High Recombination Rate Research Articles

AcesExperimental and theoretical study on photocatalytic nitrogen reduction catalyzed by Fe doped MoO2

Transition metal oxides are suitable for photocatalytic nitrogen reduction (pNRR) due to their properties of narrow band gap and high energy density. Still, it is also limited by the defects of high photogenerated carrier recombination and low adsorption capacity of nitrogen molecules, which hinder the further improvement of the activity. For high carrier recombination and low activation rate of the nitrogen molecule, herein, Fe-doped MoO2 catalyst (Fe−MoO2) was synthesized for pNRR. Combined with the experimental characterization and theoretical calculation, it shows that the doping of Fe atoms, one hand, improves the conduction band position of MoO2 and enhances the reduction ability, which is favorable to nitrogen reduction. On the other hand, it not only enhances the adsorption of Mo sites and N2 molecules, but also changes the surface electronic structure and promotes the electron transfer from MoO2 to Fe sites, and the two act synergistically to adsorb and activate nitrogen more effectively. The activity of Fe−MoO2 for pNRR is as high as 96.62 μmol g−1h−1, which is about 2.5 times that of pristine MoO2, and the activity decreases by only 10% after three cycles.

Construction of an La-BiVO4/O-Doped g-C3N4 Heterojunction Photocatalyst Embedded in Electrospinning Nanofibers

BiVO4 has been widely used in the field of photocatalysis due to its nontoxic and moderate band gap. However, single BiVO4 has the disadvantages of a high recombination rate of photogenerated carriers and weak response to visible light, inhibiting its photocatalytic applications. To explore viable solutions, a hybrid material composed of lanthanum-doped bismuth vanadate (La-BiVO4) and oxygen-doped porous graphite carbon nitride (O-doped g-C3N4), i.e., La-BiVO4/O-doped g-C3N4 powder, was prepared by a facile hydrothermal reaction and low-temperature calcination. Then, the powder was loaded on polyacrylonitrile nanofibers (NFs) through the electrospinning fiber technique. Various surface science characterizations, including transmission electron microscopy and nitrogen absorption and desorption analysis, confirmed the successful synthesis of a mesoporous heterojunction material. The La3+-doping as well as the porous morphologies and larger specific surface area of the O-doped g-C3N4 ultimately improve the photocatalytic abilities via a proposed Z-scheme heterojunction mechanism. The roles of La3+-doping and morphology modification in promoting the separation of the photogenerated carriers and broadening the optical absorption range were experimentally discussed. The RhB degradation experiment indicated that the La-BiVO4/O-doped g-C3N4 powder has excellent photocatalytic activity, which is about 2.85 and 2 times higher than that of the pure BiVO4 and O-doped g-C3N4, respectively. Meanwhile, the La-BiVO4/O-doped g-C3N4 NF shows good stability and recoverability after a 10-cycle testing. Such a hybrid photocatalyst with a proposed Z-scheme heterojunction mechanism and good plasticity might pave a feasible way to fabricate a new library of photocatalysts.

The fine-scale recombination rate variation and associations with genomic features in a butterfly.

Recombination is a key molecular mechanism that has profound implications on both micro- and macroevolutionary processes. However, the determinants of recombination rate variation in holocentric organisms are poorly understood, in particular in Lepidoptera (moths and butterflies). The wood white butterfly (Leptidea sinapis) shows considerable intraspecific variation in chromosome numbers and is a suitable system for studying regional recombination rate variation and its potential molecular underpinnings. Here, we developed a large whole-genome resequencing data set from a population of wood whites to obtain high-resolution recombination maps using linkage disequilibrium information. The analyses revealed that larger chromosomes had a bimodal recombination landscape, potentially caused by interference between simultaneous chiasmata. The recombination rate was significantly lower in subtelomeric regions, with exceptions associated with segregating chromosome rearrangements, showing that fissions and fusions can have considerable effects on the recombination landscape. There was no association between the inferred recombination rate and base composition, supporting a limited influence of GC-biased gene conversion in butterflies. We found significant but variable associations between the recombination rate and the density of different classes of transposable elements, most notably a significant enrichment of short interspersed nucleotide elements in genomic regions with higher recombination rate. Finally, the analyses unveiled significant enrichment of genes involved in farnesyltranstransferase activity in recombination coldspots, potentially indicating that expression of transferases can inhibit formation of chiasmata during meiotic division. Our results provide novel information about recombination rate variation in holocentric organisms and have particular implications for forthcoming research in population genetics, molecular/genome evolution, and speciation.

