ABSTRACT
Three material engineering strategies in the form of doping (Boron-doping), nanostructuring (nanosheet (NS) formation) and decorating with plasmonic nanoparticles (loading with Ag metal), were integrated to improve the photocatalytic activity of graphitic carbon nitride (gC3N4). Concentrations of B-doping and Ag-loading were optimized to maximize the catalytic performance in the final nanocomposite of Ag-loaded B-doped gC3N4 NS. Combined effect of all three strategies successfully produced over 5 times higher rate towards degradation of organic dye pollutant, when compared to unmodified bulk gC3N4. Detailed characterization results revealed that incorporation of B in gC3N4 matrix reduces the band gap to increase the visible light absorption, while specific surface area is significantly enhanced upon formation of NS. Decoration of Ag nanoparticles (NPs) on B-doped gC3N4 NS assists in fast transfer of photogenerated electrons from gC3N4 to Ag NPs owing to the interfacial electric field across the junctions and thus reduces the recombination process. Investigations on individual strategies revealed that decoration of Ag NPs to induce better charge separation, is the most effective route for enhancing the photocatalytic activity.
Subject(s)
Graphite , Metal Nanoparticles , Catalysis , Light , SilverABSTRACT
In the present manuscript, we explore the VN-codoped TiO2 system intended to understand the role played by each dopant in synergistic enhancement in performance of TiO2 photocatalyst. The photocatalytic decomposition of organic pollutants in aqueous solution under visible light was used as a probe reaction to evaluate the performance of VN-codoped TiO2 samples with different V and N concentrations. An optical measurement of VN-codoped TiO2 shows considerable improved visible light absorption with increase in V-concentration as compared to increase in N concentration, which was due to the effective narrowing of the band gap by V-doping. The energy levels formed by N-dopants act as the trapping centers for photogenerated holes to suppress recombination process as indicated by PL and TRPL results. It is also observed that at high V-concentrations recombination centers are created in the form of oxygen vacancies as indicated by XPS and PL. In VN-codoped TiO2 , addition of N partially fills these oxygen vacancies to reduce the number of recombination centers and prolong the lifetime of charge carriers. Thus, V improves the visible light absorption while N reduces the recombination of electron-hole pairs, thus creating the synergistic effect to produce three times better performance than pure TiO2 .
ABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: Since urolithiasis is the third most common disease, found throughout the world, with a prevalence of 1-5% in Asia and two stone belts have been identified in India, one of which includes the study area, so an ethnobotanical study was conducted in and around the Bhopal district of Madhya Pradesh, India to investigate the range of plant species used in the treatment of urolithiasis. MATERIALS AND METHODS: Survey was undertaken in 75 villages of four directions of the Bhopal district and in the 3 herbal fairs that were organized in this area during the study period. Interviews were conducted with 304 people in whom 270 people were of villages in the four directions while 18 were traditional medicine dealers or Ayurveda consultants and 16 were knowable people. RESULTS: Total 67 plant species belonging to 40 families were encountered during the study. The most predominant families in terms of number of species were Asteraceae and Papilionaceae with 5 species each. In the four directions, the people of eastern direction were found to have maximum knowledge of antilithic plants, but the Ayurveda consultants and knowable people were found to have much more knowledge than all the general people of the villages. Nine plant species, namely, Citrullus lanatus Thunb.(Cucurbitaceae), Malva sylvestris L. (Malvaceae), Urginea indica (Roxb.) Kunth (Liliaceae), Bauhinia variegata L. (Caesalpiniaceae), Dolichos uniflorus L.(Papilionaceae), Psidium guajava L. (Myrtaceae), Calotropis procera (Ait.) R.Br. (Asclepiadaceae), Picrorhiza kurroa Royle ex Benth. (Plantaginaceae) and Piper longum L. (Piperaceae) was not found to be previously mentioned for the treatment of lithiasis. Boerhaavia diffusa L. was found to have the highest use value. On the basis of habit of these plants, herbs constituted 41.79% of the total plant species used. CONCLUSIONS: From this study, it can be concluded that complete ethnobotanical knowledge can be gained only when thorough literature survey along with field survey with respect to common man, traditional medicine dealers or Ayurveda consultants and knowable people has been extensively undertaken. This study will help in making the people aware about the selected plants or other suggested plants for use in lithiasis.
