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Hydrogen production from water splitting by sunlight is a promising approach to solve the increasing energy and environmental crises, and the two-dimensional (2D) g-C3N4 monolayer is a red star in this realm. However, it suffers from low quantum efficiency caused by the fast combination of photogenerated electrons and holes. In this work, we investigate the electronic and photocatalytic properties of three newly proposed g-C3N4/SiP–GaS-α, -β and -γ heterojunctions via first principles predictions. Theoretical results demonstrate that the three g-C3N4/SiP–GaS heterojunctions exhibit direct bandgaps of ∼2.2 eV, and have a type-II band alignment with the valence band maximum (VBM) located at the g-C3N4 layer and the conduction band minimum (CBM) at the SiP–GaS layer. Furthermore, their band edges straddle the redox potential of water in a wide range of biaxial strain. Their absorption coefficients are several times larger than that of most previously discovered 2D heterojunctions. Moreover, the in-built electric field adds a driving force to separate photogenerated electrons and holes. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) successfully take place on the g-C3N4 and SiP–GaS layers, respectively. Briefly, separated charge carriers, suitable band edges and strong visible-light absorbance, successful OER and HER enable the three g-C3N4/SiP–GaS heterojunctions to be promising water-splitting photocatalysts. [ABSTRACT FROM AUTHOR]

In this investigation, we demonstrated a controlled electrodeposition method by varying the current density to generate hierarchical structures of zinc (Zn) on a carbon steel surface, which serves as a hydrophobic and anticorrosion coating when further modified by stearic acid to form a covalently bonded layer that offers low surface energy. The chemical composition, surface morphology and roughness of the modified Zn coatings were analyzed via X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM), and confocal laser scanning microscopy (CLSM). The water contact angle and wettability tests have shown that the modified Zn coating with a micro/nanostructure displayed a water contact angle of 158.7° and a sliding angle of 6.4°, indicating strong superhydrophobicity. Interestingly, the modified Zn coating with a micro/nanostructure exhibited strong mechanical stability during knife scratching and adhesive tape peeling tests. In addition, the modified superhydrophobic Zn coating showed improved corrosion resistance that provided protection to the carbon steel. The protection mechanism can be attributed to the hierarchical micro/nanostructure of the Zn surface itself and the formation of a hydrophobic zinc stearate complex compound. The superhydrophobic Zn coating has good application prospects in a neutral corrosion environment, where it retards corrosion and reduces the adhesion of water. [ABSTRACT FROM AUTHOR]

Hydrogen production from water splitting by sunlight is a promising approach to solve the increasing energy and environmental crises, and the two-dimensional (2D) g-C 3 N 4 monolayer is a red star in this realm. However, it suffers from low quantum efficiency caused by the fast combination of photogenerated electrons and holes. In this work, we investigate the electronic and photocatalytic properties of three newly proposed g-C 3 N 4 /SiP-GaS-α, -β and -γ heterojunctions via first principles predictions. Theoretical results demonstrate that the three g-C 3 N 4 /SiP-GaS heterojunctions exhibit direct bandgaps of ∼2.2 eV, and have a type-II band alignment with the valence band maximum (VBM) located at the g-C 3 N 4 layer and the conduction band minimum (CBM) at the SiP-GaS layer. Furthermore, their band edges straddle the redox potential of water in a wide range of biaxial strain. Their absorption coefficients are several times larger than that of most previously discovered 2D heterojunctions. Moreover, the in-built electric field adds a driving force to separate photogenerated electrons and holes. The oxygen evolution reaction (OER) and hydrogen evolution reaction (HER) successfully take place on the g-C 3 N 4 and SiP-GaS layers, respectively. Briefly, separated charge carriers, suitable band edges and strong visible-light absorbance, successful OER and HER enable the three g-C 3 N 4 /SiP-GaS heterojunctions to be promising water-splitting photocatalysts.