Modulation of Surface Ti-O Species in 2D-Ti3C2TX MXene for Developing a Highly Efficient Electrocatalyst for Hydrogen Evolution and Methanol Oxidation Reactions.

Developing cost-effective and earth-abundant noble-metal-free electrocatalysts is imperative for the imminent electrochemical society. Two-dimensional Ti3C2TX (MXene) exhibits tunable properties with high electrical conductivity and a large specific surface area, which improve its electrochemical performance. Herein, the low-temperature annealing method is used to enrich MXene with a maximum number of Ti-O terminals without formation of titanium dioxide (TiO2) under neutral pH conditions. MXene annealed at 200 °C is found to have a large number of Ti-O termination groups, resulting in a large electrochemically active surface area and increased active sites (-O termination groups) and hence excellent electrocatalytic performance compared to other samples as well as previous reported work. The optimized sample is found to show the lowest overpotential value of 0.07 V at 10 mA cm-2 and a Tafel slope of 0.15 V dec-1 toward the hydrogen evolution reaction (HER), whereas for the methanol oxidation reaction (MOR), the current density is 18.08 mA cm-2, and the onset potential is -0.51 V. In addition, it also shows long-term stability and durability toward HER as well as MOR.

Bimetallic Implanted Plasmonic Photoanodes for TiO2 Sensitized Third Generation Solar Cells.

An auspicious way to enhance the power conversion efficiency (PCE) of third generation sensitized solar cells is to improve the light harvesting ability of TiO2 sensitizer and inhibition of back recombination reactions. In the present work, we have simultaneously comprehended both the factors using stable bimetallic Au and Ag metal nanoparticles (Mnps) embedded in TiO2 with ion implantation technique at lower fluence range; and explored them in third generation dye sensitized solar cells (DSSCs). The best performing Au-Ag implanted DSSC (Fluence- 6 × 1015 ions cm-2) revealed 87.97% enhancement in its PCE relative to unimplanted DSSC; due to plasmon induced optical and electrical effects of Mnps. Here, optimized bimetallic Au-Ag Mnps embedded in TiO2 improves light harvesting of N719 dye; due to the well matched localized surface plasmon resonance (LSPR) absorption band of Au and Ag with low and high energy absorption bands of N719 dye molecules, respectively. Furthermore, Au and Ag acts as charge separation centers in TiO2 that inhibit the recombination reactions occurring at photoanode/electrolyte interface via prolonging photo-generated electron lifetime; resulting in efficient inter-facial charge transportation in DSSCs.

Fabrication of plasmonic dye-sensitized solar cells using ion-implanted photoanodes.

Plasmonic dye-sensitized solar cells containing metal nanoparticles suffer from stability issues due to their miscibility with liquid iodine-based electrolytes. To resolve the stability issue, herein, an ion implantation technique was explored to implant metal nanoparticles inside TiO2, which protected these nanoparticles with a thin coverage of TiO2 melt and maintained the localized surface plasmon resonance oscillations of the metal nanoparticles to efficiently enhance their light absorption and make them corrosion resistant. Herein, Au nanoparticles were implanted into the TiO2 matrix up to the penetration depth of 22 nm, and their influence on the structural and optical properties of TiO2 was studied. Moreover, plasmonic dye-sensitized solar cells were fabricated using N719 dye-loaded Au-implanted TiO2 photoanodes, and their power conversion efficiency was found to be 44.7% higher than that of the unimplanted TiO2-based dye-sensitized solar cells due to the enhanced light absorption of the dye molecules in the vicinity of the localized surface plasmon resonance of Au as well as the efficient electron charge transport at the TiO2@Au@N719/electrolyte interface.