By using plane-wave density functional theory, the reaction mechanism of ethanol steam reforming (ESR) on the Co(0001) surface is investigated by systematically exploring the barriers and reaction energies of elementary steps. Our results suggest that ESR is initiated by decomposition of ethanol: CH

A catalyst composed of monolayer nonstoichiometric titanate nanosheets (denoted as TN) and Pd clusters is constructed for precise synthesis of cyclohexanone from phenol hydrogenation with high conversion (>99%) and selectivity (>99%) in aqueous media under light irradiation. Experimental and DFT calculation results reveal that the surface exposed acid and basic sites on TN could interact with phenol molecules in a nonplanar fashion via a hexahydroxy hydrogen-bonding ring to form a surface coordination species. This greatly facilitates the adsorption and activation of phenol molecules and suppresses the further hydrogenation of cyclohexanone. Moreover, the surface Pd clusters serve as the active sites for the adsorption and dissociation of hydrogen molecules to provide active H atoms. The synergistic effect of the surface coordination species, TN and Pd clusters remarkably facilitate the high yield of cyclohexanone in photocatalysis. Finally, the possible thermo/photocatalytic mechanisms on Pd/TN are proposed. This work not only highlights the great potential for monolayer nonstoichiometric composition nanosheets in the construction of catalysts for precise organic synthesis but also provides insight into the inherent catalytic behavior at a molecular level.

A Cu(111) supported h-BN nanosheet (h-BNNS) has been systematically investigated by first-principles DFT using dispersion corrections. During the interaction between Cu and h-BNNS, the electrons migrate from the metal to the h-BNNS, leading to the formation of gap states above and under the Fermi level. Significant electrons are observed to migrate from the supported h-BNNS to the O2 molecule, resulting in the activation of the adsorbed O2. While for the unsupported h-BNNS, the absorbed O2 is almost intact with a very weak binding energy. CO oxidation is chosen as a benchmark probe reaction to better understand the enhanced catalytic activity induced by the Cu(111) metal substrate. The calculated energy barrier of the reaction CO + O2* → CO2* + O* is found to be only 0.51 eV with a large exothermicity of -2.93 eV. Even for the process of CO reacting with the residual atomic O* to generate CO2*, the barrier is found to be nearly null, helping the catalyst to facilely recover itself. Our calculation results suggest that the Cu(111) supported h-BNNS is a potential low cost and high activity catalyst for CO oxidation.

Defective hexagonal boron nitride nanosheets (h-BNNSs) supported by Ni(111) and Cu(111) surfaces have been systematically studied in this work by first-principles methods. The calculation results show that various defects play an important role in enhancing the stability of h-BNNS/metal heterostructure. Importantly, significant electron transfer through the interface between metal substrate and h-BNNS to the defect sites can make h-BNNS more catalytically active. Using the oxygen reduction reaction (ORR) as a probe, it is shown that the binding energies of O2*, OH*, OOH*, and O* on h-BNNS/Cu(111) with a boron vacancy (VB) are quite similar to those observed on the Pt(111) surface, suggesting inert h-BNNS materials with defects can be functionalized by metal surfaces to become catalytically active for the ORR process. On the other hand, the reaction mechanism of CO oxidation on Ni(111) and Cu(111) supported h-BNNS with VB is systematically investigated. The h-BN/Cu(111) catalyst with a VB precovered by a CO species exhibits catalytic capacity for CO oxidation with a lower energy barrier compared with that on h-BN/Cu(111) without any defect. While on Ni(111) supported h-BNNS with a N vacancy, the defect site turns to be dominated by O2 and the energy barrier is significantly increased, indicating its dependence on the type of defect. This work will provide information for designing h-BN-based catalysts in heterogeneous catalysis.

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