Phase-pure M1 MoVNbTeOx/TiO2 nanocomposite catalysts: highly catalytic performance for oxidative dehydrogenation of ethane

The catalytic performance of the phase-pure M1 MoVNbTeOx catalyst is enhanced by introducing TiO2 in oxidative dehydrogenation of ethane (ODHE). The space-time yield (STY) of the M1/TiO2 composite catalyst increases...

A novel two-step strategy to fabricate phase-pure SnS photoelectrode with tunable conductivity: formation mechanism and photoelectrochemical properties

Tin monosulfide (SnS), as a narrow band gap semiconductor for visible-light harvesting, nevertheless the easy formation of secondary phases such as Sn2S3 and SnS2 severely restricts its photoelectrochemical properties. Herein, we proposed a novel two-step strategy to fabricate phase-pure SnS photoelectrode with tunable conductivity on Ti foil substrate and carefully investigated the formation mechanism and photoelectrochemical properties. The tunable conductivity is determined by Na2SO4 pretreatment before annealing, which is supported by the EDS, XPS, and EPR characterizations. Na+ adsorbed to the edge of the precursor SnS2 nanosheets forming a dangling bond adsorption will protect S2- against reacting with the trace oxygen in the CVD system within a certain temperature range (< 525 ℃), thereby reducing the generation of S vacancies to adjust the S/Sn ratio and further regulating the conductivity type. Moreover, the anodic photocurrent density of SnS thin films was about 0.32 mA/cm2 at 1.23 V vs. RHE with the separation and injection efficiency of 1.22 % and 72.78 % and a maximum cathodic photocurrent density can reach approximately -0.36 mA/cm2 at 0 V vs. RHE with the separation and injection efficiency 1.15 % and 5.44 % respectively. The method shown in this work provides an effective approach to control the electrical conductivity of SnS thin films with considerable photocurrent response for phase-pure SnS.

Alcohol Assisted Solution-Combustion Technique for the Synthesis of Phase-Pure BaSnO3 Nanoparticles at 130 °C

Lowering the synthesis temperature to obtain phase pure BaSnO3, which is the host material for high figure-of-merit (FOM) perovskite transparent conductors (TCs), can expand the horizons for its optoelectronic applications, with an obvious reduction in the thermal budget. In this work, we have developed a novel solution combustion technique for the synthesis of BaSnO3 nanoparticles. A peroxo/superoxo precursor to the nanoparticles is first synthesized by co-precipitation of the tin and barium salts via the H2O2 assisted or the `CSMC' route. The phase evolution, under different drying conditions of the wet precursor to crystalline BaSnO3 nanoparticles is then studied. We find that the crystallization temperature of BaSnO3 is significantly reduced by adding an organic solvent such as ethanol or propanol to the precursor; temperatures as low as 130 °C yield phase pure BaSnO3 nanoparticles. We establish that the organic solvent increases the reactive O2 ligand content, which plays a pivotal role in the synthesis. Due to this, an exothermic reaction occurs around 130 °C, thereby providing the heat of reaction for conversion of the precursor to phase-pure BaSnO3. Importantly, this method should also allow for the facile incorporation of dopants, paving the way for synthesis of high FOM TCs at low temperatures. Such low synthesis temperatures enable BaSnO3 to be used in devices having temperature limitations during device processing, such as heterojunction Si solar cells or perovskite-based solar cells in an n-i-p architecture.