LHM & ERM NO oxidation and the adsorption configurations of NO2* bidentate

[Tingchenlee]

Inspired by this paper, NO oxidation can proceed by

1. NO* + O* <=> NO2* Langmuir–Hinshelwood Mechanism(LHM)
2. NOgas + O* <=> NO2* Eley–Rideal Mechanism (ERM)

This paper also proposed a more stable O,O' bidentate structure of NO2 adsorbate on the bimetallic surface that We have thermo data for both structures, it can be found by searching these two adjcencyLists

multiplicity 2
1 O u0 p2 c0 {3,S} {5,S}
2 O u1 p2 c0 {3,S}
3 N u0 p1 c0 {1,S} {2,S} {4,S}
4 X u0 p0 c0 {3,S}
5 X u0 p0 c0 {1,S}

and

multiplicity 2
1 O u0 p2 c0 {3,S} {5,S}
2 O u0 p2 c0 {3,S} {4,S}
3 N u1 p1 c0 {1,S} {2,S}
4 X u0 p0 c0 {2,S}
5 X u0 p0 c0 {1,S}

Presently, we don’t have a family or library to deal with these mechanisms (both LHM and ERM). One similar template is from the Surface_Dissociation family

 *1--*2                 *1     *2                        *O--*N=O               *O     *N=O
  |            ---->    ||      |        which is         |            ---->    ||      | 
~*3~ + ~*4~~           ~*3~ + ~*4~~                     ~*3~ + ~*4~~           ~*3~ + ~*4~~

Another similar one is in the Surface_Bidentate_Dissociation family

 *1--*2              *1   +   *2                      *O--*N-O              *O   +   *N-O      
  |   |     ---->    ||       ||          and          |   |     ---->      ||       ||          
~*3~~*4~~           ~*3~~ +  ~*4~~                   ~*3~~*4~~             ~*3~~ +  ~*4~~             

while X=N-O is not a representative species in RMG and we don't have thermo data of this adsorbate

Maybe we can consider a template or library like this?

 *1       *2=*5          *1--*2-*5              *O       *N=*O          *O--*N-*O
 ||        |    ---->     |   |         and     ||        |    ---->     |   |
~*3~  +  ~*4~~          ~*3~~*4~~              ~*3~  +  ~*4~~          ~*3~~*4~~

---

One more thing to discuss is the value of sticking coefficient for reaction NO2gas + * <=> NO2* reported in table I, which is: A= ((2.24E2 /bar)/ s)(2.483E-9 mol/cm2)sqrt(2pi46 g/mol * molar gas constant * 298 kelvin)= 1.4884E-6 Comparing the value reported in RMG is A= 0.2, which is very different. I am not confident with this value and not sure if we could include this in the training reactions.

[rwest]

Thanks for openining this issue, Ting-Chen. Although you say we have thermo for both structures, when I search the one where the two oxygens are on the surface (as you showed me this morning), which your referenced paper says is the more stable configuration, here I see RMG estimating it from some crazy tri-radical gas phase thing, with incorrect radical groups, and ending up with an enthalpy 107 kcal/mol higher than the one with N=O bound to the surface like this, which should be less stable. (I also note that both your adjacency lists have radical adsorbates, which I thought we usually avoided somehow?)

[rwest]

Replace the N with CH and we have the same species we were discussing elsewhere:

O-CH-O
|    |
X    X

where there's some kind of resonance.

Short term, maybe remove a surface bond:

O-N=O
|    
X   X