Nanotube array-like WO_3/W photoanode fabricated by electrochemical anodization for photoelectrocatalytic overall water splitting

Photoactive WO3is attractive as a photocatalyst for green energy evolution through water splitting.In the present work,an electrochemical anodic oxidation method was used to fabricate a photo‐responsive nanotube array‐like WO3/W(NA‐WO3/W)photoanode from W foil as a precursor.Compared with a reference commercial WO3/W electrode,the NA‐WO3/W photoanode exhibited enhanced and stable photoelectrocatalytic(PEC)activity for visible‐light‐driven water splitting with a typical H2/O2stoichiometric ratio of2:1and quantum efficiency of approximately5.23%under visible‐light irradiation from a light‐emitting diode(λ=420nm,15mW/cm2).The greatly enhanced PEC performance of the NA‐WO3/Wphotoanode was attributed to its fast electron–hole separation rate,which resulted from the one‐dimensional nanotube array‐like structure,high crystallinity of monoclinic WO3,and strong interaction between WO3and W foil.This work paves the way to a facile route to prepare highly active photoelectrodes for solar light transfer to chemical energy.

Two flowers per seed:Derivatives of CoG@F127/GO with enhanced catalytic performance of overall water splitting

In this work,cobalt glycerate(CoG@F127)nanosheets grown on the surface of graphene oxide(GO),i.e.CoG@F127/GO,have been synthesized with the assistance of nonionic surfactant Pluronic F127 via a hydrothermal method.After calcination,CoG@F127/GO is transformed into one derivative,Co nanoparticles coated with a trace amount of carbon(Co-C)on GO(Co-C/GO).The Co nanoparticles consist of an atypical core-shell structure,in which the core and the shell are both Co.Co-C anchored on GO can avoid the nanoparticles aggregation and expose more active sites for hydrogen evolution reaction(HER)to significantly improve the catalyst activity of HER.CoG@F127/GO is phosphatized to form the other derivate,cobalt pyrophosphate coated with a small amount of carbon(Co_(2)P_(2)O_(7)-C)on GO(Co_(2)P_(2)O_(7)-C/GO).Co_(2)P_(2)O_(7)-C/GO composite owns a large electrochemical active surface area(ECSA)and fast rate towards oxygen evolution reaction(OER).Furthermore,the two derivatives of CoG@F127/GO,i.e.Co-C/GO and Co_(2)P_(2)O_(7)-C/GO as twin flowers,are assembled into an overall water splitting electrolytic cell with a cell voltage of 1.56 V to deliver a current density of 10 mA cm^(-2).

In-situ fabrication SnO2/SnS2 heterostructure for boosting the photocatalytic degradation of pollutants

Heterostructure photocatalysts with a built-in electric field have become one of the most promising strategies to enhance photogenerated electron-hole pair separation. However, close contact between the two active components of heterogeneous photocatalysts remains a problem. Herein, the in-situ fabrication of an SnO2/SnS2 heterostructure photocatalyst was performed;the structure showed enhanced photocatalytic performance resulting from the tight-contact heterostructures. The results of photoelectrochemical measurements further verified that a tight-contact heterostructure improved the separation of photogenerated electron-hole pairs. The results of EIS Bode plots also demonstrated that such in-situ fabricated SnO2/SnS2 samples exhibited the longest carrier lifetime(41.6 μs) owing to the intimate interface of SnO2/SnS2 heterostructures.

Morphological and phylogenetic analysis of a new Melosira species and revision of freshwater Melosira in China

Melosira is one of the most common diatom genera found in freshwater ecosystems.There are many freshwater species of Melosira,of which M.varians is the most common.In our investigation of periphytic diatoms in the Jinsha River,China,a new species,M.capsularum sp.nov,was characterized in combined morphological and molecular approaches.M.varians was also analyzed using molecular data.The new species is similar to M.varians,M.moniliformis,M.nummuloides,and M.lineata in morphology.The cells are capsular and join to filaments by mucilage pads that are secreted on the valve face and united into pairs by their cingula.The valve face is domed and covered with small granules,and the valve mantle edge has a milled appearance.The two strains of M.capsularum are in a single clade obviously away from other Melosira species,as determined in phylogenetic analysis based on nuclear small subunit(SSU)rDNA sequences and the chloroplast-encoded rbc L gene.Thus,the results of morphological comparisons and phylogenetic analysis based on molecular data provide strong evidence that M.capsularum is a new species,thereby increasing the total number of recognized freshwater diatom species in China.In addition,we have systematically reclassified the freshwater Melosira that have been recorded in China.