Chemical synthesis of silver/titanium dioxide nanoheteroparticles for eradicating pathogenic bacteria and photocatalytically degrading organic dyes in wastewater

Titanium dioxide photocatalysis is a promising technology for the treatment of pollutants in wastewater. However, it remains challenging to overcome its inherent drawbacks, such as a high recombination rate of photogenerated charges and low solar-energy utilization. Herein, Ag/TiO 2 nanoheteroparticles (ATNs) were synthesized using a modified deposition method, and their physical, chemical, antibacterial, and photocatalytic properties were subsequently analyzed. The ATNs with 8 wt% Ag deposition exhibited an excellent antibacterial activity. For Staphylococcus aureus, Enterococcus faecalis, Escherichia coli, Pseudomonas aeruginosa, and Candida albicans, the minimum inhibitory concentrations of ATNs were 250.00, 62.50, 125.00, 250.00, and 62.50 mg/L, whereas the minimum bactericidal concentrations were 250.00, 1000.00, 125.00, 250.00, and 1000.00 mg/L, respectively. The antibacterial activity of the ATNs could be correlated to the amount of Ag deposition. Furthermore, the ATNs with 3 wt% Ag deposition showed 90.1% rhodamine B degradation under simulated sunlight conditions in 90 min. The optimum Ag deposition of 8 wt% effectively promoted the efficient separation of optical charges and improved the photocatalytic properties of the catalyst. Therefore, the ATN composite materials can eliminate pathogenic bacteria and degrade organic pollutants in wastewater. The synthesized ATNs exhibit significant application potential in the field of wastewater treatment.

Repeat-Induced Point Mutation and Gene Conversion Coinciding with Heterochromatin Shape the Genome of a Plant-Pathogenic Fungus.

Meiosis is associated with genetic changes in the genome-via recombination, gene conversion, and mutations. The occurrence of gene conversion and mutations during meiosis may further be influenced by the chromatin conformation, similar to the effect of the chromatin conformation on the mitotic mutation rate. To date, however, the exact distribution and type of meiosis-associated changes and the role of the chromatin conformation in this context are largely unexplored. Here, we determine recombination, gene conversion, and de novo mutations using whole-genome sequencing of all meiotic products of 23 individual meioses in Zymoseptoria tritici, an important pathogen of wheat. We confirm a high genome-wide recombination rate of 65 centimorgan (cM)/Mb and see higher recombination rates on the accessory compared to core chromosomes. A substantial fraction of 0.16% of all polymorphic markers was affected by gene conversions, showing a weak GC-bias and occurring at higher frequency in regions of constitutive heterochromatin, indicated by the histone modification H3K9me3. The de novo mutation rate associated with meiosis was approximately three orders of magnitude higher than the corresponding mitotic mutation rate. Importantly, repeat-induced point mutation (RIP), a fungal defense mechanism against duplicated sequences, is active in Z. tritici and responsible for the majority of these de novo meiotic mutations. Our results indicate that the genetic changes associated with meiosis are a major source of variability in the genome of an important plant pathogen and shape its evolutionary trajectory. IMPORTANCE The impact of meiosis on the genome composition via gene conversion and mutations is mostly poorly understood, in particular, for non-model species. Here, we sequenced all four meiotic products for 23 individual meioses and determined the genetic changes caused by meiosis for the important fungal wheat pathogen Zymoseptoria tritici. We found a high rate of gene conversions and an effect of the chromatin conformation on gene conversion rates. Higher conversion rates were found in regions enriched with the H3K9me3-a mark for constitutive heterochromatin. Most importantly, meiosis was associated with a much higher frequency of de novo mutations than mitosis; 78% of the meiotic mutations were caused by repeat-induced point mutations-a fungal defense mechanism against duplicated sequences. In conclusion, the genetic changes associated with meiosis are therefore a major factor shaping the genome of this fungal pathogen.

