Photocatalytic Activity Research Articles

In-situ preparation of BiOBr/Bi-doped CsPbBr3 S-scheme heterojunction for efficient photocatalytic CO2 reduction

Metal halide perovskite nanocrystals have garnered significant attention in the realm of photocatalytic CO2 reduction in recent years owing to their remarkable reducing properties and high selectivity. However, the issue of low photocatalytic activity due to severe carrier recombination phenomena in perovskite has posed a significant challenge. To address this, a one-pot in-situ preparation strategy was employed to create a BiOBr/Bi-doped perovskite nanocrystal S-scheme heterojunction, resulting in a significant improvement in the CO2 photoreduction performance. The heterojunction material exhibited a CO yield of 151.56 μmolg-1h−1, with a selectivity for CO of 93.6 %. The molar ratio of the components was modulated using an in-situ water aging strategy, yielding a photocatalyst performance that exceeded that of pure BiOBr. The synthesis strategy of one-step in-situ preparation of heterojunctions overcomes the problem of insufficient bonding caused by two-step methods. And various characterizations and DFT calculations strongly support the S-scheme mechanism of the photocatalyst. The active site effectively reduces the energy barrier for the transition from *COOH to *CO intermediate, thereby significantly improving photocatalytic activity.

Visible-light photocatalytic performance of SrTiO3 nanoparticles modified with cobalt.

In this article, an experimental study on the photocatalytic performance of SrTi1-yCoyO3 nanoparticles (with y = 0.0, 0.03, 0.06, and 0.09) synthesized by the Pechini-type sol-gel method is presented. The crystalline structure analysis revealed that all the samples exhibited the cubic perovskite phase of SrTiO3. In particular, the SrTi0.91Co0.09O3 sample was found to consist of rough spherical-like particles with an average size of 26 ± 0.5 nm. Cobalt ions with 2+ and 3+ oxidation states are responsible for modifying the electronic band structure of the semiconductor and a narrowing of optical band gap from 3.1 to 1.08 eV. The resulting Co-doped SrTiO3 nanoparticles exhibited photocatalytic activity under visible light due to their enhanced light absorption, effective charge transport and effective surface chemisorption. In particular, the SrTi0.91Co0.09O3 sample exhibited the highest photocatalytic activity with 91% degradation efficiency of methylene blue dye within 120 min of simulated solar irradiation.

Shining light on broad-spectrum responded NaYF4:Yb,Er,Tm@Bi@BiOI: Understanding the enhanced photodegradation performance of bisphenol A and mechanisms

This work reported a novel ternary heterogeneous photocatalyst NaYF4:Yb,Er,Tm@Bi@BiOI (NBEG-6h). NBEG-6h exhibits broad-spectrum absorption from ultraviolet to near-infrared. The elimination efficiency of BPA by NBEG-6h under simulated sunlight and near-infrared light irradiation was 88% (24 min) and 93.9% (160 min), respectively. It also has the universality of degrading various pollutants, good reusability and stability. The exceptional photocatalytic activity can be attributed to the absorption of near-infrared light by NaYF4:Yb,Er,Tm, which improves the total efficiency of sunlight utilization. The localized surface plasmon resonance effect of Bi nanoparticles enhances the light absorption performance of the heterostructure. Furthermore, combining Bi and BiOI accelerates carrier migration and improves the separation efficiency of photogenerated electron-hole pairs. h+, ·O2− and 1O2 play the pivotal roles during the photocatalytic process. This research offers new insights into the design, development, and mechanism understanding of full-spectrum-driven heterostructure photocatalysts. It provides an environmentally sustainable approach to the treatment of harmful organic pollutants.

