Highly stable and durable ZnIn2S4 nanosheets wrapped oxygen deficient blue TiO2(B) catalyst for selective CO2 photoreduction into CO and CH4.

Developing new and highly stable efficient photocatalysts is crucial for achieving high performance and selective photocatalytic CO2 conversion. In this paper, we designed a one-dimensional oxygen-deficient blue TiO2(B) (BT) catalyst for improved electron mobility and visible light accessibility. In addition, hexagonal ZnIn2S4 (ZIS) nanosheets with a low bandgap and great visible light accessibility are employed to produce effective heterostructures with BT. The synthesized materials are tested for photocatalytic conversion of CO2 into solar fuels (H2, CO and CH4). The optimized composite yields 71.6 and 10.3 µmol g-1h-1 of CO and CH4, three and ten times greater than ZIS, respectively. When ZIS nanosheets are combined with a one-dimensional oxygen-deficient BT catalyst, improved electron mobility and visible light accessibility are achieved, charge carriers are effectively segregated, and the transfer process is accelerated, resulting in efficient CO2 reduction. The photocatalytic CO2 conversion activity of the constructed BT/ZIS heterostructures is very stable over a 10-day (240-hour) period, and CO and CH4 production rates increase linearly with time; however, as time goes on, the rates of H2 production decrease. Further, a five-time recycling test confirmed this, revealing essentially equal activity and selectivity throughout the experiment. As a result, CO2 to CO and CH4 conversion has high selectivity and longer durability. The band structure of the BT/ZIS composite is determined using Mott-Schottky measurement, diffuse reflectance spectroscopy, and valence band X-ray photoelectron spectroscopy. This research demonstrates a novel approach to investigating effective, stable, and selective photocatalytic CO2 reduction systems for solar-to-chemical energy conversion.

Synthesis of carbon molecular sieves from agricultural residues: Status, challenges and prospects.

Adsorption is the most promising technology used in the gas separation and purification process. The key success of this technology relies on the selection of an adsorbent. Activated carbon and zeolites are the most commonly used adsorbents in the separation of particular gas from gaseous mixtures. Activated carbon deriving from fossil and biomass-based resources has wide pore size distribution and thereby results in lower selectivity. Whereas, zeolites synthesized from natural minerals are expensive which increases the cost of the purification process. Taking this into concern, the quest for synthesizing low-cost and effective adsorbents has gained greater attention in recent years. Carbon Molecular Sieves (CMSs), are considered as an attractive alternative to replace the conventional adsorbents. Furthermore, CMSs exhibit higher selectivity and adsorption capacity, due to their narrow micropore size distribution (0.3-0.5 nm). CMSs are synthesized from any organic carbonaceous precursor with low inorganic content. Since most of the agricultural residues fall under this category, they can be used as a feedstock for CMSs production. The synthesis of CMSs involves three stages: carbonization, activation, and pore modification. In this review, physicochemical characteristics of various agricultural residues, the effects of carbonization process parameters, activation methods, and pore modification techniques adopted for producing CMSs are comprehensively discussed. The effect of deposition temperature, time, and flow rate of depositing agent on pore characteristics of CMSs is briefed. The prospects and challenges in CMSs production are also studied. The insights in this review provide guidelines for synthesizing CMSs from agro-residues.

Effective dye degradation by an environment-friendly porous few-layered carbon nitride photocatalyst developed using sequential molecule self-assembly.

Two-dimensional (2D) g-C3N4 (CN) has garnered massive interest for photocatalytic applications owing to its excellent photon contact area, visible-light absorption, and easy transport of photogenerated charge carriers to the surface. However, bulk CN suffers from intrinsically poor charge separation, limited specific surface area, and insufficient visible-light absorption, significantly limiting its photocatalytic efficiency. Exfoliation of bulk crystals into nanosheets with few layers has proven to be an effective and widely used strategy to enhance photocatalytic performance; however, this process is quite complicated, requiring longer times and external energy. Here, a few-layered porous g-C3N4 (PCN) was synthesized using the molecular self-assembly process. This prepared PCN exposes more active sites, leading to enhanced separation of charge carriers, resulting in a higher photocatalytic activity than regular CN. PCN achieved the best photocatalytic degradation (97.46%) of Rhodamine B (RhB) dye in 1 h, which is three times higher than that by CN (32.57%) because of enhanced porosity of the photocatalyst with few layers. This enhanced degradation performance of PCN was caused by increased visible-light absorption and charge separation along with higher number exposed active sites triggered by the high porosity under visible light, which is greater than those of other metal-free photocatalysts reported thus far.

