments. Herein, a synergistic strategy of phase boundary and defect co-engineering has been proposed to enhance the piezocatalytic performance of BaTiO3-based ceramic materials: a ceramic system material ((1-x)BaTiO3-x(Ca0.9Sr0.1)(Sn0.5Hf0.5)O3, (1-x)BT-xCSSH) was constructed to achieve the coexistence of multiple ferroelectric phases by co-doping ions in the A/B-sites, and defect engineering was realized by a high-temperature annealing. The 0.95BT-0.05CSSH ceramic exhibits the coexistence of rhombic (R), orthorhombic (O), and tetragonal (T) phases, with multiple spontaneous polarization directions and low polarization rotational energy barriers, thereby demonstrating high piezoelectricity (d33 = 450 pC/N) and thus outstanding piezocatalytic performance. The degradation rate/reaction rate constant of the 0.95BT-0.05CSSH ceramic material for rhodamine B (RhB) is 71.35 %/13.5 × 10−3 min−1. After undergoing a high-temperature annealing, the catalytic activity of the 0.95BT-0.05CSSH ceramic is further improved, resulting in a degradation rate/reaction rate constant of 92.84 %/28.5 × 10−3 min−1 for rhodamine B (RhB). The catalytic activity of the 0.95BT-0.05CSSH material is enhanced by the generation of abundant oxygen vacancies during high-temperature annealing, which facilitates the separation and migration of electron-hole pairs. In this study, we propose a novel strategy to upgrade the piezocatalytic performance of BaTiO3-based piezoelectric materials, which is useful for the remediation of aquatic environments.

Designing a novel 3D structured PVP-assisted Bi-TDC coordination polymers catalyst with tunable bandgap structure to decompose dyes

The exploration of an efficient porous hybrid materials is significant due to their unique properties and good development prospects in catalytic applications. Herein, the PVP-assisted 3D Bi-TDC (2,5-thiophene dicarboxylate acid) is designed by solvothermal reaction to capture solar and mechanical energy for the degradation of rhodamine B (RhB, 5 mg/L) and methylene blue (MB, 5 mg/L). The RhB and MB degradation of the PVP-assisted Bi-TDC reached 99.6 % and 90.2 % under the ultrasonic vibrations and photocatalysis, which displays a higher catalytic activity compared to the bare Bi-TDC. The obviously enhanced catalytic activity can be ascribed to the integrated of ultrasonic vibrations and photocatalysis, the efficient separation of electron-hole pairs and its uniform and regular structure. This present work provided a new strategy to develop a controllable structures and excellent catalytic material for the environmental and energy application.

ZnIn2S4 nanostructure grown on electronegative h-BN for highly efficient photocatalytic hydrogen evolution

The photo-corrosion issue inherent in metal sulfide semiconductors is quite pronounced, making the enhancement of electron-hole pair separation efficiency in these photocatalysts a pivotal strategy for boosting photocatalytic hydrogen production. This study introduces a novel approach where hexagonal boron nitride (h-BN) acts as a substrate for the in situ growth of ZnIn2S4 nanostructures, resulting in the formation of h-BN@ZnIn2S4 (BN@ZIS) nanocomposites. The electronegativity of h-BN nanosheets is harnessed to facilitate the recombination or electrostatic attraction of photogenerated holes in the ZnIn2S4 photocatalyst. This strategy effectively promotes the separation of photogenerated electron-hole pairs, which is crucial for enhancing photocatalytic performance. The microstructure, morphology and optical properties of BN@ZIS nanocomposites were meticulously investigated. The findings reveal that the incorporation of h-BN nanosheets loads to a more uniform dispersion of the ZnIn2S4 nanostructure, which not only increases the specific surface area but also fosters a tight heterojunction interface between h-BN and ZnIn2S4. In conclusion, the photocatalytic hydrogen production capabilities of the BN@ZIS nanocomposites were rigorously evaluated. Pure h-BN lacks photocatalytic hydrogen production activity. Conversely, the optimized BN@ZIS composite demonstrated a remarkable enhancement, exhibiting a photocatalytic efficiency that is 9.65 times greater than that of pristine ZnIn2S4. Furthermore, a plausible mechanism by which BN@ZIS augments photocatalytic hydrogen production has been proposed. This strategy, leveraging the synergistic interaction between h-BN and ZnIn2S4, is anticipated to be applicable to other semiconductor systems, opening avenues for the advancement of photocatalytic technologies.

