Enhanced electron storage capacity achieved by coupling NiO with WO3/BiVO4 for persistent photocathodic protection of 316 stainless steel

• Published in: Materials today communications Vol. 39; p. 108768
• Main Authors: Zhou, Zemin, Li, Ming, Hu, Yu, Chen, Zhipeng
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2024
• Subjects: Electron storage; Long-term performance; Photocathodic protection; Ternary heterojunction; Ternary heterojunction; Photocathodic protection; Long-term performance; Electron storage
• ISSN: 2352-4928; 2352-4928
• DOI: 10.1016/j.mtcomm.2024.108768

Employing a photoanode with energy self-storage capability is crucial to provide continuous photocathodic protection (PCP) for metal under intermittent irradiation. In this work, NiO, a hole collector, was coupled with WO3/BiVO4 to improve photoelectrochemical properties and photocathodic protection ability for stainless steel (316 SS). The optimal WO3/BiVO4/NiO photoanode (WB2N2) exhibited 35.1% and 26.6% increase in energy storage capacity compared with WO3 and WO3/BiVO4 under illumination, respectively. The open-circuit potential (OCP) of 316SS coupled with irradiated WB2N2 was reduced from −143 mV (uncoupled OCP) to −726 mV, and the electrode potential can maintain at −540 mV after light was turned off. It was calculated that electrons of about 1.286×10−2 C was transferred from WB2N2 to 316 SS after 50 s illumination, which was 11.7 and 5.1 times of that WO3 and WB2 passed to 316SS, respectively, confirming the best persistent PCP performance of WB2N2 in the absence of light. The positive role of NiO on the PCP and persistent PCP performance was analyzed. The long-term OCP test and XRD analysis proved the stability of WO3/BiVO4/NiO in PCP performance and chemical composition. [Display omitted] •NiO, a hole collector, was coupled with WO3/BiVO4 to achieve 26.6% higher capacitance.•The optimal WB2N2 photoanode can polarize 316SS to −726 mV under irradiation.•The electric quantity WB2N2 passed to 316SS after irradiation reached 1.286×10−2 C.•WB2N2 exhibited long-term stability in PCP performance and chemical composition.•Charge transfer between 316SS, WO3, BiVO4 and NiO were mechanistically analyzed.