Tuning Band Alignments and Charge-Transport Properties through MoSe2 Bridging between MoS2 and Cadmium Sulfide for Enhanced Hydrogen Production.

Transition-metal dichalcogenide materials play a major role in the state-of-the-art innovations for energy conversion because of potential applications resulting from their unique properties. These materials additionally show inordinate potential toward the progress of hygienic power sources to deal with increasing environmental disputes at the time of skyrocketing energy demands. Herein, we report earth-abundant, few-layered, MoSe2-bridged MoS2/cadmium sulfide (CdS) nanocomposites, which reduce photogenerated electron and hole recombination by effectively separating charge carriers to achieve a high photocatalytic efficiency. Accordingly, the MoSe2-bridged MoS2/CdS system produced effective hydrogen (193 µmol·h-1) as that of water using lactic acid as a hole scavenger with the irradiation of solar light. The presence of few-layered MoSe2 bridges in MoS2/CdS successfully separates photogenerated charge carriers, thereby enhancing the shuttling of electrons on the surface to active edge sites. To the best of our knowledge, this few-layered MoSe2-bridged MoS2/CdS system exhibits the most effective concert among altogether-reported MoS2-based CdS composites. Notably, these findings with ample prospective for the development of enormously real photocatalytic systems are due to their economically viable and extraordinary efficiency.

Designing CdS Mesoporous Networks on Co-C@Co9 S8 Double-Shelled Nanocages as Redox-Mediator-Free Z-Scheme Photocatalyst.

Designing porous nanostructures with unprecedented functionalities and an effective ability to harvest the maximum energy region of the solar spectrum and suppress the charge-carrier recombination rate offers promising potential for sustainable energy production. Although several functional porous nanostructures have been developed, high-efficiency materials are still needed. Herein, we report a new, highly active, noble-metal-free, and redox-mediator-free Z-scheme photocatalyst, CdS/Co-C@Co9 S8 , for H2 production through water splitting under solar irradiation. The designed photocatalytic system contains open 3 D CdS mesopores as a light absorber for wider solar-light harvesting. Metal-organicframework-derived cobalt nanocrystal-embedded few-layered carbon@Co9 S8 double-shelled nanocages were used as a co-semiconductor to hamper the photo charge-carrier recombination by accelerating the photogenerated electrons and holes from the other semiconductor. The optimized catalyst shows a H2 evolution rate of 26.69 mmol g-1 h-1 under simulated solar irradiation, which is 46 times higher than that of the as-synthesized CdS mesoporous nanostructures. The apparent quantum yield reached 7.82 % at λ=425 nm in 5 h. The outstanding photocatalytic activity of CdS/Co-C@Co9S8 reflects the favorable suppression of the charge-carrier recombination rate, as determined by photoluminescence, photocurrent, and impedance analyses. We believe that the findings reported here may inspire the design of new noble-metal-free porous nanohybrids for sustainable H2 production.

Heterostructured WS2 -MoS2 Ultrathin Nanosheets Integrated on CdS Nanorods to Promote Charge Separation and Migration and Improve Solar-Driven Photocatalytic Hydrogen Evolution.

Solar-driven photocatalytic hydrogen evolution is important to bring solar-energy-to-fuel energy-conversion processes to reality. However, there is a lack of highly efficient, stable, and non-precious photocatalysts, and catalysts not designed completely with expensive noble metals have remained elusive, which hampers their large-scale industrial application. Herein, for the first time, a highly efficient and stable noble-metal-free CdS/WS2 -MoS2 nanocomposite was designed through a facile hydrothermal approach. When assessed as a photocatalyst for water splitting, the CdS/WS2 -MoS2 nanostructures exhibited remarkable photocatalytic hydrogen-evolution performance and impressive durability. An excellent hydrogen evolution rate of 209.79 mmol g-1 h-1 was achieved under simulated sunlight irradiation, which is higher than the values for CdS/MoS2 (123.31 mmol g-1 h-1 ) and CdS/WS2 nanostructures (169.82 mmol g-1 h-1 ) and the expensive CdS/Pt benchmark catalyst (34.98 mmol g-1 h-1 ). The apparent quantum yield reached 51.4 % at λ=425 nm in 5 h. Furthermore, the obtained hydrogen evolution rate was better than those of several noble-metal-free catalysts reported previously. The observed high rate of hydrogen evolution and remarkable stability may be a result of the ultrafast separation of photogenerated charge carriers and transport between the CdS nanorods and the WS2 -MoS2 nanosheets, which thus increases the number of electrons involved in hydrogen production. The proposed designed strategy is believed to potentially open a door to the design of advanced noble-metal-free photocatalytic materials for efficient solar-driven hydrogen production.