2D TiO2 Nanosheets Decorated Via Sphere-Like BiVO4: A Promising Non-Toxic Material for Liquid Phase Photocatalysis and Bacterial Eradication.

An in-depth investigation was conducted on a promising composite material (BiVO4/TiO2), focusing on its potential toxicity, photoinduced catalytic properties, as well as its antibiofilm and antimicrobial functionalities. The preparation process involved the synthesis of 2D TiO2 using the lyophilization method, which was subsequently functionalized with sphere-like BiVO4 through wet impregnation. Finally, we developed BiVO4/TiO2 S-scheme heterojunctions which can greatly promote the separation of electron-hole pairs to achieve high photocatalytic performance. The evaluation of concentration- and time-dependent viability inhibition was performed on human lung carcinoma epithelial A549 cells. This assessment included the estimation of glutathione levels and mitochondrial dehydrogenase activity. Significantly, the BiVO4/TiO2 composite demonstrated minimal toxicity towards A549 cells. Impressively, the BiVO4/TiO2 composite exhibited notable photocatalytic performance in the degradation of rhodamine B (k=0.135 min-1) and phenol (k=0.016 min-1). In terms of photoinduced antimicrobial performance, the composite effectively inactivated both gram-negative E. coli and gram-positive E. faecalis bacteria upon 60 minutes of UV-A light exposure, resulting in a significant log 6 (log 10 CFU/mL) reduction in bacterial count. In addition, a 49 % reduction of E. faecalis biofilm was observed. These promising results can be attributed to the unique 2D morphology of TiO2 modified by sphere-like BiVO4, leading to an increased generation of (intracellular) hydroxyl radicals, which plays a crucial role in the treatments of both organic pollutants and bacteria. This research has significant potential for various applications, particularly in addressing environmental contamination and microbial infections.

Degradation performance and mechanism of VOCs in asphalt by alkali metal-doped La2Ce2O7-based fluorite through pyroelectric and photocatalytic synergy

Under high-temperature construction conditions, the use of asphalt can release a large amount of volatile organic compounds (VOCs), which has adverse effect on the environment and human health. Part of fluorite oxides show potential application in VOCs conversion due to their excellent photoresponse and chemical stability in addition to ferroelectricity, piezoelectricity and pyroelectricity properties. In this paper, La2Ce2O7-based fluorite was modified with alkali metal doping and its photo-thermal coupling catalytic effects on the degradation performance of VOCs in asphalt were investigated. The results show that the fluorite catalysts La1.85A0.15Ce2O7 (A=Li, Na, K, Rb, Cs) have efficient electron-hole pair separation ability. Among them, the Rb+ doped La2Ce2O7 sample not only has stronger pyroelectric effect due to increased lattice distortion and oxygen vacancies, but also has the best photogenerated charge transport property and more favorable valence band position for oxidation reaction. Under the photo-thermal synergistic effect, the catalytic degradation performance of VOCs in asphalt by Rb+ doped La2Ce2O7 catalyst can reach 82.61 % at 50 min. Additionally, dynamic shear rheological tests indicate that the addition of catalysts at this blending ratio can enhance the rutting resistance of the asphalt material. This study introduces an innovative approach to enhance the efficiency of multi-field coupled degradation processes of volatile organic compounds (VOCs) in asphalt.

Efficient CdIn2S4/MgIn2S4 heterojunction for ultrasensitive detection of lung cancer marker neuron-specific enolase

In this work, a photoelectrochemical (PEC) immunosensor was constructed for the ultrasensitive detection of lung cancer marker neuron-specific enolase (NSE) based on a microflower-like heterojunction of cadmium indium sulfide and magnesium indium sulfide (CdIn2S4/MgIn2S4, CMIS) as photoactive material. Specifically, the well-matched energy level structure and narrow energy level gradients between CdIn2S4 and MgIn2S4 could accelerate the separation of electron-hole (e−-h+) pairs in the CMIS heterojunction to enhance the photocurrent of CMIS, which was increased 5.5 and 80 times compared with that of single CdIn2S4 and MgIn2S4, respectively. Meanwhile, using CMIS as photoactive material, increasing the biocompatibility by dropping Pt NPs on the surface of CMIS to immobilize the antibody through Pt–N bond. Fe3O4-Ab2, acting as the quencher, competitively consumes electron donors and absorbs light, leading to photocurrent quenching. With the increasing of quencher, the photocurrent decreased. Hence, the developed “signal-off” PEC immunosensor realized the trace detection of NSE within the range from 1.0 fg/mL to 10 ng/mL with a low detection limit of 0.34 fg/mL. This strategy provided a new perspective for establishing ternary metal sulfide heterojunction to construct PEC immunosensor for sensitive detection of disease biomarkers.