Design of new CoFe2O4/MXene/NaTaO3 double heterostructures for efficient photodegradation of antibiotic

Facilitating the dissociation and transfer of light-excited electrons and holes in semiconductors is crucially important for enhancing their photocatalytic activities and promoting their photocatalytic application in pollutant elimination. In this study, we have immobilized Ti3C2 (TC) nanoparticles (derived from TC MXene) as well as CoFe2O4 (CFO) nanoparticles on the surface of NaTaO3 (NTO) cubes to construct new CFO/TC/NTO double heterostructure photocatalysts. A series of experiments combined with theoretical calculations evidence the formation of interface electric fields at the TC/NTO and CFO/NTO heterojunction interfaces and efficient photocarrier dissociation/transfer behavior. Simulated-sunlight-driven photodegradation of ciprofoxacin (CIP) demonstrates a significantly enhanced photocatalysis of the heterostructured photocatalysts; particularly, the 40CFO/20TC/NTO, photodegrading 97.7 % of CIP within 60 min, exhibits a photodegradation performance that is enhanced by 3.2 (or 3.5) times over that of bare NTO (or CFO). The interface-field-facilitated dissociation/transfer of photocarriers is the crucial mechanism for the heterostructure-enhanced photocatalysis. Additionally, the photodegradation processes of CIP and potential toxicities of the intermediate products were elucidated. The present study supplies researchers with a significant guidance for designing excellent heterostructured photocatalysts.

Novel S-scheme WO3/ZnO-modified g-C3N4 heterojunction for optimizing norfloxacin photodegradation condition via DoE: Synthesis, characterization, and mechanism evaluation

Norfloxacin, an antimicrobial agent, has been recurrently observed in municipal wastewater facilities, posing a conjectured threat to human health and environmental integrity. Herein, novel ternary heterojunction of WO3/ZnO-modified g-C3N4 was fabricated utilizing the impregnation technique for the organic pollutant degradation, presenting a significant challenge. XRD, XPS, TEM, HR-TEM, SEM, EDS, BET, EIS, Mott-Schottky, ESR, PL, photocurrent, and DRS techniques were used to explore the structural, morphological, textural, and optical features of the produced materials. In this ternary system, ZnO served as an electron transfer conduit, facilitating the formation of a heterojunction interface between the semiconductor constituents. Establishment of the S-scheme within the charge transfer dynamics of the heterojunction markedly augmented charge separation, enhancing the efficacy of the photocatalytic activity. Under optimized conditions via the DoE software (i.e.; photocatalyst dosage: 0.54 g/L, NOR concentration: 25.87 mg/L, Irradiation time: 41.71 min and pH: 6.9), 97.19 % of NOR elimination was achieved by the optimized 20-WZC photocatalyst with a pseudo-first-order kinetic model (k = 0.05 min−1). ESR data, alongside quenching experiments, corroborated the pivotal involvement of O2−, OH, and h+ in the NOR degradation mechanism. The investigation of NOR's potential decontamination pathways was performed using HRLC-MS. TOC analysis revealed a significant mineralization of 82.45 %, indicating the conversion of NOR into H2O, CO2, and other degradable substances. The optimized photocatalyst also demonstrated notable efficiency in the degradation of Tetracycline: 98.15 %, Ciprofloxacin: 93.27 %, Methylene Blue: 98.89 %, and Enrofloxacin: 91.54 % pollutants. The photocatalytic activity of the 20-WZC catalyst remained consistently high, without significant reduction, over five successive cycles.

G-C3N4 coupled with GO accelerates carrier separation via high conductivity for photocatalytic MB degradation

Graphitic carbon nitride (g-C3N4) is widely utilized in photocatalysis due to its responsiveness to visible light, low cost, and non-toxicity. However, its efficiency is limited by factors such as the rapid recombination of photogenerated electron-hole pairs, slow electron transfer rates, and a limited number of active surface sites. In this study, g-C3N4 was synthesized through thermal polymerization, and varying amounts of graphene oxide (GO) were incorporated via physical blending to fabricate composite photocatalysts. The results indicated that the incorporation of GO not only increased the specific surface area and modified the pore size distribution of g-C3N4 but also affected the heptazine ring structure through chemical bonding, thereby enhancing the density of active sites. Photocatalytic degradation experiments with methylene blue (MB) indicated that g-C3N4 containing 2% GO exhibited photocatalytic activity 2.84 times greater than that of pristine g-C3N4. Kinetic simulations indicated that the Kapp value for the 2% GO-g-C3N4 composite was 0.00469min-1, which is 4.34 times higher than that of pure g-C3N4 (0.00108min-1). Furthermore, this composite maintained high photocatalytic activity after four cycles of reuse. An analysis of the photocatalytic degradation mechanism revealed that the incorporation of GO effectively promoted the separation and transfer of photogenerated electron-hole pairs, enhanced photocurrent density, and improved carrier separation efficiency. Electron spin resonance (ESR) and free radical scavenging experiments confirmed that the primary active species involved in the degradation of MB by the composite photocatalyst were ·O2- and h+. This study presents a novel approach for enhancing the photocatalytic performance of g-C3N4 by modifying its electronic structure and surface properties.

