scholarly journals Synthesis, Characterization and Optimization of Hydrothermally Fabricated Binary Palladium Alloys PdNix for Use as Counter Electrode Catalysts in Dye Sensitized Solar Cells

Materials ◽  
2019 ◽  
Vol 12 (19) ◽  
pp. 3116
Author(s):  
Nyengerai Zingwe ◽  
Edson Meyer ◽  
Johannes Mbese

The hydrothermal synthesis, characterization and optimization of binary palladium alloys PdNix is hereby presented in this work. Comparison of the reduction capability of the developed PdNix alloys intended for use as alternative counter electrode catalysts in dye sensitized solar cells was made relative to the standard platinum counter electrode catalyst as well as the carbon supported PdNi-rGO sample. Optimization was accomplished through varying the molar ratio of the reagents. The unsupported PdNi3 sample produced the highest catalytic efficiency with reduction current density, peak to peak potential difference and charge transfer resistance of 35 mA cm−2, 0.15 mV and 0.47 Ω respectively. Obtained results show that the unsupported PdNi3 alloy was catalytically more effective than the platinum and PdNi-rGO thus could be a viable replacement in dye sensitized solar cell counter electrodes.

Author(s):  
Robert A. Sayer ◽  
Stephen L. Hodson ◽  
Timothy S. Fisher

Dye sensitized solar cells (DSSCs) offer many advantages in comparison to their Si-based counterparts, including lower cost of raw materials, faster manufacturing time, and the ability to be integrated with flexible substrates. Although many advances have been made in DSSC fabrication over recent years, their efficiency remains lower than commercially available Si photovoltaic cells. Here we report improved efficiency of TiO2/anthocyanin dye solar cell using aligned arrays of carbon nanotubes (CNTs) as a counter electrode. Dense vertically oriented CNT arrays are grown directly on the counter electrode using microwave plasma chemical vapor deposition and a tri-layer (Ti/Al/Fe) catalyst. The resulting arrays are 30 micrometers in height and have a number density of approximately five hundred million per square millimeter. By directly growing the CNTs on the counter electrode substrate, electrical interface conductance is enhanced. The performance of both as-grown and N-doped (using a nitrogen plasma) CNT arrays is reported. The fabricated DSSCs are tested under AM1.5 light. Increased short circuit current is observed in comparison to graphite and Pt counter electrodes. We attribute this improvement to the large surface area created by the 3D structure of the arrays in comparison to the planar geometry of the graphite and Pt electrodes as well as the excellent electrical properties of the CNTs.


Metals ◽  
2019 ◽  
Vol 9 (7) ◽  
pp. 796
Author(s):  
Edson Meyer ◽  
Raymond Taziwa ◽  
Dorcas Mutukwa ◽  
Nyengerai Zingwe

This article details the development and characterization of binary palladium alloys synthesized via a hydrothermal process. Palladium alloys, being good redox catalysts, could potentially replace platinum in many applications such as in dye sensitized solar cells, capacitors and vehicular catalytic converters where platinum is vital for maximum productivity. A good replacement should be cheap, readily available and be able to offer comparable catalytic activity to that of platinum. As such we hereby attempt to hydrothermally fabricate and characterize binary palladium alloys PdNi and PdCo that could be ideal replacements for platinum. XRD analysis of the as-synthesized binary alloys revealed the existence of only palladium peaks at 2θ values of 40.1°, 46.7°, 68.1°, 82.1° and 86.6°, indicative of the successful formation of the binary alloys. SEM micrographs revealed that both alloys consisted of spherical particles with PdCo agglomerating to an extent, whereas PdNi was widely distributed, thus it could enhance electrolyte adsorption during catalytic reduction reactions. Cyclic voltammetry analysis at 50 mV∙s−1 revealed that PdNi is more electrocatalytically active with a reduction current density of 41 mA∙cm−2 compared to 18 mA∙cm−2 for PdCo. Lower charge transfer resistance from electrochemical impedance spectroscopy confirmed the superior catalytic ability of PdNi. The two palladium alloys also produced maximum specific capacitances of 68 and 27 F∙g−1 for PdNi and PdCo respectively. Analysis of the sample stability yielded coulombic efficiency retention of 98.7 and 97% for PdNi and PdCo respectively after 1000 cycles. Results obtained have shown that the palladium alloys with their low charge transfer resistance could be ideal replacements for platinum in dye sensitized solar cells. Modest specific capacitance for PdNi illustrates its potential as an electrode catalyst in capacitors.


2015 ◽  
Vol 3 (45) ◽  
pp. 23028-23034 ◽  
Author(s):  
Ranran Zhou ◽  
Wenxi Guo ◽  
Ruomeng Yu ◽  
Caofeng Pan

We present a highly flexible dye-sensitized solar cell composed of TiO2 nanotube arrays (TNARs) as the photoanode and a transparent Pt network electrode as the counter electrode (CE).


