| 324 |
|
\hline |
| 325 |
|
& Calculated & Experimental \\ |
| 326 |
|
\hline |
| 327 |
< |
\multirow{2}{*}{\textbf{Pt-CO}} & \multirow{2}{*}{-1.84} & -1.4 \bibpunct{}{}{,}{n}{}{,} |
| 327 |
> |
\multirow{2}{*}{\textbf{Pt-CO}} & \multirow{2}{*}{-1.81} & -1.4 \bibpunct{}{}{,}{n}{}{,} |
| 328 |
|
(Ref. \protect\cite{Kelemen:1979}) \\ |
| 329 |
|
& & -1.9 \bibpunct{}{}{,}{n}{}{,} (Ref. \protect\cite{Yeo}) \\ \hline |
| 330 |
|
\textbf{Au-CO} & -0.39 & -0.40 \bibpunct{}{}{,}{n}{}{,} (Ref. \protect\cite{TPDGold}) \\ |
| 362 |
|
{\it et al.}\cite{Tao:2010}, who also showed that the addition of CO |
| 363 |
|
leads to a reversal in stability. |
| 364 |
|
|
| 365 |
< |
The DFT calculations suggest an increased stability of 0.1 kcal/mol |
| 366 |
< |
per Pt atom, while our force field gives an approximately 0.4 kcal/mol |
| 367 |
< |
increase in stability per Pt atom. |
| 365 |
> |
The DFT calculations suggest an increased stability of 0.08 kcal/mol |
| 366 |
> |
(0.7128 eV) per Pt atom for going from the single to double step |
| 367 |
> |
structure in the presence of carbon monoxide. |
| 368 |
|
|
| 369 |
|
The gold systems show much smaller energy differences between the |
| 370 |
|
single and double layers. The weaker binding of CO to Au is evidenced |
| 371 |
|
by the much smaller change in relative energy between the structures |
| 372 |
|
when carbon monoxide is present. Additionally, as CO-Au binding is |
| 373 |
< |
much weaker, it would be unlikely that CO would approach the 50\% |
| 374 |
< |
coverage levels operating temperatures. |
| 373 |
> |
much weaker than CO-Pt, it would be unlikely that CO would approach |
| 374 |
> |
the 50\% coverage levels operating temperatures for the gold surfaces. |
| 375 |
|
|
| 376 |
|
%Table of single step double step calculations |
| 377 |
|
\begin{table}[H] |
| 386 |
|
\textbf{Step} & \textbf{N}\textsubscript{M} & \textbf{N\textsubscript{CO}} & \textbf{Relative Energy} & \textbf{$\Delta$E/M} & \textbf{$\Delta$E/CO} \\ |
| 387 |
|
\hline |
| 388 |
|
Pt(557)-S & 480 & 0 & 0 & 0 & - \\ |
| 389 |
< |
Pt(557)-D & 480 & 0 & 114.783 & 0.239 & -\\ |
| 390 |
< |
Pt(557)-S & 480 & 40 & -124.546 & -0.259 & -3.114\\ |
| 391 |
< |
Pt(557)-D & 480 & 44 & -34.953 & -0.073 & -0.794\\ |
| 389 |
> |
Pt(557)-D & 480 & 0 & 119.788 & 0.2495 & -\\ |
| 390 |
> |
Pt(557)-S & 480 & 40 & -109.734 & -0.2286 & -2.743\\ |
| 391 |
> |
Pt(557)-D & 480 & 48 & -110.039 & -0.2292 & -2.292\\ |
| 392 |
|
\hline |
| 393 |
|
\hline |
| 394 |
|
Au(557)-S & 480 & 0 & 0 & 0 & - \\ |
| 395 |
< |
Au(557)-D & 480 & 0 & 79.572 & 0.166 & - \\ |
| 396 |
< |
Au(557)-S & 480 & 40 & -157.199 & -0.327 & -3.930\\ |
| 397 |
< |
Au(557)-D & 480 & 44 & -123.297 & -0.257 & -2.802 \\ |
| 395 |
> |
Au(557)-D & 480 & 0 & 83.853 & 0.1747 & - \\ |
| 396 |
> |
Au(557)-S & 480 & 40 & -253.604 & -0.5283 & -6.340\\ |
| 397 |
> |
Au(557)-D & 480 & 48 & -156.150 & -0.3253 & -3.253 \\ |
| 398 |
|
\hline |
| 399 |
|
\end{tabular} |
| 400 |
|
\label{tab:steps} |