Biochar coupling induced charge transfer switching of a NiAl2O4/NiCr2O4 photocatalyst to enhance photocatalytic degradation of tetracycline hydrochloride

A series of novel (NiAl2O4 (NAO)/NiCr2O4 (NCO)) (S1)/GL heterojunction photocatalysts, denoting as x%GL/S1 (x = 5, 10, 15 and 20), were prepared by the polyacrylamide gel method combined with low temperature sintering technique. Various characterizations confirm that there is special interfacial contact and charge transfer between NAO, NCO and GL. The 10%GL/S1 heterojunction exhibited the best photocatalytic activity and cyclic stability for the degradation of tetracycline hydrochloride (TC). Compared to NAO, NCO and NAO/NCO, the degradation efficiency of 10%GL/S1 was significantly improved, and the degradation percentage reached 83.2% within 30 min. The activity of 10%GL/S1 was studied in relation to catalyst content, drug concentration, pH value, water quality, and co-existing anion. Trapping experiments and free radical verification experiments confirmed that the holes, hydroxyl radicals and superoxide radicals played crucial roles in the photocatalysis process. Possible pathways for TC degradation were studied by HPLC-MS, and the ecotoxicity of TC and its degradation intermediates was evaluated by T.E.S.T. software. The charge transfer and photocatalytic mechanisms confirm that the introduction of GL enhances the interfacial interaction between the components, promotes the carrier migration efficiency, provides a large number of active sites for 10%GL/S1 heterojunction, and produces active free radicals after redox reaction with photoinduced electrons, effectively improving the degradation efficiency of TC.

Enhanced photocatalytic performance of (Mg, Cu) Dual-Doped ZnS nanosheets for Solar-Driven water treatment and embedded with PVA polymer membrane for reusability

Photocatalysis uses semiconductor materials to solar energy effectively purify to water by eliminating pollutants. Organic Dye degradation serves as a standard to assess the photocatalytic effects of the materials. In this study Mg, Cu dual-doped ZnS nanosheets were synthesized using the coprecipitation method. The impact of the concentration on the structural, morphology, optical, and degradation efficiency was investigated with XRD, XPS, TEM with EDAX, and UV spectroscopy. The pure ZnS and Zn0.98-xCu0.02MgxS (x = 0, 0.01, 0.02) (ZCM1, ZCM2, ZCM3, and ZCM4) nanosheets, exhibited cubic structure with high phase purity. The average crystalline size was calculated as 1.66, 1.60, 1.45, and 1.47 nm for the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets, respectively. TEM analysis revealed the presence of crumpled nanosheets. The bandgap of the ZCM1, ZCM2, ZCM3, and ZCM4 nanosheets were 3.99, 3.78, 4.03, and 4.09 eV respectively. This study investigated the photocatalytic activity of crystal violet dye when exposed to natural sunlight irradiation. Notably, ZCM3 nanosheets exhibited a high degradation rate of 99 % over 120 min under sunlight. Furthermore, the proposed dye degradation mechanism, effect of dosage, effect of dye variation, reusability, scavenging activity, and hemolytic activity were comprehensively discussed. The nanosheets embedded with the Polyvinyl alcohol (PVA) polymer membrane for reusability.

