In this study, S-doped graphitic carbon nitride (S-C3N4) was prepared using the high-temperature polymerization method, and then S-C3N4/AgCdS heterojunction photocatalyst was obtained using the chemical deposition method through loading Ag-doped CdS nanoparticles (AgCdS NPs) on the surface of S-C3N4. Experimental results show that the AgCdS NPs were evenly dispersed on the surface of S-C3N4, indicating that a good heterojunction structure was formed. Compared to S-C3N4, CdS, AgCdS and S-C3N4/CdS, the photocatalytic performance of S-C3N4/AgCdS has been significantly improved, and exhibits excellent photocatalytic degradation performance of Rhodamine B and methyl orange. The doping of Ag in collaboration with the construction of a Z-scheme heterojunction system promoted the effective separation and transport of the photogenerated carriers in S-C3N4/AgCdS, significantly accelerated its photocatalytic reaction process, and thus improved its photocatalytic performance.
In this paper, the electrodeposition and hydrothermal methods were used to prepare the Bi2MoO6/BiVO4 photoelectrode, and the intrinsic mechanism of significantly enhanced photoelectrochemical performance of the prepared Bi2MoO6/BiVO4 heterojunction system was studied. Work functions of Bi2MoO6 and BiVO4 were analyzed using a scanning Kelvin probe, and the direction of the heterojunction electric field and the transfer direction of photogenerated carriers were finally determined by the relative positions of the energy bands and the Fermi levels of Bi2MoO6 and BiVO4. A type II Bi2MoO6/BiVO4 heterojunction system was finally confirmed to be formed. Formation of the type II Bi2MoO6/BiVO4 heterojunction system reduces the recombination efficiency of photogenerated electrons and holes and thus improves the photoelectrochemical performance. The photogenerated current density of the Bi2MoO6/BiVO4 photoelectrode reaches 1.47 mA·cm-2, which is 4.9 times that of pure BiVO4 and thousands of times that of Bi2MoO6. The successful application of a scanning Kelvin probe in the verification of the heterojunction type provides theoretical and technical bases for the design and construction of efficient heterojunctions.
Photo-electrochemical cathodic protection (CP) technology is considered to be a green metallic corrosion protection technology that uses solar energy to protect from corrosion and does not consume any anode materials. In this work, a CdIn2 S4 /WO3 nanocomposite photoelectrode was prepared, and its photo-electrochemical CP performance and mechanism were studied and analyzed. WO3 has a well band matching with CdIn2 S4 , leading to a significantly enhanced photo-electrochemical CP performance of the nanocomposite. Meanwhile, as confirmed in this work, the CdIn2 S4 /WO3 nanocomposite can store photoinduced electrons under light illumination through intercalation reactions and changing the valence state of tungsten. Moreover, it can discharge in the dark state to provide continuous CP for the coupled metals. This research will promote the practical application process of the photo-electrochemical CP technology.
