A theoretical study of formaldehyde adsorption and decomposition on a WC (0001) surface
Dandan Wang1,2, Yingying Fan1, Zhonghui Sun1
1Center for Advanced Analytical Science, c/o School of Chemistry and Chemical Engineering, Guangzhou University Guangzhou 510006 P. R. China dxhan@gzhu.edu.cn +8643185262800 +8643185262425.
Abstract:
A lot of research attention has been paid to designing and exploring efficient adsorbents for HCHO adsorption and decomposition. Herein, we have demonstrated a highly active material, WC, for HCHO adsorption through first-principles calculations. Due to the exposed three-coordinated W atoms (W3c) of the WC (0001) surface, HCHO molecules can be settled on the WC (0001) surface through newly formed OF-W3c and/or CF-W3c bonds, forming different adsorption configurations. When settled on the WC (0001) surface, the molecular configuration of the HCHO molecule and the corresponding CF-HF and CF-OF bond lengths would be greatly changed. Due to the enlarged CF-HF and CF-OF bond lengths, the adsorbed HCHO molecules tend to dissociate through two possible pathways; these are the two-step CF-HF bond scission or the one-step CF-OF bond scission. The former results in two H adatoms and a CO molecule chemisorbed to the surface and the latter produces an O adatom and a CH2 group on the surface. Further Cl-NEB calculations demonstrate that the pre-adsorbed O atom has little influence on the first CF-HF bond scission and the CF-OF bond scission, while promoting the second CF-HF bond scission. Considering the dissociative products, H and CH2 have the potential to couple into a CH3 group (or even a CH4 molecule) and two CH2 groups may couple into a C2H4 molecule. In the end, we propose that OH ions may couple with the dissociative products of HCHO, so an alkali solution could be used to post-process the WC (0001) surface to restore its surface active sites. These results demonstrated the potential of WC in HCHO sensing and abatement.