Investigation of the Effects of Different Phases of TiO2 Nanoparticles on PVA Membranes

Introduction: PVA/TiO2 nanocomposite membranes are prepared by solution casting technique where different phases of TiO2 nanoparticles like brookite, brookiterutile and rutile are dispersed in PVA matrix. Sol-gel method was employed to prepare TiO2 nanoparticles, while different phases of TiO2 have been obtained by controlling the calcination temperature. Methods: PVA/TiO2 nanocomposite membranes were characterized by XRD, FTIR, AFM, TEM, UV-visible and PL techniques. XRD results confirmed the presence of different phases of TiO2, exhibiting 3.3 nm, 8.4 nm, and 35.7 nm mean crystalline size. The XRD studies also confirmed that TiO2 nanoparticles became properly dispersed to the PVA matrix, leading to increased PVA crystallinity after doping of different phases of TiO2 nanoparticles. UV-visible analysis revealed an increase in absorption intensity and peak position shifts slightly towards longer wavelengths, which indicates that nanofillers tuned the band gap of PVA. The doping of the TiO2 (brookite) phase in the PVA matrix results in a decreased in PL intensity. Results: This suggests that the PVA/TiO2 (brookite) membrane exhibits a greater degree of photocatalytic activity in comparison to the other two composites. According to the FTIR investigation, the hydroxyl (OH) groups present in PVA interact with the dopants Ti+ ions via intra- and intermolecular hydrogen bonds to produce charge transfer complexes (CTC). The AFM study shows surface roughness details for PVA and PVA/TiO2 composite membranes. The average grain size of TiO2 nanoparticles calculated from TEM images is in good agreement with the grain size calculated by XRD. Conclusion: By adjusting the phase of TiO2 nanoparticles into PVA matrix, composites can be developed that are optimized for a variety of applications such as water purification, UV protection, self-cleaning surfaces, lithium-ion batteries, and optoelectronic devices.

Synergistic Role of Indium Doping and g-C3N4 Reinforcement in Boosting the Visible Light-Triggered Rhodamine B and Diclofenac Sodium Salt Degradation over Rare Earth Molybdate

Designing and fabricating cost-efficient and eco-friendly photocatalysts for removing organic pollutants from wastewater streams is a crucial research objective for effectively managing industrial effluents to tackle environmental sustainability issues. In this study, we prepared bare cerium molybdate (Ce2(MoO4)3, M1) and indium-doped cerium molybdate (In- Ce2(MoO4)3, M2) photocatalysts via a hydrothermal method. We then synthesized a nanocomposite of In- Ce2(MoO4)3 (M3) with the promising material graphitic carbon nitride (g-C3N4) using an ultrasonication approach. The synthesized photocatalysts were effectively applied to degrade the Rhodamine B dye and diclofenac sodium salt (a drug) from synthetic industrial wastewater through a photocatalysis approach. The impact of indium (In3+) doping on the bare (Ce2(MoO4)3 and the strong interaction between the (In-Ce2(MoO4)3 and g-C3N4 nanosheets were analyzed through physical and electrochemical techniques, including SEM, EDS, XRD, FTIR, UV-Vis spectroscopy, and EIS analysis. The comprehensive photocatalytic degradation of dye and the drug via first-order kinetic parameters under visible light irradiation for all the prepared catalyst samples was evaluated. The nanocomposite In-Ce2(MoO4)3/g-C3N4 exhibited excellent photocatalytic activity, degrading the maximum amount of RhB dye and drug (RhB:96%, drug:87%) in 90 minutes with a higher rate constant (k) compared to In-Ce2(MoO4)3 (RhB:69%, drug:56%) and Ce2(MoO4)3 (RhB:56%, drug:38%). Furthermore, the In-Ce2(MoO4)3/g-C3N4 samples produced a 7-fold and 3-fold increase in transient photogenerated current response compared to pristine Ce2(MoO4)3 and In-Ce2(MoO4)3 samples, respectively. These findings pave the way for synthesizing an economical, versatile, and efficient In-Ce2(MoO4)3/g-C3N4 photocatalyst to eliminate pollutants from industrial wastewater streams and boost environmental sustainability.

