Search

The development of efficient blue thermally activated delayed fluorescence (TADF) emitters with an aggregation-induced emission (AIE) nature, for the construction of organic light-emitting diodes (OLEDs), is still insufficient. This can be attributed to the challenges encountered in molecular design, including the inherent trade-off between radiative decay and reverse intersystem crossing (RISC), as well as small singlet–triplet energy splitting (ΔEST) and the requirement for high photoluminescence quantum yields (ΦPL). Herein, we present the design of three highly efficient blue TADF molecules with AIE characteristics by combining π-extended donors with different acceptors to modulate the differences in the electron-donating and electron-withdrawing abilities. This approach not only ensures high emission efficiency by suppressing close π–π stacking, weakening nonradiative relaxation, and enhancing radiative transition but also maintains the equilibrium ratio between the triplet and singlet excitons by facilitating the process of RISC. These emitters exhibit AIE and TADF properties, featuring quick radiative rates and low nonradiative rates. The ΦPLof these emitters reached an impressive 88%. Based on their excellent comprehensive performance, nondoped PICzPMO and PICzPMO OLEDs achieved excellent electroluminescence performance, exhibiting maximum external quantum efficiency (EQEmax) of up to 19.5%, while the doped device achieved a higher EQEmaxof 20.8%. This work demonstrated that by fusing π-extended large rigid donors with different acceptors, it is possible to regulate the difference in electron-donating and electron-withdrawing abilities, resulting in a small ΔEST, high ΦPL, and fast RISC process, which is a highly feasible strategy for designing efficient TADF molecules.

The construction of Z-scheme heterostructures using matching band semiconductors is an effective strategy for producing highly efficient photocatalysts. In this study, MgIn2S4(MIS) was grown in situ on In2O3microrods created with an In-based MOF material (In-MIL-68) as a template to successfully establish a unique MIS-In2O3heterojunction with a well-matched Z-scheme interface charge transfer channel. Tetracycline (TC) as a typical antibiotic was chosen as the target pollutant to evaluate the photocatalytic activity. After 120 min of visible light irradiation, the MIS-In2O3-(10:1) material had the greatest photocatalytic degradation activity of tetracycline with 96.55%, which was 2.39 and 4.26 times that of MIS and In2O3, respectively. The improved photocatalytic activity is attributed to the in situ growth of MIS on In2O3, forming a Z-scheme heterojunction at the interface, which not only increases the specific surface area, exposes the abundant active site, and improves light utilization but also facilitates the migration and separation of photogenic carriers. The photocatalytic degradation products of TC were detected by liquid chromatography–mass spectrometry (LC-MS), and a preliminary degradation pathway was proposed. Radical capture experiments and ESR analysis confirmed that the main active species were holes (h+), superoxide radicals (•O2–), and superoxide and hydroxyl radicals (•OH). Finally, combined with band position analysis, this study proposes a direct Z-scheme heterojunction mechanism to improve the photocatalytic degradation of tetracycline in MIS under visible light.

The fabrication of S-scheme heterojunctions with fast charge transfer and good interface contacts, such as intermolecular π–π interactions, is a promising approach to improve photocatalytic performance. A unique two-dimensional/two-dimensional (2D/2D) S-scheme heterojunction containing TpPa-1-COF/g-C3N4nanosheets (denoted as TPCNNS) was developed. The established maximum interfacial interaction between TpPa-1-COF NS and g-C3N4NS may result in a π–π conjugated heterointerface. Furthermore, the difference in the work functions of TpPa-1-COF and g-C3N4results in a large Fermi level gap, leading to upward/downward band edge bending. The spontaneous interfacial charge transfer from g-C3N4to TpPa-1-COF at the π–π conjugated interface area results in the presence of a built-in electric field, according to the charge density difference analysis based on density functional theory calculations. Such an enhanced built-in electric field can efficiently drive directional charge migration via the S-scheme mechanism, which enhances charge separation and utilization. Thus, an approximately 2.8 and 5.6 times increase in the photocatalytic hydrogen evolution rate was recorded in TPCNNS-2 (1153 μmol g−1h−1) compared to pristine TpPa-1-COF and g-C3N4NS, respectively, under visible light irradiation. Overall, this work opens new avenues in the fabrication of 2D/2D π–π conjugated S-scheme heterojunction photocatalysts with highly efficient hydrogen evolution performance.

Recently, the seawater desalination process has gained widespread attention due to lack of drinking water. Among several membrane distillation methods for desalination, vacuum membrane distillation (VMD) is one of the emerging technologies that has mostly focused. In this study, an integrated heat and mass transfer model for the VMD process is established and the simulation results are validated with experimental data available in the literature. The numerical model is solved using in-house coding in Mathcad. The effect of some influential process parameters like feed circulation velocity, feed temperature, salinity, and heat transfer coefficient (HTC) on VMD flux is investigated. Moreover, the influence of some membrane characteristics like membrane porosity, membrane pore size and membrane thickness on permeate flux is also considered. Furthermore, the effect of some operating parameters on temperature polarization is also presented in this paper. Results of the numerical model indicated that the VMD flux enhanced with an increase in velocity, feed temperature, membrane porosity, membrane pore size, and HTC, whereas permeate flux declined with an increase in salt concentration, vacuum pressure, and membrane thickness. The maximum increase in permeate flux was 21.62 kg/m2h by increasing feed temperature from 35°C to 65°C at a constant feed velocity of 1.0 m/s. Additionally, it was confirmed that an optimum value of the membrane parameter is preferable for a substantial improvement in overall VMD performance.

