Self-Enhanced Antibacterial and Antifouling Behavior of Three-Dimensional Porous Cu₂O Nanoparticles Functionalized by...

Cu₂O 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 Cu²⁺. However, disproportionation of Cu⁺ in the natural environment leads to its reduced bioavailability and weakened reactivity. Novel and functionalized Cu₂O composites could enable efficient and environmentally friendly applications of Cu⁺. To this end, a series of three-dimensional porous Cu₂O nanoparticles (3DNP-Cu₂O) functionalized by organic (redox gel, R-Gel)-inorganic (reduced graphene oxide, rGO) hybrids─3DNP-Cu₂O/rGO_x@R-Gel─at room temperature by immobilization-reduction method was prepared and applied for protection against marine biofouling. 3DNP-Cu₂O/rGO_1.76@R-Gel includes rGO and R-Gel shape 3D porous Cu₂O nanoparticles with diameters ∼177 nm and strong dispersion and antioxidant stability. Compared with commercial Cu₂O (Cu₂O-0), 3DNP-Cu₂O/rGO_1.76@R-Gel exhibited an ∼50% higher bactericidal rate, ∼96.22% higher water content, and ∼75% lower adhesion of mussels and barnacles. Moreover, 3DNP-Cu₂O/rGO_x@R-Gel maintains the same excellent, stable, and long-lasting bactericidal performance as Cu₂O-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-Cu²⁺ and R-Gel-Cu²⁺, photocurrent tests of 3DNP-Cu₂O/rGO_1.76@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 Cu²⁺ (Cu²⁺ → Cu⁺) and the diffusion of Cu⁺. Thus, a self-growing antibacterial and antifouling system of 3DNP-Cu₂O/rGO_1.76@R-Gel was achieved. The mechanism of accelerated bacterial inactivation and resistance to mussel and barnacle adhesion by 3DNP-Cu₂O/rGO_1.76@R-Gel was interpreted. It is shown that rGO and R-Gel are important players in the antibacterial and antifouling system of 3DNP-Cu₂O/rGO_1.76@R-Gel.