Enhanced photocatalytic hydrogen evolution via yolk–heteroshell TiO2@TiO2/SiO2 nanoreactor with confined Pt nanoparticles

The upper limit of photocatalytic efficiency is largely determined by the light-harvesting capability of a semiconductor. To address this challenge, we developed a yolk-heteroshell TiO2@TiO2/SiO2 (T@T/S) nanoreactor, leveraging a novel design based on an in-depth understanding and innovative utilization of light-matter interactions. The T@T/S nanoreactor significantly enhances solar light capture and utilization efficiency through total internal reflection mechanisms facilitated by the heterogeneous shell. This heteroshell, consisting of an outer SiO2 shell an inner monolayer of TiO2 nanoparticles, maximizes light confinement due to the different refractive indices of SiO2 and TiO2, while also minimizing mass transfer resistance due to the thin inner shell layer. These unique structural features result in high photocatalytic activity under simulated solar light. Additionally, we successfully applied a “ship-in-a-bottle” strategy for the confined growth of platinum nanoparticles within T@T/S nanoreactor. The Pt0.5-T@T/S nanoreactors demonstrated excellent hydrogen production, achieving a hydrogen evolution rate of 24.43 mmol g−1h−1 under simulated sunlight and an apparent quantum efficiency (AQE) of 7.8 % at 350 nm. This study highlights the importance of nano-engineered designs in optimizing semiconductor photocatalysts and shows the significant potential of our approach for sustainable energy conversion and environmental protection.

Facile fabrication of BiOI/ZIF-67 Z-scheme heterojunction photocatalyst for visible-light-driven tetracycline degradation

In this paper, a novel Z-scheme BiOI/ZIF-67 photocatalyst (BOI/ZIF) was successfully prepared using an in-situ growth method, and its effectiveness in degrading tetracycline (TC) under visible light was assessed. Using a range of characterization techniques, the crystal structure, elemental composition, microstructure and optical characteristics of the composite catalyst were examined. Simultaneously, a 30% mass ratio catalyst (BOI/ZIF-30) could remove 91% of TC under visible light, which was 41% and 28% greater than the degradation rates of BiOI and ZIF-67, respectively. These results demonstrated that BOI/ZIF exhibited strong photocatalytic activity and excellent stability. The results of the radical quenching experiment and electron spin resonance revealed that h+ and •O2− were the principal chemical substances responsible for TC degradation, corresponding with the suggested charge transfer mechanism of Z-scheme heterojunction. The Z-scheme heterojunction created between BiOI and ZIF-67 improved the effective separation of photogenerated carriers and boosted the efficiency of TC degradation. This study offers a promising method for designing photocatalytic systems to break down antimicrobial contaminants.

Photocatalytic ZnIn2S4 for 2-Mercaptobenzothiazole Degradation: Facile Synthesis, Influencing Factors and Mechanism

The development of an efficient, stable and environmentally friendly semiconductor photocatalyst is great research significance in the field of environment and energy. In this paper, ZnIn2S4 semiconductor photocatalysts with flower-like hierarchies were prepared by simple and environmentally friendly method. The influence of ZnIn2S4 dosage, pH and different inorganic salt ions on the photocatalytic degradation of 2-mercaptobenzothiazole (MBT) under visible light was investigated in detail. The results showed that the photocatalyst dosage was 0.05 g, and the photocatalytic degradation efficiency of MBT was the highest in the weakly acidic environment with pH was five. Meanwhile, the addition of some inorganic anions has a significant inhibitory effect on the photocatalytic activity of ZnIn2S4 semiconductor photocatalyst, while cations have less effect. Moreover, the ZnIn2S4 semiconductor photocatalyst had excellent stability and recyclability, and its photodegradation mechanism had been deeply studied. This work provides a theoretical and experimental foundation for exploring the different influencing factors of photocatalytic degradation of organic pollutants in wastewater by other semiconductors.

