Highly electrocatalytic activity of RuO₂ nanocrystals for triiodide reduction in dye-sensitized solar cells

Designing Multifunctional Co and Fe Co-Doped MoS2 Nanocube Electrodes for Dye-Sensitized Solar Cells, Perovskite Solar Cells, and a Supercapacitor

In the present study, three types of specific solid, core-shell, and hollow structured cobalt and iron co-doped MoS2 nanocubes (denoted as s-Co-Fe-MoS x , c-Co-Fe-MoS x , and h-Co-Fe-MoS x ) are controllably synthesized for the first time by regulating the reactant mass ratios. The prepared Co-Fe-MoS x nanocubes can function as a counter electrode in dye-sensitized and perovskite solar cells (DSCs and PSCs) and a working electrode in a supercapacitor. In the DSC system, the c-Co-Fe-MoS x nanocubes exhibit the maximum catalytic activity to the Co3+/2+ redox couple regeneration, and the device achieves a power conversion efficiency (PCE) of 8.69%, significantly higher than the devices using s-Co-Fe-MoS x (6.61%) and h-Co-Fe-MoS x (7.63%) counter electrodes. Similarly, all of the prepared Co-Fe-MoS x nanocubes show decent activity in PSCs and the device using the c-Co-Fe-MoS x counter electrode achieves the highest PCE of 6.88%. It is worth noting that, as the supercapacitor working electrode, the h-Co-Fe-MoS x exhibits a specific capacitance of 85.4 F g-1, significantly higher than the parallel values achieved by the s-Co-Fe-MoS x and c-Co-Fe-MoS x electrodes under identical conditions.

PVDF HFP_RuO2 Nanocomposite Aerogels Produced by Supercritical Drying for Electrochemical Oxidation of Model Tannery Wastewaters

A supercritical CO₂ drying process was used to prepare an innovative nanocomposite, formed by a poly(vinylidene fluoride-co-hexafluoropropylene) (PVDF HFP) aerogel loaded with RuO₂ nanoparticles. The produced nanocomposites, at 10% and 60% w/w of RuO₂, were tested for the electrochemical oxidation of model tannery wastewaters. The effect of the electrochemical oxidation parameters, like pH, temperature, and current density, on tannic acid, intermediates, and chemical oxygen demand (COD) removal, was investigated. In particular, the electrolysis of a simulated real tannery wastewater, using PVDF HFP_RuO₂ 60, was optimized working at pH 10, 40 °C, and setting the current density at 600 A/m². Operating in this way, surfactants, sulfides, and tannins oxidation was achieved in about 2.5 h, ammonium nitrogen oxidation in 3 h, and COD removal in 5 h. When chloride-containing solutions were tested, the purification was due to indirect electrolysis, related to surface redox reactions generating active chlorine. Moreover, sulfide ions were converted into sulfates and ammonium nitrogen in gaseous N₂.

WB crystals with oxidized surface as counter electrode in dye-sensitized solar cells

Tungsten boride (WB) crystals, whose surface tends to be oxidized when exposed to air, were demonstrated to have a comparable activity to platinum as counter electrode material in dye-sensitized solar cells. The synergistic effect of both catalytically active surface layer WO_x and electronically conductive internal WB is considered to be responsible for the high activity of the WB crystals.

Counter electrodes in dye-sensitized solar cells

This article panoramically reviews the counter electrodes in dye-sensitized solar cells, which is of great significance for the development of photovoltaic and photoelectric devices.

Penternary chalcogenides nanocrystals as catalytic materials for efficient counter electrodes in dye-synthesized solar cells

The penternary chalcogenides Cu₂CoSn(SeS)₄ and Cu₂ZnSn(SeS)₄ were successfully synthesized by hot-injection method, and employed as a catalytic materials for efficient counter electrodes in dye-synthesized solar cells (DSSCs). The structural, compositional, morphological and optical properties of these pentenary semiconductors were characterized by X-ray diffraction (XRD), Raman spectroscopy, transmission electron microscopy (TEM), energy-dispersive spectrometer (EDS) and ultraviolet-visible (UV–Vis) spectroscopy. The Cu₂CoSn(SeS)₄ and Cu₂ZnSn(SeS)₄ nanocrystals had a single crystalline, kesterite phase, adequate stoichiometric ratio, 18–25 nm particle sizes which are forming nanospheres, and band gap energy of 1.18 and 1.45 eV, respectively. Furthermore, the electrochemical impedance spectroscopy and cyclic voltammograms indicated that Cu₂CoSn(SeS)₄ nanocrystals as counter electrodes exhibited better electrocatalytic activity for the reduction of iodine/iodide electrolyte than that of Cu₂ZnSn(SeS)₄ nanocrystals and conventional platinum (Pt). The photovoltaic results demonstrated that DSSC with a Cu₂CoSn(SeS)₄ nanocrystals-based counter electrode achieved the best efficiency of 6.47%, which is higher than the same photoanode employing a Cu₂ZnSn(SeS)₄ nanocrystals (3.18%) and Pt (5.41%) counter electrodes. These promising results highlight the potential application of penternary chalcogen Cu₂CoSn(SeS)₄ nanocrystals in low-cost, high-efficiency, Pt-free DSSCs.

The role of Mott-Schottky heterojunctions in Ag-Ag8SnS6 as counter electrodes in dye-sensitized solar cells

Well-defined uniform pyramidal Ag-Ag8SnS6 heterodimers are prepared via a one-pot method. A plausible formation mechanism for the unique structures based on a seed-growth process and an etching effect due to oleylamine is proposed. The formed metal-semiconductor Mott-Schottky heterojunction promotes electron transfer from semiconducting Ag8 SnS6 to metallic Ag, which catalyzes the reduction of I3 (-) to I(-). When used as counter electrode in dye-sensitized solar cells, the heterodimers show comparable performance to platinum.

Identifying the distinct features of geometric structures for hole trapping to generate radicals on rutile TiO2(110) in photooxidation using density functional theory calculations with hybrid functional

Using density functional theory calculations with HSE 06 functional, we obtained the structures of spin-polarized radicals on rutile TiO₂(110), which is crucial to understand the photooxidation at the atomic level, and furthermore the thermodynamic stability of the radicals and their promotion effect on water photooxidation are also investigated.

Ruthenium based nanostructures driven by morphological controls as efficient counter electrodes for dye-sensitized solar cells

We introduce a facile approach to use ruthenium dioxide (RuO₂) and ruthenium (Ru) nanostructures as effective counter electrodes instead of using platinum (Pt) for dye-sensitized solar cells (DSSCs).