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Large specific surface area porous g-C3N4 nanosheets were prepared by utilizing acetaldehyde-mediated melamine. The synthetic processes adopted two-step thermal treatments which are in N2 and then in an air atmosphere. The introduced acetaldehyde made melamine condensation incompletely and generated body defects in g-C3N4 when heated in N2. Further heating in air realized pores formation at sites of body defects, thus increase the specific surface area of g-C3N4. Notably, the introduction of acetaldehyde is beneficial to generate high concentration defects, which are active sites for thermal oxidative etching, and increase the yield of g-C3N4 by inhibiting the sublimation of melamine. The photocatalytic performance of obtained g-C3N4 was evaluated by the degradation of 2-propanol under visible light irradiation (λ > 4 2 0 nm). The porous g-C3N4 exhibits excellent photocatalytic performance than bulk g-C3N4. The addition of trace acetaldehyde significantly increased the specific surface area and enhanced photocatalytic activity, providing a new idea for the development of simple, low-cost and high active g-C3N4 photocatalyst. Porous g-C3N4 nanosheets were obtained by heating acetaldehyde mediated melamine. The introduced acetaldehyde made melamine condensation incompletely and generated body defects in g-C3N4 when heated in N2. These body defects facilitated the formation of porous g-C3N4 in the following heating in air due to thermal oxidative etching. The precursor of acetaldehyde mediated melamine is also beneficial to increase the yield of g-C3N4 by inhibiting the sublimation of melamine. Finally, the obtained g-C3N4 exhibits excellent photocatalytic performance than pristine g-C3N4. [ABSTRACT FROM AUTHOR]

Graphitic carbon nitride (g-C 3 N 4) is a promising material for photocatalytic environmental purification. However, the application of g-C 3 N 4 has been limited by its synthetic processes, where a low-cost and high-activity synthetic method could promote its application. Here, by utilizing formaldehyde and changing the thermal condensation processes, g-C 3 N 4 with a large specific surface area was obtained, and its photocatalytic activity was 12.3 and 6.5 times that of pristine g-C 3 N 4 for photocatalytic organic pollutant degradation and photocatalytic water splitting, respectively. The enhanced photocatalytic performance can be attributed to the large specific surface area, which reached 137.3 m2/g, as well as the improved efficiency of the separation and transfer of charge carriers. Moreover, the additional trace amounts of formaldehyde can increase the yield of g-C 3 N 4 , and the yield reached 21%, which is 7 times that obtained with traditional thermal condensation processes. • The yield of g-C 3 N 4 reached 21% by heating formaldehyde-treated melamine. • The synthetic method has easy scale-up, low cost, and environmental friendliness. • The photocatalytic activity of the obtained g-C 3 N 4 was increased by 12.3 times. [ABSTRACT FROM AUTHOR]

A new precursor was developed for the preparation of graphitic carbon nitride (g-C 3 N 4) with a large specific surface area and N vacancies. The SEM and TEM results show that the obtained samples have porous nanosheet structure, XPS, EPR and UV–Vis spectra indicate N vacancy defects existed in the g-C 3 N 4. During the synthesis process, glyoxylic acid inhibited the condensation of melamine, thus increasing the porosity of g-C 3 N 4 , generating abundant defects, and improving yield. Under light irradiation, g-C 3 N 4 samples prepared by glyoxylic acid mediated melamine shown enhanced photocatalytic activities in gaseous organic pollution photodegradation. This study developed a potential agent for producing inexpensive and highly active g-C 3 N 4 photocatalysts. The large specific surface area porous g-C 3 N 4 sheets with nitrogen vacancies have been fabricated successfully by using a glyoxylic acid treated melamine. This method is a high-yield and low-cost synthetic pathway to form large specific surface area porous g-C 3 N 4 nanosheet. The photocatalytic activity of g-C 3 N 4 was enhanced in gaseous pollution photodegradation. Image 1 • Glyoxylic acid results in harvesting specific surface area, and generating defects in g-C 3 N 4 simultaneously. • Glyoxylic acid reduces the cost of g-C 3 N 4 greatly by increase the yield. • Enhanced activities in gaseous iso-propanol photodegradation and photoelectric properties. [ABSTRACT FROM AUTHOR]

In this study, novel dendritic TiO 2 nanofibers (D-Ti NFs) with ultrahigh surface area were for the first time synthesized through in situ hydrothermal treatment of the electrospun TiO 2 nanofibers (E-Ti NFs) and their microstructure, formation mechanism, in vitro biocompatibility and drug delivery property were investigated. SEM observations showed that D-Ti NFs had dendritic and fibrous morphology with the controllable diameter of 899 ± 26 nm to 1955 ± 64 nm. TEM observations showed the individual D-Ti NF was assembled by numerous primary nanowires with the diameter of 7 ± 1 nm. XRD pattern showed that the D-Ti NFs displayed the characteristic peaks at 24.1°, 28.1°, and 48.3°, all of which were assigned to hydrogen titanium oxide hydrate. BET measurement indicated that D-Ti NFs had the ultrahigh specific surface area of 213.41 m2/g. D-Ti NFs showed good in vitro biocompatibility when exposed to Hela cells. After soaked in solution of tetracycline hydrochloride (TH, one of the representative antibiotics, model drug), D-Ti NFs supported the loading of TH with the loading efficiency of 63.73 ± 4.61%. TH-loaded D-Ti NFs supported a sustained release model for TH when immersed in the phosphate buffer saline. After separately incubated with two representative types of bacteria: Escherichia coli and Staphylococcus aureus , TH-loaded D-Ti NFs showed excellent antibacterial property to inhibit the growth of the bacteria, indicating that the released TH was biologically active. • Dendritic TiO 2 nanofibers with high surface area were facilely synthesized. • They were biocompatible when exposed to Hela cells. • They supported the loading and sustained release behavior of drugs. • They well maintained the biologic activity of loaded drugs. [ABSTRACT FROM AUTHOR]