Mechanistic Insights into Selective CO2 Conversion via RWGS on Transition Metal Phosphides: A DFT Study

Guharoy, Utsab, Ramirez Reina, Tomas, Gu, Sai and Cai, Qiong (2019) Mechanistic Insights into Selective CO2 Conversion via RWGS on Transition Metal Phosphides: A DFT Study Journal of Physical Chemistry C, 123 (37). pp. 22918-22931.

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Abstract

Selective conversion of CO2 to CO via the reverse water gas shift (RWGS) reaction is an attractive CO2 conversion process, which may be integrated with many industrial catalytic processes such as Fischer−Tropsch synthesis to generate added value products. The development of active and cost friendly catalysts is of paramount importance. Among the available catalyst materials, transition metal phosphides (TMPs) such as MoP and Ni2P have remained unexplored in the context of the RWGS reaction. In the present work, we have employed density functional theory (DFT) to first investigate the stability and geometries of selected RWGS intermediates on the MoP (0001) surface, in comparison to the Ni2P (0001) surface. Higher adsorption energies and Bader charges are observed on MoP (0001), indicating better stability of intermediates on the MoP (0001) surface. Furthermore, mechanistic investigation using potential energy surface (PES) profiles showcased that both MoP and Ni2P were active toward RWGS reaction with the direct path (CO2* → CO* + O*) favorable on MoP (0001), whereas the COOH-mediated path (CO2* + H* → COOH*) favors Ni2P (0001) for product (CO and H2O) gas generation. Additionally, PES profiles of initial steps to CO activation revealed that direct CO decomposition to C* and O* is favored only on MoP (0001), while H-assisted CO activation is more favorable on Ni2P (0001) but could also occur on MoP (0001). Furthermore, our DFT calculations also ascertained the possibility of methane formation on Ni2P (0001) during the RWGS process, while MoP (0001) remained more selective toward CO generation.

Item Type:	Article
Divisions :	Faculty of Engineering and Physical Sciences > Chemical and Process Engineering
Authors :	Name Email ORCID Guharoy, Utsab Ramirez Reina, Tomas t.ramirezreina@surrey.ac.uk Gu, Sai sai.gu@surrey.ac.uk Cai, Qiong q.cai@surrey.ac.uk
Date :	19 September 2019
Funders :	Engineering and Physical Sciences Research Council (EPSRC)
DOI :	10.1021/acs.jpcc.9b04122
Copyright Disclaimer :	© 2019 American Chemical Society
Additional Information :	Financial support for this work was provided by the Department of Chemical and Process Engineering at the University of Surrey and EPSRC Grants EP/M027066/1, EP/R512904, EP/J020184/2, and EP/P003354/1. The authors would like to acknowledge the access to HPC clusters including Eureka and KARA (University of Surrey) and ARCHER (U.K. National HPC resource) for performing the DFT simulations.
Depositing User :	Diane Maxfield
Date Deposited :	16 Oct 2019 15:39
Last Modified :	16 Oct 2019 15:51
URI:	http://epubs.surrey.ac.uk/id/eprint/852941

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