Construction of NH2-MIL-101(Cr)/TiO2 heterojunction for enhancing visible light response in photocathodic protection

Photocathodic protection has obtained enormous attention in the field of metal corrosion control as an efficient and eco-friendly technology. Developing the photoelectrode with good photoelectrochemical properties is a prerequisite for achieving satisfactory photocathodic protection performance. Here, the NH 2 -MIL-101(Cr)/TiO 2 heterostructures are prepared. Meanwhile, the organic linkers and metal ions from NH 2 -MIL-101(Cr) are used to synthesize the N- and Cr-doped TiO 2 anodes, respectively. The UV–vis DRS, photoluminescence spectra and photoelectrochemical tests conducted under visible light demonstrate the enhanced light absorption, suppressed photoinduced charge carrier recombination, and accelerated separation and transfer rates of photoinduced electron-hole pairs in the TiO 2 composites. The 304 stainless steel connected with NH 2 -MIL-101(Cr)/TiO 2 heterostructures shows the most negative potential (about −0.72 V vs. SCE) and satisfied stability in a 3.5 wt% NaCl solution. The result can be explained by the significantly enhanced optical and photoelectrochemical properties and the strong electric field intensity in the composite heterojunctions. Besides, it has been observed that the NH 2 -MIL-101(Cr)/TiO 2 heterostructures exhibit the best photocathodic protection performance than Cr and N-doped TiO 2 anodes. This research broadens the application scope of MOFs in corrosion resistance and helps to assess the effect of heterostructure construction and element doping on TiO 2 .