RESUMO
The structure-activity relationship in the electrochemical OER has been studied widely, but aspects of the photoelectrochemical (PEC) O2 evolution activity with different manganese oxides are not fully explored. In the present study different manganese oxides (MnO2, MnOx (a mixture of Mn3+ and Mn4+ ions), Mn2O3, and Mn3O4) have been electrodeposited onto the BiVO4 photoanode as co-catalysts for PEC water splitting. We find that BiVO4-MnOx shows the lowest onset potential of 0.33 V vs. RHE and the highest activity among the manganese oxides. Annealing at different temperatures results in the improvement of the OER kinetics at the interface with some detrimental effect on the activity of BiVO4. Such a study may lead to useful changes in the fabrication of semiconductor thin film photoelectrodes useful for PEC water splitting.
RESUMO
van der Waals heterostructures formed by 2D materials have attracted much attention in the last few years. Recently, 2D nanosheets linked by covalent bonds have been found to exhibit novel properties. In the present study we have investigated supramolecular layered heterostructures formed by nanosheets of MoS2 with BC7 N, g-C3 N4 and graphene. These materials have been synthesized via a non-covalent host-guest synthetic design using cucurbit[8]uril (CB[8]) hosts. In addition to offering reversible disassembly, these heterostructures show good visible-light-driven hydrogen evolution reaction (HER) activity as well as reasonable gas adsorption and other properties.
RESUMO
The nanocomposites of MoS2 nanosheets with the metal-organic framework, ZIF-8, have been synthesized starting with the layers of 1T-MoS2 generated by Li intercalation of bulk MoS2, followed by exfoliation. The nanocomposites contain the Zn-S bond and exhibit reasonably high surface areas. They exhibit CO2 uptake higher than ZIF-8. Heating the nanocomposites to 900 °C under a N2 atmosphere yields MoS2-ZnS nanocomposites which show good activity for the visible-light induced hydrogen evolution reaction.
