The g-C3N4 porous nanosheets with different loading amount of Ag nanoparticles (NPs) are successfully prepared by a simple liquid-phase reduction method. These Ag/g-C3N4 composites have an improved photocatalytic performance for decomposing organic pollutants compared with that of pure g-C3N4 nanosheets. Many measurements have been used for characterizing the samples, such as XRD, FTIR, UV-Vis DRS, PL, XPS, EDS, SEM, and TEM. In Ag/g-C3N4, the Ag NPs are uniformly coated on the g-C3N4 surface, the diameter is mainly in the range of 8~18 nanometers. Loading of Ag NPs expand the response to the visible light for g-C3N4 and increasing the producing rate of photogenerated e−-h+ pairs. The loading of silver NPs obviously enhances the photocatalytic activity of C3N4 nanosheets toward the Rhodamine B (RhB) decomposition under the simulated sunlight irradiation. With different loading amounts of Ag NPs, Ag/g-C3N4 (3 wt% of Ag) showed the highest photocatalytic activity for RhB decomposition among these as-prepared samples, which is 10 times of the rate of pure C3N4. Based on the experimental results, a possible photocatalytic mechanism for Ag/g-C3N4 is proposed.
Redox stable SrFe0.75Mo0.25O3-δ and SrFe0.5Mn0.25Mo0.25O3-δ electrode materials were studied in terms of their physicochemical properties and electrochemical performance in symmetrical SOFCs, with focus on their tolerance toward carbon deposition and sulfur poisoning. Both materials possess cubic, B-site cation-disordered Pm-3m structure in air up to high temperatures. SrFe0.5Mn0.25Mo0.25O3-δ was found to transform to a B-site cation-ordered structure after reduction in dry 5 vol% H2/Ar at 1100°C, while no structural changes were observed for SrFe0.75Mo0.25O3-δ. Weight change upon annealing up to 850°C in air and in dry 5 vol% H2/Ar indicated an increase in oxygen deficiency on the order of δ = 0.2. Seebeck coefficient and conductivity dependence on the oxygen partial pressure pO2 showed that both oxides exhibit p-type conductivity in air and n-type conductivity under reducing conditions. Carbon deposition was found to depend on temperature, gas composition (CO or CH4), and presence of Ce0.8Gd0.2O1.9 electrolyte in the composite-type electrode. Stable fuel cell performance, without carbon deposition, was obtained for SrFe0.75Mo0.25O3-δ-based SOFC in 10 vol% of CO in CO2. Also, SOFC operation with CH4 as fuel was achieved without coking at temperatures ≤ 700°C. However, both oxides suffer from sulfur poisoning-related effects in atmosphere with 800 ppm H2S.