Radiation damage in GaN/AlGaN and SiC electronic and photonic devices

The wide bandgap semiconductors SiC and GaN are commercialized for power electronics and for visible to UV light-emitting diodes in the case of the GaN/InGaN/AlGaN materials system. For power electronics applications, SiC MOSFETs (metal–oxide–semiconductor field effect transistors) and rectifiers and GaN/AlGaN HEMTs and vertical rectifiers provide more efficient switching at high-power levels than do Si devices and are now being used in electric vehicles and their charging infrastructure. These devices also have applications in more electric aircraft and space missions where high temperatures and extreme environments are involved. In this review, their inherent radiation hardness, defined as the tolerance to total doses, is compared to Si devices. This is higher for the wide bandgap semiconductors, due in part to their larger threshold energies for creating defects (atomic bond strength) and more importantly due to their high rates of defect recombination. However, it is now increasingly recognized that heavy-ion-induced catastrophic single-event burnout in SiC and GaN power devices commonly occurs at voltages ∼50% of the rated values. The onset of ion-induced leakage occurs above critical power dissipation within the epitaxial regions at high linear energy transfer rates and high applied biases. The amount of power dissipated along the ion track determines the extent of the leakage current degradation. The net result is the carriers produced along the ion track undergo impact ionization and thermal runaway. Light-emitting devices do not suffer from this mechanism since they are forward-biased. Strain has also recently been identified as a parameter that affects radiation susceptibility of the wide bandgap devices.

The morphology of reionization in a dynamically clumpy universe

ABSTRACT A recent measurement of the Lyman-limit mean free path at z = 6 suggests it may have been very short, motivating a better understanding of the role that ionizing photon sinks played in reionization. Accurately modelling the sinks in reionization simulations is challenging because of the large dynamic range required if ∼104−108M⊙ gas structures contributed significant opacity. Thus, there is no consensus on how important the sinks were in shaping reionization’s morphology. We address this question with a recently developed radiative transfer code that includes a dynamical sub-grid model for the sinks based on radiative hydrodynamics simulations. Compared to assuming a fully pressure-smoothed intergalactic medium, our dynamical treatment reduces ionized bubble sizes by $10-20~{{\ \rm per\ cent}}$ under typical assumptions about reionization’s sources. Near reionization’s midpoint, the 21 cm power at k ∼ 0.1 hMpc−1 is similarly reduced. These effects are more modest than the $30-60~{{\ \rm per\ cent}}$ suppression resulting from the higher recombination rate if pressure smoothing is neglected entirely. Whether the sinks played a significant role in reionization’s morphology depends on the nature of its sources. For example, if reionization was driven by bright (MUV < −17) galaxies, the sinks reduce the large-scale 21 cm power by at most 20 per cent, even if pressure smoothing is neglected. Conveniently, when bright sources contribute significantly, the morphology in our dynamical treatment can be reproduced accurately with a uniform sub-grid clumping factor that yields the same ionizing photon budget. By contrast, if MUV ∼ −13 galaxies drove reionization, the uniform clumping model can err by up to 40 per cent.

Traps inhomogeneity induced conversion of Shockley–Read–Hall recombination in NiO/β-Ga2O3 p+–n heterojunction diodes

In this Letter, the trap inhomogeneity within β-Ga2O3 is correlated with the conversion of Shockley–Read–Hall (SRH) recombination in NiO/β-Ga2O3 p+–n heterojunction diodes. For the virgin epi-wafer, both near-surface traps E2 (EC-0.82 eV) and E3 (EC-1.11 eV) and bulk E2* traps (EC-0.76 eV) are identified by a transient capacitance analysis, and the corresponding forward current–voltage characteristics of diodes are well fitted in the framework of field-dependent SRH recombination. The SRH recombination rates for E2, E3, and E2* traps are determined to be 1.3 × 107, 8.6 × 108, and 2.4 × 108 s−1, respectively. In this circumstance, carrier transport under forward bias is governed by trap-assisted tunneling through E3 traps with high recombination rates, and the hysteresis is pronounced. With the removal of the defective surface layer, E2 and E3 traps are almost completely eliminated, together with the reduced density of E2* traps to 5.6 × 1014 cm−3. The resultant diode performs an improved rectification ratio of >1011 at ±3 V and an enhanced reverse breakdown voltage of 1692 V. The elimination of near-surface traps leads to the conversion of carrier transport into the conventional SRH recombination, accompanied by the negligible forward hysteresis characteristics. The established fundamental correlation of carrier transport and traps within Ga2O3 is beneficial to develop a high-performance power rectifier toward practical applications.

