Self-Enhanced Antibacterial and Antifouling Behavior of Three-Dimensional Porous CuO Nanoparticles Functionalized by an Organic-Inorganic Hybrid Matrix.

CuO is currently an important protective material for domestic engineering and equipment used to exploit marine resources. Cu is considered to have more effective antibacterial and antifouling activities than Cu. However, disproportionation of Cu in the natural environment leads to its reduced bioavailability and weakened reactivity. Novel and functionalized CuO composites could enable efficient and environmentally friendly applications of Cu. To this end, a series of three-dimensional porous CuO nanoparticles (3DNP-CuO) functionalized by organic (redox gel, R-Gel)-inorganic (reduced graphene oxide, rGO) hybrids─3DNP-CuO/rGO@R-Gel─at room temperature by immobilization-reduction method was prepared and applied for protection against marine biofouling. 3DNP-CuO/rGO@R-Gel includes rGO and R-Gel shape 3D porous CuO nanoparticles with diameters ∼177 nm and strong dispersion and antioxidant stability. Compared with commercial CuO (CuO-0), 3DNP-CuO/rGO@R-Gel exhibited an ∼50% higher bactericidal rate, ∼96.22% higher water content, and ∼75% lower adhesion of mussels and barnacles. Moreover, 3DNP-CuO/rGO@R-Gel maintains the same excellent, stable, and long-lasting bactericidal performance as CuO-0@R-Gel while reducing the average copper ion release concentration by ∼56 to 76%. This was also confirmed by X-ray diffraction, X-ray photoelectric spectroscopy (XPS), atomic absorption spectroscopy, and antifouling tests. In addition, XPS tests of rGO-Cu and R-Gel-Cu, photocurrent tests of 3DNP-CuO/rGO@R-Gel, and energy-dispersive spectrometry pictures of bacteria confirm that R-Gel and rGO act as electron donors and transfer substrates driving the reduction of Cu (Cu → Cu) and the diffusion of Cu. Thus, a self-growing antibacterial and antifouling system of 3DNP-CuO/rGO@R-Gel was achieved. The mechanism of accelerated bacterial inactivation and resistance to mussel and barnacle adhesion by 3DNP-CuO/rGO@R-Gel was interpreted. It is shown that rGO and R-Gel are important players in the antibacterial and antifouling system of 3DNP-CuO/rGO@R-Gel.