A selective synthesis of taon nanoparticles and their comparative study of photoelectrochemical properties

A simplified ammonolysis method for synthesizing single phase TaON nanoparticles is presented and the resulting photoelectrochemical properties are compared and contrasted with as-synthesized Ta2O5 and Ta3N5. The protocol for partial nitridation of Ta2O5 (synthesis of TaON) offers a straightforward simplification over existing methods. Moreover, the present protocol offers extreme reproducibility and enhanced chemical safety. The morphological characterization of the as-synthesized photocatalysts indicate spherical nanoparticles with sizes 30, 40, and 30 nm Ta2O5, TaON, and Ta3N5 with the absorbance onset at ~320 nm, 580 nm, and 630 nm respectively. The photoactivity of the catalysts has been examined for the degradation of a representative cationic dye methylene blue (MB) using xenon light. Subsequent nitridation of Ta2O5 yields significant increment in the conversion (ζ: Ta2O5 95% ζ for a lower (0.1 g) loading and with a lamp with lower Ultraviolet (UV) content. Improved Photoelectrochemical performance is noted after a series of chronoamperometry (J/t), linear sweep voltammetry (LSV), and electrochemical impedance spectroscopy (EIS) measurements. Finally, stability experiments performed using recovered and treated photocatalyst show no loss of photoactivity, suggesting the photocatalysts can be successfully recycled

Large expert-curated database for benchmarking document similarity detection in biomedical literature search

Document recommendation systems for locating relevant literature have mostly relied on methods developed a decade ago. This is largely due to the lack of a large offline gold-standard benchmark of relevant documents that cover a variety of research fields such that newly developed literature search techniques can be compared, improved and translated into practice. To overcome this bottleneck, we have established the RElevant LIterature SearcH consortium consisting of more than 1500 scientists from 84 countries, who have collectively annotated the relevance of over 180 000 PubMed-listed articles with regard to their respective seed (input) article/s. The majority of annotations were contributed by highly experienced, original authors of the seed articles. The collected data cover 76% of all unique PubMed Medical Subject Headings descriptors. No systematic biases were observed across different experience levels, research fields or time spent on annotations. More importantly, annotations of the same document pairs contributed by different scientists were highly concordant. We further show that the three representative baseline methods used to generate recommended articles for evaluation (Okapi Best Matching 25, Term Frequency-Inverse Document Frequency and PubMed Related Articles) had similar overall performances. Additionally, we found that these methods each tend to produce distinct collections of recommended articles, suggesting that a hybrid method may be required to completely capture all relevant articles. The established database server located at https://relishdb.ict.griffith.edu.au is freely available for the downloading of annotation data and the blind testing of new methods. We expect that this benchmark will be useful for stimulating the development of new powerful techniques for title and title/abstract-based search engines for relevant articles in biomedical research.Peer reviewe

Hydrogen Generation Using a Borohydride-Based Semi-continuous Milli-scale Reactor: Effects of Physicochemical Parameters on Hydrogen Yield

It is well-known that hydrogen for portable applications can be generated by hydrolysis of sodium borohydride stabilized in an alkali medium over suitable catalysts. This paper describes hydrogen generation by hydrolysis of solid sodium borohydride (NaBH₄) powder in a milli-scale semi-continuous reactor. Acidified (hydrochloric acid) water is used as an accelerator for hydrogen generation. The effects of liquid−solid interfacial contact area, NaBH₄ loading, liquid flow rate, and temperature on the hydrogen yield in the milli-scale reactor have been studied. The results indicate that up to 80% of the theoretical hydrogen can be produced from 2 mg (0.053 mM) of NaBH₄ using a 6 N HCl solution at a flow rate of 1 μL/min. The hydrolysis of NaBH₄ produces byproducts, such as NaBO₂ and NaCl. Acidified water increases the porosity of the interfacial reaction zone consisting of byproducts. This improves liquid delivery to unreacted NaBH₄ and results in greater hydrogen generation over longer durations

Materials and Processes for Solar Fuel Production

XII, 237 p. 147 illus., 107 illus. in color.onlin

Review of photocatalytic and photo-electrocatalytic reduction of CO2 on carbon supported films