Synergistic effect of phosphorus doping and MoS2 co-catalysts on g-C3N4 photocatalysts for enhanced solar water splitting

Carbon nitride (g-C3N4) is a promising metal-free and visible-light-responsive photocatalyst. However, its photocatalytic efficiency still suffers from high recombination rates of photoinduced charge carriers, slow kinetics of surface redox reactions, and relatively poor light absorption. Herein, a non-noble metal photocatalyst of MoS2 nanodots anchored on P-doped g-C3N4 via in situ photodeposition was constructed. With the synergetic effect of the P-doping and MoS2 co-catalyst, the as-prepared P-doped g-C3N4/MoS2 catalyst has achieved efficient photocatalytic overall water splitting with a hydrogen evolution rate of 121.7 μmol h−1 g−1. Experimental results and Density functional theory (DFT) simulations indicate that the enhanced photo-absorption capacity originates from the reduced band gaps by P doping. Meanwhile, the MoS2 reduces the overpotential of the water oxidation process and improves hydrogen adsorption capability in the hydrogen evolution reaction. This work can pave a new avenue to design and develop noble-metal-free water-splitting photocatalysts for future large-scale applications.

Enhanced visible-light-driven heterogeneous photocatalytic CO2 methanation using a Cu2O@Cu-MOF-74 thin film

• Cu 2 O@Cu-MOF-74 core-shell photocatalyst nanocomposite. • Charge transport of photoinduced charge carriers. • Photocatalytic CO 2 reduction under visible light. • Surface coating of a metal-organic framework produced via topotactic conversion. Cuprous oxide is a potential photocatalyst for the reduction of CO 2 . However, its high rate of charge recombination and low ability to adsorb CO 2 limit its activity, particularly when gaseous CO 2 was used. Herein, a Cu-based metal-organic framework (Cu-MOF-74) with high CO 2 adsorption is coated onto Cu 2 O nanowires by a topotactic transformation method. The optimized Cu 2 O@Cu-MOF-74 composite thin film showed a CH 4 evolution rate 4.5 times higher than that of bare Cu 2 O under visible light illumination (>420 nm), with water vapor as the electron donor. Analysis results of electrochemical impedance spectroscopy, transient photocurrent measurements, and fluorescence spectroscopy collectively suggest that the decoration of Cu 2 O with Cu-MOF-74 facilitates electron extraction from excited Cu 2 O, thereby inducing long-lived photocharges for the reduction of CO 2 . This study provides insights into the modification of transition metal oxides for application in photocatalysis by coating the surface with metal-organic frameworks.

Woronichinia naegeliana: A common nontoxigenic component of temperate freshwater cyanobacterial blooms with 30% of its genome in transposons

Monitoring in the U.S. state of Washington across the period 2007–2019 showed that Woronichinia has been present in many lakes state-wide. This cyanobacterium was commonly dominant or sub-dominant in cyanobacterial blooms in the wet temperate region west of the Cascade Mountains. In these lakes, Woronichinia often co-existed with Microcystis, Dolichospermum and Aphanizomenon flos-aquae and the cyanotoxin microcystin has often been present in those blooms, although it has not been known whether Woronichinia is a toxin producer. We report the first complete genome of Woronichinia naegeliana WA131, assembled from the metagenome of a sample collected from Wiser Lake, Washington, in 2018. The genome contains no genes for cyanotoxin biosynthesis or taste-and-odor compounds, but there are biosynthetic gene clusters for other bioactive peptides, including anabaenopeptins, cyanopeptolins, microginins and ribosomally produced, post-translationally modified peptides. Genes for photosynthesis, nutrient acquisition, vitamin synthesis and buoyancy that are typical of bloom-forming cyanobacteria are present, although nitrate and nitrite reductase genes are conspicuously absent. However, the 7.9 Mbp genome is 3–4 Mbp larger than those of the above-mentioned frequently co-existing cyanobacteria. The increased genome size is largely due to an extraordinary number of insertion sequence elements (transposons), which account for 30.3% of the genome and many of which are present in multiple copies. The genome contains a relatively large number of pseudogenes, 97% of which are transposase genes. W. naegeliana WA131 thus seems to be able to limit the potentially deleterious effects of high rates of recombination and transposition to the mobilome fraction of its genome.

