Nickel iron layered double hydroxide (LDH) with low cost and high catalytic activity in oxygen evolution reaction (OER) has attracted tremendous research interests. In this work, we report a NiS 2 /FeS 2 -decorated Ni-Fe-LDH catalyst (Ni-Fe-LDH/Li 2 S 8 -140) synthesized through a sulfidation treatment of Ni-Fe-LDH. The lithium polysulfide (Li 2 S x , x = 4, 6, 8) was employed as the sulfur source to treat the Ni-Fe-LDH for the first time. The NiS 2 and FeS 2 in the obtained Ni-Fe-LDH/Li 2 S 8 -140 can adjust the valence state of the Ni and Fe, increase the amount of oxygen vacancies (Vo) and improve the OER kinetics. The Ni-Fe-LDH/Li 2 S 8 -140 shows an overpotential of 246 mV at 10 mA cm −2 in alkaline electrolytes with a low Tafel slope of 39.89 mV dec −1 . The Ni-Fe-LDH/Li 2 S 8 -140 can deliver a constant potential without large variation for over 165 h at 20 mA cm −2 . It is interesting that the Ni-Fe-LDH/Li 2 S 8 -140 transformed from aggregated nanosheets to long nanowires after duration test. However, the Ni-Fe-LDH still remains the particle morphology after duration test. This structure evolution possibly induced by the NiS 2 and FeS 2 which may facilitate the charge transfer and benefit the electrolyte penetration can explain the higher stability of Ni-Fe-LDH/Li 2 S 8 -140 than that of Ni-Fe-LDH. Besides, the Ni-Fe-LDH/Li 2 S 8 -140 was also employed as the anode catalyst for a two-electrode electrolyzer which maintains an output voltage of ca. 1.8 V for over 40 h under the continuous current density of 50 mA cm −2 .
Senyang Wang,Jie Sun,Zixin Wang,Qian Zhang,Rao Fan,Wenming Zhang,Ling Li
NiS 2 -FeS 2 composite material is uniformly coated on CNFs by a one-step hydrothermal method with carbon nanofibers (CNFs) prepared by the electrostatic spinning method. A composite NiS 2 -FeS 2 /CNFs with Ti-mesh substrate counter electrode (NiS 2 -FeS 2 /CNFs CE) is prepared by scraping and coating method on a metal titanium mesh and applied to quantum dot sensitized solar cells (QDSSCs). The photoelectric power conversion efficiency of QDSSCs assembled on NiS 2 -FeS 2 /CNFs electrode substrate is 9.85%, which is much higher than that of traditional Cu 2 S/brass (7.85%). The exceptional achievement can be attributed to the superb amalgamation of the Ti-mesh's excellent electrical conductivity and the NiS 2 -FeS 2 /CNFs nanostructure's high and stable catalytic activity. The co-loading of NiS 2 and FeS 2 reduces the particle size of the composite, enhancing the specific surface area of the counter electrode. It provides abundant catalytic active sites for QDSSCs. The experimental results show that NiS 2 -FeS 2 is expected to be a competitive and efficient QDSSCs CE material.
Due to the heterogeneous and complex tumor microenvironment (TME), it remains challenging to effectively treat solid tumors with monotherapy. The development of a versatile nanomaterial strategy for synergistic chemodynamic/photodynamic/photothermal therapies has the potential to overcome this challenge. Herein, we designed and synthesized NiS 2 /FeS 2 hybrid nanoparticles (NiS 2 /FeS 2 NPs), which are further modified with polyvinyl pyrrolidone (PVP) to improve their biocompatibility. PVP-NiS 2 /FeS 2 NPs exhibit synergistic activities of chemodynamic therapy (CDT), photodynamic therapy (PDT), and photothermal therapy (PTT) with multimodal imaging capabilities. With the presence of Fe 2+ /Fe 3+ and Ni 2+ /Ni 3+ redox couples, the PVP-NiS 2 /FeS 2 NPs exhibit GSH peroxidase-like reactivity and trigger Fenton reaction, leading to robust ·OH generation and pyroptosis/ferroptosis after near infared irradiation (NIR). In response to the PVP-NiS 2 /FeS 2 NPs and PVP-NiS 2 /FeS 2 NPs + NIR treatment, the breast tumors formed in the syngeneic BABL/c mice were eliminated and their metastases suppressed by inhibiting the EMT pathway. Consistent with the apparent involvement of these programmed cell death pathways in activating tumor immunity, we demonstrate that PVP-NiS 2 /FeS 2 NPs + NIR can eliminate metastatic tumors in an immune system dependent manner. Therefore, PVP-NiS 2 /FeS 2 NPs represent a promising strategy to treat metastatic breast cancer.
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