Kinetic Insights into Solar-Assisted Fabrication and Photocatalytic Performance of CoWO4/NCW Heterostructure

This work studies the kinetic model for the solar-driven fabrication of CoWO4/NCW heterostructure photocatalysts and investigates their enhanced photocatalytic degradation activity. The synthesis of CoWO4/NCW, its characterization, and the kinetic aspects of photocatalytic degradation under solar light. New nanocomposite prepared from Nano cellulose (NCW) by hydrolysis cotton waste (CW) by nitric acid and cobalt tungstate (CoWO4) prepared from sodium tungstate and cobalt chloride by wet chemical method and characterized through XRD, FTIR, EDX, and FE-SEM analyses. The composite's performance in organic oxidation from refinery wastewater (RWW) was evaluated under solar light. The high removal ratio was 97.4% for organic pollutants (OP) in refinery wastewater. The results indicate that the heterostructure exhibits improved photocatalytic performance compared to individual components, which kinetics model was the best to represent the photocatalytic degradation of organic pollutants from oily wastewater over the heterostructure CoWO4/NCW catalyst. Add future applications of this finding in the relevant industries. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Improving Photocatalytic Efficiency with Titanium Dioxide Quantum Dots

Titanium dioxide quantum dots (TiO2-QDs), synthesized using a microwave-assisted method, represent a significant advancement in photocatalysis, particularly in the treatment of environmental pollutants. This study focuses on TiO2-QDs synthesized at 200°C for a duration of 5 minutes, using titanium butoxide as a precursor. Characterization through TEM, XRD, PL, and UV-Vis-DRS analyses revealed uniform quantum dots with an average size of 5.28 nm, a bandgap energy of 3.22 eV, and a crystalline anatase phase, indicative of high photocatalytic activity. Notably, these TiO2-QDs demonstrated exceptional performance in degrading methylene blue (MB) in water, achieving a remarkable treatment efficiency of 97.6% in 120 min, significantly outperforming both conventional titanium dioxide nanoparticles and commercial titanium dioxide materials. The reaction conditions were evaluated based on factors such as catalyst dose, initial MB concentration, and pH. The results indicate that optimal degradation efficiency of MB was achieved at a pH of 7, with a catalyst dose of 0.15 g/L and at a low MB concentration. The efficiency slightly decreased to 94.5% after five reuse cycles, emphasizing its significant reusability and stability. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Fabrication of Zn and Ti-loaded Carbon-silica Composite Derived from Gelatin Template for the Photodegradation of Methylene Blue

Carbon-silica nanocomposites (CSNs) from gelatin as a carbon source and natural template and TEOS as a silica source have been successfully synthesized and impregnated into ZnO and TiO2 photocatalysts. The structural, morphological, and textural properties and photocatalytic activity for methylene blue degradation of TiO2/CSNs and ZnO/CSNs were investigated. XRD data revealed that TiO2/CSNs and ZnO/CSNs had different structural characteristics with similar crystallinity. FTIR spectra demonstrated the presence of Zn–O and Ti–OC bonds, respectively, at about 500-450 cm-1 and 1500 cm-1. The morphological surface exhibited stacked tubular shapes of TiO2/CSNs and ZnO/CSNs with the primary elements of Ti, Zn, Si, C, and O. The nitrogen adsorption-desorption curves revealed both micropores and mesopores of TiO2/CSNs and ZnO/CSNs where the surface area reduced due to the blocking pore after impregnation. Moreover, ZnO/CSNs verified a higher degradation percentage against methylene blue than that of TiO2/CSNs. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

Optimal Suppression of Photocatalytic Activity of Hybrid TiO2 Particles in Epoxy Thin Film by Using Taguchi Method

In this study, two different Al2O3-TiO2 and SiO2-TiO2 hybrid TiO2 particles were synthesised by using silica (SiO2) and alumina (Al2O3) to suppress the photocatalysis of TiO2. Key variables such as the concentration of the hybridization material (C), heating temperature (Th), and calcinating temperature (Tc) were selected with performance measured by photodegradation rate. The Taguchi L9 orthogonal array, a systematic approach used in the design of experiments (DOE), confirmed A333 (Al2O3-TiO2) achieved 99% photodegradation suppression with photodegradation rate reduced significantly from 0.01305 min−1 to 0.00009 min−1 and improved yellowing resistance by 63%, while S323 (SiO2-TiO2) achieved 75% suppression with photocatalysis activity decreased from 0.01305 min−1 to 0.0033 min−1 and 42% improved resistance. X-ray Diffraction (XRD) analysis showed A333 had a higher rutile phase (40.1% vs. 10.2% for S323), and Fourier Transform Infra Red (FTIR) and Field Emission Scanning Electron Microscopy (FESEM) analyses revealed A333's rougher surface and lower surface area compared to S323 and pure TiO2. Overall, A333 effectively suppressed photocatalysis and improved yellowing resistance of epoxy thin film. Copyright © 2024 by Authors, Published by BCREC Publishing Group. This is an open access article under the CC BY-SA License (https://creativecommons.org/licenses/by-sa/4.0).