Synthesis of Z-scheme heterostructure FeWO<sub>4</sub>/rGO/g-C<sub>3</sub>N<sub>4</sub> as a visible-light photocatalyst for removal of organic pollutant

Photocatalysts have been effectively applied for water treatment. Narrow bandgap energy semiconductors show good photocatalytic performance at visible light. However, high recombination rate of the photogenerated electrons and holes leads to their low photocatalytic activity. Moreover, the conduction and valence band potentials of these materials are not suitable for the redox reactions with water and oxygen to generate HO• and •O2⁻ radicals, respectively. Therefore, the development of new photocatalyst systems to overcome these disadvantages is necessary. This study investigated the photocatalytic activity of FeWO4/rGO/g-C3N4 Z-scheme photocatalytic system via the degradation of Rhodamine B in water. The photocatalyst was synthesized by simple hydrothermal method and characterized by X-ray diffraction method (XRD), fluorescence spectroscopy (PL) and diffuse reflectance spectra (UV-vis). The results showed that after 150 minutes illumination, the Rhodamine B decomposition efficiency on FeWO4/g-C3N4 and FeWO4/rGO/g-C3N4 were 93.07 and 99.21%, respectively. These values were significantly higher than that of g-C3N4 under the same catalytic concentration of 0.1g/L. In the FeWO4/rGO/g-C3N4 heterostructure, rGO acted as electron mediator and transporter between two semiconductors, resulting in a lower recombination rate of photogenerated charges. As the results, the photocatalytic performance was enhanced.

Potassium Poly(heptazine imide) Coupled with Ti3C2 MXene-Derived TiO2 as a Composite Photocatalyst for Efficient Pollutant Degradation.

The photocatalytic degradation of pollutants is an effective and sustainable way to solve environmental problems, and the key is to develop an efficient, low-cost, and stable photocatalyst. Polymeric potassium poly(heptazine imide) (K-PHI), as a new member of the carbon nitride family, is a promising candidate but is characterized by a high charge recombination rate. To solve this problem, K-PHI was in-situ composited with MXene Ti3C2-derived TiO2 to construct a type-II heterojunction. The morphology and structure of composite K-PHI/TiO2 photocatalysts were characterized via different technologies, including TEM, XRD, FT-IR, XPS, and UV-vis reflectance spectra. Robust heterostructures and tight interactions between the two components of the composite were verified. Furthermore, the K-PHI/TiO2 photocatalyst showed excellent activity for Rhodamine 6G removal under visible light illumination. When the weight percent of K-PHI in the original mixture of K-PHI and Ti3C2 was set to 10%, the prepared K-PHI/TiO2 composite photocatalyst shows the highest photocatalytic degradation efficiency as high as 96.3%. The electron paramagnetic resonance characterization indicated that the·OH radical is the active species accounting for the degradation of Rhodamine 6G.

Direct Z-Scheme Polymer/Polymer Double-Shell Hollow Nanostructures for Efficient NADH Regeneration and Biocatalytic Artificial Photosynthesis under Visible Light

The design of a highly efficient polymer photocatalyst is an essential prerequisite for photo-biocatalysis in a polymer–enzyme coupled system, which offers an important platform for the synthesis of pharmaceuticals and fine chemicals. However, current polymers still suffer drawbacks of poor water wettability, low visible light absorption, and high recombination rate of photoinduced electron/hole pairs, which severely limit their application in photo-biocatalysis. Herein, we demonstrate a polymer/polymer double-shell hollow nanostructure (PCN@PDBTS-HN) via a facile two-step polymerization with polymeric carbon nitride (PCN) and poly-dibenzothiophene sulfone (PDBTS) as internal and external shells, respectively. The covalent connection of those two polymer layers ensures the spontaneous electron transfer from PDBTS to PCN, as reflected in X-ray photoelectron spectroscopy (XPS), electron paramagnetic resonance (EPR), and fluorescence spectra, which could effectively accelerate the charge separation and migration. Thanks to its improved light-harvesting, increased hydrophilicity, and enhanced redox capacity, the obtained PCN@PDBTS-HN demonstrates an excellent catalytic efficiency in visible-light-promoted NADH regeneration with a conversion of 85.4% being achieved in 40 min (turnover frequency of 0.859 mmol g–1 h–1). This value is 1.4 and 2.6 times higher than that of pristine PCN and PDBTS, respectively, indicating an essential role of Z-scheme heterojunction in improving the catalytic efficiency. In addition, PCN@PDBTS-HN also displays excellent photocatalytic selectivity for 1,4-NADH regeneration, remarkable photostability, and good biocompatibility. A total amount of 2.12 mM methanol and 8.39 mM l-glutamate was accumulated in the polymer/alcohol dehydrogenase (YADH) and polymer/glutamate dehydrogenase (GDH) coupled system, respectively, implying high flexibility of fine chemical production via the photo-biocatalytic approach.

