Synergistic effect of Ni and Fe in Fe-doped NiS2 counter electrode for dye-sensitized solar cells: Experimental and DFT studies

Iron-doping and facet engineering of NiSe octahedron for synergistically enhanced triiodide reduction activity in photovoltaics

Reasonable design of cost-effective counter electrode (CE) catalysts for triiodide (I3-) reduction reaction (IRR) by simultaneously combining heteroatom doping and facet engineering is highly desired in iodine-based dye-sensitized solar cells (DSSCs), but really challenging. Herein, the density function theory (DFT) calculations were first conducted to demonstrate that the Fe-doped NiSe (111) showed an appropriate adsorption energy for I3-, increased number of metal active sites, reinforced charge-transfer ability, and strong interaction between 3d states of metal sites and 5p state of I1 atoms in I3-, compared to NiSe (111). Based on this finding, the well-defined Fe-NiSe octahedron with exposed (111) plane (marked as Fe-NiSe (111)) and NiSe octahedron with the same exposed plane (named as NiSe (111)) are controllably synthesized. When the as-prepared Fe-NiSe (111) and NiSe (111) worked as CE catalysts, Fe-NiSe (111) exhibits improved electrochemical performance with higher power conversion efficiency (PCE) than NiSe (111), providing new opportunity to replace precious Pt for DSSCs.

Insight into the Fe atom-FeS cluster synergistic catalysis mechanism for the oxygen evolution reaction in NiS2-based electrocatalysts

The development of highly active oxygen evolution reaction (OER) catalysts with fast kinetics is crucial for the advancement of clean energy and fuel conversion to achieve a sustainable energy future. Recently, the synergistic effect of single-atom doping and multicomponent clusters has been demonstrated to significantly improve the catalytic activity of materials. However, such synergistic effects involving multi-electron and proton transfer processes are quite complex and many crucial mechanistic details need be well comprehended. We ingeniously propose a catalyst, (Fed-FeSc)@NiS2 (d stands for doping and c stands for clustering), with Fe and FeS acting synergistically on a NiS2 substrate. Specifically, fully dynamic monitoring of multiple active sites at the (Fed-FeSc)@NiS2 interface using metadynamics is innovatively performed. The results show that the rate determining step value at the overpotential of 1.23 V for the synergistic (Fed-FeSc)@NiS2 is 1.55 V, decreased by 6.67% and 35.29% compared to those of the independently acting single-atom doping and multi-clusters. The unique synergistic structure dramatically increases the d-band centre of the Fe site (-1.45 eV), endowing (Fed-FeSc)@NiS2 with more activity than conventional commercial Ir-C catalysts. This study provides insights into the synergistic effects of single-atom doping and multi-component clusters, leading to exploratory inspiration for the design of highly efficient OER catalysts.

Emergence of Ni-Based Chalcogenides (S and Se) for Clean Energy Conversion and Storage

Nickel chalcogenide (S and Se) based nanostructures intrigued scientists for some time as materials for energy conversion and storage systems. Interest in these materials is due to their good electrochemical stability, eco-friendly nature, and low cost. The present review compiles recent progress in the area of nickel-(S and Se)-based materials by providing a comprehensive summary of their structural and chemical features and performance. Improving properties of the materials, such as electrical conductivity and surface characteristics (surface area and morphology), through strategies like nano-structuring and hybridization, are systematically discussed. The interaction of the materials with electrolytes, other electro-active materials, and inactive components are analyzed to understand their effects on the performance of energy conversion and storage devices. Finally, outstanding challenges and possible solutions are briefly presented with some perspectives toward the future development of these materials for energy-oriented devices with high performance.