In this study, Bi₂MoO₆ nanoflowers with different molybdenum sources were in situ grown on the surface of g-C₃N₄ nanosheets (OCN) by a simple one-step solvothermal method. The effects of doping and different molybdenum sources on the photocatalytic degradation and bactericidal activity of Bi₂MoO₆/OCN were discussed. Among them, the solvothermal preparation of P-Bi₂MoO₆/OCN using phosphomolybdic acid as molybdenum source can make up for the shortcomings caused by the destruction of OCN structure by generating more lattice defects to promote charge separation and constructing Lewis acid/base sites to effectively improve the photocatalytic performance. In addition, by adding phosphoric acid to increase the P-doped content, more exposed alkaline active sites are induced on the surface of P-Bi₂MoO₆/OCN, as well as larger specific surface area and charge transfer efficiency, which further improve the photocatalytic performance. Finally, the optimized 16P-Bi₂MoO₆/OCN showed a degradation rate of 99.7% for 20 mg/L rhodamine B (RhB) within 80 min under visible light, and the antibacterial rates against E. coli, S. aureus and P. aeruginosa within 300 min were 99.58%, 98.20% and 97.48%, respectively. This study provides a reference for optimizing the synthesis of environmentally friendly, solar-responsive, photocatalytic sterilization materials from the perspective of preparation, raw materials and structure.

Microbiologically influenced corrosion (MIC) is one of the key causes of material failure in marine engineering, and sulfate-reducing bacteria (SRB) and iron-oxidizing bacteria (IOB) are typical representatives of anaerobic and aerobic microorganisms, respectively. These microorganisms are widely present in marine environments and can form synergistic communities on the surface of metal materials, posing a corrosion threat to them. At the same time, the presence of mixed bacteria may have an effect on cathodic protection, so this study investigates the growth metabolism of mixed SRB and IOB under different cathodic protection potentials in an impressed current cathodic protection (ICCP) system in a marine environment containing SRB and IOB. It also examines the attachment of these microorganisms to the anode and cathode, and the impact on cathodic protection efficiency. The results indicate that in a marine environment containing IOB and SRB, the cathodic protection efficiency of the ICCP system increases with the negative shift of the protection potential. A more positive cathodic protection potential promotes the adhesion of mixed bacteria on the electrode surface and the formation of a biofilm, which reduces cathodic protection efficiency. In contrast, at a cathodic protection potential of −1.05 V (SCE), bacterial growth is inhibited, and a dense crystalline corrosion film primarily composed of Fe₂O₃ and Fe(OH)₃ forms on the cathode surface. This film effectively protects the cathodic metal, significantly mitigating MIC.

Juglone (5-hydroxy-1,4-naphthalenedione), a natural compound derived from walnut husks, was investigated as a sustainable dual-function antibacterial agent and corrosion inhibitor for Q235 steel in sulfate-reducing bacteria (SRB)-containing seawater. Juglone was synthesized via an improved one-pot method, and its performance was evaluated through antibacterial assays, weight loss measurements, surface characterization (SEM, XPS, XRD), and electrochemical techniques (EIS, PDP). Juglone exhibited potent antibacterial activity against Desulfovibrio sp., with a minimum inhibitory concentration (MIC) of 40 mg/L. At 20 mg/L (0.5 MIC) and 40 mg/L (1 MIC), it effectively suppressed bacterial growth and metabolism, mitigating corrosion. At 80 mg/L (2 MIC), a dual-action mechanism was observed: strong antibacterial effect combined with chemical reaction with H₂S, a corrosive SRB metabolite, forming a protective thiol-containing film on the steel surface. This reduced the corrosion current density from 3.16 × 10⁻⁵ A/cm² to 7.94 × 10⁻⁷ A/cm², achieving an inhibition efficiency of 97.5%. Juglone represents a promising green alternative to conventional toxic antibacterial agents, aligning with circular economy principles.