Construction of Z-scheme ɑ-Fe2O3/graphene/Bi2O2S heterojunction for visible-light-driven photocatalytic CO2 conversion

Dibismuthoxysulfide (Bi2O2S) is considered as a promising photocatalyst candidate due to its high photo-response and strong reduction ability. However, high photo-induced charge recombination rate has restricted its photocatalytic activity. Here, we have successfully fabricated a Bi2O2S-based Z-scheme nanocomposite, ɑ-Fe2O3/graphene/Bi2O2S(ɑ-Fe2O3/GR/Bi2O2S), for highly active and stable visible-light-driven catalytic CO2 conversion with addition of water vapor. By creating large interfacial contact, efficient Z-scheme electron migrate from ɑ-Fe2O3 to Bi2O2S is established, resulting in boosted charge carriers separation as well as lengthen their lifetimes, as systematically evidenced by photoluminescence (PL) spectra, photoelectrochemical characterization and electron spin resonance (ESR). As a consequence, such ɑ-Fe2O3/GR/Bi2O2S heterojunction achieved the highest yields of CO(13.00 μmol/g/h), CH4(4.27 μmol/g/h) and C2H4(2.88 μmol/g/h) under visible light irradiation, which is approximately 5.4, 12.5 and 16.9 times that of Bi2O2S, respectively. Meanwhile, the ɑ-Fe2O3/GR/Bi2O2S heterojunction exhibited outstanding photocatalytic activity for bisphenol A (BPA) removal in contrast with Bi2O2S. This study provides a viable strategy to build effective Bi2O2S-based Z-scheme nanocomposite for CO2 conversion and beyond.

Plasma synthesis of K-doped amorphous carbon nitride with passivated trap states for enhanced photocatalytic H2O2 production

Amorphous carbon nitride (ACN) is a promising semiconductor photocatalyst for photocatalytic H2O2 production. However, its actual activity is hindered by a high recombination rate of photoexcited charge carriers. Herein we report a K-doped ACN (K-ACN) photocatalyst synthesized via Ar plasma treatment to the modified melamine and KCl powder mixture at a moderate temperature. The as-synthesized K-ACN exhibits significantly enhanced photocatalytic properties for H2O2 production with a yield of 6.21 mM h−1, which is 6 times higher than that of bulk CN. Moreover, the H2O2 yield can be further increased to 13.95 mM h−1 by adjusting the pH value. The significantly enhanced photocatalytic property is mainly attributed to the introduction of K+, which is conducive to tuning the electronic structure, extending π conjugated system, passivating trap states and enhancing photocatalytic activity. The result has provided a facile and effective strategy for the modification of ACN to significantly boost its photocatalytic activity.

Research Progress of Tungsten Oxide-Based Catalysts in Photocatalytic Reactions

Photocatalysis technology is a potential solution to solve the problem of environmental pollution and energy shortage, but its wide application is limited by the low efficiency of solar energy conversion. As a non-toxic and inexpensive n-type semiconductor, WO3 can absorb approximately 12% of sunlight which is considered one of the most attractive photocatalytic candidates. However, the narrow light absorption range and the high recombination rate of photogenerated electrons and holes restrict the further development of WO3-based catalysts. Herein, the studies on preparation and modification methods such as doping element, regulating defects and constructing heterojunctions to enlarge the range of excitation light to the visible region and slow down the recombination of carriers on WO3-based catalysts so as to improve their photocatalytic performance are reviewed. The mechanism and application of WO3-based catalysts in the dissociation of water, the degradation of organic pollutants, as well as the hydrogen reduction of N2 and CO2 are emphatically investigated and discussed. It is clear that WO3-based catalysts will play a positive role in the field of future photocatalysis. This paper could also provide guidance for the rational design of other metallic oxide (MOx) catalysts for the increasing conversion efficiency of solar energy.