Materials ◽  
2021 ◽  
Vol 14 (21) ◽  
pp. 6563
Author(s):  
Md. Mahbubur Rahman

Novel nickel nitroprusside (NNP) nanoparticles with incorporated graphene nanoplatelets (NNP/GnP) were used for the first time as a low-cost and effective counter electrode (CE) for dye-sensitized solar cells (DSSCs). NNP was synthesized at a low-temperature (25 °C) solution process with suitable purity and crystallinity with a size range from 5 to 10 nm, as confirmed by different spectroscopic and microscopic analyses. The incorporation of an optimized amount of GnP (0.2 wt%) into the NNP significantly improved the electrocatalytic behavior for the redox reaction of iodide (I-)/tri-iodide (I3-) by decreasing the charge-transfer resistance at the CE/electrolyte interface, lower than the NNP- and GnP-CEs, and comparable to the Pt-CE. The NNP/GnP nanohybrid CE when applied in DSSC exhibited a PCE of 6.13% (under one sun illumination conditions) with the Jsc, Voc, and FF of 14.22 mA/cm2, 0.628 V, and 68.68%, respectively, while the PCE of the reference Pt-CE-based DSSC was 6.37% (Jsc = 14.47 mA/cm2, Voc = 0.635 V, and FF = 69.20%). The low cost of the NNP/GnP hybrid CE with comparable photovoltaic performance to Pt-CE can be potentially exploited as a suitable replacement of Pt-CE in DSSCs.


Author(s):  
Lu Zhang ◽  
Wei-Chao Chen ◽  
Ting Wang ◽  
Yun-Jiang Li ◽  
Chun-Hui Ma ◽  
...  

In the development of bifacial dye-sensitized solar cells (DSSCs), the exploration of cost-benefit transparent counter electrode is a permanent target. Herein, we put forward a simple one-step strategy to load...


RSC Advances ◽  
2014 ◽  
Vol 4 (79) ◽  
pp. 42087-42091 ◽  
Author(s):  
Lijuan Sun ◽  
Yu Bai ◽  
Kening Sun

Organic molecule controlled synthesis of three-dimensional rhododendra-like CoS and its application as counter electrode in DSSCs.


2010 ◽  
Vol 132 (2) ◽  
Author(s):  
Robert A. Sayer ◽  
Stephen L. Hodson ◽  
Timothy S. Fisher

Dye-sensitized solar cells (DSSCs) offer many advantages in comparison to their Si-based counterparts, including lower cost of raw materials, faster manufacturing time, and the ability to be integrated with flexible substrates. Although many advances have been made in DSSC fabrication over recent years, their efficiency remains lower than commercially available Si photovoltaic cells. Here we report improved efficiency of TiO2/anthocyanin dye solar cell using vertically aligned arrays of carbon nanotubes (CNTs) as a counter electrode. Dense vertically oriented CNT arrays are grown directly on the counter electrode using microwave plasma chemical vapor deposition and a trilayer (Ti/Al/Fe) catalyst. The resulting arrays are 30 μm in height and have a number density of approximately 5×108/mm2. By directly growing the CNTs on the counter electrode substrate, electrical interface conductance is enhanced. The performance of both as-grown and N-doped (using a nitrogen plasma) CNT arrays is reported. The fabricated DSSCs are tested under AM1.5 light. Increased short-circuit current is observed in comparison to graphite and Pt counter electrodes. We attribute this improvement to the large surface area created by the 3D structure of the arrays in comparison to the planar geometry of the graphite and Pt electrodes, as well as the excellent electrical properties of the CNTs.


2012 ◽  
Vol 512-515 ◽  
pp. 242-245 ◽  
Author(s):  
Shun Jian Xu ◽  
Yu Feng Luo ◽  
Wei Zhong ◽  
Zong Hu Xiao ◽  
Xiao Yun Liu

Hexagonal boron nitride (HBN), which has the same crystal structure as graphite, has been used as catalytic material for a counter electrode in dye-sensitized solar cells (DSCs) to investigate its potential application. X-ray diffraction (XRD) has been used to confirm the crystal structure of HBN, scanning electron microscopy (SEM) has been used to characterize the morphology of HBN film on counter electrode, and electrochemical workstation has been employed to obtain the electrochemical impedance spectroscopy (EIS) and corresponding impedance parameters. Results show that the HBN film has rough surface and porous structure with pore size of less than 1 μm. When employed the HBN counter electrode to DSCs, the conversion efficiency (η) is only about a tenth of that of graphite based DSCs. Low efficiency of HBN based DSCs is induced by high charge transfer resistance (Rct) of HBN counter electrode, which means that HBN can hardly provide catalytic activity for the reduction of the triiodide ion. Therefore, the crystal structure is not a crucial factor to select the catalytic material for a counter electrode in DSCs. Moreover, the short circuit photocurrent density (Jsc) and the open circuit voltage (Voc) of device also evidently depend on the characteristics of catalytic material.


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