A Supramolecular-Nanocage-Based Framework Stabilized by π-π Stacking Interactions with Enhanced Photocatalysis.

π frameworks, defined as a type of porous supramolecular materials weaved from conjugated molecular units by π-π stacking interactions, provide a new direction in photocatalysis. However, such examples are rarely reported. Herein, we report a supramolecular-nanocage-based π framework constructed from a photoactive Cu(I) complex unit. Structurally, 24 Cu(I) complex units stack together through π-π stacking interactions, forming a truncated octahedral nanocage with sodalite topology. The inner diameter of the nanocage is 2.8 nm. By sharing four open faces, each nanocage connects with four equivalent ones, forming a 3D porous π framework (π-2). π-2 shows good thermal and chemical stability, which can adsorb CO2, iodine, and methyl orange molecules. More importantly, π-2 can serve as a photocatalyst for hydrogen evolution reaction. With ultrafine Pt subnanometer particles (0.9±0.1 nm) incorporated into the nanocages as a co-catalyst, the hydrogen evolution rate reaches a record-high value of 524012 μmol/gPt/h in the absence of any additional photosensitizers. The high photocatalytic activity can be ascribed to the ultrafine size of the Pt particles, as well as the fast electron transfer from π-2 to the highly active Pt upon illumination. π-2 represents the unique stable supramolecular-cage-based π framework with excellent photocatalytic activity.

Preparation of SnO2/TiO2 composite photocatalysts using yeast and their catalytic performance

Constructing coupled semiconductor photocatalysts is an important approach to improve the photocatalytic activity of TiO[Formula: see text]. Herein, SnO[Formula: see text]/TiO[Formula: see text] composite photocatalysts were successfully synthesized through a hydrothermal method using yeast as a biological template. The as-obtained products were characterized by X-ray diffraction, Fourier-transformed infrared spectroscopy, scanning electron microscopy (SEM), ultraviolet-visible spectra and nitrogen adsorption/desorption testing methods. Results showed that the nano-sized SnO[Formula: see text] particles could be solvothermally synthesized at 150–180[Formula: see text]C, and the C=O and C–O groups in the yeast were the main capping ligands of the SnO[Formula: see text] particles, playing a key role in the synthesis of SnO[Formula: see text]. SEM demonstrated that the SnO[Formula: see text]/TiO[Formula: see text] composites possessed very loose structures and good uniformity. Finally, the application experiment showed that the as-obtained SnO[Formula: see text]/TiO[Formula: see text] composites exhibited exceptional effectiveness in degrading Rhodamine B.

General Synthesis of Single-Crystalline Ta2O5 Nanorods Towards Enhanced Photocatalytic H2 Production Activity.

As a potential candidate for photocatalytic H2 production from water splitting, Ta2O5 catalyst presents suitable conduction and valence band positions, but suffers from poor charge transfer ability, which seriously limits its photocatalytic performance enhancement. Here, a facile and eco-friendly hydrothermal method was developed for the fabrication of one-dimensional (1D) Ta2O5 nanorods using the freshly precipitated tantalic acids as the precursors. An oriented attachment mechanism was proposed for the growth of Ta2O5 nanorods. Moreover, the present synthetic approach was further extended to direct synthesis of nine kinds of alkaline tantalates and alkaline-earth tantalates nanostructures, suggesting its general applicability. A significant increase in activity in photocatalytic H2 production was revealed on 1D Ta2O5 nanorods. The improved photocatalytic H2 production activity of Ta2O5 nanorods was mainly attributed to its 1D nanorods structure with high crystallization and large specific surface areas as well as excellent charge transfer efficiency.