In this paper, we developed an integrated model of coal gasification with methanol synthesis reactor using Aspen Plus®. Gasification process and methanol synthesis are modelled and simulated based on low grade coal of Thar coalfield. After validation of the simulation results with experimental data, the thermodynamic analysis of integrated process is carried out to predict the optimal methanol yield. Moreover, the influence of reactor operating temperature and pressure, CO2/H2ratio and amount of catalyst, on the methanol synthesis is investigated. The results indicated that for coal input feed of 60 kg/s, the syngas flow rate of 9.4 kg/s was obtained in the gasification section. Whereas, the optimal methanol yield of 23.8% and 28.2% are obtained for Vanden Bussche (VB) and Graaf model, respectively in methanol synthesis reactor. Furthermore, the optimal operating temperature in methanol reactor was 210°C and 240°C for Graaf model and VB model, respectively.

WO3, a visible-light responsive photocatalyst, absorbs light up to 480 nm with several intriguing advantages such as low cost, harmlessness, and stability in acidic and oxidative conditions. In this review, the relationship between the morphology control and the photocatalytic activity of WO3is analyzed in detail. In particular, the WO3exposed {002}-dominant facet with high-surface-energy generally shows excellent photocatalytic performance, and the quantum-confined WO3nanoparticles exhibit a promising future. Furthermore, some main strategies for improving the photocatalytic activity of WO3, such as surface hybridization with graphene, noble metal deposition, semiconductor coupling, and alkali hydroxide loading, are systematically summarized and highlighted. In the noble metal/WO3composite, the noble metal always works as an electron pool and catalyzes O2reduction through a multi-electron reduction process to form H2O2and H2O instead of the traditional single-electron process. In addition, the preparation methods, photocatalytic enhancement factors and possible photocatalytic mechanisms for the WO3/semiconductor composites are described. Moreover, various photocatalytic applications of WO3-based photocatalysts, such as photodegradation of organics, air purification, self-cleaning, CO2photoreduction, heavy metal ion treatment, hydrogen evolution from splitting water, and bacterial disinfection, are introduced and summarized. Finally, the main conclusions and future perspectives of WO3-based photocatalysts are pointed out. It is anticipated that this review could offer guidelines for designing novel WO3-based photocatalysts with low cost and high efficiency, which can possess promising prospects of application to meet the urgent demands of highly efficient solar energy conversion in the areas of renewable energy and environmental purification.

Bismuth vanadate (BiVO4) is a promising photocatalyst for water pollution degradation and photocatalytic oxygen evolution. In this work, we prepared 2D/2D BiVO4–Bi4V2O10heterostructure with tight interfacial contact via a facile one-step hydrothermal process. The crystal structure and morphology of the samples could be easily regulated by changing the pH values of the solution. The BiVO4–Bi4V2O10heterostructure exhibited an enhanced photodegradation rate of Cr(VI) and oxygen evolution that of bare BiVO4, indicating that the synergistic effect and the interfacial fusions between BiVO4and Bi4V2O10can effectively promote the migration and separation rate of photoexcited charge carriers.

High-color purity organic emitters with a simultaneous combination of aggregation-induced emission (AIE) and thermally activated delayed fluorescence (TADF) characteristics are in great demand due to their excellent comprehensive performances toward efficient organic light-emitting diodes (OLEDs). In this work, two D−π–A-structure emitters, ICz-DPS and ICz-BP, exhibiting AIE and TADF properties were developed, and both the emitters have narrow singlet (S1)–triplet (T1) splitting (ΔEST) and excellent photoluminescence (PL) quantum yields (ΦPL), derived from the distorted configurations and weak intra/intermolecular interactions, suppressing exciton annihilation and concentration quenching. Their doped OLEDs based on ICz-BP provide an excellent electroluminescence external quantum efficiency (ηext) and current efficiency (ηC) of 17.7% and 44.8 cd A–1, respectively, with an ηextroll-off of 2.9%. Their nondoped OLEDs based on ICz-DPS afford high efficiencies of 11.7% and 30.1 cd A–1, with pure-blue emission with Commission Internationale de l’Éclairage (CIE) coordinates of (0.15, 0.08) and a low roll-off of 6.0%. This work also shows a strategy for designing AIE–TADF molecules by rational use of steric hindrance and weak inter/intramolecular interactions to realize high ΦPLvalues, fast reverse intersystem crossing process, and reduced nonradiative transition process properties, which may open the way toward highly efficient and small-efficiency roll-off devices.