Enhancement in the photocatalytic and optoelectronic properties of erbium oxide by adding zinc oxide and molybdenum

Rare earth metals like erbium oxide (Er2O3) show outstanding photocatalytic properties. However, its high recombination rate and low surface area limit its performance. Therefore, various metal oxide composites with Er2O3 have been reported to improve their photocatalytic and optoelectronic properties. In this study, a composite of Er2O3 and zinc oxide (ZnO) was synthesized using the sol-gel combustion method to enhance its surface area. Moreover, molybdenum (Mo) was loaded on the matrix to suppress the charge recombination. The detailed characterizations were conducted by employing X-ray Diffraction (XRD), Raman Spectroscopy, Field Emission Scanning Electron Microscopy (FESEM), Brunauer–Emmett–Teller (BET) analysis, Photoluminescence (PL) spectroscopy and UV–Vis spectroscopy. BET analysis revealed the enhancement in surface area by adding ZnO and Mo (from SBET = 29.07 m2/g to SBET = 45.71 m2/g). Additionally, the loading of Mo enhanced the immobilization of carriers that facilitate the photooxidation process and suppressed the electron-holes recombination (from 800 counts to 100 counts) as confirmed by the PL spectroscopy. Photocatalytic studies were comparatively analyzed by degradation of textile dye named methylene blue (MB). The efficiency of Er2O3 improved by up to 80% by adding the ZnO and Mo. The composite of Er2O3 with ZnO and loading of Mo, not only improved the photocatalytic properties but also improved the electrical properties of the Er2O3 (σ = 4.4 × 10−4 Sm−1 to σ = 5.1 × 10−4 Sm−1) as confirmed by the Hall Effect. Due to enhancement in properties, the proposed material can be rendered as one of the most suitable candidates for optoelectronic applications.

Recombination Variation Shapes Phylogeny and Introgression in Wild Diploid Strawberries.

Introgressive hybridization is widespread in wild plants and has important consequences. However, frequent hybridization between species makes the estimation of the species' phylogeny challenging, and little is known about the genomic landscape of introgression as it results from complex interactions of multiple evolutionary processes. Here, we reconstructed the phylogeny of ten wild diploid strawberries with whole genome resequencing data and then investigated the influence of recombination rate variation on phylogeny and introgression. We found that genomic regions with low recombination showed reduced levels of incomplete lineage sorting and introgression, and concentrated phylogenetic signals, thus contributing to the most likely species tree of wild diploid strawberries. We revealed complex and widespread introgression across the genus Fragaria, with an average proportion of approximately 4.1% of the extant genome. Introgression tends to be retained in the regions with high recombination rates and low gene density. Furthermore, we identified four SLF genes under selective sweeps that may play potential roles in the possible regain of self-incompatibility by ancient introgression. Altogether, our study yielded novel insights into the evolutionary history and genomic characteristics of introgression in wild diploid strawberries and provides evidence for the role of introgression in plant mating system transitions.

Polypyrrole modification on BiVO4 for photothermal-assisted photoelectrochemical water oxidation.

The bismuth vanadate (BiVO4) photoanode receives extensive attention in photoelectrochemical (PEC) water splitting. However, the high charge recombination rate, low electronic conductivity, and sluggish electrode kinetics have inhibited the PEC performance. Increasing the reaction temperature for water oxidation is an effective way to enhance the carrier kinetics of BiVO4. Herein, a polypyrrole (PPy) layer was coated on the BiVO4 film. The PPy layer could harvest the near-infrared light to elevate the temperature of the BiVO4 photoelectrode and further improve charge separation and injection efficiencies. In addition, the conductive polymer PPy layer acted as an effective charge transfer channel to facilitate photogenerated holes moving from BiVO4 to the electrode/electrolyte interface. Therefore, PPy modification led to a significantly improved water oxidation property. After loading the cobalt-phosphate co-catalyst, the photocurrent density reached 3.64 mA cm-2 at 1.23V vs the reversible hydrogen electrode, corresponding to an incident photon-to-current conversion efficiency of 63% at 430nm. This work provided an effective strategy for designing a photothermal material assisted photoelectrode for efficient water splitting.