I think that appropriate method may be measurement characteristic frequencies of a Ti holder before and after growth of tube arrays with the help of quartz generator.

First of all these are all my assumptions I have not tried any of them but may be helpful

Firstly, I think the porosity measurements may be used to interpret to mass of the formed nano tubes with a rough estimation by considering the initial mass of the substrates, mass differences of the atoms, absorption and adsorption of the gas on the modified surface and density.

Further techniques can be EDX analysis by using a reference but the penetration dept can cause uncertainties on the evaluations. The advantage of the tech will come from the non dependency of the crystal phase of the TiO2 .

If the product is a single phase, then Confocal Raman or IR spectroscopy techniques may be used to calculate the mass of the oxide layer.

Finally XPS analysis while etching can be used. The elemental analysis with time correlation can be used if the homogenety of the product is assured.

So, it is mostly depend on your environmental opportunity. Good luck !

EDX is probably a better method, although accuracy will remain the issue. The accuracy can be improved by taking EDS measurement on many spots of the surface and calculating the average.

Absolutely measurement of the mass difference before and after oxide growth is very difficult, we usually avoid to discuss this problem. I hope to get the right answer, too.

You can measure mass of TiO2 nanotubes layer by weighting the sample before and after anodization using an accurate scale (0.0001g). You may find such a scale in some material or chemistry labs. They use this method also for oxidation and corrosion monitoring of alloys at high temperatures by checking the weight added to the samples due to oxide film formation. These scales usually have a range up to 210 g by keeping the accuracy in the order of 0.1 mg.

You may need to dry your samples well before weighting because the electrolyte within the pores may take a long time to dry up.

If you have TiO2 array attached to the film and want to get rid of it after weighting the sample you can put the sample in an electrochemical cell i.g. use a salt added to water as the electrolyte. Under negative polarization (a few volts), hydrogen bobbles forming on the surface will remove the film from the substrate easily.

ECQM or ECQN

If you can grow the nanotubes on a quartz-crystal microbalance with a Ti electrode, you should be able to measure the mass before and after growth. For example, see A.J. Slavin; Stabilization of sample temperature in a surface-science vacuum chamber to 0.03 K and quartz-crystal microbalance frequency to 0.06 Hz over 0.5 h. Rev. Sci. Instrum. 81, 103901-103905 (2010) and L. Bouzidi and A. J. Slavin; Ultrathin films of lead oxide on gold: Dependence of stoichiometry, stability and thickness on O2 pressure and annealing temperature. Surf. Sci. 580, 195-206 (2004).

I said the same above, in short

I do not know the configuration and layer thickness of your sample. If you have a planar substrate, say a thin Ti layer on SiO2, with a thin layer of Ti-oxide on the surface of Ti, with a thickness of a few 10 to a few hundred nm thick. The Ti mass per unit area of the compound can be measured by RBS depth profiling. Earlier papers on thin SiO2 on Si thickness and composition studies will be a good example for you. If you sample is layered structure.

First of all, you did not give any information about Ti-substrate. Is it a thin film or foil.?? What is its thickness.?? The growth of anodic TiO2 nano-array is a top down approach like a drilling in the wood. Therefore, nano arrays will be the part of Ti-Substrate. In this way, it will be difficult to weight on as deposited nano-arrays. It is better to use sonification in Acetone for 10 min and a layer of TiO2 nano array will be separated from the Ti-substrate. You can fish out that separated thin layer of TiO2 nano-arrays and weigh it.

I agree with Alexander

The problem with straightforward weighing difference (or QMB) is some of Ti atoms get etched away into solution in the form of [TiF6]2- complex ions. Or putting it another way, if, say, 500 nm of Ti substrate got turned into TNTs, only some fraction of it actually turned into TiO2 and some got lost irreversibly into solution. Even if you measure your substrate mass before and after anodic oxidation very accurately (avoiding solvent effect etc.), you can not really say how much of the measured mass difference is actually due to Ti loss and how much is due to oxygen addition. So your TiO2 nanotube mass estimate may have quite a large error.

A relatively easy method would be to sacrifice your prepared sample and to physically separate TiO2 nanotube array from Ti substrate (preferably intact or as a scratched powder) and measure its mass directly on a sensitive analytical scale.

I agree with Rizwan Ur Sagar and Oleksandr Kuzmych. It is better to physically separate TiO2 nanotube array from Ti substrate and measure its weight directly on a sensitive scale.

Therer is another way, you can estimate the mass by the charge passed through the system.

You can definitely measure the thicknesslooking through the SEM. You may be able to estimate the density by ellipsometry or XRR and then extrapolate that to the volume of your sample. That can be very accurate. In Anodized aluminum oxide you can separate the membrane by selectively etching the aluminum below the membrane, maybe you can do the same and, as some of the previous comments suggest, weight the membrane separately. What is your estimated thickness?

Hi,

I think suggested techniques are applicable but you should mansion its application for which you want to use. Different researcher who measure gravimetric specific capacity in mAh/g they used following methods:

D. Fangetal./ Journal of Alloys and Compounds 464 (2008) L5–L9:

The volume of TiO2 nanotube is estimated from the geometry as shown in Fig.3. Then a nanotube is taken to be 11.37 um in length, and the other dimensions are shown in the figure. Both fractions of the area and volume occupied by the nanotube are calculated to be 0.34. Therefore, the volume of TiO2 nanotube is 3.87×10−3cm3 TiO2 per cm2 of surface area of foil. When multiplied by the density (estimated as that of anatase, 3.84gcm−3 ) , this yields to be 0.0149g TiO2 formed per cm2 surface area including the mass of titanium dioxide in the barrier layer at the bottom of the nanotube.

Nanotechnology 20 (2009) 225701

The specific capacity and current density were calculated based on the mass of TiO2 only. The net mass of TiO2 nanotubes on Ti substrate was measured By weighing a sample using the balance of a thermo gravimetric analyser (Netsch STA 449C Jupiter, with precision of 1 μg) before and after stripping the TiO2 nanotubes from the Ti substrate by a type of adhesive.

Don't know reference:

To evaluate the gravimetric capacities, the films were subjected to ultrasounds in order to separate the nanotubes from the Ti substrate, and weighed again. Thus ,the active material mass (nt-TiO2 and graphene) was ca.1.03(2) mg/cm2.

Search for papers of Rainer Adelung vom CAU Kiel, he has done such work with ZnO, TiO2, and Al2O3, his methods maybe applicable

I agree with Nadia Shahzad