CO2 capture/conversion is one of the biggest challenges facing humanity. This review reports on the analysis of the research performed over the last five years on the application of carbon-based materials as supports for CO2 conversion using the photo (electro)catalytic approach. Three types of photocatalyst materials - metals, metal-oxides, non-oxides, and their combinations with carbon are presented. Our focus has been on i) carbon - based structures and their unique features that assist with photocatalysis, ii) the approaches to consider for photo (electro)catalytic CO2 conversion, iii) representative examples of different carbon allotrope supported composites for CO2 conversion, and iv) tools to perform quantitative estimation of their performance. We have provided insights into the benefits of reduced graphene oxide (rGO) based on our team's research and listed the areas where not only improvement in CO2 reduction reactions can be considered but also areas of interest in other applications where rGO can be leveraged in a beneficial manner.Several efforts have been made to increase FE (or selectivity), combining metals and metal-oxide catalysts on metal-free carbon support has provided better selectivity, exhibited good activity and CO2 mass transport in water. In which case the active electrocatalyst is usually the reduced metal while the carbon support plays its role of improving its selectivity. Table 4 summarizes the key physical parameters of CO2, and ideal surface characteristics of carbon based photocatalysts for effective CO2 adsorption and improved selectivity towards CO2 reduction products [131,141].Scopu

Inactivation of Human Coronavirus by Titania Nanoparticle Coatings and UVC Radiation: Throwing Light on SARS-CoV-2

The newly identified pathogenic human coronavirus, SARS-CoV-2, led to an atypical pneumonia-like severe acute respiratory syndrome (SARS) outbreak called coronavirus disease 2019 (abbreviated as COVID-19). Currently, nearly 77 million cases have been confirmed worldwide with the highest numbers of COVID-19 cases in the United States. Individuals are getting vaccinated with recently approved vaccines, which are highly protective in suppressing COVID-19 symptoms but there will be a long way before the majority of individuals get vaccinated. In the meantime, safety precautions and effective disease control strategies appear to be vital for preventing the virus spread in public places. Due to the longevity of the virus on smooth surfaces, photocatalytic properties of “self-disinfecting/cleaning” surfaces appear to be a promising tool to help guide disinfection policies for controlling SARS-CoV-2 spread in high-traffic areas such as hospitals, grocery stores, airports, schools, and stadiums. Here, we explored the photocatalytic properties of nanosized TiO2 (TNPs) as induced by the UV radiation, towards virus deactivation. Our preliminary results using a close genetic relative of SAR-CoV-2, HCoV-NL63, showed the virucidal efficacy of photoactive TNPs deposited on glass coverslips, as examined by quantitative RT-qPCR and virus infectivity assays. Efforts to extrapolate the underlying concepts described in this study to SARS-CoV-2 are currently underway

Structural studies of silica modified titania and its photocatalytic activity of 4-chlorophenol oxidation in aqueous medium

867-875A series of titania samples with different loadings of silica (0.5-10 wt.%) has been prepared by wet impregnation method. The presence of Ti-O-Si linkage for all silica loadings has been confirmed by DRIFT spectra. High dispersion of silica in the titania matrix and the bonding of Ti-O-Si in silica-titania samples are found to inhibit the transformation of amorphous to anatase titania. The UV-vis/DRS show an increase in UV and visible light absorbance for 7.5 wt.% silica calcined at 500 °C. Evaluation of photocatalytic activity of the samples for the decomposition of 4-chlorophenol shows greater activity for samples modified with silica with an optimal loading of 7.5 wt.% silica calcined at 500 °C. Conversion of 90 % and 35 % of 4-chlorophenol for UV-visible and visible light respectively is observed. Photocatalytic activity of the silica-titania samples is found to decrease with increasing crystallinity

CdSe Nanocrystal Assemblies on Anodized TiO₂ Nanotubes: Optical, Surface, and Photoelectrochemical Properties

The in situ preparation of high-quality organically synthesized cadmium selenide (CdSe) nanocrystals on TiO₂ nanotubes (T_NT) prepared by anodization is presented. The deposition of CdSe nanocrystals has been facilitated under a high-pressure and low-viscosity solvothermal process. The formation, growth, and assembly of CdSe nanocrystals in the form of a dense film on T_NT have been studied using thermal (thermogravimetry and calorimetry) and optical (UV–vis and microscopy) techniques. It has been concluded that an organic treatment, followed by annealing under a nitrogen atmosphere at reduced temperatures, helps control CdSe nanocrystal morphology without causing significant particle size growth. Photoelectrochemical measurements indicate that the electrode assembly consisting of T_NT and CdSe can achieve a stable photocurrent density of 6.7 mA/cm² and a charge-separation efficiency of 35%