Modified Ta2O5-x prepared by NaBH4 reduction for enhance its photocatalytic activity

The generation of oxygen vacancies assumes a pivotal role in the photocatalytic degradation of antibiotics. Surface oxygen vacancies serve as deterrents to the recombination of photogenerated carriers, thereby augmenting photocatalytic efficiency. In this work, the NaBH4 reduction technique was adopted to introduce oxygen vacancies onto the surface of Ta2O5-x, thus enhancing its photocatalytic powers. Remarkably, the photocatalytic activity of the modified Ta2O5-x-0.5 M samples exhibited significant improvement upon treatment with NaBH4 solution at varied concentrations. Characterization of the modified Ta2O5-x samples was conducted using a suite of techniques including XRD, FT-IR, UV–vis DRS, ESR, XPS, and EPR. Notably, the EPR spectrum provided compelling evidence of the presence of oxygen vacancies, affirming their existence on the surface of the modified Ta2O5-x samples. To further corroborate the formation of oxygen vacancies, tetracycline (TC) solution was employed as a simulated pollutant, revealing a marked enhancement in visible light catalytic activity through experimental observations. The findings elucidate that the defect sites engendered by oxygen vacancies primarily enhance the efficiency of electron-hole pair separation and facilitate greater absorption of visible light, thereby amplifying photocatalytic activity. The modification of Ta2O5-x samples by NaBH4 reduction predominantly facilitates the introduction of oxygen vacancies on the surface, consequently bolstering photocatalytic performance. This exemplifies a noteworthy approach for significantly enhancing the photocatalytic activity of Ta2O5-x, providing valuable insights for future design strategies.

Crystallinity control on Bi2MoO6 microspheres for improved photocatalytic oxygen evolution

Crystallinity of the photocatalyst has a profound impact on its reactivity. Here, flower-like Bi2MoO6 microspheres were synthesized via a solvothermal method and subsequently calcined at varying temperatures to regulate the crystallinity and particle size. The thermally treated samples exhibited enhanced photocatalytic oxygen evolution compared to the pristine Bi2MoO6. Higher calcination temperatures led to the formation of larger crystallites, significantly boosting the activity. We demonstrate that crystallinity, rather than surface area, plays a more vital role in governing the photocatalytic performance of Bi2MoO6. Improved crystallinity can thicken the space charge layer (SCL), resulting in a greater band bending that facilitates the separation of electron-hole pairs. Conversely, poor crystallinity leads to an abundance of surface and bulk defects, promoting electron-hole recombination. Overall, efficient charge separation and suppressed recombination endow the calcined Bi2MoO6 with enhanced water oxidation efficiency.

Ferrocene-based 2D metal–organic framework nanosheet for highly efficient photocatalytic seawater uranium recovery

Sustainable uranium supply is critical for the long-term development of nuclear energy. The photocatalytic reduction of soluble hexavalent uranium to insoluble tetravalent uranium using photocatalysts has been recognized as a highly promising method for uranium recovery. However, existing photocatalysts face limitations such as restricted visible-light absorption and poor charge transfer capability, which hinder their photocatalytic uranium recovery performance. In this work, 1,1′-ferrocene dicarboxylic acid (FcDA) was introduced to synthesize the photocatalyst Zr-Fc-MOF3. The incorporation of FcDA broadened the visible light absorption range and reduced the band gap of Zr-Fc-MOF3, thereby enhancing electron-hole pair separation and carrier transport efficiencies. Moreover, the two-dimensional (2D) nanosheet structure of Zr-Fc-MOF3 provided a large surface area, allowing full exposure of active sites. Additionally, Fe(II) in FcDA generated photoelectrons upon light excitation to facilitate uranium reduction, and the recyclable redox behavior of Fe(II) conferred high reusability of the photocatalyst. Consequently, Zr-Fc-MOF3 demonstrated a high photocatalytic uranium recovery capacity of 8.29 mg g−1 over 10 days in nature seawater (NSW), with a uranium recovery rate of 0.829 mg g−1 d−1, surpassing most other photocatalysts applied in NSW. These findings suggest that designing 2D nanosheet materials with ligands capable of efficient photoelectron generation is a promising approach for developing high-performance uranium recovery photocatalysts.

