(44a) Designing Carbon-Based Materials for Efficient Hydrocarbon Synthesis

Authors: 
Siahrostami, S., Stanford University
Jiang, K., Washington University in St Louis
Karamad, M., Stanford University
Nørskov, J., Stanford University and SUNCAT
Electrochemical reduction of CO2 (CO2RR) using renewable electricity has emerged as an attractive approach to synthesize hydrocarbons and mitigate atmospheric CO2 concentration. Carbon-based materials have recently attracted a particular attention as electrocatalysts for CO2RR due to their extraordinary properties such as low cost and flexibility in tuning the morphology and electronic structure. Wide range of different N-doped carbon materials have been experimentally tested and reported for CO2RR. The performance map for CO2RR over reported N-doped carbon-based materials presents diverse activities and in most cases the major product of the CO2 reduction is found to be CO. Based on a simple thermochemical analysis Wu et al previously suggested pyridinic-N as the active sites.1 Using density functional theory (DFT) calculations we study a wide range of different possible active motifs included in the defective carbon materials to rationalize the associated trends in their intrinsic activities. We study both CO2RR and hydrogen evolution reaction (HER) using thermochemical analysis. We identify several active motifs that are expected to exhibit a comparable or even better activity to the state-of-the-art gold catalyst, and several configurations are suggested to be selective for CO2RR over HER. This study provides insights in the nature of active and selective motifs for CO2RR and rationalizes a number of reports in the literature.2 We also show that in the presence of metal impurities further reduced products can be synthesized with significantly improved activity and selectivity.3

References:

(1) Wu, J.; Yadav, R. M.; Liu, M.; Sharma, P. P.; Tiwary, C. S.; Ma, L.; Zou, X.; Zhou, X.-D.; Yakobson, B. I.; Lou, J.; Ajayan, P. M. ACS Nano 2015, 9 (5), 5364–5371.

(2) Siahrostami, S.; Jiang, K.; Karamad, M.; Chan, K.; Wang, H.; Nørskov, J. ACS Sustain. Chem. Eng. 2017, acssuschemeng.7b03031.

(3) Jiang, K.; Siahrostami, S.; Li, Y.; Lu, Z.; Gardener, J.; Lattimer, J; Stokes, C.; Hill, W.; Bell, D.; Chan, K.; Nørskov, J.K.; Yi Cui, Y.; Wang, H. Chem 2017 https://doi.org/10.1016/j.chempr.2017.09.014.

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