Optimization of media components for chitinase production by chickpea rhizosphere associated Lysinibacillus fusiformis B-CM18.

Chitinase producing strain B-CM18 was isolated from chickpea rhizosphere and identified as Lysinibacillus fusiformis B-CM18. It showed in vitro antifungal activity against a wide range of fungal plant pathogens and was found to produce several PGPR activities. Further, a multivariate response surface methodology was used to evaluate the effects of different factors on chitinolytic activity and optimizing enzyme production. A central composite design was employed to achieve the highest chitinase production at optimum values of the process variables, viz., temperature (20-45 °C), sodium chloride (2-7%), starch (0.1-1%) and yeast extract (0.1-1%), added in the minimal medium supplemented with colloidal chitin (1-10%; w:w). The fit of the model (R(2) = 0.5692) was found to be significant. The production medium to achieve the highest chitinase production (101 U ml(-1) ) was composed of the minimal medium composed of chitin (6.09%), NaCl (4.5%), starch (0.55%) and yeast extract (0.55%) with temperature (32.5 °C). The results show that the optimization strategy led to an increase in chitinase production by 56.1-fold. The molecular mass of the chitinase was estimated to be 20 kDa by anion exchange and gel filtration chromatography. Further, purified chitinase showed strong antifungal activity against test pathogens. Overall, these results may serve as a base line data for enhancing the chitinolytic potential of bacterial antagonists for bio-management of chickpea pathogens.

Evaluation of canine retraction through distraction of the periodontal ligament: a clinical study.

AIM: The aim of this study is to evaluate the efficiency of canine distraction and also to evaluate the position of canine in the arch after distraction. MATERIALS AND METHODS: The study sample consisted of five patients, (4 males and 1 female), in the age group of 14 to 25 years who needed canine retraction (ten maxillary canines including both left and right) and first premolar extraction as their treatment protocol were included in the study. This study used a in-house manufactured periodontal ligament distractor. RESULTS: The maxillary canines were distracted distally by 6.42 mm in three and half weeks with a distal tipping of around 15.1° and the maxillary first molars tipped mesially by an average of 6.1°. The maxillary canines rotated mesiobucally by an average of 7.8° bilaterally. CONCLUSION: Canines can be distracted rapidly with minimal effects on the vitality and the periodontal condition and almost all of extraction space can be used for anterior dental alignment or retraction. Maxillary canines can be rapidly retracted into the first premolar extraction space at the rate of about 2.43 mm per week. CLINICAL SIGNIFICANCE: The overall treatment time is reduced as the time taken for retraction of canine is decreased considerably from 6 and 8 months to 3 weeks. Also there is no significant anchorage loss during this period and is well suitable for cases with group a anchorage where the whole extraction space is needed for retraction of anterior teeth.

Studies on Exo-Chitinase Production from Trichoderma asperellum UTP-16 and Its Characterization.

The growth conditions for chitinase production by Trichoderma asperellum UTP-16 in solid state fermentation was optimized using response surface methodology based on central composite design. The chitinase production was optimized, using one-factor at a time approach, with six independent variables (temperature, pH, NaCl, incubation period, nitrogen and carbon sources) and 3.31 Units per gram dry substrate (U gds(-1)) exo-chitinase yield was obtained. A 21.15% increase was recorded in chitinase activity (4.01 U gds(-1)) through surface response methodology, indicates that it is a powerful and rapid tool for optimization of physical and nutritional variables. Further, efficiency of crude enzyme was evaluated against phytopathogenic Fusarium spp. and a mycelial growth inhibition up to 3.5-6.5 mm was achieved in well diffusion assay. These results could be supplemented as basic information for the development of enzyme based formulation of T. asperellum UTP-16 and its use as a biocontrol agent.