Enhanced photocatalytic degradation of toluene on surface C- and CN-modified TiO2 microspheres

Surface modified TiO2 materials are widely used in photocatalytic environmental purification processes. The employment of solution might exert a discernible influence on the catalyst. In this study, we incorporated tetrahydrofuran (THF) and pyrrolidine (PY) during the hydrolysis of titanium butoxide (TBOT) to modify the surface of TiO2, successfully synthesizing surface C-modified TiO2 (THF-TiO2) and surface CN-modified TiO2 (PY-TiO2) catalysts. The assistance of THF and PY not only reduced agglomeration, but also increased the specific surface area of both catalysts, leading to the exposure of more active sites in TiO2 during the photocatalytic degradation of toluene. When compared to the unsatisfactory degradation of toluene (80%) and CO2 mineralization efficiencies (40–45 %) observed using unmodified TiO2, the synthesized THF-50-TiO2 and PY-1-TiO2 microspheres demonstrated enhanced toluene degradation efficiency to 100 % and 99.8 %, respectively, and improved mineralization efficiencies to 76 % and 80 % after 120 min of ultraviolet irradiation. The experimental data and characterization results indicate that the surface-modified carbon species in THF-50-TiO2 facilitate the acceleration of electron-hole pair separation and suppress recombination. In contrast, partial nitrogen species introduced into the surface lattice of PY-1-TiO2 narrow its band gap and induce a visible light response. Overall, this study provides two methods to modify the surface of TiO2, which can be applied to prepare outstanding photocatalysts for possible application in the degradation of volatile organic compounds (VOCs) present in the air. Furthermore, it has been confirmed that solution have a significant impact on the catalyst.

Reasonably construct GDY/CeO2/Mn0.2Cd0.8S double S-scheme heterojunction for improvement photocatalytic hydrogen production

Reasonably designing and optimizing the structure of photocatalysts aims to effectively enhance light absorption, accelerate charge separation and transfer, and achieve sustainable photocatalytic hydrogen production. In this study, a simple self-assembly method was used to prepare the GDY/CeO2/Mn0.2Cd0.8S ternary system. The addition of GDY and CeO2 significantly enhances the light absorption range of Mn0.2Cd0.8S, enhancing the separation and transmission of electron hole pairs and provides more active sites for hydrogen production. Moreover, an S-scheme heterojunction was constructed between the three catalysts, maximizing their oxidation–reduction ability. In addition, the built-in electric field formed between the catalysts also provides power for electron transfer, ensuring efficient and orderly reaction. This work provides ideas for the rational construction of heterojunctions, improving charge transfer, and designing high-performance catalysts to solve energy problems.

Sulfur-Vacancy-Engineered Two-Dimensional Cu@SnS2-x Nanosheets Constructed via Heterovalent Substitution for High-Efficiency Piezocatalytic Tumor Therapy.

Ultrasound (US)-mediated piezocatalytic tumor therapy has attracted much attention due to its notable tissue-penetration capabilities, noninvasiveness, and low oxygen dependency. Nevertheless, the efficiency of piezocatalytic therapy is limited due to an inadequate piezoelectric response, low separation of electron-hole (e--h+) pairs, and complex tumor microenvironment (TME). Herein, an ultrathin two-dimensional (2D) sulfur-vacancy-engineered (Sv-engineered) Cu@SnS2-x nanosheet (NS) with an enhanced piezoelectric effect was constructed via the heterovalent substitution strategy of Sn4+ by Cu2+. The introduction of Cu2+ ion not only causes changes in the crystal structure to increase polarization but also generates rich Sv to decrease band gap from 2.16 to 1.62 eV and inhibit e--h+ pairs recombination, collectively leading to the highly efficient generation of reactive oxygen species under US irradiation. Moreover, Cu@SnS2-x shows US-enhanced TME-responsive Fenton-like catalytic activity and glutathione depletion ability, further aggravating the oxidative stress. Both in vitro and in vivo results prove that the Sv-engineered Cu@SnS2-x NSs can significantly kill tumor cells and achieve high-efficiency piezocatalytic tumor therapy in a biocompatible manner. Overall, this study provides a new avenue for sonocatalytic therapy and broadens the application of 2D piezoelectric materials.