Layered Co(OH)₂ Deposited Polymeric Carbon Nitrides for Photocatalytic Water Oxidation

Here we report a facile impregnation synthesis of layered Co­(OH)₂ deposited with g-C₃N₄ while the pH value is adjusted by using ammonia solution for photocatalytic water oxidation with UV–vis and visible light illumination. This surface modification not only accelerates the interface transfer rate of charge carriers but also reduces the excessive energy barrier for O–O formation, thus leading to enhanced reaction kinetics for photocatalytic water oxidation. The optimum oxygen evolution rates (OERs) of the Co­(OH)₂/g-C₃N₄ sample reached 27.4 and 7.1 μmol h^–1 under UV–vis (λ >300 nm) and visible light (λ >420 nm) irradiation, which are 5.5 and 7 times faster than those for pristine g-C₃N₄, respectively. These results underline the possibility for the development of effective, robust, and earth-abundant WOCs for the promotion of water-splitting photocatalysis by sustainable g-C₃N₄ polymer photocatalysts

Strong Metal Support Effect of Pt/g-C₃N₄ Photocatalysts for Boosting Photothermal Synergistic Degradation of Benzene

Catalysis is the most efficient and economical method for treating volatile organic pollutants (VOCs). Among the many materials that are used in engineering, platinized carbon nitride (Pt/g-C3N4) is an efficient and multifunctional catalyst which has strong light absorption and mass transfer capabilities, which enable it to be used in photocatalysis, thermal catalysis and photothermal synergistic catalysis for the degradation of benzene. In this work, Pt/g-C3N4 was prepared by four precursors for the photothermal synergistic catalytic degradation of benzene, which show different activities, and many tests were carried out to explore the possible reasons for the discrepancy. Among them, the Pt/g-C3N4 prepared from dicyanamide showed the highest activity and could convert benzene (300 ppm, 20 mL·min−1) completely at 162 °C under solar light and 173 °C under visible light. The reaction temperature was reduced by nearly half compared to the traditional thermal catalytic degradation of benzene at about 300 °C

Ce_1−xSn_xO₂ Catalysts Prepared with Combustion Method for Catalytic Combustion of Ethyl Acetate

A series of Ce1−XSnXO2 (X = 0, 0.2, 0.3, 0.4, 0.5, 0.9, 1) catalysts were synthesized via the combustion method. The physical and chemical structures of the prepared catalysts were systematically characterized by XRD, BET, SEM, TEM, XPS, and TPR. The Ce1−XSnXO2 catalysts have higher catalytic activities than the mono-oxide catalysts, as there are synergistic effects between CeO2 and SnO2. The catalytic activities of the Ce1−XSnXO2 catalysts are dependent on the X for the catalytic combustion of ethyl acetate (EA). The Ce1−XSnXO2 (X 0.8Sn0.2O2 and Ce0.7Sn0.3O2 catalysts display the highest catalytic performance, with T50 = 190 °C and T90 = 210 °C. More importantly, the Ce0.8Sn0.2O2 catalyst exhibits superior thermal and catalytic activity stability. It is found that the Ce1−XSnXO2 catalysts form solid solutions, as the X is 4+ species to Sn2+ is significantly promoted by the CeO2, which is an important factor attributed to the high catalytic activities of the solid solution Ce1−XSnXO2 catalysts. The catalytic activities of the Ce1−XSnXO2 catalysts exhibit a strong correlation to the surface atomic areas of Ce3+ and Oα (VO). In other words, the higher surface atomic areas of Ce3+ and Oα (VO) are, the higher the catalytic activities will have

Tunable Carrier Transfer of Polymeric Carbon Nitride with Charge-Conducting CoV2O6∙2H2O for Photocatalytic O2 Evolution

Photocatalytic water splitting is one of the promising approaches to solving environmental problems and energy crises. However, the sluggish 4e− transfer kinetics in water oxidation half-reaction restricts the 2e− reduction efficiency in photocatalytic water splitting. Herein, cobalt vanadate-decorated polymeric carbon nitride (named CoVO/PCN) was constructed to mediate the carrier kinetic process in a photocatalytic water oxidation reaction (WOR). The photocatalysts were well-characterized by various physicochemical techniques such as XRD, FT-IR, TEM, and XPS. Under UV and visible light irradiation, the O2 evolution rate of optimized 3 wt% CoVO/PCN reached 467 and 200 μmol h−1 g−1, which were about 6.5 and 5.9 times higher than that of PCN, respectively. Electrochemical tests and PL results reveal that the recombination of photogenerated carriers on PCN is effectively suppressed and the kinetics of WOR is significantly enhanced after CoVO introduction. This work highlights key features of the tuning carrier kinetics of PCN using charge-conducting materials, which should be the basis for the further development of photocatalytic O2 reactions