Research Progress on Photocatalytic/Photoelectrocatalytic Oxidation of Nitrogen Oxides

The emission of nitrogen oxides(NO_(x))increases year by year,causing serious problems to our livelihoods.The photocatalytic oxidation of NO_(x)has attracted more attention recently because of its effi cient removal of NO_(x),especially for low concentra-tions of NO_(x).In this review,the mechanism of the photocatalytic oxidation of NO_(x)is described.Then,the recent progress on the development of photocatalysts is reviewed according to the categories of inorganic semiconductors,bismuth-based compounds,nitrogen carbide polymer,and metal organic frameworks(MOFs).In addition,the photoelectrocatalytic oxida-tion of NO_(x),a method involving the application of an external voltage on the photocatalytic system to further increase the removal effi ciency of NO_(x),and its progress are summarized.Finally,we outline the remaining challenges and provide our perspectives on the future directions for the photocatalytic oxidation of NO_(x).

Microwave assisted synthesis of PQ-GDY@NH_(2)-UIO-66(Zr) for improved photocatalytic removal of NOx under visible light

Pyrazinoquinoxaline-based graphdiyne (PQ-GDY) contains a fixed number of sp-sp2hybridized carbon atoms and pyrazine-like sp2hybridized N atoms.In this paper,NH_(2)-UIO-66(Zr) on PQ-GDY substrate was successfully constructed with the help of microwaveassisted heating.PQ-GDY surface acts as a microwave antenna under microwave irradiation to rapidly absorb microwave energy and form hot spots (hot spot effect),which facilitates the formation of well-dispersed NH2-UIO-66(Zr) with good crystallinity.Transient absorption spectra show that high hole transport property of PQ-GDY can accelerate the migration of photogenerated holes from NH2-UIO-66(Zr) to PQ-GDY and greatly reduce the recombination rate of photogenerated electrons and holes due to the strong interaction between PQ-GDY and NH2-UIO-66(Zr).Under visible light (λ≥420 nm),PQ-GDY@NH_(2)-UIO-66(Zr) shows high photocatalytic stability and high NO_(x)removal rate up to 74%,which is 44% higher than that of primitive NH_(2)-UIO-66(Zr).At the same time,it inhibits the formation of toxic byproducts (NO2) and limits its concentration to a low level.

Electrospun Bi-decorated Bi_(x)Ti_(y)O_(z)/TiO_(2) flexible carbon nanofibers and their applications on degradating of organic pollutants under solar radiation

Presently,photocatalytic degradation has emerged as an attractive and efficient technology for wastewater treatment.In order to avoid hurdles,such as difficulty in the suspended photocatalyst segregation from the aqueous system and low reutilization rate,the strategy of immobilizing photocatalysts with electro-spun fibers has been widely studied.However,those methods usually require multi-step preparation and complex operations.Considering this,a novel metallic Bi-decorated flexible multiphase Bi_(x)Ti_(y)O_(z)/TiO_(2) electrospun carbon nanofibers(Bi/Bi_(x)Ti_(y)O_(z)-TiO_(2)/CNFs)with high photocatalytic efficiency,good mechanical property,good stability,easy separation,and recovery were synthesized via a one-step approach of pre-oxidation and carbonization treatment.The as-prepared Bi/Bi_(x)Ti_(y)O_(z)-TiO_(2)/CNFs with multiphase Bi_(x)Ti_(y)O_(z),anatase TiO_(2),and metallic Bi particles embedded not only enhance the harvest of light but also pro-vide more separation paths for photogenerated carriers,which improve photocatalytic efficiency greatly.The Bi/Bi_(x)Ti_(y)O_(z)-TiO_(2)/CNFs(S3)exhibited excellent photocatalytic performance and the degradation rate of 10 mg L^(-1) Rhodamine B(RhB)was up to 97%in only 30 min under simulated sunlight irradiation.Also,S3 exhibited stable activity during 5 cycles of experiments since the degradation rates remained at about 97%in 30 min.The mechanism of degradation of RhB by Bi/Bi_(x)Ti_(y)O_(z)-TiO_(2)/CNFs in the photocat-alytic process was also proposed based on active species trapping experiments.The work in this paper shows that Bi/Bi_(x)Ti_(y)O_(z)-TiO_(2)/CNFs are easy to prepare and have high photocatalytic ability and stability,thereby offering a new strategy in catalyst immobilization and wastewater treatment.

