Dear Steve,

You may choose either of the technique.

However, doing a DFT study, in the beginning, will save the material and may help in the prediction of the reaction mechanisms.

Whereas, carrying out the kinetic and mechanistic study of the catalyst supported by XRD, XPS, and DRIFT studies will help in the prediction of the actual reaction mechanism taking place for your catalyst system.

Agree with Mohammad Yusuf

The kinetic and mechanistic study supported by characterizations may help in the approximate prediction of the reaction mechanism, whereas a DFT study will help in loss of material and hit and trial method for the optimum catalyst.

Dear Steve

following the prior comments. There is not definite answer to such a question - a fundamental question. Essential will be the objective of your work.

Do you want "just" find a catalyst that works well?

Do you want to understand how the reaction you are studying functions on a specific catalyst or group of catalysts?

Which feature of the catalyst are you interested in: atomic structure, micro-structure, etc.?

Knowing the answer to these questions may guide you to the methods you need for your work.

With respect to the two general approaches that you were raising: Theory vs. Experiments. I would like to handwavy point out some general issues.

Both approaches can be enormously time-consuming so there is no clear advantage of one over the other.

For theory, you got the essential issue, that you have to hypothesize some sort of structure beforehand. In your case, you could say: "I want to look at Ni-X(111) alloy (X = metal) surfaces." Then you may be able to predict which of the alloys has some advantage over the other. However, your synthesized catalyst will not be a pure Ni-X(111) surface, it will be a plethora of structures (metals, metal-oxide interfaces, nanostructures ...). So whatever you are predicting has the risk to be irrelevant for the catalysis. Same goes for the reaction mechanism, that you have to hypothesize beforehand. Yet, theory is extremely informative if it is used correctly, but this is not easy.

If you go down the experimental route, you face the same problem from another direction. Obviously your catalytic activity measurements will tell you which of the catalysts you are test is e.g. performing the best. However, your catalyst will be so complex and dynamic under reaction conditions that is hard to decipher what is the cause of the enhanced activity.

So there is no clear answer to this. However, in my opinion, essential to whatever you do is to read the literature in great detail. Look into work which was done decades ago as well as into the recent literature. This is by far the most time efficient way to understand what works and what not and what the scientific community is not understanding.

Maybe this helps, at least it helped me a lot.

Cheers, Arik