Due to their excellent performance, superhydrophobic materials have received a lot of attention and research in friction reduction and wear resistance. However, the effect of different contact angles of superhydrophobicity on friction and wear properties has not been thoroughly studied. In this paper, a nanosecond pulsed laser was used to realize the preparation of a superhydrophobic nickel surface, which indeed reduced the coefficient of friction but also increased the wear volume when compared to the unprocessed surface. As the contact angle of the superhydrophobic nickel surface increased, the coefficient of friction gradually increased, and the wear volume decreased gradually in superhydrophobic nickel surfaces. When the laser energy density was 1 J/cm², the contact angle was 150.3° and the minimum friction coefficient was 0.4. However, when the laser energy density was 50 J/cm², the maximum contact angle was 156.4° and the minimum wear volume was 4.23 × 10⁷ μm³. The friction direction also influenced the tribological properties of the superhydrophobic-textured surface. This method makes it possible to process superhydrophobic surfaces with more suitable friction and wear properties.

Pulsed high-voltage electrical discharge was used in treating azo dye (Acid Orange II, AO7) wastewater. The effects of initial pH, Fe²⁺ concentration, discharge mode, conductivity of initial aqueous solution and the type of bubbling gas (air, O₂, N₂) on AO7 degradation were studied. A new gas–liquid discharge (NGL) mode, by which a plate was exposed to air and needles were immersed in liquid, displayed a remarkably better AO7 degradation than the gas–liquid discharge (GL) mode and the liquid discharge (L) mode. The lower conductivity of aqueous solution and the higher oxygen concentration in bubbled gas were of benefit to the degradation process. In addition, owing to the multi-point structure and self-provided Fe²⁺, the electrode with iron mesh-plate discharge showed a more competitive degradation performance than that with multi-needle-plate discharge. The oxidant of ˙OH and H₂O₂ induced by the discharge process were also studied to explore the degradation processes. By NGL mode with iron mesh electrode and bubbled air in reactor, the degradation efficiency of AO7 was up to 85.8% when the initial pH, conductivity and Fe²⁺ concentration were 2.28, 200 μS·cm⁻¹ and 1.635 mmol L⁻¹, respectively.