Highly catalytic nickel sulfide counter electrode for dye-sensitized solar cells

Porous TiO2/Co9S8 core-branch nanosheet arrays with high electrocatalytic activity for a hydrogen evolution reaction

Exploring new non-noble metallic catalysts with highly efficient and stable catalytic performance toward a hydrogen evolution reaction (HER) is a major requirement in the field of electrochemical water splitting. In this study, we report a facile strategy to synthesize a three-dimensional (3D) porous TiO₂/Co₉S₈ core-branch nanosheet arrays on Ni foam with superior HER catalytic activity. The hierarchically 3D porous architecture not only provides rich active sites, but also enables fast electron transport and easy electrolyte permeation. Consequently, the TiO₂/Co₉S₈ core-branch nanosheet arrays achieve a remarkably low overpotential of 150 mV at 10 mA cm^-2, small Tafel slope of 71 mV Dec^-1 and outstanding long-term stability for the HER reaction. The elaborate design should provide a new strategy to controllably synthesize porous and rational nanostructured materials as a prominent electrocatalyst for water splitting applications.

Metal Sulphides and Their Carbon Supported Composites as Platinum-Free Counter Electrodes in Dye-Sensitized Solar Cells: A Review

Energy sufficiency is a critical requirement for the economic prosperity of modern countries. Efficient harnessing of solar energy using technologies such as the dye-sensitized solar cell could solve the energy problem which persistently plagues developing countries. Despite having a simple operational procedure and modest power conversion efficiency of 13.8%, the dye-sensitized solar cell consists of an expensive platinum counter electrode which makes commercial success futile. Thus, this review intends to establish the progress researchers have attained in the development of sulphide based counter electrodes as alternatives to platinum, thereby lowering cost of production. Metallic sulphides are good electrocatalysts and cheap, hence, they possess the necessary requirements for effective functional counter electrodes. Furthermore, ternary metallic sulphides are known to exhibit higher efficiencies stemming from the synergistic effect produced by the co-existence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability. Incorporation of metallic sulphides with carbon materials, which are exceptional electrical conductors, could potentially produce more efficient counter electrodes. In that regard, this review seeks to establish the effect recently developed composite counter electrodes comprising metallic sulphides and carbon-based materials have induced on the functionality of the counter electrode (CE).

A Review on the Advancement of Ternary Alloy Counter Electrodes for Use in Dye-Sensitised Solar Cells

A dye-sensitised solar cell (DSSC) counter electrode (CE) plays a vital role in catalysing the conversion of triiodide ( I 3 − ) to iodide ions ( I − ), thereby ensuring the completion of the repetitive cycle of electricity generation. The platinum CE, despite being the standard counter electrode in DSSCs, has drawbacks of platinum’s rarity and high cost. Platinum is an excellent redox catalyst, and consequently, it is the most sought-after metal for catalytic conversions. The huge demand for platinum in the automotive industry for vehicular catalytic converters, the pharmaceutical industry, and in oil refining, as well as other industries, has driven its price to unprecedented levels. The prohibitive price of platinum has caused newer thin film technologies, such as the DSSC which depends on the platinum CE, to be cost-ineffective, thus meaning they cannot compete with the better-established silicon-based solar cells. These problems have stagnated the development of the DSSC, which in turn has dampened larger commercialisation prospects for this thin film technology. With this in mind, this review paper focuses on recent progress in the research and development of alternative cost-effective materials to replace Pt-based CEs. Ternary alloys are amongst the possible alternatives that have been explored, yielding varied results. Alloys, especially ternary sulphides, selenides, and oxides, are attractive as alternatives as they are cheap and are easily fabricated. Ternary alloys also have a synergistic effect produced by the coexistence of two metal ions in a crystal structure, which is believed to induce greater catalytic capability, thus making them ideal cost-effective materials to replace the Pt CE in DSSCs. This review intends to highlight the performance of ternary alloy counter electrodes through the analysis of charge transfer resistance and power conversion efficiencies. Focus is also given to the restrictions and impediments to the attainment of higher power conversion efficiency in alternative CEs. The advances in fabrication of simple ternary alloys, as well as more advanced hierarchical nanostructured counter electrodes, are discussed here in detail. Results obtained to date indicate that the efficiencies of ternary alloy counter electrodes are still below that of the platinum counter electrode, and hence more research is required to enhance their efficiencies.

Microwave-assisted synthesis of a graphene–Bi8La10O27 nanocomposite as an efficient catalytic counter electrode for dye-sensitized solar cells

A graphene–Bi₈La₁₀O₂₇ nanocomposite (GBL) was successfully synthesized by a facile microwave-assisted method, and applied as a counter electrode for efficient dye-sensitized solar cells.

The synthesis and characterization of lead sulfide with cube-like structure as a counter electrode in the presence of urea using a hydrothermal method

PbS counter electrodes at different concentrations of urea.