Non-noble metal single-atom catalyst of Co 1 /MXene (Mo 2 CS 2 ) for CO oxidation
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Published online 9 Spetember 2020 | https://doi.org/10.1007/s40843-020-1458-5
Non-noble metal single-atom catalyst of Co1/MXene (Mo2CS2) for CO oxidation 1
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Shamraiz Hussain Talib , Sambath Baskaran , Xiaohu Yu , Qi Yu , Beenish Bashir , 4 5 5 1,2* Shabbir Muhammad , Sajjad Hussain , Xuenian Chen and Jun Li ABSTRACT MXene is a variety of new two-dimensional (2D) materials with early transition metal carbides, nitrides, and carbonitrides. Quantum chemical studies have been carried out on the geometries, electronic structures, stability and catalytic properties of a non-noble metal single-atom catalyst (SAC) with single Co atom anchored on MXene materials of Mo2CS2. The Co adatom anchored on top of the Mo atom of this MXene is found to be rather stable, and this SAC is appropriate for CO oxidation. The charge transfers from the surface to the adsorbed CO and O2 play a significant role in the activation of these molecules on Co1/Mo2CS2. With this catalyst, the Eley-Rideal (ER), Langmuir-Hinshelwood (LH), and Termolecular Eley-Rideal (TER) mechanisms are explored for CO oxidation. We find that, while all the three mechanisms are feasible at low temperature, Co1/Mo2CS2 possesses higher catalytic activity for CO oxidation through the TER mechanism that features an intriguing OC(OO)CO intermediate (IM) adsorbed on Co single atom. The calculated activation energy barriers of the rate-limiting step are 0.67 eV (TER), 0.78 eV (LH) and 0.88 eV (ER), respectively. The present study illustrates that it is promising to develop and design low-cost, non-noble metal SACs using MXene types of 2D materials. Keywords: heterogeneous catalysis, 2D MXene monolayer, CO oxidation, DFT calculations, Co1/Mo2CS2 single-atom catalyst
INTRODUCTION The CO oxidation at low temperature has been one of the
archetypal reactions in heterogeneous catalysis due to its importance in environmental catalysis, fuel cell applications, combustion, and other industrial processes [1–5]. Hence, CO oxidation reaction serves as a benchmark for the scrutiny of catalytic activity of heterogeneous catalysts. Noble metal catalysts such as Pt, Pd, Au, Rh [6–14], reveal promising catalytic activity for CO oxidation even in the presence of moisture [15]. However, these noblemetal catalysts are expensive, which is detrimental for their economical applications in industry. Thus, practical applications at large-scale require low-cost catalysts with high activity. Plentiful efforts have been made, including utilization of non-noble metals and reducing the size of metal catalysts [15–18]. Sub-nanosized metal clusters and nanoparticles usually possess higher catalytic activity and selectivity as compared with bulk metal [19–22]. As an effective approach to lower the cost and consumption of catalysts, single-atom catalysts (SACs), which was first proposed in 2011 [23–26], have become promising alternative in heterogeneous catalysis [27–30]. SACs embedded on different supports have revealed superb catalytic activity and selectivity as compared with subnanosized
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