Kodi Summers

Application of ZnxCd1−xSe-sensitized TiO2 nanotube arrays as photoanodes for solar cells

This study reports the synthesis of ZnxCd1−xSe quantum dot-sensitized titania nanotube array photoelectrodes using a successive ionic layer adsorption and reaction technique and evaluates the photoelectrochemical performance as anodes. The effect of altering the number of sensitization cycles and annealing temperature on optical and photoelectrochemical properties of prepared photoanodes was studied. Surface morphology of the sensitized tubes was analyzed by scanning electron microscopy, while the phase composition was determined using X-ray diffraction and X-ray photoelectron spectroscopy techniques. Spectral response measurements indicated that TiO2 nanotube arrays coupled with ZnxCd1−xSe quantum dots synthesized in 7 cycles of deposition and annealed at 300 °C for 1 h under N2 exhibited excellent photoelectrochemical properties. The notably high photovoltaic characteristics demonstrate the potential of the ZnxCd1−xSe/TiO2 heterostructure as an efficient photoanode.

Ni-Ci oxygen evolution catalyst integrated BiVO4 photoanodes for solar induced water oxidation

A nickel-based oxygen evolution catalyst, nickel-bicarbonate (Ni-Ci), was electrochemically deposited for varying intervals on the surface of W-doped BiVO4 in a 0.1 M bicarbonate electrolyte at neutral pH conditions. Optimally deposited Ni-Ci successfully catalyzed the photoelectrochemical water oxidation of W-doped BiVO4 photoelectrodes under benign pH conditions as evidenced by an enhanced photocurrent during photocurrent–potential characterizations. Efficient charge-transfer at the electrode–electrolyte interface in the presence of the Ni-Ci catalyst improved the kinetics of the W-doped BiVO4 photoanodes. The W-doped BiVO4 photoanodes integrated with a Ni-Ci oxygen evolution catalyst exhibited a large cathodic shift (∼371 mV) in the onset potential for water oxidation and maintained a stable photocurrent.

Sensitization of TiO2 nanotube array photoelectrodes with MnxCdySe

The photoanode obtained by the deposition of MnxCdySe nanocrystals onto TiO2 nanotube arrays using a successive ionic layer adsorption and reaction technique realized a significant improvement in the charge transport and current generation compared with a pristine TiO2 nanotube based anode. The concentration of manganese was determined to be 10% of the concentration of cadmium, and thus x = 0.1y. The widening of absorption spectra and the magnitude of photocurrent density were found to be significantly affected with a variation in the number of SILAR cycles and the annealing temperature. A stable photocurrent density of ∼8 mA cm−2 under AM 1.5 illumination (1 sun) was achieved for MnxCdySe nanocrystals-embedded TiO2 nanotube arrays heterostructure based photoelectrodes prepared through 9 cycles of SILAR deposition, followed by annealing at 400 °C under a nitrogen atmosphere. The results obtained suggest the versatility of the MnxCdySe-sensitized TiO2 nanotube matrix as an efficient electrode for photovoltaic applications.

Effect of quinone additives on the performance of electrolytes for vanadium redox flow Batteries

Anthraquinone-2, 6-disulfonic acid (AQDS) was added to the electrolyte of a vanadium redox flow battery (VRFB) with the goal of enhancing its performance. This study utilized carbon paper electrodes and a Nafion 117 ion exchange membrane for the membrane-electrode assembly. The cycling performance was investigated over multiple charge and discharge cycles. The addition of AQDS was found to increase capacity efficiency by an average of 7.6% over the control VRFB containing no AQDS, while decreasing the overall cycle duration by ~18%. It is thus reported that the addition of AQDS to a VRFB electrolyte has the potential to inexpensively increase the activity and capacity.Graphical Abstract