Highly selective and efficient photocatalytic NO removal:Charge carrier kinetics and interface molecular process

The widespread nitrogen oxides(NOx,mainly in NO)in the atmosphere have threatened human health and ecological environment.The dilute NO(ppb)is difficult to efficiently remove via the traditional process due to its characteristics of low concentration,wide range,large total amount,etc.Photocatalysis can utilize solar energy to purify NO pollutants under mild conditions,but its application is limited due to the low selectivity of nitrate and poor activity of NO removal.The underlying reason is that the interface mechanism of NO oxidation is not clearly understood,which leads to the inability to accurately regulate the NO oxidation process.Herein,the recent advances in the photocatalytic oxidation of NO are summarized.Firstly,the common strategies to effectively regulate carrier dynamics such as morphology control,facet engineering,defect engineering,plasma coupling,heterojunction and single-atom catalysts are discussed.Secondly,the progress of enhancing the adsorption and activation of reactants such as NO and O_(2) during NO oxidation is described in detail,and the corresponding NO oxidation mechanisms are enumerated.Finally,the challenges and prospects of photocatalytic NO oxidation are presented in term of nanotechnology for air pollution control.This review can shed light on the interface mechanism of NO oxidation and provide illuminating information on designing novel catalysts for efficient NOx control.

Photoelectrocatalytic reduction of CO_2 to methanol over a photosystem Ⅱ-enhanced Cu foam/Si-nanowire system

A solar-light double illumination photoelectrocatalytic cell（SLDIPEC） was fabricated for autonomous CO2 reduction and O2 evolution with the aid of photosystem II（PS-II, an efficient light-driven water-oxidized enzyme from nature） and utilized in a photoanode solution. The proposed SLPEC system was composed of Cu foam as the photoanode and p-Si nanowires（Si-NW） as the photocathode. Under solar irradiation, it exhibited a super-photoelectrocatalytic performance for CO2 conversion to methanol, with a high evolution rate（41.94 mmol/hr）, owing to fast electron transfer from PS-II to Cu foam.Electrons were subsequently trapped by Si-NW through an external circuit via bias voltage（0.5 V）, and a suitable conduction band potential of Si（-0.6 e V） allowed CO2 to be easily reduced to CH3 OH at the photocathode. The constructed Z-scheme between Cu foam and Si-NW can allow the SLDIPEC system to reduce CO2（8.03 mmol/hr） in the absence of bias voltage. This approach makes full use of the energy band mismatch of the photoanode and photocathode to design a highly efficient device for solving environmental issues and producing clean energy.

Boosting the photocatalytic nitrogen reduction to ammonia through adsorption-plasmonic synergistic effects

Ammonia is one of the most essential chemicals in the modern society but its production still heavily relies on energy-consuming Haber-Bosch processes.The photocatalytic reduction of nitrogen with water for ammonia production has attracted much attention recently due to its synthesis under mild conditions at room temperature and atmospheric pressure using sunlight.Herein,we report a high-performance Au/MIL-100(Cr)photocatalyst,comprising MIL-100(Cr)and Au nanoparticles in photocatalytic nitrogen reduction to ammonia at ambient conditions under visible light irradiation.The optimized photocatalyst(i.e.,0.10Au/MIL-100(Cr))achieved the excellent ammonia production rate with 39.9μg g_(cat)^(-1) h^(-1) compared with pure MIL-100(Cr)(2.73μg gcat^(-1) h^(-1)),which was nearly 15 times that on pure MIL-100(Cr).The remarkable activity could be attributed to the adsorption-plasmonic synergistic effects in which the MIL-100(Cr)and Au are responsible to the strong trapping and adsorption of N2 molecules and photo-induced plasmonic hot electrons activating and decomposing the N2 molecules,respectively.This study might provide a new strategy for designing an efficient plasmonic photocatalyst to improve the photocatalytic performance of N2 fixation under visible light irradiation.