g-C3N4: Properties, Pore Modifications, and Photocatalytic Applications

Graphitic carbon nitride (g-C3N4), as a polymeric semiconductor, is promising for ecological and economical photocatalytic applications because of its suitable electronic structures, together with the low cost, facile preparation, and metal-free feature. By modifying porous g-C3N4, its photoelectric behaviors could be facilitated with transport channels for photogenerated carriers, reactive substances, and abundant active sites for redox reactions, thus further improving photocatalytic performance. There are three types of methods to modify the pore structure of g-C3N4: hard-template method, soft-template method, and template-free method. Among them, the hard-template method may produce uniform and tunable pores, but requires toxic and environmentally hazardous chemicals to remove the template. In comparison, the soft templates could be removed at high temperatures during the preparation process without any additional steps. However, the soft-template method cannot strictly control the size and morphology of the pores, so prepared samples are not as orderly as the hard-template method. The template-free method does not involve any template, and the pore structure can be formed by designing precursors and exfoliation from bulk g-C3N4 (BCN). Without template support, there was no significant improvement in specific surface area (SSA). In this review, we first demonstrate the impact of pore structure on photoelectric performance. We then discuss pore modification methods, emphasizing comparison of their advantages and disadvantages. Each method’s changing trend and development direction is also summarized in combination with the commonly used functional modification methods. Furthermore, we introduce the application prospects of porous g-C3N4 in the subsequent studies. Overall, porous g-C3N4 as an excellent photocatalyst has a huge development space in photocatalysis in the future.

Medium-Low-Temperature NO2 Sensor Based on YSZ Solid Electrolyte and Mesoporous WO3 Sensing Electrode for Detection of Vehicle Emissions

A mixed potential-type NO2 sensor was fabricated using yttria-stabilized zirconia (YSZ) as the electrolyte and mesoporous WO3 as the sensing electrode for the detection of NO2 in vehicle exhausts. The mesoporous WO3 with a diameter of 7 nm was synthesized using the hard template method. The sensor showed excellent performance in the detection of 30–500[Formula: see text]ppm of NO2 at 300∘C and 500∘C. However, commercial WO3 only operate well at 500∘C. The response of the mesoporous WO3 was higher and the test temperature was lower compared to that of commercial WO3. XPS combined with NO2-TPD was used to explain the high activity of mesoporous WO3 at medium-low temperature, and the mechanism of mixed electromotive force was verified by electrochemical impedance spectroscopy. Furthermore, the sensor exhibited high NO2 selectivity in the presence of interfering gases, such as NO, CO, CO2 and NH3. Most importantly, the sensor had excellent repeatability and stability.

Potassium-Promoted Three-Dimensional Mesoporous Pt/MnO2 for Formaldehyde Elimination at Zero Degree

In this work, three-dimensional mesoporous MnO2, K/MnO2, Pt/MnO2 and K-Pt/MnO2 catalysts were prepared through hard-template method. The additional K/Pt had significantly improved the HCHO oxidation activity. The K-Pt/MnO2 catalyzed complete HCHO oxidation was achieved at 0℃ with space velocity (GHSV) at 50000 ml/(gand#183;h). With the excellent catalytic performance, K-Pt/MnO2 exhibited a higher ratio of Oads(surface adsorbed oxygen)/Olatt(surface lattice oxygen) and Mn3+/Mn4+ ions than the other catalysts. Meanwhile, it was still stable after running a 70h reaction. Overall, the K-Pt/MnO2 was a promising material for HCHO elimination.

Preparation and Progress in Application of Gold Nanorods

Gold nanorods (Au NRs) have attracted extensive research interest due to their unique optical properties, adjustable aspect ratio, and easy surface modification in the fields of biosensing, bioimaging, and disease diagnosis and detection. In this review, we present a comprehensive review of various methods for preparing gold nanorods including hard template method, electrochemistry method, photochemistry method, seed-mediated growth method, secondary growth method, and amorphous seed method. The unique optical properties of the gold nanorods and its applications in biomedical, detection, catalysis, and information storage will also be discussed in detail.