Inverse single-site Fe1(OH)X/Pt(111) model catalyst for preferential oxidation of CO in H2

Inverse oxide/metal model systems are frequently used to investigate catalytic structure-function relationships at an atomic level. By means of a novel atomic layer deposition process, growth of single-site Fe1Ox on a Pt(111) single crystal surface was achieved, as confirmed by scanning tunneling microscopy (STM). The redox properties of the catalyst were characterized by synchrotron radiation based ambient pressure X-ray photoelectron spectroscopy (AP-XPS). After calcination treatment at 373 K in 1 mbar O2 the chemical state of the catalyst was determined as Fe3+. Reduction in 1 mbar H2 at 373 K demonstrates a facile reduction to Fe2+ and complete hydroxylation at significantly lower temperatures than what has been reported for iron oxide nanoparticles. At reaction conditions relevant for preferential oxidation of CO in H2 (PROX), the catalyst exhibits a Fe3+ state (ferric hydroxide) at 298 K while re-oxidation of iron oxide clusters does not occur under the same condition. CO oxidation proceeds on the single-site Fe1(OH)3 through a mechanism including the loss of hydroxyl groups in the temperature range of 373 to 473 K, but no reaction is observed on iron oxide clusters. The results highlight the high flexibility of the single iron atom catalyst in switching oxidation states, not observed for iron oxide nanoparticles under similar reaction conditions, which may indicate a higher intrinsic activity of such single interfacial sites than the conventional metal-oxide interfaces. In summary, our findings of the redox properties on inverse single-site iron oxide model catalyst may provide new insights into applied Fe-Pt catalysis.

Stacking design in photocatalysis: synergizing cocatalyst roles and anti-corrosion functions of metallic MoS2 and graphene for remarkable hydrogen evolution over CdS

The advantages of stacking design over traditional core–shell and supported photocatalytic structures have been highlighted with CdS firstly supported by rGO and then covered with metallic MoS2 as a model catalyst.

Reusability of Ni2Fe3 Metal Catalyst for Upgrading Pyrolyzed Bio-Oil from Cellulose

Recyclable catalysts are desperately needed for upgrading pyrolyzed bio-oil which is produced from biomass conversion in order to reduce cost and protect the environment. However, most catalysts used for producing bio-oil from the pyrolysis of biomass cannot be recycled, leading to costly catalyst regeneration or waste if disposed of. In this study, Ni2Fe3 has been chosen as the model catalyst to test the recyclable property of the metal cluster catalyst system. Cellulose is used as the biomass model reactant. The results from pyrolysis experiments and GC-MS show that the catalytic property of Ni2Fe3 remains constant even after repeated experiments. From the analysis of bio-oil by GC-MS, the catalyst even shows slightly better performance with repeated use due to the pyrolytic interaction with cellulose during the experiment.

Simultaneous sulfidation of Mo and Co oxides supported on Au(111)

Co-Promoted MoS2 model catalyst for fundamental hydrodesulfurization studies can be synthesized from a mixed Co and Mo oxide precursor.