1. Why do stepped and kinked Pt surfaces exhibit higher catalytic activity than flat surfaces, considering their lower atomic coordination and abundance of unsaturated surface sites?

2. Among lattice oxygen, adsorbed oxygen, and surface oxygen, which form(s) play the dominant role in hydrocarbon oxidation?

My question is why ROR of aromatization oof n-alkane is faster by (111) Pt but slower in isomerization of isobutanr according to slide 9. Structure of HC affects the catalyst activity?

I look forward to receiving any answer from the other coursemates or Dr Sheela. Lastly, thank you Dr Sheela and anyone for your time on read my questions and any attempt to solve my doubts.

Thank you Dr.

My question is can dr describe how the structure and morphology of platinum catalysts (e.g., flat Pt(100), Pt(111), stepped Pt(755), kinked (10,8,7)) influence their catalytic performance in hydrocarbon conversion reactions such as aromatization and isomerization.

-How does surface area and porosity of a metal catalyst affect its performance?

Can Dr explain a bit of detail on gamma alumina, which is on slide 10, pages 16-18? Because I'm confused and couldn't catch up with the concept of Lewis acid and Bronsted acid in the case of gamma alumina.

Thank you Dr.

May I ask, what does it mean by 'the Fermi levels of the metal and semiconductor align causing electrons to flow to the metal from the semiconductor.'

How surface defects can act as both catalytic active sites and potential deactivation points?

Why might stepped and kinked surfaces be more catalytically active than flat surfaces, even though they represent defects?

1. Why is Pt(111) more effective for aromatization reactions (e.g., n-hexane → benzene), while Pt(100) is better for isomerization reactions (e.g., isobutane → n-butane)?

2. Why is Fe³⁺ a suitable dopant for TiO₂ photocatalysts, while Cr³⁺ increases recombination? Discuss the electronic interactions and propose an optimal doping concentration for Fe³⁺.

My second question is what roles do the conduction band, valence band, and hydroxyl radicals play in the degradation of organic pollutants in water treatment? Why is anatase TiO₂ preferred over the rutile form?

How do kinked and stepped surface sites on a catalyst influence its catalytic activity and selectivity compared to flat surface sites?

Is the typical reaction mechanisms (e.g., Langmuir-Hinshelwood & Eley-Rideal) differ or remain similar for reactions occurring on (a) metal surfaces and (b) metal oxide surfaces?

Most studies describe catalyst surfaces as static, but during real reactions, do catalyst surfaces undergo restructuring, shape changes, or even break apart? If so, how does this dynamic behavior influence their catalytic activity and the reaction mechanism?

Also, I’m interested in the role of semiconductor materials in environmental cleanup. How do the positions of the valence and conduction bands in TiO₂ facilitate the generation of oxidative species during photocatalytic water treatment? And why is the anatase structure generally regarded as more reactive than the rutile form in such applications?

As we know, a band gap energy greater than 3.2 eV is typically required for UV light absorption. But how can the band gap of a photocatalyst be determined?

My question is why are some metal surfaces more active in catalysis even though they have the same chemical composition?

Here is my question, what are some limitations or challenges currently faced in photocatalytic processes for industrial or municipal use?

Dr., what would happen if the metal surface used in a catalyst becomes rough or damaged over time? Will it affect the reaction?

What risks or by products might occur if photocatalysts like TiO₂ break down complex pollutants in wastewater? Are all products safe

so i want to ask why does the same metal work differently depending on the surface, isn’t it still the same metal?

I want to ask about the n-type and p-type semiconductor. Is there any significant difference between that two type semiconductor in term of their catalytic activity. Also, between those two, what do you prefer?

may i know how does adding metals like platinum or iron to TiO₂ help improve the photocatalytic process, and how do we know how much metal to add without making it less effective?

I want to ask on transition metal doping.Why do certain transition metals like Fe³⁺ enhance photocatalytic activity while others like Cr³⁺ reduce it. What causes this difference at the electronic level?.

One of the defects of n-type semiconductors is Anion vacancy with trapped electrons.

1. Is it meant that oxygen in metal oxide is always missing, left behind its electrons in the vacancy?

2. If yes, when the metal oxide is doped with other material such as liquid crystal, can these free electrons interact with LUMO of liquid crystal to form hybridised state that alter the energy bandgap of liquid crystal?

How do crystallographic defects like oxygen vacancies affect both the catalytic activity and selectivity of a metal oxide surface? Can too many defects become detrimental?

I’ve read that TiO₂ can break down pollutants using light, but how does it actually work if I mixed into soil. Does it still react the same way ?

If TiO₂ is added to soil, does it help clean up harmful chemicals and can it help improve soil health, or is it mainly used for pollution control ?

I would like to can the platinum be substituted with another noble metal that can act as electron trap? As I know, platinum is quite expensive and maybe there is another noble metal that can replace the Pt.

I would like to ask why transition metals like Pt, Pd, or Ni are commonly used for surface catalysis in hydrogenation reactions, whereas metal oxides are more suited for oxidation reactions?

Now, my question is how does surface acidity or basicity of a metal oxide catalyst influence selectivity in condensation reactions?

Thank you Dr.