Developing highly nanoporous titanate structures via wet chemical conversion of DC magnetron sputtered titanium thin films

Nanostructured, Alkaline Titanate‐Converted, and Heat‐Treated Ti6Al4V Microspheres via Wet‐Chemical Alkaline Modification and their ORR Electrocatalytic Response

“…An additional peak for the Ti6_TC sample was noted at 1071.6 eV (65.6%) corresponding to Na–O, characteristic of sodium titanate structures. Collectively, these results correlate well with previous studies by Takadama et al., [ 49 ] Zárate et al, [ 50 ] and the present authors, [ 15 ] which detail the formation of sodium hydrogen titanate species, such as Na 2 Ti 3 O 7 ; Na 2 Ti 3 O 7 ∙ n H 2 O; Na 2 Ti 2 O 5 ∙ n H 2 O, Na x H 2− x Ti 3 O 7 , and/or mixtures of these phases.…”

“…An additional peak for the Ti6_TC sample was noted at 1071.6 eV (65.6%) corresponding to Na-O, characteristic of sodium titanate structures. Collectively, these results correlate well with previous studies by Takadama et al, [49] Zárate et al, [50] and the present authors, [15] which detail the formation of sodium hydrogen titanate species, such as After the heat treatment stage (Ti6_TC_HT), subsequent modifications were noted in the XPS analysis. The O 1s peak remained constant in number of components, but shifts were noted in peak positions.…”

“…The microspherical nature of the substrate, which possesses higher exposed surface areas, did not appear to modify the thickness of the produced structures, unlike the conversion of magnetron sputtered films with higher surface roughness which resulted in titanate thickness on the order of 1-1.5 µm. [15] The films presented in this study were comparable to other studies which converted bulk Ti discs (titanate thickness ≈1 µm [16] ).…”

“…Following the alkaline titanate conversion, nanoporous ( ≈ 100 nm) dendritic structures were observed, (Figure 1D–F), characteristic of wet‐chemically converted titanate structures. [ 15 ] Similar structures were present in the Ti6_TC_HT powder (Figure 1G–I), with minor differences specifically regarding “webbing” between the titanate struts (Figure 1I). The probable cause for such a change is either minor formation of rutile crystals, or the subtle modification/crystallization of the formed titanate surface.…”

“…Compared to the XPS measurements, Na and O were shown to be concentrated, particularly the case for Na, in the surface and demonstrates a clear diffusion gradient as seen in the literature. [ 15,54,55 ] Further differences were noted following heat treatment (Ti6_TC_HT), with additional increases seen for Na and O to ≈5.4 and 59.1 at%, respectively, as a result of increased diffusion. [ 56 ] Similar trends were also seen in the XPS results.…”