Design of PtRu alloy/reduced graphene oxide nanohybrid counter electrodes for highly efficient dye-sensitized solar cells

Self-Assembly Synthesis of the MoS2/PtCo Alloy Counter Electrodes for High-Efficiency and Stable Low-Cost Dye-Sensitized Solar Cells

In this work, MoS₂ microspheres/PtCo-alloy nanoparticles (MoS₂/PtCo-alloy NPs) were composited via a novel and facile process which MoS₂ is functionalized by poly (N-vinyl-2-pyrrolidone) (PVP) and self-assembled with PtCo-alloy NPs. This new composite shows excellent electrocatalytic activity and great potential for dye-sensitized solar cells (DSSCs) as a counter electrode (CE) material. Benefiting from heterostructure and synergistic effects, the MoS₂/PtCo-alloy NPs exhibit high electrocatalytic activity, low charge-transfer resistance and stability in the cyclic voltammetry (CV) and electrochemical impedance spectroscopy (EIS) test. Meanwhile, a high power-conversion efficiency (PCE) of 8.46% is achieved in DSSCs with MoS₂/PtCo-alloy NP CEs, which are comparable to traditional Pt CEs (8.45%). This novel composite provides a new high-performance, stable and cheap choice for CEs in DSSCs.

Optimizing graphene content in a NiSe/graphene nanohybrid counter electrode to enhance the photovoltaic performance of dye-sensitized solar cells

Nickel selenide (NiSe) nanoparticles were grown on graphene nanosheets (GN) with different mass ratios to obtain their corresponding NiSe/GNx (x = 0.25 to 1.00) nanohybrids by a facile in situ hydrothermal process to integrate the advantages of the high specific surface area of graphene and the homogeneously immobilized catalytic sites of NiSe. The nanohybrid with a mass ratio of 1 : 0.50 (i.e., NiSe/GN0.50) exhibited higher electrocatalytic activity and electrolyte diffusion. Thus, NiSe/GN0.50 exhibited an improved photo-conversion efficiency (PCE) of 12% (η = 8.62%) compared to a standard Pt (η = 7.68%)-based dye-sensitized solar cell (DSSC). This improved PCE mainly originated from the catalytic ability of NiSe and the multiple interfacial electron transfer pathways of graphene, resulting in enhanced charge transfer and fast tri-iodide reduction kinetics at the counter electrode/electrolyte interface. The results obtained from the cyclic voltammetry (CV), electrochemical AC-impedance (EIS) and Tafel polarization studies validated the synergistic effects of NiSe and GN and the high potential of this nanohybrid as an efficient counter electrode (CE) for DSSCs.

Synergistically Enhanced Electrochemical Performance of Ni3S4-PtX (X = Fe, Ni) Heteronanorods as Heterogeneous Catalysts in Dye-Sensitized Solar Cells

Platinum (Pt)-based alloys are considerably promising electrocatalysts for the reduction of I^-/I₃^- and Co²⁺/Co³⁺ redox couples in dye-sensitized solar cells (DSSCs). However, it is still challenging to minimize the dosage of Pt to achieve comparable or even higher catalytic efficiency. Here, by taking full advantages of the Mott-Schottky (M-S) effect at the metal-semiconductor interface, we successfully strategize a low-Pt-based M-S catalyst with enhanced electrocatalytic performance and stability for the large-scale application of DSSCs. The optimized M-S electrocatalyst of Ni₃S₄-Pt₂X₁ (X = Fe, Ni) heteronanorods is constructed by rationally controlling the ratio of Pt to transition metal in the hybrids. It was found that the electrons transferred from Ni₃S₄ to Pt₂X₁ at their interface under the Mott-Schottky effect result in the concentration of electrons onto Pt₂X₁ domains, which subsequently accelerates the regeneration of both I^-/I₃^- and Co²⁺/Co³⁺ redox shuttles in DSSCs. As a result, the DSSC with Ni₃S₄-Pt₂Fe₁ manifests an impressive power conversion efficiency (PCE) of 8.79% and 5.56% for iodine and cobalt-based electrolyte under AM1.5G illumination, respectively. These PCEs are obviously superior over those with Ni₃S₄-Pt, PtFe, Ni₃S₄, and pristine Pt electrodes. The strategy reported here is able to be further expanded to fabricate other low-Pt-alloyed M-S catalysts for wider applications in the fields of photocatalysis, water splitting, and heterojunction solar cells.

Utility of Pt in PtNi alloy counter electrodes as a new avenue for cost effective and highly efficient liquid junction photovoltaic devices

This study presents the synthesis of PtNi alloys with different volume ratios of Pt and Ni precursors in mixture solutions using dry plasma reduction under atmospheric pressure and low temperature. The developed materials are applied as efficient counter electrodes (CEs) in dye-sensitized solar cells (DSCs). The investigation of the Pt utility in PtNi alloys for electrocatalytic activity, and cost effective and highly efficient DSCs are also investigated. Compared with the reference electrodes (Pt and Ni CEs), the developed PtNi alloy CEs exhibit better reversibility as indicated by the peak-to-peak separation and better catalytic activity for the regeneration of iodide ions from triiodide ions. Thus, the DSC with the developed PtNi CEs provides higher efficiency than that of the device fabricated with the reference electrodes.