Ultrafine Cobalt Catalysts on Covalent Carbon Nitride Frameworks for Oxygenic Photosynthesis

The rational cooperation of sustainable catalysts with suitable light-harvesting semiconductors to fabricate photosynthetic device/machinery has been regarded as an ideal technique to alleviate the current worldwide energy and environmental issues. Cobalt based species (e.g., Co-Pi, Co₃O₄, and Co-cubene) have attracted particular attentions because they are earth-abundant, cost-acceptable, and more importantly, it shows comparable water oxidation activities to the noble metal based catalysts (e.g., RuO₂, IrO₂). In this contribution, we compared two general cocatalysts modification strategies, based on the surface depositing and bulk doping of ultrafine cobalt species into the sustainable graphitic carbon nitride (g-C₃N₄) polymer networks for oxygenic photosynthesis by splitting water into oxygen, electrons, and protons. The chemical backbone of g-C₃N₄ does not alter after both engineering modifications; however, in comparison with the bulk doping, the optical and electronic properties of the surface depositing samples are efficiently promoted, and the photocatalytic water oxidation activities are increased owing to much more exposed active sites, reduced overpotential for oxygen evolution and the accelerated interface charge mobility. This paper underlines the advantage of surface engineering to establish efficient advanced polymeric composites for water oxidation, and it opens new insights into the architectural design of binary hybrid photocatalysts with high reactivity and further utilizations in the fields of energy and environment

Gene flow and an anomaly zone complicate phylogenomic inference in a rapidly radiated avian family (Prunellidae)

Abstract Background Resolving the phylogeny of rapidly radiating lineages presents a challenge when building the Tree of Life. An Old World avian family Prunellidae (Accentors) comprises twelve species that rapidly diversified at the Pliocene–Pleistocene boundary. Results Here we investigate the phylogenetic relationships of all species of Prunellidae using a chromosome-level de novo assembly of Prunella strophiata and 36 high-coverage resequenced genomes. We use homologous alignments of thousands of exonic and intronic loci to build the coalescent and concatenated phylogenies and recover four different species trees. Topology tests show a large degree of gene tree-species tree discordance but only 40–54% of intronic gene trees and 36–75% of exonic genic trees can be explained by incomplete lineage sorting and gene tree estimation errors. Estimated branch lengths for three successive internal branches in the inferred species trees suggest the existence of an empirical anomaly zone. The most common topology recovered for species in this anomaly zone was not similar to any coalescent or concatenated inference phylogenies, suggesting presence of anomalous gene trees. However, this interpretation is complicated by the presence of gene flow because extensive introgression was detected among these species. When exploring tree topology distributions, introgression, and regional variation in recombination rate, we find that many autosomal regions contain signatures of introgression and thus may mislead phylogenetic inference. Conversely, the phylogenetic signal is concentrated to regions with low-recombination rate, such as the Z chromosome, which are also more resistant to interspecific introgression. Conclusions Collectively, our results suggest that phylogenomic inference should consider the underlying genomic architecture to maximize the consistency of phylogenomic signal

Additional file 1 of Gene flow and an anomaly zone complicate phylogenomic inference in a rapidly radiated avian family (Prunellidae)

Additional file 1: Fig. S1. Synteny of aligned P. strophiata genome with zebra finch genome and these two genomes showed high collinearity. Fig. S2. Polytomy test for the MP-EST and ASTRAL species trees as the guide trees. Fig. S3. Tree topology weights vary with recombination rate (estimated from PyRho). Fig. S4. Interplay between topology and variation in introgression rate. Fig. S5. Hi-C heatmap reconstructed for Prunella strophiata genome. Table S1. Statistics of the assembly of Prunella strophiata genome. Table S2. Completeness of the genome assembly of Prunella strophiata evaluated by BUSCO. Table S3. Chromosome synteny of aligned Red-breasted accentor genome with zebra finch genome. Table S4. List of the species were used for phylogenetic analyses. Table S5. Resequencing information and genome wide coverage of 36 individuals used in this study. Table S6. Gene concordance factor (gCF) for the nodes (1–7, Fig. 4a-b) that support the species tree (gCF), the two most common alternative topologies (gDF1 and gDF2), and the relative frequency of all other topologies (gDFp)